U.S. Navy Aircraft History

What was the Bell Aircraft F2L?

2012-01-16T15:54:00.002-05:00

This is another one of those works-in-progress, since I don't have everything nailed down yet. However, I have enough bits and pieces to start with.

The first Bell Aircraft Navy fighter was, of course, the XFL-1. I've written a monograph on it for Steve Ginter's Naval Fighters series. It's pretty comprehensive if I do say so myself and addresses some common misconceptions about the Airabonita. It's available from Amazon and others.

Some have written that the P-59A was the F2L (more on that in a minute). The Navy History Center lists two F2Ls with BuNos, the XF2L (90060 and 90061) and the F2L-1K (91102 and 91103). The XF2L is stated to be canceled P-63s*, which sort of makes sense because those Bureau Numbers were used to contract for the L-39s, swept-wing configured P-63s. (For more on the L-39s, see http://thanlont.blogspot.com/2011/04/bell-l-39-wing-sweep-evaluation.html)

The F2L-1Ks were postwar modifications of Army P-39Qs as drones. These were flown at Cape May, New Jersey. I don't have any pictures yet. A Navy History Center list includes the crash of an F2L in 1946. I've requested a copy of the crash report. These may have been preceded by an XTDL-1 (another P-39 modification that wasn't given a Bureau Number, which would be rare but not unknown) or they may have originally designated or intended to be designated TDL, which makes more sense than F2L, since the airplanes were to be used operationally as target drones, not fighters. Although some references list as many as seven were created, it appears more likely that only two P-39s were converted and the remainder cancelled.

Back to the P-59A. In 1941, when the Army asked Bell to design and develop its first jet airplane, Bell had a contract with the Army for the XP-59. It was to be powered by a P&W R-2800 driving a contrarotating pusher propeller. It had reached the mockup stage and was also being proposed to the Navy.

Photo provided by Niagara Aerospace Museum

Note the inlet in the nose for cooling air to the R-2800 and the cannon or machine gun barrels at the front of the tail booms. The stand reads Proposed Navy VF Fighter Spec. SD 112.18. F2L does not appear, although of course this would have been its designation if the Navy had contracted for it.

Some of the mockup pictures include the words "Proposed Navy Fighter" and in others, like this one, Navy Fighter has been carefully erased.

Photo provided by Niagara Aerospace Museum

Lest one think that it was pictures of the mockup of the Army airplane with captions added for the Navy's benefit, a picture of the mockup's cockpit shows the presence of a chart board, which was a Navy requirement.

When the Army contracted with Bell for a jet airplane in December 1941, it did so with the designation XP-59A, presumably using the same contract as the now unwanted XP-59. It was, of course, a completely different configuration. The objective was to add a layer of secrecy to the program.

The Navy obtained two YP-59As and three P-59Bs for its evaluation and pilot familiarization. This is the first Navy YP-59A, as received in late 1943.

It was given BuNo 63960. It was subsequently repainted in the Navy tri-color paint scheme. Note that it does not have guns.

At some point after that, it was brought up to production P-59 standard (square wing tips, ventral fin, etc.) and repainted again, this time with yellow wings for some reason.

Tom Doll collection via Rich Dann

Note, however, that the designation marked on it is "YP59-A".

One theory behind a Navy designation of YF2L for its YP-59A is the existence of the F2L-1Ks to provide misdirection. This almost certainly wasn't the case given that the Navy's drone P-39 program was later in time. Somewhat more plausible is that the YF2L designation was a subterfuge equivalent to the Army's use of the P-59A designation since the XP-59 had been proposed to the Navy. If so, the Navy doesn't appear to have used it in any documents found to date. Its P-59s are always referred to as P-59s.

The Navy also kept pretty good track of assigned designations so it seems likely that the post-war contract for P-39 drones would have used the designation F3L if F2L had been used in the early 1940s for the Airacomet, unless the designation was not a subterfuge but the program considered so secret that the designation was never revealed...

*Bell reportedly proposed a carrier-based P-63. It's conceivable that these Bureau Numbers, originally assigned to an RY-3 Privateer contract, might have intended for that evaluation before they were used for the L-39s. However, they seem to be too high for that possibility.

Portable Air-Start Cart

2012-01-07T12:50:00.000-05:00

In the early days of jet airplanes, there weren't very many at civil airports or some military fields either. This wasn't a problem when jet engines were started with electric motors like piston engines. However, electric starters were heavy so they were replaced on many jet engines in the late 1940s by a small turbine that required high pressure/volume air that spun the engine up to start rpm. This meant landing at an airport without an air-start cart meant being stranded until one could be located and made available.

The Navy's solution was a start unit that could be carried as a store shaped like an external fuel tank. It incorporated a amall AiResearch jet engine, designed as an APU (Auxiliary Power Unit), to provide the air. Panels were opened or removed to expose the APU inlet and exhaust, the attachment of the air hose, and the control panel.

Also stowed within the cart were the hose, wheels, and a handle to pull it along like child's wagon.

The pod was often present at airshows at civil airports, carried there and back on a standard external stores pylon.

It remained useful to the Blue Angels up through the retirement of their A-4s powered by the J52 with an impingement starter:

Also see http://a4skyhawk.org/2c/a4start.htm

Project Steam

2012-01-01T13:06:00.002-05:00

The superiority of airplanes powered by jet engines was bad news for the carrier navy. Jets required a lot of fuel, which meant bigger and heavier airplanes, and didn't provide much thrust at low speeds. Both dictated the need for a more powerful catapult. Unfortunately, the hydraulic catapult was pretty much at the top end of its capability. The U.S. Navy had evaluated a German design for a hydrogen peroxide powered catapult (it was used to launch the V-1 pulse-jet surface-to-surface missile) using both hydrogen peroxide and steam but dropped it in favor of developing one that used gun powder. An explosive charge had been used to launch seaplanes from cruisers and battleships since 1925 and was projected to be the simpler and require less space and weight.

Just in time, Colin Mitchell perfected the steam catapult. See http://thanlont.blogspot.com/2011/03/steam-catapult-development.html. After a demonstration, the Navy immediately bought five, one for test at the Philadelphia Navy Yard, and two each for Hancock and Ticonderoga. Hancock was completed first, recommissioned on 15 February 1954, and so it was that only a few months later, in June, she sailed out into the Pacific waters off San Diego in support of Project Steam, an at-sea evaluation of its new catapults.

There was no question that the steam catapult was superior in throw weight. The question was the compatibility of jet engines with the steam catapult among other operational issues. So the Navy gathered up samples of the newest versions of carrier-capable aircraft they had and launched them from Hancock, including sending a couple of F7U-3s cross country from Patuxent River.

(Photo by Maurice Duke)

Many of the test subjects, however, were from West coast squadrons, flown by fleet pilots, not NATC pilots. Although FJ-2s were assigned to the Marines and almost never deployed on aircraft carriers, this VMF-235 Fury could be considered a stand-in for the FJ-3, which was to be assigned to Navy fighter squadrons:

(Photo by Maurice Duke)

The F9F-6 was evaluated as well.

Similarly, although F3Ds only rarely deployed on aircraft carriers, this VX-4 F3D-2M carrying four Sparrow I missiles made for a relatively heavy test subject:

Propeller-driven airplanes were included in addition to the jets. An NATC Flight Test S2F (note that the catapult pendant has been tied on so as to minimize the number required and shorten the time to hook up for the next launch):

(Photo by Maurice Duke)

Other aircraft launched included the AD-5 and F2H-3/4.

And just recently, duh, I discovered that AJ Savages were also part of the trials, albeit later in the year (this picture was dated 28 September 1954):

The trials were extremely successful. One of the significant attributes of the steam catapult was that it provided acceleration for most of its stroke and there was little snatch load at the beginning of the stoke, making for a much more comfortable launch. This was particularly appreciated at night.

Grumman Comes from Behind to Win!

2011-12-24T17:01:00.007-05:00

If aerospace competitions were covered on the sports page, that would have been a headline every few years for decades. As a supplier of U.S. Navy fighters, Grumman had a penchant for starting late and then catching up or winning outright, right up until they didn't. At least Northrop kept the name on the letterhead like McDonnell did for Douglas. Unlike Boeing...

Curtiss and Boeing provided all the biplane fighters for the U.S. Navy until a few years after the fledgling Grumman company spread its wings with the FF-1 in 1931. Although both kept trying, neither got a production contract for a Navy monoplane fighter, unless you count the Boeing F-18E/F, which I choose not to.

Grumman got successive contracts for carrier-based biplane fighters up through the F3F.

Grumman was tardy about the transition to the monoplane fighter. They initially received a contract for their follow-on to the F3F as a biplane, the F4F-1, in accordance with the Navy's need for a backup to the Brewster's monoplane proposal. Grumman was subsequently allowed to change the configuration to a monoplane instead, the F4F-2, but lost the resulting fly-off to the Brewster F2A. Nevertheless, they persevered and redesigned the wings, tail, and engine installation. They then won the second round and delivered a fighter that was at least a match for the Japanese Zero early in World War II. Brewster was relegated to being a second source for Vought's Corsair.

XF4F-2

F4F -3

Grumman also lost the fighter competition that Vought won with the Corsair. Their twin-engine F5F might have come in third instead of second if the Allison V-1710 that Bell was using in their FL-1 Aerobonita had a two-stage mechanical supercharger instead of a single stage. (For much, much more, see my XFL-1 monograph) However, Grumman got a follow-on twin-engine contract for the F7F Tigercat that did go into production (and was primarily assigned to the Marine Corps) and a contract for a Wright R-2600-powered Wildcat derivative that became a direct competitor to the F4U, delayed by development and carrier-qualification problems, when re-engined with the P&W R-2800.

F5F

F7F

Design 50 Study

Grumman was not only late to jets, its D-71 wasn't selected for the second round of jet fighter development that resulted in the F2H-1, FJ-1, and F6U-1. They came in second to Douglas in the multi-engine night fighter competition but still got a contract for one. The F9F-1 was becoming an even more distant second so Grumman and the Navy changed the statement of work to a single-engine day fighter, the F9F-2/3 Panther. It was a success, but had to share the decks with the McDonnell Banshee.

D-71

F9F-5

Grumman didn't just snatch victory from the jaws of defeat with its fighters. At the end of World War II, they were developing a big propeller-driven torpedo bomber with a jet engine in the aft fuselage for extra speed during the torpedo run and withdrawal. Douglas, however, got the lion's share of the Navy's attack business with its AD Skyraider (Grumman wasn't even second: that was the Martin AM Mauler) but Grumman was able to redirect its AF to be a submarine hunter and killer.

They then repurposed a previous design for a heavily armed twin-engine torpedo bomber, the TB2F, that did not proceed past the mockup stage to be the S2F (S-2), which begat the AEW WF-2 (E-1B) and the COD TF-1 (C-1).

Grumman was also late to swept-wing jets. The BuAer class desk officer at the time tried to get them to design the Panther with a swept wing but settled for a straight-wing development and a swept-wing study. That spiraled out of control when he left and resulted in a fiasco, the variable-sweep-wing F10F Jaguar, which was cancelled after a year of flight test disappointments of the only one completed.

However, when the Navy became so desperate for swept-wing performance that they ordered a carrier-based modification of the Air Force's F-86 Sabre, Grumman did what they should have done in the first place: took a Panther fuselage off the production line and put swept wings and a horizontal tail on it.

The resulting F9F-6 Cougar was more carrier suitable than the North American's FJ-2 Fury, which was relegated to Marine Corps. North American put a more powerful engine in the FJ-3 Fury, creating a pretty good carrier-based, albeit short-legged, day fighter but Grumman countered by putting a new wing on the F9F-8 Cougar, which had more endurance.

Sticking with what worked and what its boss in BuAer wanted didn't always work out. The BuAer fighter class deck officer in the early 1950s led both Grumman and North American astray, asking for a simple day fighter: small, light, maneuverable, inexpensive, and subsonic, i.e. no afterburner. Both complied and got contracts without a formal competition. Grumman at least had the sense to insist on an afterburner for what became its little F11F Tiger. Vought won the formal competition with the F8U Crusader and subsequently, the lion's share of production. The North American FJ-4 got shuffled off to the Marines Corp as a fighter (the Navy bought an attack variant as the FJ-4B to provide Douglas with an incentive to be more responsive on A4D shortcomings as perceived by BuAer engineers) and the F11F wound up performing in airshows with the Blue Angels and training budding fighter pilots.

BuAer contracted with Lockheed to modify the TV-2 (T-33) to a carrier-capable jet pilot trainer, the T2V.

Grumman sold a backup plan to the Navy, a modification to the forward fuselage of the F9F-8T to be a two-seat prototype and demonstrator of an armed (two cannon were retained), carrier-capable, two-seat jet trainer. Unfortunately for Lockheed, it took more time to develop the SeaStar, in part due to the addition of boundary layer control, than Grumman did to get the F9F-8T in front of the Navy, which wound up buying only 150 T2Vs (T-1A) as opposed to 399 F9F-8Ts (TF-9J).

Grumman finally missed the boat completely with the Navy's next fighter program, a fleet air defense fighter armed with Sparrow III missiles. McDonnell caught a break when the Fighter Class Desk hijacked his AH program. It became the F4H Phantom. Grumman immediately submitted an unsolicited proposal for a similar airplane powered by two General Electric J79s but was forced to revise it to have a single engine and compete with Vought's J75-powered derivative of the F8U Crusader. It lost to Vought and then Vought lost to McDonnell.

Note: This is not the F12F. See http://thanlont.blogspot.com/2008/09/is-this-grummman-f12f.html

Grumman did get a consolation prize at Vought's expense however. Vought won the competition for the follow-on to Grumman's WF-2 (E-1B) for AEW. From Vought's patent application:

Nevertheless, the BuAer production branch chief convinced the Chief of the Bureau of Aeronautics, Rear Admiral James S. Russell, to award the contract to Grumman instead due to industrial base considerations, i.e. Grumman needed the work. The W2F became the E-2, still in production today more than 50 years later.

Grumman got back in the fighter business as a partner to General Dynamics on the F-111 program. In my opinion, the F-111B has been unjustly maligned (see my F-111B monograph) but to be fair to those who have swallowed the Navy's PR whole, the F-14 was more appropriate to the Navy's needs. Once again, Grumman made a silk purse out of the ear of a "sea pig." (I do hate that nickname but I can't resist the phrase.)

Their luck (and reportedly and more importantly their close working relationship with the Navy: see Inside the Iron Works) ran out when the Navy had to choose between derivatives of the F-14D and McDonnell Douglas F-18C/D. The Borg, er Boeing, then absorbed McDonnell Douglas and was finally back in the fighter business with the F-18E/F; Grumman had to sell itself to Northrop.

If Lockheed doesn't get its act together with the F-35C, Boeing may very well become the only U.S. manufacturer of carrier-based fighters.

For more on the development of U.S. Navy jet fighters through the F4H Phantom, see my book U.S. Naval Air Superiority.

A Brief History of Tailhook Design

2011-12-16T01:12:00.014-05:00

I have been meaning to expand on my first discussion of the tailhook (HERE). The recent problems with the F-35C's brought that topic up to first on the list. More on that after a brief history of the tailhook.

The first landing of an airplane on a U.S. Navy ship, the cruiser Pennsylvania, was accomplished by a civilian pilot, Eugene Ely, on 18 January 1911—hence 2011 being the Centennial of Naval Aviation. A temporary wooden platform about 134 feet long and 32 feet wide had been added aft of the mainmast, extending aft over the after turret and past the stern of the ship. It angled upward from the fantail, the first 14-foot section at about a 30-degree angle and the remainder, less steeply but still "uphill" so as to help slow the airplane. Two low, wooden guide rails ran fore and aft on the platform about 12 feet apart to help keep the airplane on the deck. Two low canvas screens were strung across the deck about ten feet from its forward end and a high canvas screen was hung from the mast to the forward end of the platform. These foreshadowed the barriers and barricade respectively used on axial deck carriers to protect the crew forward and hopefully the pilot in the event that the airplane overran the landing area. Canvas was also slung outboard on both sides of the forward two thirds of the landing area to keep the airplane from falling into the sea if it came off the platform.

The arresting gear consisted of 22 pairs of 50-lb sandbags, each connected by a rope and placed outboard of the guide rails, which helped hold the rope above the deck. Each pair was three feet apart going up the deck. Three steel hooks were attached to the longitudinal frame of the landing gear of Ely's Curtiss pusher. These were intended to snag the ropes, with the bags then dragging the airplane to a stop. (The weight of each bag was carefully measured to insure that they were equal in order to reduce the likelihood of a bag having more drag than its partner and pulling the airplane to the side.)

The arresting system worked exactly as planned. The heritage of today's system is clearly evident.

It took a few more years of aircraft development before the U.S. Navy was ready to operate land planes from an actual aircraft carrier. The tailhook was instrumental to the success of the enterprise and a closely held innovation.

The first arresting-gear systems incorporated longitudinal wires as well as the cross-deck pendants. These were engaged by two-pronged hooks hanging down from the spreader bar between the main landing gear wheels. The purpose was to keep the airplanes from slewing off the deck or bouncing but they soon proved to be more trouble than they were worth and discarded.

A successful tailhook design was not as easy as it might seem. The first requirement was structural: the attachment had to withstand a load two or three times greater than the weight of the airplane. Most installations were on the bottom of the aft fuselage, with the hook pivoting down from, in effect, the keel of the airplane ahead of the tail wheel. This was mechanically and structurally simple, but meant that the retarding load of the hook ran below the aircraft center of gravity, causing the nose to pitch down during the arrestment to eliminate the resulting moment. This Grumman SF-1 tailhook is typical:

"Tail rise" with a low-mounted tailhook was a problem, as in this Bell Aircraft XFL-1 arrested landing, with the prop dangerously close to pecking the deck:

Grumman moved on to a "stinger" installation, in which the tailhook extended directly aft from the end of the tail fuselage. This was more complicated mechanically and structurally, but the retardation force was acting higher on the airframe, causing less of a pitch-down moment when the hook engaged a wire.

Vought originally utilized the stinger-type tailhook on its XF4U-1 Corsair but relocated it to the tail landing gear, still somewhat higher relative to the cg than the usual installation:

A beef up proved to be in order:

The Ryan FR-1 had a piston engine in the nose and a jet engine in the tail. Access to the jet engine was provided by removal of the aft fuselage. In order to avoid high loads on the attachment of the aft fuselage, the tail hook was attached forward of that joint, probably as far forward as ever done.

Tail rise wasn't expected to be a problem because the airplane had a nose landing gear that protected the propeller. However, the length of the hook resulted in inflight engagements and its location, as would be expected, a nose-down pitching moment.

Loads on the nose wheel and landing gear attach structure proved to be excessive.

For more on the FR-1, en français, see: http://prototypes.free.fr/fr1/fr1-2.htm

Grumman continued with the stinger tailhook through its F9F series. It continued to be satisfactory, although in one early test of the Panther, the arrestment pulled the removable aft fuselage off. This is a proof load test of the F9F-5 installation.

After landing, however, the Panther/Cougar hook was not retracted but simply raised to the "stinger" position so the airplane could be taxied over the arresting wires, barriers, and barricade. It was then reloaded.

Grumman greatly simplified the mechanics and structure of the aft mounted hook in the F11F. It was stowed upside down and backwards so it simply dropped down from the extreme aft end of the fuselage.

After landing, the pilot raised it to the stinger position like the F9F's:

(The sailor was out there to pull the arresting cable off the hook if it did not fall off of its own accord.)

The hook was double-jointed so it could be reloaded after the airplane had taxied forward and parked.
This installation was innovative* but not imitated. For one thing, if when making a field landing the pilot decided after touchdown to drop the hook to engage the emergency arresting gear, it probably wouldn't rotate into position behind the aircraft.

Concerned with the nose-down pitching moment of even a stinger location of the tailhook for the F7U-1, Vought created a double-jointed installation in which the hook was attached at the top of the fuselage:

The design proved to be overly complicated and heavy (it also had a device that ejected the cross-deck pendant from the throat of the hook), so Vought reverted to a conventional belly mounting for the F7U-3. For more on the F7U-1 tail hook, click HERE.

Tail rise problems caused by low-hook attach points were dealt with by beefing up what broke, for example the F8U nose wheel.

In addition to structural and pitching moment concerns dealt with during predesign, the engineers also had to fine tune hook design and operation during development test and Navy evaluation. Hook damping was a cut and try process. Too little damping and the hook would skip, sometimes missing all the wires. Too much was hard on the aircraft structure, not to mention the deck. Hook length might also require experimentation in conjunction with damping changes. Too short a hook and long touchdowns risked missing all the wires; too long and an inflight engagement and overly hard landing might result. Trail angle was another; after problems were encountered in field and at-sea trials, the F4H tailhook operation was modified so that the trail angle decreased after main gear touchdown.

Which brings us to the F-35C. The first roll-in arrestment attempts at Lakehurst earlier this year were disappointing to say the least: zero traps in eight tries. According to the recently published Quick Look Review of the Joint Strike Fighter Program:

"Root cause analysis identified three key AHS (Arresting Hook System) design issues: (1) the aircraft geometry has a relatively short distance between the aircraft’s main landing gear tires and tailhook point (when lowered), (2) tailhook point design was overemphasized for cable shredding (n.b. the tendency for the hook point to dig into and damage the cable) features versus ability to scoop low positioned cables, and (3) tailhook hold-down damper performance is ineffective to support damping of small bounces relative to runway/deck surface profiles."

This picture provides an approximation of the height of the hook above the deck relative to the main landing gear with the oleos fully extended with the F-35C at my guess at its angle of attack on approach. Note that the hook point is not below the wheels as it is on most other carrier-based airplanes and much closer to the wheels horizontally.

Contrast this hook-point position relative to the wheels both vertically and longitudinally with that of an F-18F Super Hornet's:

My guess is that the relative shortness of the hook is related to its closeness to the wheels, since an inflight engagement of a hook located so far forward relative to the wheels would generate a greater nose-down pitching moment than a hook located farther aft. Inflight engagement incidents would be minimized by having a short hook. However, the hook point's closeness to the wheels longitudinally appears to have resulted in an unanticipated problem that can be best understood by looking at this excellent summary of what happens when the wheels tramp down the arresting wire, also know as the cross-deck pendant: http://instapinch.com/?p=456#more-456

Basically, the landing gear wheels mash down (trample is the term of art used in the report) the cross-deck pendant and it doesn't rebound high enough and quickly enough so that the current hook point (which was based on the proven F-18 design) can get under it. The proposed fixes are to revise the shape of the hook point and modify the damping of the hook so that it is less likely to skip over all the wires.

These changes will probably be sufficient so that more onerous changes to the hook installation are not required. However, it once again illustrates the degree of difficulty in achieving the desired result on the first try and the necessity to plan time for redesign and retest of even the most basic and well known requirement.

* It was, however, not the first such installation. The Brits put a tailhook on an Airacobra I to evaluate arrestment of an airplane with a nose landing gear. It pivoted from a fitting just in front of the tail post and was manually stowed upside down and backwards. I'm not sure whether this unusual installation was because of the need to find a solid piece of structure to attach the hook to or to minimize the nose-down pitch on engagement. Maybe both. Captain Eric Brown made an unauthorized deck landing with it on Pretoria Castle on 4 April 1945 at the conclusion of a series of hook-up passes to evaluate flexible-deck approaches. By his own admission, he declared an emergency without cause in order to be get permission to land aboard and make the first landing of a tricycle aircraft on a British aircraft carrier. (The U.S. Navy had already done so, one of the few times that the Brits came in second on aircraft carrier milestones.)

The hook had to be relatively long because of the tricycle landing gear (see the FR-1 example above).

Scooter! Stuff

2011-11-13T13:00:00.002-05:00

My latest book, Scooter!, has yet to get many reviews on line or in periodicals (actually only one so far, from an on-line friend) but what I really appreciate are the complimentary and congratulatory emails from individuals, particularly those who bring something more to the story.

For example, Larry Blumenthal provided the following, scanned from FDR's 1960 cruise book picture of tied-down A4D-2s with protective covers in place, including specially created GSE for the Tinkertoy:

T.J. (Jeff) Brown provided a summary assessment of the A-4 versus the A-7 for the book, but he had more to add:

There is one thing that I forgot to mention in my submission that you might include, should you ever do a reprint. The A-4F nose struts that included the nosewheel steering (NWS) feature did not hold up well under the punishment of repeated carrier landings and leaked hydraulic fluid profusely. When a strut failed, there was no indication to the pilot except his repeated pushes on the stick button were doing nothing, and this detraction with his head down in the cockpit sometimes caused late brake applications when exiting the arresting gear. This caused great concern to all who might be in charge of flight operations, namely the Air Boss and the Skipper, especially if foul-deck waveoffs resulted. The nosewheel steering was also not accurate enough to keep from sliding off the side of the "turtle back" on the catapult (that held the bridle) that the airplane had to go up and over, either, and this operation had to be done with a Blue Shirt on the deck with a nosewheel tiller bar. This was dangerous for the Blue Shirt if the a/c had an operative nosewheel steering, since if it were engaged with the tiller bar connected, it could cause anything from broken bones to his being tossed over the side. For these reasons, most A-4F squadrons (as we did in Air Wing 21) replaced the Foxtrot nose struts with Echo struts. Problem solved, and we operated as had A-4 units since time immemorial: take the trap at 100%; on the pullback, simultaneously pull the power to idle, retract the speedbrakes, raise the flaps and hit the left brake, causing the aircraft to cock to the right since it was being pulled aft by the arresting cable; then smartly taxi out of the gear, pleasing all hands.

In the Training Command, it would not have been practical to do this with the T-birds, since carrier landings were few and some of the students needed all the help they could get anyway. Instead, the LSOs just put the Fear of God into them NOT to touch the NWS while on the ship and the tiller bar was connected (hand signal: index finger placed alongside the nose, and clearly acknowledged by the pilot).

Us Old Salts endured the inconvenience of not having NWS on the beach, since it would be a major job for Maintenance to change the struts all out and back on a short turnaround, which we usually had. All this taken into account, the A-7 always had NWS, since there was no turtle-back on the nose-tow cat system, and the NWS was much more accurate and easy to steer onto the nose-tow box. This is my story and I'm stickin' to it! :-)

Jack Anderson provided more color as well from his experience:

Reading (Scooter!) brought back a lot of memories that had been dormant about flying the the first A4D-1's. We were so pleased with them after flying F7U-3s that we just enjoyed the simplicity, reliability and the performance of them. I had forgotten about the engine problems and the mandatory safety inspections. One of those occurred while we were at sea doing our first carquals.

In a clean configuration we could exceed Mach one in a 30-degree dive. It performed well up to 35,000 ft. As it passed through 40,000 ft it was getting very sensitive. I once nursed one to 49,500 ft but it took a lot of work and required a step climb from about 43,000 ft. One my squadron mates said he made it to 50,000 ft by doing the same technique. We could out dogfight anything at Cecil Field except the F8U-1. The roll rate was spectacular and the throttle response was very good. The aerodynamic slats could flip you upside down in a high-altitude dogfight especially above 40,000 ft if you pulled too hard in the turn. I don't remember too much trouble with fuel shift in the wings on the dash 1, probably because of our nuke delivery mission and the requirement for a lot of low level nav practice.

Walt Fink, another contributor to Scooter!, and a long-time acquaintance, had his memory jogged as well:

The photo of the EPI on page 63 brought back a couple memories. The little windows for fuel pressure and oil pressure were flip-flop things with two readings (when powered), NORM and OUT, or something like that. We discovered, after a couple of unnecessary aborts by some of our more senior aviators, that the oil pressure flip-flop would show OUT when in reality the oil pressure was high. Apparently the circuitry inside it just recognized the normal range and anything above or below it defaulted to OUT. Since the J-65 was built around an oil leak anyhow, that did result in a couple moments of panic and high pucker factor.

That little quirk caused the Navy to retrofit the airplanes with what we called a "nickel gauge" for direct oil pressure reading. So-called because it was the tiniest little gauge in the airplane, only about the size of a nickel.

Jim Rotramel, my go-to guy for external stores and F-111 stuff, took the time to go through the book and provide corrections and additions to the captions for pictures that I hadn't shown him before going to press:

Pg 130: Mk 81/Mk 14 Snake Eyes, not Mk 82s. The Scooter was so small that Mk 82s looked enormous on it. The key thing to look for was that you couldn't carry a fully loaded MER/TER of Mk 82s, while you could with Mk 81s.

Pg 137: Small photo is not an M117 (wrong shape/fin). Outboard appears to be Mk 82/Mk 15 SE, inboard is probably AN-M65 1,000-lb bomb. (Large photo is Mk 81/Mk 14 Snake Eyes again.)

Pg 140: Bottom photo is CBU-55 FAE, not Napalm.

Pg 141: Mk 81/Mk 14 Snake Eye

Pg 145: No "-" in M118 (or any other M series bomb, just M and the number with no space or dash).

Pg 150: the outboard pylons aren't loaded with CBU (no fins, no fuzes). They appear to be 19-tube rocket pods, probably LAU-61s, which were 10 in. longer than LAU-3s.

Pg 151: 221 has Mk 81/Mk 14Snake Eyes. 227 probably has an AGM-12E Standoff Cluster Missile loaded with BLU-62 and 63s.

Pg 169: Nearest A-4 carrying a TP Mk 82 and NTP Mk 83

Pg 175: Nice shot of a Mk 83 LGB.

Pablo Calcaterra sent me this picture of an Argentine pilot attacking HMS Glasgow on 12 May 1982. The picture was taken from the deck of HMS Brilliant and is indicative of the height of the A-4 on the run-in:

A better reproduction of Captain Carballo's and Lt Rinke's attack on Broadsword on 25 May and a painting by Carlos A. Garcia are provided here: http://thanlont.blogspot.com/2011/09/scooter.html

Douglas F6D Missileer

2011-10-25T11:49:00.000-04:00

One of the Navy's ongoing concerns is defense of its ships from attacks by aircraft and/or missiles. The Chinese anti-ship missile threat is only the latest. In the 1950s, it was long-range, high-performance missiles launched from Soviet bombers. The first solution was the Sparrow air-to-air missile carried by fighters whose development had begun in the late 1940s. The F4H Phantom was the first Navy fighter specifically designed for the mission and was also armed with the Sparrow. However, the Navy continued to fret about a combination of faster bombers and longer range air-to-surface missiles that the Phantom/Sparrow approach was not capable of adequately addressing.

The solution from operational analyses was the Missileer concept. The Operational Requirement was issued on 11 July 1955. The "fighter" would simply be a subsonic platform that loitered out on a station on the threat axis, lugging a huge, long-range radar and up to eight very long-range air-to-air missiles. The missile's range requirement necessitated that it be provided with its own radar for terminal guidance. That and fuel required range that it was a very big missile indeed. It was to be called Eagle.

Work on the missile and engine design definition began first, because they would take much more time to develop and qualify than the airframe. The Bendix Corporation was selected as the prime contractor for the Eagle, including the airborne radar and missile control system, in December 1958. Grumman (airframe and flight test), Westinghouse (aircraft radar), Litton (tactical computer), Sanders (missile active pulse doppler seeker), and Aerojet (propulsion) were subcontractors.

The missile and booster were 16-feet long. Together, they weighed 1,288 lbs, including the missile's on-board radar and 110-lb warhead. The maximum range from launch to intercept was 100 nautical miles against a bomber flying at 60,000 feet and Mach 2.

The Pratt & Whitney TF30 engine was one of the first turbofan-type engines, desired for its benefit on endurance. It was based on an engine that Pratt was developing for airlines.

The invitation to bid on the aircraft wasn't requested until 11 December 1959. Bids were received at the end of February from Chance Vought, Douglas, Grumman, McDonnell, and North America. Douglas was selected. The decision was announced on 21 July 1960.

The Navy's press release was explicit about the F6D's role: "The EAGLE-MISSILEER weapon system employs the concept of building long range and high performance into the missile, rather than into the launching aircraft." The 50,000-lb takeoff-gross-weight airplane was to be capable of operating from Essex-class carriers and loiter on station for four hours at 35,000 feet.

The bulbous nose was necessary to accommodate the Westinghouse AN/APQ-81 radar dish, which was five feet in diameter. (Big as the radar was, the missile's maximum range could only be utilized with the Bendix home-on-jam option.) The two-man crew sat side-by-side, surrounded by avionics. The normal missile load was six, all carried under the wings. Two additional missiles could be carried under the fuselage, increasing the takeoff gross weight by 4,800 lbs.

Unfortunately, the incoming Secretary of Defense, Robert McNamara, decided that it would be cost effective to combine two nascent "fighter" programs, the Navy's carrier-based, subsonic, 35,000-ft loiter Missileer and the Air Force's land-based, supersonic, tree-top ingress, nuclear-strike TFX. Strictly speaking, neither was a fighter and what's worse, two more different tactical airplane requirements would be difficult to imagine. The F6D program was formally terminated in April 1961 (it had been on hold since December 1960 awaiting the Kennedy administration's DoD programs review); Hughes took over the development of the radar/missile program, which was appropriately renamed Phoenix.

The F-111 train wreck, particularly given the Navy's outrage at being subservient to Air Force program management and subsequent passive-aggressive cooperation, was inevitable. For more on the F-111B program history, buy my F-111B monograph HERE.

A Designation Story

2011-10-15T23:02:00.004-04:00

The Grumman WF-2 (E-1B) is an interesting example of the Navy designation system and a little known false start for an iconic Navy airplane, the "Stoof with a roof". For starters, what was the WF-1? And why is there no E-1A?

The basic designation was W for Airborne Early Warning (AEW) and F for Grumman. Up until then, W was a suffix, not a prime mission designation, as in TBM-3W. It indicated that an existing airplane type, the third modification (3) of the first Torpedo Bomber (TB) to be built by Eastern Aircraft (M), had been modified for the AEW mission (W) by substituting a large radar and its cover for the bomb bay. (The 3 actually reflected that it was the third modification of the TBF, since the airplane was originally designed, developed, and produced by Grumman as its first torpedo bomber, with Eastern Aircraft, a division of General Motors, taking over its production from Grumman.)

The TBF-3W was followed by a series of AD Skyraiders, like the AD-3W shown here, modified similarly to carry the APS-20 radar aloft.

As an aside, the similarly configured Grumman AF-2W was used for AntiSubmarine Warfare (ASW), not AEW, with the radar being used to detect a surfaced submarine or more likely, its snorkel. It was paired as a hunter with the AF-2S, the killer half of an ASW team, which was equipped and armed to localize and sink the submarine.

Grumman was in the process of replacing the AF-2W and AF-2S with the S2F, a twin-engine airplane that combined the mission equipment and armament of those two airplanes into one. The S for ASW was now a prefix as W would be for AEW.

The S2F's small radar that was housed in a retractable "dustbin" dome under the aft fuselage was optimized for surface surveillance, not AEW. Grumman therefore proposed a minimally modified S2F airframe for the AEW role, with the APS-20 radar and dome mounted above the cockpit rather than under the fuselage, which would have required a much longer landing gear and therefore required a folding vertical fin/rudder to meet the hangar-height limitation. The forward location of the radome meant that the existing S2F wing-fold system that overlapped the fuselage could be retained. The only change required to the airframe therefore was a slightly deeper fuselage with an aft cabin door and the addition of finlets to the horizontal stabilizer to compensate for the sail area forward that was added by the radar dome.

The Navy ordered two prototypes as the WF-1 and assigned them BuNos 133043 and 133044. Grumman accomplished wind tunnel tests and a fuselage mockup before the WF-1 effort was terminated, probably due to budget priorities and the availability of the AD-5W.

Vought got a contract for the WU-1 and two Bureau Numbers were assigned, 133780/1, but it was also cancelled. (Note the wing-fold arrangement used to accommodate the radar dome.)

Eventually, however, the Navy felt the need to use a bigger, better radar for the AEW mission. The existence of and commonality with the TF-1 Carrier on Board Delivery (COD) variant of the S2F, which had been proposed at the same time as the WF-1, was no doubt one of the deciding factors in the decision to award the program to Grumman.

The resulting WF-2 bore only a family resemblance to the S2F and TF, however. The radar was now mounted above the fuselage, which required the substitution of an H-tail and a reversion to the sto-wing fold system that was a Grumman invention. The capacious TF-1 fuselage was lengthened ahead of the wing, probably to maintain the required center of gravity. Because of uncertainty about the aerodynamic implications of the huge radome, TF BuNo 136792 was modified, except for the fuselage extension and sto-wing, for initial flight test with the radome. (Note the feathered engine.)

In the following picture, the aerodynamic prototype is flying in formation with a production WF-2. Note the different location of the propeller strip versus the pilot's side window, which indicates where the forward fuselage was extended forward.

The sto-wing necessitated the use of a free-swiveling tail wheel because of the aft shift in the center of gravity when the wings were folded.

I can't confirm that the prototype was designated the XTF-1W as Wikipedia currently states. It doesn't seem likely and Larry Webster confirmed that its history card only states TF-1 and C-1A. A very early (but not dated) Grumman S2F brochure describes the AEW and the COD versions as the WF-1and TF-1 respectively. I've also read that the aerodynamic prototype was designated WF-1, with the production airplane therefore being the WF-2. That's definitely bogus.

After Grumman flight test of the aerodynamic prototype, the radome was removed, the TF/C-1 interior installed, and the aircraft utilized as a transport by NAS Quonset Point, RI.

According to Angelo Romano, there were three other topless Tracers that were used for pilot training since field carrier landings and real carrier landings, not to mention catapult launches, were hard on the electronics, not to mention that the radar and guys in back were unnecessary for that requirement.

When Navy aircraft designations were changed in 1962 to be consistent with the Air Force system, the WF-2 became the E-1B. Although it could have been argued that there was no need to reflect a universe in which the WF-1 had not been cancelled, the group in charge of redesignation chose to do so.

For a multi-part history of U.S. Navy AEW by a naval aviator, Steeljaw Scribe, who has forgotten more about the subject than I will ever know, see:
http://steeljawscribe.com/2010/10/06/project-cadillac-the-beginning-of-aew-in-the-us-navy
http://steeljawscribe.com/2010/10/09/project-cadillac-the-beginning-of-aew-in-the-us-navy-part-ii
http://steeljawscribe.com/2010/10/17/project-cadillac-the-beginning-of-aew-in-the-us-navy-part-iii

Attack on the Broadsword

2011-10-05T19:13:00.001-04:00

Captain Carballo and noted Argentinian artist and illustrator Carlos A. Garcia provided more material and Carballo's copilot's name for my post on the one disappointing reproduction in Scooter!. For the update, go to http://thanlont.blogspot.com/2011/09/scooter.html

Halcyon Days - 1950

2011-09-13T17:45:00.007-04:00

National Archives 80-G-419777

Patuxent River Naval Air Test Center (NATC), September 1950 Static Display

Clockwise from the facing airplane on the left-hand side of the ramp:

McDonnell F2H-2N Banshee (note the elongated nose)

Grumman F9F-2 Panther being flown by Electronic Test

North American AJ-1 Savage

Pratt & Whitney-operated, civil-registered JB-17G (Ron Lewis: See http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=2455) with an XT34 turboprop engine in the nose (the T34 was a Navy program but no production resulted for Navy airplanes)

Martin P4M Mercator (Almost certainly BuNo 122208; per Ron Lewis, see http://www.vpnavy.com/vp21_aircraft.html for other pictures of this airplane)

Douglas XF3D-1 Skyknight*

McDonnell F2H-2 Banshee

Vought F7U-1 Cutlass

Grumman F9F-2 BuNo 122563 with photo registration marks

Vought F4U-5P Corsair

Does anyone have any other information about these specific airplanes (particularly the Panther with the X on the fuselage) or the event?

* I had identified the Skyknight as an XF3D because of the small tail bumper (the production airplanes had a bigger one that incorporated a small wheel). Sharp-eyed viewer Ron Lewis noted that and also that part of the BuNo was visible, a 4 and a vertical line that could be part of a 1. Digging further, I'm all but certain that this is XF3D-1 BuNo 121457 that had just arrived at Pax for evaluation of control system modifications accomplished by Douglas.

Picture from Roger Besecker

Self Boarding for the Douglas Skyhawk

2011-09-07T19:07:00.003-04:00

Up until the early 1950s, self-boarding was a requirement for U.S. Navy carrier aircraft. Boarding ladders were unwelcome on a windy, crowded carrier deck. (Similarly, you didn't see pilots walking to and from their airplanes wearing parachutes: the consequences of a parachute accidentally opening were too serious. As a result, the parachutes were left in the cockpit and the pilot strapped it on or hooked it to a separate harness once he was seated.)

With the advent of the large jets that set nose high like the F3H Demon and F7U Cutlass, however, self-boarding provisions began to require mountaineering skills. See HERE and HERE for the two different approaches McDonnell used on the F3H Demon, for example. These proved to be inadequate, particularly on a wet, windy flight deck.

The Douglas A4D Skyhawk appears to have been the first exception to the self-boarding requirement, justified by Ed Heinemann's focus on weight reduction and the degree of difficulty involved in providing a self-contained boarding capability for it. The bespoke ladder was equipped with a tube that inserted into a hole in the left side of the fuselage. Wheels on the bottom of the side frames of the ladder minimized the loads on the mounting structure.

Boarding ladders were subsequently provided for the F3H and F7U although the self-boarding "feature" was retained. The XF4D self-boarding capability was removed for production and a ladder similar to the A4D's provided by Douglas for it. However, there were few exceptions made to the requirement— or provision of boarding ladders as GSE—after these aircraft were retired. (The North American A3J/A-5 Vigilante was one.)

Since a ladder was not always available, particularly for an urgent dismount, some Skyhawk pilots occasionally used the inflight refueling probe installation on the right side of the fuselage to exit the cockpit and move aft around the inlet to the wing and then jump off the trailing edge.

The more surefooted and athletic would go forward and execute a high bar dismount. (In the midst of the Forrestal fire, with his A-4's ladder having been removed, John McCain simply got out onto his probe, went forward on it, and jumped off.) Former gymnastics reportedly even gained access to the cockpit by muscling up on the probe.

With the introduction of the A4D-5 and the strakes forward and below the engine inlets, the degree of difficulty of self-boarding was somewhat reduced and became more common, particularly if malcontent sailors had tossed all the boarding ladders overboard as happened on at least one deployment. It helped if you were flexible and had long legs (but not too long because of the size of the Skyhawk's cockpit) like young T.J. (Jeff) Brown pictured here.

Douglas provided a self-boarding capability for the Blue Angel A-4s that consisted of a very narrow folding ladder stowed in a tube extending from the 20mm gun port in the left wing root.

The two-seat TA-4s had a ladder with a stepped platform that provided access to both the front and rear cockpits.

The TA-4s used for training were much more likely to fly into airfields that didn't have appropriate ladders for ingress and egress. As a result, some squadrons formally condoned and marginally improved the use of the strakes and the cover over the IFR pipe by treating them with a skid-resistant coating on them, as well as on the aft end of the external tanks and a wing walkway as shown here in a picture provided by Rick Burgess:

The front seater used one of the fins on the right external tank to get up on the wing and then went forward around the inlet to the strake and thence along the refueling boom. The guy in the back seat could enter and exit from either side using the strake.

A video of this egress is on Youtube: HERE

Scooter!

2011-09-04T14:49:00.001-04:00

As I said, I'm very pleased with the publication quality of my history of the A-4 Skyhawk, Scooter!, which should be shipping from Amazon, among others, in a couple of weeks. One small disappointment, however, was the reproduction of the picture of Capt Pablo Carballo and Lt Carlos Rinke's attack on Broadsword on 25 May 1982. It wasn't a very high resolution picture to begin with and this regrettably resulted in it being too small in the book to provide the impression that I wanted to convey. Here it is as big as I can make it (click on it for a larger size) and annotated as well:

Both Carballo and Rinke survived the attack (as did Broadsword), reportedly because the Sea Wolf missile system could not choose between their A-4s in the short time that they could be engaged.

Noted Argentinian aviation and maritime artist and illustrator Carlos A. Garcia created the following painting of the action, The Volcanos, based on this picture and interviews with Capt Carballo:

More of Senor Garcia's work can be seen at his website, http://www.aviationart.com.ar/Carlos_Adrian_Garcia_eng/Welcome.html.

Halcyon Days

2011-07-28T16:09:00.003-04:00

Click Here for 23 minutes of footage taken aboard CV-59 Forrestal during its shakedown with ATG-181 in February/March 1956, courtesy of the video library of the San Diego Air and Space Museum.

The Air Task Group, tail code I, consisted of:

VF-41 Black Aces F2H-3 1XX
VF-21 Mach Busters FJ-3 2XX
VA-86 Sidewinders F7U-3M 3XX
VA-42 Green Pawns AD-6 4XX

Detachments were:
VAH-6 (NH) Det 42 Go-Devils AJ-2 XX
VC-12 (NE) Det 42* AD-5W 7XX
VC-33 (SS) Det 42 Night Hawks AD-5N 8XX
VC-62 (PL) Det 42 Fighting Photos F2H-2P 9XX
HU-2 (UR) Det 42 Fleet Angels HUP-2 XX

*Possibly not in any of the footage

There are a number of transitions to be seen. For one thing, some aircraft are blue and others in the same squadron are grey/white. (The F7Us are still in the experimental "unpainted" scheme.) Click Here for some background on the color scheme change that was decreed a year earlier.

One of the grey/white AD Skyraiders has a black-painted area where the exhaust stains would have otherwise been evident. This was typical of gray/white USAF A-1s in the Vietnam War but I'd not noticed it before on a Navy AD.

Another transition example is that the pilots are still using the flat approach to a cut as directed by the LSO, not the descending approach using the mirror landing system. In one segment, an F2H is on short final with another close behind.

Too close, perhaps, because the LSO can subsequently be seen waving off the second Banshee.

All but one of the FJ-3 landings are with the canopies closed as would subsequently be the practice.

The F2H and F7U pilots all have their canopies open for landing. Although open canopies for carrier takeoffs and landings had been standard since canopies were introduced, this became pilot's choice on straight-deck carriers at some point following the addition of the barricade (click Here for a description of the barriers and the barricade) after an incident or two when the upper strap of the barricade went into the cockpit of a crashing jet. Note that the FJ-3s are taking off with open canopies.

Why are the F7Us in an attack squadron, particularly since they are supposedly the Sparrow-missile armed Ms? The answer is probably that the Navy was transitioning to jet attack and had F7U-3Ms excess to their fighter requirements. Note that in the F7U wave-offs (both of which appear to be from too high a start) and the bolter, the Cutlass hooks are not down. This was a familiarization process building up to the first trap: the approach was the important part of the maneuver and more could be fit into a flight period if there were no traps in between.

The deck runs made the launch a lot quicker but were only practical with propeller-driven airplanes. (The white stripes at an angle to the dashed stripe led to the bow catapults.)

However, it appears that the A3D and A4D were qualified with JATO to allow them to make deck runs if the catapults were down the nuclear strike was called for. An F4D pilot also made a successful deck run, off a British carrier, after he unknowingly lost his catapult holdback capability upon launch from Saratoga to land aboard Ark Royal. Click Here

The F2H-3/4 Banshees had a nose gear that extended for launch. This (and the steam catapult) mostly made up for the fact that they were heavier than the F2H-2 but had the same wing and engines. Note the difference between the attitude of this Banshee about to be launched and the ones in the picture above.

The FJ-3s were started and taxied forward to the bow catapults with the FOD screen in place.

Lots of other details of carrier operation can also be seen, like the little three-wheel self-powered start carts as well as a contrast between the personnel cranials and float coats used today versus their absence then. The use of catapult straps and a separate holdback as described Here instead of todays nose launch arrangement is also noteworthy.

Block Designation Letter

2011-07-21T09:06:00.001-04:00

Occasionally, someone notices that the Bureau Number marked on some Navy aircraft is followed by a letter, usually lower case, and wonders what that is all about. This practice dates back to at least the late 1950s.

U.S. Navy aircraft were usually purchased in annual batches. There were almost always changes (improvements, problem fixes, different avionics, etc.) from batch to batch or even within a batch, which meant that there were groups of aircraft that were slightly different configurations, but not so different as to justify a change in the designation dash number. From a manufacturing configuration control standpoint, these were referred to as blocks. The maintenance documents provided to the Navy provided a cross reference of Bureau Numbers for each block for initial configuration definition and subsequent control. For convenience, the blocks were designated by letters, with A being assigned to the first one, B to the second, and so forth. Although not the usual practice in these matters, the letter "O" was not skipped for the 14th block as shown here.

However, aircraft were updated and improved during the periodic overhauls and aircraft from the same batch did not necessarily go through overhaul at the same time. Since changes continued throughout the life of the aircraft, that meant that the configuration of aircraft that had been produced in a particular block began to diverge from others in that block. As a result, the block designation letter was not as meaningful from a configuration definition standpoint after the first overhaul or so and not necessarily put back on when the aircraft was repainted, as on this post-1962-designation-change F3H.

Also, not all manufacturers seem to have followed this practice. However, it was common on those from Douglas and McDonnell.

One Hundred Years of U.S. Navy Air Power

2011-07-15T11:13:00.001-04:00

Look! No Hands

2011-07-10T12:19:00.004-04:00

What was actually only the latest in "hands-free" carrier landings was accomplished on 2 July aboard Eisenhower by an F/A-18D Hornet "modified to emulate an unmanned aircraft"

The unmanned aircraft being emulated is the Northrop Grumman X-47B, which is currently in flight test and scheduled for at-sea carrier-suitability testing in 2013.

As it happens, the hands-off carrier landing capability has been around for a long time, with the first aboard a carrier being accomplished more than 50 years ago and used operationally since 1965. However, the X-47B system has to provide greater functionality—for example a hands-off bolter (a touch down with no arrestment)—and much greater reliability. since there is no pilot to take over when the electrons and ones/zeros begin to lose their way.

The impetus for a hands-off system in 1950 was the desire to minimize the shortcomings of jets with respect to all-weather operations and the amount of time that a carrier was unable to operate aircraft due to ship motion or ceiling/visibility. In those days, before inflight refueling, jets were unable to wait out poor weather due to their limited endurance.

Bell Aerospace won a competition with Honeywell and began developing the system in the early 1950s. It was ship-based, with a computer using radar data to determine the airplane's location relative to the glide slope and then sending corrections to the airplane's autopilot to alter its flight path to fly to and on the glide slope at the proper approach speed. All the pilot had to do was fly the airplane through an imaginary gate four miles aft of the ship on final approach and verify that the airplane was being guided by the ALCS, All-weather ( or Automatic) Carrier Landing System.

The first automatic landing of the Navy test airplane, a Douglas F3D Skyknight, took place in May 1954 at the Niagara Falls Airport, New York.

One addition required to the airplane in addition to an auto throttle was a corner reflector, seen above just in front of the nose landing gear doors, to insure the best possible radar data for the ship-based system.

Part of the interval between the successful demonstration at Bell and the first landing aboard a carrier was dedicated to developing a ship-motion compensation capability. During the last 12 seconds before the touchdown, ship motion was included in the computations; a second or two from touchdown, the corrections to the autopilot ceased and it simply maintained pitch and bank.

The first at-sea demonstration was on Antietam in 1957. At the time, the system was housed in large vans and not ready for deployment in the operating environment aboard an aircraft carrier. Redesign and environmental (shake, vibration, EMI, etc.) qualification testing was required now that proof of the concept had been demonstrated.

A production contract was finally awarded to Bell in March 1960 for the SPN-10 ALCS. NATC accomplished the first fully automated landings with the production system in June 1963 on Midway with an F-4 Phantom and an F-8 Crusader, modified for the capability. However, another round of development and improvements were required so the first operational use was delayed to late 1965, when operational evaluations were accomplished with F-4Gs, ALCS-modified F-4Bs, aboard Kitty Hawk. The capability was subsequently retrofitted to F-4Bs and incorporated in new production F-4Js. After a Vietnam deployment aboard Kitty Hawk with VF-213, the 11 surviving F-4Gs (one was shot down) became F-4Bs again. (Either the Navy's F-4G's existence was forgotten/considered irrelevant or used to disguise the purpose of yet another F-4 variant, the Air Force F-4G Wild Weasel.)

The radar reflector on the aircraft was substantially reduced in size and made retractable. On the F-4, it was attached to a door that opened just forward of the nose gear.

On the F-111B, it was mounted on the upper link of the nose gear torque scissors so it deployed into position when the gear was down in flight.

When the system was working, the performance was brilliant, the airplane coming down the glide slope toward a three-wire arrestment like it was on rails. As might be expected from the vacuum-tube-based technology of the time, however, reliability proved to be a problem. A field change was made to improve SPN-10 reliability but at the expense of its automatic touchdown capability: the pilot had to take over at weather minimums and make the final corrections before touchdown.

In 1966, Bell received a contract to "digitize" the system with solid state electronics and computers and restore full functionality. The redesigned system was designated the SPN-42. A subsequent improvement, the SPN-42A, incorporated an X-Band radar for better system performance in heavy precipitation. It was operationally approved in 1968.

Development of the next ALCS generation, the SPN-46, was begun in 1980 to take advantage of advancements in gyro, computer, and radar technology. It was declared operational in 1987 after an operational evaluation involving Kennedy and F-14s. It is being continually improved but will eventually be replaced by a GPS-based system being developed as a joint service program, JPALS (Joint Precision Approach and Landing System).

Scooter!

2011-06-27T10:54:00.000-04:00

It took longer than we hoped, but Scooter! is in the last stages of the publishing process and should be available in the fall. This is the final cover:

It is being published by Crecy Publications in England (Home Page), distributed by Specialty Press (Home Page) in the United States and available for advance order from Amazon, HERE.

See HERE for an example illustration that I posted a year ago.

A Brief, F4U Corsair-oriented History of Navy Color Schemes and Markings

2011-06-19T14:58:00.002-04:00

One of the useful aspects of the Vought F4U Corsair's long career is that it can be used to illustrate three decades of U.S. Navy color schemes and markings. With the exception of two schemes, one arguably and the other definitely experimental, it lasted from the "yellow" wings of biplanes of the 1930s through to the change to gull gray and white in the mid 1950s.

n.b. Federal Standard 595 was first issued in March 1956 to provide a reference for "Colors Used in Government Procurement." The colors are identified by five-digit numbers but no names. Before that, there was Federal Specification TT-C-595 issued in January 1950 that identified colors by four-digit numbers. It was preceded by an Army/Navy Aeronautics Bulletins that identified colors by three digit numbers and names. For some, this will be a gross oversimplification of aircraft color specification history but it's not my specialty.

The XF4U-1 flew for the first time on 29 May 1940. In conformance with the exterior color scheme at the time, metal surfaces were painted with aluminized lacquer and fabric surfaces were finished with alumininized dope except for the upper surface of the wings (including the ailerons), which was painted Orange Yellow so an airplane could be easily spotted if ditched in the ocean. (It would float because like most Navy airplanes of the era, it was equipped with flotation bags in the wing.)

Note that the national insignia is a blue circle with a white star encompassing a red circle and that the propeller tip has bands of blue, yellow, and red.

The first scheme that the F4U missed (the first production airplane did not fly until mid 1942 and the prototype doesn't appear to have been repainted) was an overall Light Gray scheme with white markings that marked the prewar change to low visibility in early 1941 as illustrated by this Grumman F4F Wildcat. It also added the national insignia to the sides of the fuselage and removed it from the upper right and lower left wings.

The single shade of gray approach was short-lived and replaced with a Blue Grey over Light Grey scheme for carrier-based airplanes on 20 August 1941. On 5 January 1942, the national insignia was reinstated on the upper right and lower left wings.

Note that the red centers have been removed from the national insignia as of 15 May 1942 in order to avoid confusion with the Japanese red rising-sun markings. (The original scheme, which did not appear on the first production Corsairs, also had red and white rudder stripes that somewhat detracted from the camouflage effect and were removed by the same directive.)

In January 1943, the U.S. Navy released a specification that replaced the simple Blue Gray over Light Gray camouflage scheme scheme with a complex one that employed counter-shading and counter-shadowing. Four colors were used: Semigloss Sea Blue on upper surfaces, non-specular Sea Blue on the wing leading edges, non-specular Intermediate Blue Sides, and non-specular Insignia White on the lower surfaces. Four-place national insignia were again decreed on 1 February 1943 in order to further minimize the likelihood of confusion with Japanese six-place markings.

It took some time for the Navy to repaint delivered aircraft and probably a month or more for the contractors to develop and switch over to color schemes in accordance with the specification. For example, VF-17, which was working up for combat, was still flying Corsairs in two-tone gray scheme with six-place national insignia when carrier qualifying aboard Charger in March 1943.

However, by the time that Bunker Hill was available for shakedown of its air group in July 1943, VF-17 had F4U-1s that had been repainted by the Navy rework/repair facility at Norfolk, Virginia in their version of the new multi-color scheme. (Click HERE for background on it.)

(National Archives 80-G-205087 via Jim Sullivan)

The addition of white bars with a red surround of the national insignia was decreed on 28 June 1943. At least one VF-17 F4U-1 received the change in time to participate in the pilot qualifications and proficiency operations on Bunker Hill in July.

In August, VF-17 reequipped with factory new (and factory painted) F4U-1As for their departure on Bunker Hill to the Pacific. In September 1943 the red surround was ordered to be replaced by blue, again due to reduce the potential for confusion with the Japanese markings. (It had already been deleted in the Pacific by an edict on 31 July 1943.) Note the difference in demarcation between the upper and side colors on the repainted airplanes above and this one.

This VF-17 Corsair, BuNo 17640, is marked with 1 and "Big Hog" for the squadron commander, Tom Blackburn, who is fourth from the left. (The dark patches behind the "1" are reportedly repairs of bullet holes made when one of his pilots mistook his airplane for a Japanese fighter.)

The complex multi-color scheme was eventually replaced by an overall gloss Sea Blue one by a directive issued on 26 June 1944.

(F4U-1D on Essex July 1945 via Jim Sullivan)

It was eventually suggested, probably by Grumman, that the Insignia Blue surround of the national insignia was redundant and should be eliminated on all-blue airplanes. It was reportedly deleted well before the official authorization to do so was issued in June 1946. A red bar was added in January 1947 to reinstate all the colors of the U.S. flag.

Although no Corsairs were involved in the experimental (and again short-lived) unpainted approach of the early 1950s (click HERE for a brief discussion), there was an F4U-1A created from various wrecked Corsairs by Service Squadron 11 of Marine Aircraft Group 11 based at Espiritu Santos (Vanuatu). However, it appears to be not unpainted but instead have been given an aluminum paint finish. "Sally" was marked on the cowling.

(Photo provided by Jim Sullivan.)

The Corsair lasted long enough in service, as the AU-1 attack version, to be repainted light gull gray (36440) and white in accordance with the change introduced on 23 February 1955. This one was assigned to Aircraft Engineer Squadron-12 at Quantico, Virginia, circa 1957, to provide training for air-to-ground controllers.

New soft-cover Corsair books well worth your consideration have been published recently: Jim Sullivan has completely rewritten and re-illustrated his F4U Corsair In Action published by Squadron/Signal Publications. Is is a very good summary of the various versions with many previously unpublished photos.

Rafe Morrissey and Joe Hegedus have authored The Vought F4U Corsair: A Comprehensive Guide, SAM Publications. As you might guess from the title, it provides more detail (and more than twice as many pages) as Jim's monograph, including coverage of the kits and decals that had been produced at the book's publication.

The Navy and Liquid-Cooled Engines

2011-06-11T09:06:00.008-04:00

Although the Navy effectively ended deployments of airplanes powered by a liquid-cooled engine in the late 1920s, that wasn’t the end of its interest and involvement in the technology. Its racers were powered by liquid-cooled engines up through 1930. The Navy funded development of the Wright H-2120 engine from 1933 to 1936 (click HERE). In 1938, the Navy’s Bureau of Aeronautics included the Allison-powered FL-1 Airabonita in its competition for a new high-performance fighter.*

In 1940, the Navy began funding the development of Lycoming’s 2,200 hp H-2470 engine and in June 1941, BuAer contracted with Curtiss for the F14C to be powered by that engine. Pratt & Whitney’s even bigger H-3730 also received Navy funding for a time

At some point in World War II, the Navy acquired an Allison-powered early P-51, 41-37426, from the Army Air Force. It was one of a production lot of Mustang Mk 1As that were ordered by the RAF, some of which were taken instead by the Army Air Force. It was assigned BuNo 57987.

None of the post-1930 programs resulted in an operational aircraft—or engine for that matter—but the F14C (which flew with an air-cooled Wright R-3350) was only the penultimate effort. In a 21 March 1944 memorandum to BuAer, the Deputy Chief of Naval Operations (Air), Admiral J. S. McKain, asked for what proved to be the final evaluation of the technology:
1. It is requested that the Aviation experimental program be subjected to a study and review.
2. It is considered that experiences of the war and the present trend of design within the Navy may point to the necessity of reefing our sails and. departing on a new tack.
3. The weights and physical measurements of our newer airplanes are increasing rapidly with the result that we shall soon be forced into reduction of carrier complements. To obtain increased performance the natural and logical step has been an increase in power. However, the direct result of this has been larger engines presenting greater frontal areas with correspondingly larger fuselages to accommodate them.
4. Possibly we have reached the place in the development of the air-cooled engine where we should sever our many years of allegiance and look to a design of aircraft incorporating liquid cooled in-line power plants.
5. The size and weights of our projected designs is ample evidence of the fact that our engineers must concentrate on smaller and more compact aircraft with which to do the job at hand. If the liquid cooled in line engine represents the step necessary to achieve the results, we should then be spending some of our time and money on development of that article.

That direction proved controversial within BuAer, but it was not without supporters. The performance of the North American P-51 Mustang had impressed some. As a result, BuAer agreed to request proposals for a liquid-cooled engine powered fighter, as well as one powered by a combination of a liquid-cooled and jet engines. In July 1944, BuAer Military Requirements stated that the Navy’s next fighter should have a Vmax of at least 425 mph at sea level and 475 mph at a critical altitude of 25,000 feet. It would be able to climb to 30,000 ft. in five minutes. Its combat radius should be 300 miles in the escort version, 75 miles in the interceptor version. Either version should be able to remain in the air for six hours.

In August, Boeing, Grumman, Curtiss, Ryan, and McDonnell all informally declined an informal invitation to propose a liquid-cooled engine powered fighter, either because they sensed that the Navy wasn't serious about liquid-cooled engines or realized that the performance requirements were beyond challenging. In the event, only North American submitted a proposal, in October 1944; Vought responded with a design study that concluded “that other types of power plants were more suitable for future fighters.”

The North American proposal was based on its P-51H, the culmination of its effort to improve on the P-51D, focusing on a better rate of climb and roll. The Army had ordered the P-51H into production in April 1944. It was very similar in appearance to the P-51D but was slightly longer, with an elongated ventral cooling installation, and very different in detail.

The NAA-133 was to be powered by a Merlin V-1650-11 engine planned for the stillborn P-51L. The wing was redesigned to increase the wing area by 10 square feet (an increase in wing chord of about three inches since the wing span was not changed), substitute larger and slotted flaps, and incorporate wing folding. The ailerons were enlarged and hydraulically boosted. The landing gear was strengthened and an arresting hook and catapult hook added. The Mustang’s fuselage fuel tank was deleted and the wing fuel capacity was reduced to 150 gallons. The elimination of the fuselage tank allowed for a smaller horizontal tail while maintaining adequate longitudinal stability. The reduction in internal fuel capacity was to be offset by the addition of 50-gallon tip tanks when required. Here is the North American drawing of the P-51H with the NAA-133 changes shown in red:

(The NAA-133 fin and rudder are depicted with dashed lines although they are as depicted on the relatively crude North American three-view provided to BuAer.)
In November 1944, doubtless as part of this evaluation, a minimally modified P-51D was evaluated aboard Shangri-La by Bob Elder after shore-based trials.

As tested, rudder control power and the tail hook attachment were marginal. Elder stated that the rudder was on the stops at 82 mph in approach configuration and the hook structure strength limit was reached at 90 mph. As a result, he had to approach at 85 mph: “Fortunately the little lady exhibited marvelous speed control characteristics and even though operating at near minimum margins of directional and lateral controllability (limited by torque) wave-offs could be executed by judicious application of power.” He reported that visibility during approach was no problem: “Some of the radial engine fighters of that era, notably the F4U and F6F with cowl flaps open, had even more restricted forward visibility and I simply made a turning approach almost to touch-down as was the practice at the time.”

The November 1944 BuAer report on the North American proposal concluded that the NAA-133 failed to meet the desired performance by a wide margin, which wasn't a big surprise to BuAer's engineers, although it was superior to the F8F-1 and the F2G-1. The tip tank option was judged to be inferior to the use of conventional drop tanks. The engine-related “serious disadvantages… for carrier use” were:
(a) Increased vulnerability inherent in any liquid-cooled arrangement over air-cooled types.
(b) Increased maintenance because of addition of radiators and aftercoolers.
(c) The airplane as presented will possess the poor ditching characteristics of the P-51 series airplanes.
(d) Introduction of liquid cooled type will increase logistic problems, and necessitate an additional training program.

Fortunately, North American had also submitted a proposal, NAA-134, for a jet-powered fighter based on the P-51.

The Navy ordered it as the FJ-1 as part of its initiative to enter the jet age.

The Air Force’s P-51H flew for the first time on 3 February 1945. However, only 554 were built before production was terminated in November 1945 as part of the draw down following the end of World War II and realization that all future fighters would be jet propelled.

For much, much more on the P-51H (although nothing on the NAA-133) see the excellent monograph by David McLaren published by Steve Ginter (http://www.ginterbooks.com/AIRFORCE/AF209.htm).

For more on the P-51D carrier trials including pictures, see Mustang: The Story of the P-51D Fighter by Robert W. Gruenhagen.

*For more on liquid-cooled versus air-cooled engines and the Bell Aircraft FL-1 Airabonita, see my FL-1 monograph also published by Steve (http://www.ginterbooks.com/NAVAL/NF81.htm).

Most of the above material is derived from the research of Ryan Crierie, who generously shares his hard-won information.

Modelers will find more information on the Seahorses HERE.

United States Naval Aviation, 1919-1941

2011-06-01T16:52:00.002-04:00

I was very pleased recently when the mailman delivered a copy of United States Naval Aviation, 1919-1941: Aircraft, Airships, and Ships Between the Wars from its publisher for me to review.

This is a large format (8.5” x 11”) soft-cover 352-page book with encyclopedic coverage of the subject. (According to the publisher, the content includes 605 photographs and 40 color profiles.) A brief synopsis of the history of each of the major mission types, e.g. attack, fighter, patrol, etc. is provided ahead of each section describing each aircraft designed for that mission. As near as I can tell, every Navy, Coast Guard, and Marine Corps airplane that flew during that period—however briefly or ignominiously—is represented by a Lloyd Jones three-view drawing, a picture (sometimes two or three), technical specifications, and a description of its development and service career. Even walk-ins, like the Republic NF-1, a navalized P-35, are included, as well as gliders and the OP-1 autogyro. The same coverage is provided for airships and ships, albeit with only a side view instead of a two-view or three-view. Ship coverage includes those only peripherally associated with aviation.

Appendix 1 covers foreign aircraft and airships; Appendix 2 covers racing and experimental aircraft. Only photographs are provided in these appendices. Appendix 3 is the always useful summary of the designation systems for ships and aircraft. Appendix 4 is a listing of the type and quantity of Navy, Coast Guard, and Marine aircraft extant in December 1941. The glossary and index are also comprehensive.

Disappointments are few and more than offset by its usefulness as a one-stop source of information on the ships and aircraft described in the title. The only color included is for a set of profiles of some of the more well-known airplanes. I'd have rather had plan views of the carrier decks, preferably to the same scale. I wish the paper used were a bit higher quality although the reproduction is good enough.

Buyers should also be aware that the rear cover promises a bit more than the book delivers in terms of an in-depth discussion of “naval treaties, fleet tactics, government programs, leadership and organization.” The coverage is not significant in that regard, basically an introduction six-pages long including large photographs, but that does not detract from the book’s value to the reader interested in the aircraft and ships of the period.

The publisher is McFarland and Company, Inc. Their web site is www.mcfarlandpub.com, The phone number to order the book is 800-253-2187. It's also available from Amazon but at no discount from the list price of $45.

McFarland provided me with a review copy but I’d have bought it anyway.

A-12: It Ain't Over Until It's Over

2011-05-25T15:57:00.000-04:00

The Supremes have spoken. Unanimously. Basically, they have sent the contractors, Boeing and General Dynamics, and the federal government back to square one. In case you, understandably, haven't been paying attention, the Navy terminated the A-12 Avenger program for default in January 1991, reportedly at the direction of the Secretary of Defense, and demanded the return of $1.35 billion in progress payments. The contractors not only disagreed that they owed the Navy any money, they sued the Navy for $1.2 billion that they had incurred because the termination was for default, not for the Navy's convenience.

There were eventually trials. The contractors won the first in 1995, which the government successfully appealed. The government won the second in 2001, which the contractors successfully appealed. Things dragged at that point, in part because the contractors and the government unsuccessfully tried to agree to a settlement. In May 2007, the Court of Federal Claims, on review, decided in favor of the government, agreeing that the Navy had properly terminated the contract for default. In June, 2009 the Court of Appeals for the Federal Circuit affirmed this judgment. Boeing and General Dynamics sought a rehearing before the full Court of Appeals but their request was denied in November 2009, leading to their appeal to the Supreme Court. No money had exchanged hands so the amount claimed on each side had about doubled with interest.

In September 2010, the Supreme Court agreed to hear part of the contractors' appeal but limited the scope of their review to the Fifth Amendment issues. They declined to review the termination for default issue itself.

Their ruling was issued on 23 May. The good news for the contractors was that the Court of Appeals decision was vacated. On the other hand, the Supreme Court did not reinstate the earlier judgment against the government either: "When, to protect state secrets, a court dismisses a Government contractor’s prima facie valid affirmative defense to the Government’s allegations of contractual breach, the proper remedy is to leave the parties where they were on the day they filed suit."

For the compete text of the opinion (it's short), click HERE.

This doesn't mean that the 20-year dispute is over. There was still the question as to whether the Navy had a obligation to share highly classified information with the contractors, leading to their poor performance against the contract requirements. One or both sides may elect a do-over of the litigation within the constraints identified by the court.

Carrier Onboard Delivery

2011-05-16T00:31:00.008-04:00

This is a work in progress...

Carrier Onboard Delivery (COD) is the mission of delivering people, mail, and high-priority cargo to a carrier at sea by air. COD doesn't seem to have been a mission, certainly not a dedicated aircraft, before about 1950. For one thing, up until then there were a goodly number of airplanes in the air group with more than one seat and a bomb bay that could be used for transportation by air to and from the carrier. Tailhook-equipped utility aircraft like the Grumman J2F Duck could also be used when necessary.

The airplanes in the air group were fairly simple and reliable in any event. However, as the single-seat AD Skyraider, which did not have a bomb bay, began to replace the SB2C Helldivers and TBM Avengers and airplane electronic systems grew in number and complexity, a logistics gap appeared.

The first solution was the TBM-3R, R being the Navy designation at the time for a transport. This was one of several conversions of surplus TBMs to other purposes. In this case, the gun turret was removed and the canopy extended over the tail gunner's position. Two seats were installed in the compartment aft of the pilot and two in the former turret area. Two seats were also provided in the former radioman compartment below the turret area for a total of six passenger seats. One was usually occupied by the load master/crew chief, leaving the other five available for passengers. A basket was installed in the bomb bay for cargo.

The TBM-3R appears to have been introduced in 1950 or so. For certain, it was in widespread use during the Korean War.

The AD-5 was the next COD development. It was created as a multi-place, multi-purpose modification of the AD Skyraider. The upper fuselage was widened to provide side-by-side seating for a pilot and a crewman and create a compartment aft of them for additional crewmen.

Previous multi-place versions of the Skyraider for airborne early warning and night attack missions had a crew compartment in the fuselage aft and below the pilot. In additional to the mission-dedicated AD-5W and AD-5N, the Navy also bought AD-5s that were only equipped for day attack so the large aft compartment was empty. It could be filled with four litters, four rearward-facing passenger seats, or cargo. The AD-5s don't seem to have been assigned to the transport squadrons as CODs, however, and none received a R designation..

Neither the TBM-3R or the AD-5 was capable of filling two of the Navy's emerging high-priority cargo requirements, jet engines and nuclear weapons. The result was a variant of the Navy's new twin-engine, antisubmarine warfare aircraft, the Grumman S2F. Designated the TF-1, it had a slightly wider and somewhat deeper fuselage with a large double door on the left side of the fuselage and windows on each side. Nine seats could be set up in the passenger compartment to accommodate eight passengers and the load master.

The TF-1 first flight was made on 19 February 1955. Grumman built a total of 88. It could carry a payload of about 3,500 pounds for 1,000 miles. On 26 June 1958, a TF-1 delivered a J34 engine to Yorktown, 300 miles at sea, the first use of its cabin capability to deliver one. In 1962, it was redesignated C-1A.

In 1963, the CNO was reportedly concerned about resupply of the carriers of essential items too big for the C-1 and requested an evaluation by NATC of the C-130 for operation to and from Forrestal-class carriers. The first question was whether to train a C-130 pilot to make carrier landings or checkout a carrier-qualified pilot in the C-130. The obvious answer was that a fighter pilot, LT James H. Flatley III, would fly it along with another carrier-suitability branch pilot as copilot and a C-130 flight engineer volunteer from VR-1. The NATC pilots were checked out in the C-130 by a Lockheed test pilot. The changes to the C-130F, BuNo 148798 borrowed from the Marine Corps, were minimal and did not include the addition of a tailhook: the nose gear strut response was stiffened by the substitution of a smaller bleed orifice, higher capacity brakes were installed, and the external tanks were removed.

After shore-based trials established the feasibility of taking off from and landing on a carrier and the best technique to be used, at-sea trials were accomplished aboard Forrestal (CVA-59) in October 1963. No significant difficulties were encountered in takeoffs or landings, with the maximum takeoff weight demonstrated of 121,000 pounds. While the evaluation demonstrated the feasibility of resupply using the C-130, it was decided that the capability was not practical given the disruption of normal carrier operations when it was aboard and the risk that the C-130 might go hard down after landing, requiring it to be dumped overboard under certain circumstances due to the deck space it took up.

In any event, the Navy had already decided to buy a COD derivative of its new AEW airplane, the Grumman E-2 Hawkeye, configured for carrier onboard delivery. The E-2A had first flown in October 1961 and was first deployed in 1965. The C-2 first flew in 1964, with the wing and engines from a prototype E-2A mounted on a much wider and deeper fuselage equipped with a rear ramp. It had a four-man crew and could carry either 26 passengers or total cargo of about 10,000 pounds or a mix of passengers and cargo. Maximum range was about 1,200 nautical miles. Production totaled two converted from prototype E-2As, BuNos 148147 and 8 and 17 new C-2As, BuNos 152786-2797) followed. The first of these entered service in 1966.

The C-2 had the capability to carry outsized and heavy cargo but did not have as much range as desired for carrier onboard delivery in the Pacific and Indian Oceans. In the 1970s, the Navy had a competition for a much larger airplane. Boeing, Douglas, and Fokker proposed derivatives of their twin jet transports, the 737, DC-9, and F-28 respectively. Although the Navy thought that they were feasible, none were taken up at the time.

However, a Lockheed Full Scale Development S-3 Viking, BuNo 157998, was converted to a COD configuration, US-3A, in 1976. In this case, the existing fuselage was retained but the aft pair of ejection seats were removed and replaced with six passenger seats, three abreast, for five passengers and a load master. The bomb bay and electronic compartments were configured to carry cargo and a large cargo pod was created that was carried on the stores pylon. The prototype first flew in July 1976 and it was assigned to Kitty Hawk in 1977. It not only had a range of 2,400 miles with external fuel tanks in lieu of the cargo pods, it retained an inflight refueling capability so unlike the C-2, it was not restricted to a peacetime radius of action that allowed it to return to a shore base in the event that a carrier landing was not accomplished. It could not, however, transport large items.

Lockheed proposed a US-3A with a wider and longer fuselage that utilized the S-3 cockpit, wings, stabilizer, and engines. It would have provided seating for as many as 30 passengers or cargo space/access for two large jet engines. The Navy elected not to buy it. However, in 1981 five more US-3As were converted from FSD aircraft, BuNos 157994-997, and another test aircraft, BuNo 158868, for high-priority logistics transportation in the Pacific.

In the early 1980s, the Navy evaluated the addition of inflight refueling to the C-2 in order to remove the range restriction of requiring an airport alternate.

The modified airplane, BuNo 152797, was evaluated as a receiver behind the KA-6D, KC-130F/R, and KC135 tankers in both day and night conditions. Although more than 250 engagements were successfully accomplished without damage to either tanker or receiver, the conclusion was that the C-2 was not suited for inflight refueling due to its handling qualities and the consequences of failure to successfully refuel outweighed the benefits of being able to. The test airplane had its refueling probe removed and was returned to service with the external piping still present for a time.

Photo courtesy Rick Morgan

In 1983, Naval Air Systems Command revisited the Fokker F-28 to the extent of accomplishing a flight evaluation of the Fellowship at Fokker's factory in Amsterdam and at NAS Sigonella. It would have had the payload of the C-2 and the range of the S-3. While the conclusion of the evaluation was that the "airplane has potential for the carrier-based carrier-on-board delivery, tanker, or AEW mission," no contract resulted.

The Navy elected instead to maintain the existing mix of the C-1 and C-2 for intermediate-range missions; the US-3 for high-speed, long-range missions with high-priority, small cargo; and a huge helicopter, the Sikorsky CH-53E, for short-range transport of large, heavy items from shore bases.

A service life extension program had been accomplished on the surviving C-2As from the original purchase of 19, with deliveries of the refurbished aircraft between 1978 and 1982. However, only 12 remained, not enough to meet the demand for COD support since the C-1s were being retired and only a handful of the volume-limited US-3As were available. After considering other options, the Navy elected the unusual step of putting the C-2 back into production although the degree of difficulty was somewhat reduced by the fact that the E-2 was still in production. The Navy bought 39, BuNos 162140-2178.

The major external difference between the original C-2s and the "reprocured" C-2s was a larger APU. Less obvious was a redesigned nose landing gear. The housing for the crash recorder/locator was not carried over to the new C-2s. The first one flew in February 1985, just in time to begin replacement of the original Greyhounds, the last of which was retired by the end of 1987.

The last C-1 in service, BuNo 146048, was retired on 30 September 1988. The last of the new C-2s had been delivered in 1990. The US-3As were retired in 1994.

In the late 1990s, the Navy considered the development of the Common Support Aircraft (CSA). It was to replace the E-2C for AEW, the S-3 for ASW, the ES-3A for signal intelligence gathering (Sigint), and the C-2 for COD beginning in 2013. (The EA-6B would be replaced by a derivative of the F/A-18F.) The concept was a victim of budget priorities and mission revaluation. The S-3s and ES-3As were retired, with ASW to be accomplished by a combination of carrier-based helicopters and shore-based airplanes and Sigint by shore-based airplanes. The E-2C continued in low-rate production and is to be replaced by an upgrade, the E-2D.

As a result, there has been no replacement of the C-2s, which began going through a service life extension program including avionics upgrades in 2005. They are currently expected to serve through 2027, by which time a replacement will surely have been developed...

The Blue Angels Aircraft (Draft)

2011-04-25T20:00:00.004-04:00

This is, again, a work in progress. Knowledgeable corrections and comments, as well as better pictures, are welcome.

1946, F6F-5: In April 1946, as described by Robert K. Wilcox in First Blue, Butch Voris was tasked with establishing an official U.S. Navy flight exhibition team. Among the aircraft he considered were the Grumman F7F Tigercat, the Vought F4U Corsair, and the Grumman F6F Hellcat. He thought that the Corsair was the “nicest looking” but was concerned that the possibility of it stalling and snap-rolling at the top of a loop precluded close formation flying. “The Tigercat, he felt, was too big and not agile enough.” Moreover, he and many of the candidates for the team were very familiar with the Hellcat so he requested four, modified by the removal of armament, etc. to reduce weight and painted in a new distinctive color scheme. (For more information on Blue Angel markings, click here.) Three were flown in close formation in the air shows with the fourth available as a spare. The first public display was on 15 June 1946 at Craig Field near Jacksonville, Florida.

In this photo reportedly taken at Grumman of a Blue Angel passing overhead during their final show in the F6Fs in August 1946, the bottom of the wing appears to be marked with US on one wing and NAVY on the other. (I’ve crudely enhanced the markings which are barely visible on the photo I have.)

1946-1949, F8F-1: The team was an immediate success and very shortly reequipped with the Navy’s frontline propeller driven fighter, the Grumman F8F Bearcat. Although powered by the same basic engine as the Hellcat, it was slightly smaller and lighter, with excellent climb and roll performance. Four were modified by Grumman to remove the guns, gun sights, tail hooks, etc. and delivered to the Blues in August 1946. These early production F8Fs did not have the turnover structure behind the pilot’s headrest. They flew their first show in the Bearcats only a week after ferrying them back to Jacksonville.

The show formation was soon expanded to four airplanes.

Later F8Fs had the turnover structure added, a polished aluminum or painted leading edge on the wing and tail surfaces, and “Blue Angels” in script on the cowling.

1949-1950, F9F-2: The Blue Angels entered the jet age with the Grumman F9F-2 Panther. They initially thought that removing the Panther’s tip tanks would provide better visibility for close formation flying as well as reduce weight. However, the Panther’s tanks were necessary for cross country flights and were not intended to be readily removable (they weren’t even jettisonable) so the concept was short-lived.

However, the fact that the tip tanks couldn't be jettisoned like they could on other jets turned out to be a feature. In lieu of being able to drop the tanks to lighten the aircraft, the fuel in them could be jettisoned. This was utilized to provide a spray of fluid to accentuate a maneuver, the predecessor of the smoke used today.

One of the show innovations implemented with the introduction of the jet was the use of a solo airplane to make passes to fill the time required for the faster jets to get turned around and back in front of the crowd for the formation's next maneuver..

When the Korean War broke out, the team’s pilots and airplanes were transferred to a fleet squadron which was converting to Panthers from Bearcats. They deployed aboard Princeton (CV-37) as the nucleus of VF-191.

1952-1954, F9F-5: The team was reformed with -5s after a hiatus for the Korean War. It had a more powerful engine than the -2. Its short stint with the team was indicative of the rapid succession of new jet fighter types in the early 1950s.

1952, F7U-1: Two Vought Cutlasses were assigned to the team in January 1952. The F7U-1 was a bit too overweight to be used as an operational airplane and was being redesigned with more powerful engines as the F7U-3. In accordance with its procurement practice, however, the Navy had begun low rate production before development was complete and had few more F7U-1s than they had test and evaluation requirements for. At the behest of Vought and with the approval of senior Navy management, two were assigned to the Blue Angels to generate publicity for the Navy's hottest new fighter. It was expected that they would be flown as opposing solos rather than be part of the formation of Panthers.

(If you look closely at the picture above, you'll note that the main landing gear is angled differently on the two F7Us. The selectable position provided better center of gravity location relative to the main landing gear wheels on takeoff versus landing .)

As it turned out, the new F9F-5s assigned to the Blues were effectively grounded for the first few months of the air show season. The Cutlasses were therefore the only airplanes available for flight demonstrations during that period and the necessary workup time after that. However, they weren’t really ready for prime time, suffering from hydraulic failures, engine fires, at least one landing gear malfunction, and excessive maintenance. In July the Blues were ready to resume shows with the Panthers so the Cutlasses were parked at NAS Memphis, the site of their last show and conveniently, a Navy training facility for aircraft mechanics.

F9F-6, 1953: The team picked up six Cougars, the swept-wing successor to the Panther, from Grumman in August 1953. The ferry flight home was marred to say the least because the team leader, Ray Hawkins, experienced a runaway pitch trim at 42,000 feet. He had to make a near-sonic ejection when the airplane bunted into an outside loop. He wasn’t badly hurt but the Cougar control system had to be modified so the Blues returned the F9F-6s to Grumman without ever performing a show in them and flew the F9F-5 for another year.

1955-1957, F9F-8: The successor to the F9F-6 was received in December 1954. Their first F9F-8s did not have the splitter plate on the fuselage in front of the engine intake. It’s not clear why the Cougar’s time with the team was not only relatively short, it was replaced at mid-season, which required the team to transition to a new airplane while still flying air shows in the old one.

1957-1958, F11F-1 (early): Before committing to the F11F Tiger, the team also considered both the North American FJ-3 and the Douglas A4D. However, neither were afterburner equipped, which added an extra element of showmanship and maneuver capability to the flight demonstration. Moreover, F11Fs from the first production lot, characterized by a shorter nose with a refueling probe at its tip, were readily available since design improvements were in work.

1959-1968, F11F-1 (late): As it turned out, the marginally improved F11Fs in the second production lot were no more in demand in the fleet than those in the first due to the superior performance of the Vought F8U Crusader, so the early short-nose F11Fs were replaced with the later long-nose version.

1969-1973, F-4J: In the late 1960s, two situations resulted in the F11F finally being replaced. First, the Navy was running out of F11Fs. Second, the Navy had bought an improved version of its front line fighter, the McDonnell F-4 Phantom, but its new radar and improved engine were not available in time to be installed in the first production F-4Js. As a result, the Navy had brand-new Phantoms with lead ballast in the nose and the prior version of the J79 engine. Twelve or so of these were made available to the Blues to replace the F11F. To improve handling qualities in the very close formation maneuvers, the control system was modified, including a change to allow afterburner to be selected at a lower engine rpm. A smoke system was also added.

Although the Phantom was a terrific air show airplane, the Blues experienced a series of unfortunate events with them. Nine of the lead-nosed Js were lost in accidents between September 1969 and March 1973, requiring replacement with a few “real” Js with the J79-GE-10 engine. Another was destroyed in early July 1973 at an air show. However, the 1973 season ended in tragedy on 26 July when a midair between the team leader and a wing man occurred during an arrival display at NAS Lakehurst NJ. The boss, the pilot of the other F-4, and a Chief Petty Office in the backseat of one of the F-4s were killed. The other Chief Petty Officer riding along was able to eject successfully.

1974-1986, A-4F: After the Lakehurst disaster with the F-4Js, the benefit versus the cost of the team was questioned at the highest level of the Navy. The debate was resolved in favor of continuing but not with the fuel-guzzling and accident-prone Phantoms. The Grumman F-14 Tomcat was deemed too expensive. The Vought A-7 Corsair II was or was not favored, depending on who is telling the story, but in any event was in short supply as the more capable strike replacement for the Douglas A-4 Skyhawk. Not only was the A-4 available, the latest variant, known as the Super Fox, had a very good thrust-to-weight ratio with its uprated J52 engine in addition to an excellent roll rate. After control system modifications, bolting up the aerodynamically actuated slats, removing unneeded equipment, and adding a smoke system and a braking parachute, it proved to be an excellent air show airplane in addition to being relatively simple and easy to maintain. Its diminutive size, relatively low approach speed, and excellent handling qualities allowed the Blues to land with all six aircraft in formation.

1987-present, F-18: By mid-1985, considering that the A-7, the A-4’s replacement in the fleet, had itself been replaced, the Blues were overdue for a change of airplane. However, options included an A-4 service life extension program as well as the new trainer, the McDonnell T-45A based on the British Aerospace Hawk. However, the Navy once again had a set of airplanes, Lot IV production McDonnell F-18A Hornets that did not have the landing gear modifications necessary for carrier operations. The F-18 required control system modifications in addition to the usual weight reduction removals and unique Blue Angel show requirement additions like a smoke system and inverted fuel system capability. The conversion to a more complicated airplane was accomplished between seasons in part by retaining the same pilots, some of whom would normally be replaced, in order that there would be no pilots who would be learning both the Blues maneuvers and the characteristics of a modified F-18. The reinstatement of an airplane with afterburners added to the crowd appeal and maneuver options.

Unlike past two-seaters operated by the Blues, the F-18B could fill in as part of the diamond if required.

In the last year or so, the Blues have begun to replace their As with the newer C model, newer being relative since the last C built by McDonnell was delivered in 1999. The Bs were to be replaced by Ds. Hopefully, the changeover to "new" aircraft will allow the Blues to continue to be a powerful recruitment tool and good-will ambassadors for the U.S. Navy for many years to come.

NATF: Better is the Enemy of Good Enough

2011-04-23T16:13:00.002-04:00

Once upon a time, the Navy was developing a plan to replace the F-14 and the A-6. The Air Force needed to replace the F-15 and the F-111. In 1986, Congress essentially directed that the Navy’s fighter be the Air Force’s Advanced Tactical Fighter (ATF), its F-15 replacement, and the Air Force’s strike airplane be the Navy’s Advanced Tactical Aircraft (ATA). its A-6 replacement. The Air Force planned to buy 750 ATFs and the Navy, 618 NATFs.

The Air Force and its contractors had been planning the replacement for the F-15 for several years. A formal requirements document was first issued in January 1973. The design studies considered incorporation of the latest advancements in structures, aerodynamics, propulsion, avionics, etc to maximize mission effectiveness, with stealth being a major differentiator.

This effort culminated in a formal competition in 1986. The Air Force selected Lockheed (teamed with Boeing and General Dynamics) and Northrop (teamed with McDonnell) to build demonstrators, the YF-22 and the YF-23 respectively.

The Navy subsequently established a three-person NATF program office collocated with the Air Force program office at Wright-Patterson Air Force Base, Ohio. In September 1988, Lockheed and Northrop received contracts from the Navy to study carrier-based derivatives of their proposed aircraft.

Carrier basing imposes specific design requirements for low-speed capability, low-speed handling qualities, over-the-nose visibility, compactness, corrosion protection, structure and hardware for catapult launches and arrested landings, etc. For example, in the case of the NATF, the Navy specified a maximum takeoff weight of 65,000 lbs and a landing weight of 52,000 lbs. (The Navy estimated that the difference in requirements would result in an NATF empty weight of 4,000 lbs more than the ATF’s and a gross weight difference of two to three times that.) It was to be no longer than the F-14 (62 ft) or take up more space when folded.

The basic mission requirements of the Air Force and Navy were also different. At the risk of oversimplifying, the Air Force ATF was to be an air superiority fighter; the Navy ATF also had to have the capability to shoot down enemy bombers before they could launch cruise missiles. This fleet air defense role required long range sensors, weapons, and endurance. It also inclined the Navy toward a second crewman, whereas the Air Force wanted a single-seat fighter.

As a result, the NATF designs only superficially resembled the land-based ATF demonstrators. The Lockheed NATF had variable-sweep wings like the F-14.

The Northrop NATF retained the basic wing planform of the YF-23 but replaced the stealthy ruddervators with a canard forward and vertical fins aft.

Nevertheless, the engines and much of the avionics and aircraft systems were to be common even if the airframe was not. The Air Force estimated that the engines and avionics represented 44 percent of the ATF’s unit flyaway cost.

The Northrop YF-23 was the first to fly, lifting off on 27 August 1990. The Lockheed YF-22 flew a month later. The development and evaluation programs ran almost concurrently, with the Air Force selecting Lockheed's F-22 for qualification and production in April 1991.

The Navy, however, had withdrawn from the program before then, citing the unaffordability of the ATF, its weight, and program schedule delays. At the point, the Admirals expected to keep the F-14 in service through 2015, giving them time to develop their own advanced fighter with minimal overlap of A-12 development expenditures. Unfortunately, the Secretary of Defense unexpectedly cancelled the A-12 program in January 1991. It had gotten unacceptably behind schedule and over weight. There was no push back from Congress on the complete failure of the joint program concept.
The Navy then had to deal with OSD's disagreement with its plans for an A-12 replacement and continued F-14 production. The result was the F-18E/F program, with the F being a two-seat variant of the single-seat E. The design was based on the so-called legacy F-18 Hornet, ironically a development of the losing airplane in the Air Force’s so-called light-weight fighter competition that was supposed to result in a common Navy/Air Force fighter.

The early retirement of the F-14 with its long-range Phoenix missile capability and the A-6 with its all-weather strike capability caused a furor in the Naval Aviation community but to no avail. The F-18E/F Super Hornet was decreed to be good enough.

It certainly was not nearly as advanced as the F-22, particularly with respect to stealth. Moreover, the Navy chose to initially qualify and deploy the first Super Hornets with less avionics capability than it was planned to have, which even then would be less than that of the production F-22. The uncharacteristic restraint, however, resulted in a development/qualification program that was essentially on cost and schedule and met the Navy's near-term need for F-14 and A-6 replacements. The first F-18Es deployed in 2001 while the F-22 was only then being approved for low-rate production, several years behind schedule. The Super Hornet went into action in Iraq in 2002; the F-22 was finally declared to be operationally capable in December 2005. Its first assignment? To guard the east coast of the United States, a mission that didn't require the advanced technology and capability it possessed. Moreover, as of today, it is likely that no F-22 has yet gone in harm’s way. The latest forgone opportunity was the requirement to establish a no-fly zone in Libya, with the F-22's stealthiness having been touted beforehand as being tailor made for the purpose. The reason for its no-show, according to an Air Force spokesman, Lt.Col John Haynes, was that "[the joint task force] needed to look realistically at the fighter assets already within Europe to execute operations...Because there are no F-22 Raptors based in the European theater, they were not included in the initial stages of the operation."

To be fair, the combat-proven Super Hornets were not employed in Operation Odyssey Dawn either. There were no U.S. Navy aircraft carriers in the Mediterranean at the time, Enterprise having departed in mid-February for the Arabian Sea.

In large part because of the F-22’s very high unit cost, its production was curtailed at only 187 aircraft. In contrast, the 500th F-18E/F /G was delivered on 20 April 2011. Production of the F-18E/F/G is currently expected to continue through 2015 and even more might be procured because of ongoing program delays with the latest joint-service fighter, the F-35. The Super Hornet doesn't have the mission capability of the F-22 or the A-12, not to mention the F-14 or the A-6, but so far it is good enough.

Bell L-39 Wing Sweep Evaluation

2011-04-16T09:42:00.007-04:00

Early in 1946, BuAer had solicited proposals for a high-speed (jet) day fighter defined by Outline Specification 105. Cdr A.B. Metsger was the fighter class desk officer. According to his unpublished memoir:

“At that time no representative airplane had flown with significant sweep. Extensive wind tunnel data, mostly captured German reports, gave us reasonable confidence at operating speeds, but there were no data to insure satisfactory low speed flying characteristics—essential in carrier operations. “

Captain Walter S. Diehl, BuAer’s chief aerodynamicist, expressed doubt to Metsger that useful low-speed data could be obtained in subscale wind tunnel testing. However, Ivan Driggs, Head of Design Research, suggested an airplane could be built for that specific purpose quickly and economically.

Metsger therefore called his contacts at four aircraft companies that he thought would be interested in building a low-speed, swept-wing demonstrator. Bell proposed a 10-week, $100,000 modification of two surplus Army Air Force P-63As; Grumman, an ugly modification of an F4F Wildcat, including a nose landing gear, and a more expensive, all-new design that included a second seat for a test engineer and the capability to be configured with both swept and straight wings.

Grumman assumed that if a swept wing were to be substituted for a straight wing on an existing airplane, it would have to be positioned further forward so that the location of the mean aerodynamic chords was not changed.

With its tricycle landing gear, the Bell P-63 already resembled a jet airplane in configuration.

The Bell-proposed approach consisted of modifying the outer wing panels to attach to the center wing stub with a 35–degree sweep and zero dihedral. In effect, this moved the wings slightly forward relative to just mounting them at the side of body but not nearly as far forward as Grumman thought was required. Bell engineering calculated that the removal of the cannon and machine guns mounted in the P-63’s nose and the ammunition along with the addition of ballast in the aft fuselage would suffice to move the center of gravity aft so that a minimal forward shift of the wings would be adequate.

Slats were considered to be a very important part of providing adequate lift with a swept wing so the wing leading edge was modified to have five separate slat sections, any of which could be configured open or closed for flight. In the following picture, the four most outboard slats are open and the most inboard one is closed.

The aft part of the canopy was closed off for research instrumentation purposes. A panel with several gauges was mounted aft of the canopy door frame with a camera to photograph it.

This setup recorded data from instrumentation including those on booms mounted on each wingtip. The wings were marked with white lines and tufted so that cameras mounted on the canopy and horizontal tail could record the direction of the air flow as the airplane was stalled.

Since only low-speed flight characteristics were to be evaluated, the main landing gear attachment was reoriented but not required to be retractable. The wheel wells were covered over. The nose gear was still retractable.

Bell had referred internally to the aircraft as the XP-63N but the Navy formally designated it L-39 on 19 April 1946. This was consistent with the Navy’s practice for research aircraft, with the L being the letter assigned to Bell by the Navy and 39 being the Bell design number, as opposed to a model number. However, the number of at least one of Bell’s L-39 flight test reports began with 33, which was the model number of the early P-63s. L-39-1 was assigned BuNo 90060 and L-39-2, BuNo 90061.* (For more on U.S. Navy research aircraft designations, click Here.).

First flight of L-39-1 was on 23 April 1946. At some point, a lighter three-bladed P-39 propeller was substituted for the four-bladed P-63 propeller and a ventral fin similar to the P-63C's was added.

Eight flights were made by 3 May, when it was briefly laid up to incorporate a four-foot plug in the aft fuselage and a large ventral fin. The plug also reduced the stabilizer incidence by four degrees, building in more nose-up trim. The changes improved the longitudinal and directional stability.

Flight tests with different slat configurations quickly established that the stall characteristics with no slats extended were very poor: no warning and an abrupt and significant roll off. With most outboard (20%) slats open, there was no improvement. With the two most outboard (40%) slats open, there was some improvement. There was significant improvement with 60% and 80% slats, with excellent stall characteristics, as well as with a 40% slat configuration with the most outboard slat closed and the next two inboard open (60%-20%) as shown here.

With 100% slats, however, the airplane response was so bad that the test pilot recommended that testing with 100% flaps “be discontinued until further wind tunnel spin data is obtained.”

L-39-2 first flew on 29 May, configured with the fuselage plug and an even larger ventral fin.

It was also equipped with an automatic fuel distribution equalizer to maintain a desired center of gravity. It was used to evaluate a slightly different slat configuration with a narrower slot.

After Bell's short development program was complete, both aircraft were made available for evaluation flights by Navy and industry pilots. At one point, L-39-1 was configured with a "good" slat configuration and L-39-2 was set up with no slats, so pilots could make back-to-back evaluation flights. Grumman test pilot Corky Meyer flew the L-39s in late June 1946: "My flight ... with no leading-edge devices was short. It cavorted like a cat on catnip during the stalls and required excessive altitude for recovery. The second ... with leading-edge slats was docile during stalls and accelerated stalls. These stalls could be done with little wing dropping and the usual loss of altitude. The two prototypes made it clear that slatted, swept wings would provide carrier-suitable flight characteristics and stall-speed performance for fighters."

Flight test and evaluation using L-39-1 was completed at Bell on 26 August 1946, after which it was ferried to NACA Langley, Virginia, for a wind tunnel and flight correlation test program.

That concluded the Navy’s participation in the program. According to Cdr Metsger: “Our flights, including simulated carrier approaches and landings, assured us that sweeping the wings would not adversely affect carrier operations. We had the data in time for our (day fighter) competition evaluation.”

L-39-2 was repurposed in mid 1946 to support Bell’s X-2 program. The wing was modified to represent a swept wing with a circular-arc airfoil and the leading edge was extended forward to the side of body.

Bell engineering failed to appreciate the aerodynamic implications of a planform change. The center of lift was shifted far enough forward that the test pilot made most of the short flight on 20 July 1946 with full forward stick. Following reballasting, including reinstatement of the heavier four-bladed propeller, it was used by Bell for low-speed handling qualities and performance evaluation of the X-2 wing. L-39-2 was ferried to NACA Langley on 11 December, where it remained for three years. In December 1949, both aircraft were reportedly transferred to NACA Lewis where they were scrapped.

For drawings and other information of interest to modelers, click Here.

*The Navy History Center lists these two BuNos as P-63s that were cancelled.

I hate it when that happens

2011-03-30T18:14:00.000-04:00

However, one of the benefits of writing to a blog is that I can readily correct errors and add new information. As an example, I've been fixing errors in the Grumman sto-wing entry off and on all this afternoon. So if you read it earlier today, you might want to look at it again...

If you have a specific request

2011-03-30T18:00:00.001-04:00

If you have a specific request rather than a compliment, correction, or addition pertinent to the topic, it's best that you send me an email rather than submit it as a comment on one of the entries. My email address is tommythomason@sbcglobal.net.

Grumman Sto-Wing Redux

2011-03-30T12:15:00.017-04:00

Click HERE to see a summary of Grumman's innovative wing-fold concept that it called the sto-wing.

Pat Donahue wrote to ask me how the aileron control mechanism spanned the large gap created when the wing was folded alongside the fuselage. He had looked at the wing-fold area of the F6F at the National Naval Aviation Museum at Pensacola without being able to determine how it was done.

Uhh - that's a good question. As it turns out, Grumman created three different ways to do it, although the original one, on the F4F Wildcat, appears to be the only one that was used on more than one Grumman design. (Click on the images for a bigger picture.)

In the closeup of the area encircled in green on the first picture, you'll see a rod coming out of the wing stub that pushes/pulls on a bellcrank that has two contact points on it on either side of its pivot point. If you then look at the inboard end of the outboard wing section in about the same location, you'll see another bellcrank that has an upper and lower arm connected by two small flat plates that correspond to the contact points on the bellcrank mounted on the wing stub. It's hard to see, but the left side (aft side when the wing is in the flight position) of this bellcrank is attached to a rod that disappears into the outer wing panel.

In other words, the ailerons are disconnected at the fold joint when the wings fold down and aft. When the wing is in the flight position, the two bellcranks have come together as a unit so the push/pull tube in the wing stub is pushing and pulling on the push/pull tube in the outer wing panel.

This would seem 1) difficult to rig without loss motion or overload of the bellcranks in compression and 2) to require some means of restraining the ailerons when the wings were folded. Perhaps in recognition of these drawbacks, Grumman used a different concept on each of its next two designs.

The TBF took me a while to figure out, although the mechanism is hidden in plain sight, right where Pat thought it should be, at the wing panel pivot axis.

The Grumman Archives came to my rescue with a maintenance manual. The TBF aileron control system changed from a push-pull mechanism to a cable system in the wing stub. Two pairs of pulleys located at the pivot axis were used to transfer the motion across the fold joint This illustration depicts the pulleys on the right wing when the wings are spread:

One pair was mounted on the outer wing panel and the other on the wing fold actuator link, with the cables crossing between the two pairs so as to not introduce any slack or tension in the cables in the folding process. All that is visible are the pulleys and cables under the link that the two wing-fold hydraulic actuators are attached to. The following illustration shows the right wing pivot axis with the wings folded, looking inboard. Note that the transition between the two sets of pulleys is on the wing pivot axis.

For the F6F Hellcat, a link between two bellcranks was used to span the gap between wing stub and outer wing panel when the latter was folded back. The bellcrank in the wing stub and one in the outer wing panel were cleverly shaped and positioned so that when the wings were folded, the control stick imparted little or no motion to the ailerons. (Note that the inboard end of the gap-spanning link was positioned on the wing pivot axis.) Wing folded:

Wing Spread:

The two concepts that did not break the connection between control stick and the ailerons when the wings were folded would appear to be more desirable, particularly the approach used on the F6F, but Grumman and/or the Navy thought otherwise for some reason. Grumman reverted to the original concept used on the F4F for its subsequent designs incorporating the sto-wing: the AF Guardian, WF (E-1) Tracer, and E-2 Hawkeye.

Steam Catapult Development

2011-03-21T10:59:00.002-04:00

As part of the British development and qualification of the steam catapult, a platform containing the hardware was added on top of the flight deck of HMS Perseus.

After catapulting deadloads at dockside in mid-1951 in initial development tests, the carrier proceeded to at-sea trials in the outer Firth of Forth, beginning with deadloads and then the catapulting of six surplus, unpiloted Seafire 47s which had the wings removed at the fold joint and just enough fuel for start, warm-up, and the launch. One reportedly took umbrage at being sacrificed in even a worthy cause and managed to climb and turn back toward the ship before crashing into the sea short of the carrier. A video survives of the testing (the Seafires were not, as stated, radio controlled):

http://www.britishpathe.com/record.php?id=29482

Perseus was subsequently sent to the U.S. for demonstrations of the steam catapult in February 1952, first dockside at the Philadelphia Navy yard and then at sea. The steam catapult allowed the successful launch of a Douglas F3D Skyknight with a 10-knot tailwind. The existing Navy hydraulic catapult required a 30-knot headwind for the same airplane weight. The Navy immediately began planning to require steam catapults in its new aircraft carriers and retrofit existing carriers that had enough service life remaining to justify the conversion. As a result, bigger airplanes with higher performance could now be carrier-based.

Westinghouse: From Hero to Zero

2011-03-21T01:21:00.006-04:00

Who would have thought that a company that didn’t even know what a jet engine was (Westinghouse) and one that had never developed a carrier-based airplane (McDonnell) could have succeeded in producing a fully operational carrier-based jet fighter on the first try during World War II? But the more experience engine and airplane manufacturers were too involved in production contracts and more conventional development programs, so the Navy gave them the assignment.

The Army got the plans for the Whittle engine, which was actually running in England, and gave them to General Electric. The Army then contracted with Bell Aircraft, an experienced airplane manufacturer, to design a land-based jet fighter using two of those engines. It was, by all accounts, a dog.

Westinghouse created its engine from scratch with no outside assistance due to the secrecy imposed. It had an axial flow compressor, which was the future, instead of the centrifugal compressor used in the Whittle engine, a dead end from the standpoint of increasing thrust significantly. The little Yankee engine, only 9.5 inches in diameter, worked well enough to demonstrate that the configuration was sound. It was originally intended to be used for thrust augmentation and one was flown under an FG-1 Corsair at NATC Patuxent River beginning in January 1944.

It was subsequently used as a target drone engine and designated J32. The Yankee was scaled up to create the J30, a 19-inch diameter engine that powered the Navy's first jet fighter, the McDonnell XFD-1 Phantom.*

The Phantom incorporated all the features necessary for carrier-basing: strong landing gear, folding wings, catapult/holdback hooks, and the tail hook. It was armed with four 20 mm cannon. One squadron operated it briefly, including carrier qualification, but the FD lacked range, cockpit pressurization (necessary for comfortable operation at the altitudes jet airplanes operated most efficiently), and an ejection seat. This required a bigger, heavier airplane requiring a more powerful engine.

So Westinghouse scaled up the J30 to create the J34. It powered the McDonnell F2D Banshee and the Douglas F3D Skyknight (which necessitated the change of the McDonnell designation from D to H, so the Phantom became the FH and the Banshee, F2H). And also the Vought F7U-1 Cutlass, with the addition of a government-furnished afterburner.

The Navy needed still bigger, more capable jet fighters so it held a competition for an even more powerful engine. Picking Westinghouse to scale its engine up again as the J40 must have seemed like a no-brainer. The J40-WE-6 was to power the A3D Skywarrior and the J40-WE-8, which was essentially the -6 with a Westinghouse-developed afterburner added, was to provide the thrust for the Douglas F4D Skyray, the McDonnell F3H Demon, and the Grumman F10F Jaguar.

Unfortunately, Westinghouse, which had been so successful up until then, failed miserably with the new engine. Development problems delayed the availability of the Navy's new fighters and long-range jet bomber, first by putting Westinghouse well being behind schedule on deliveries of engines for flight test and then by it not being able to qualify the engine for production at the necessary thrust, requiring Douglas and McDonnell to substitute other engines for the J40. A smaller version of the J40, the J46, was almost as complete a failure but it was at least put into production, albeit a lower thrust and higher fuel consumption than specified, insuring that the F7U-3 Cutlass would forever be known as "gutless."

Although production and support of the J34 continued, Westinghouse eventually exited the aircraft engine business.

Where did Westinghouse go wrong? One theory is the early successes did not result in a problem-solving culture within the engine division. Another is that the company did not continue to invest in technology and innovation like P&W and General Electric did. For example, to improve compression ratio for better thrust to weight and lower specific fuel consumption without incurring compressor stalls, P&W developed the two-spool engine and General Electric, the variable inlet guide vane concept. Westinghouse just kept scaling up the basic design, which eventually proved inadequate to the task.

* I'm not certain that the 9.5-inch engine came before the 19-inch one. There are conflicting reports in the literature. However, this version seems more plausible to me based on a close reading of the documents and reports that I have.

Transition to Martin-Baker Ejection Seats

2011-02-06T12:04:00.003-05:00

Early on, even before there were ejection seats in jets, the U.S. Navy established a relationship with Martin-Baker, a company located in England and dedicated to the development of the ejection seat. Two of its officers went there in 1945 to witness ejection seat testing. Although the Navy continued to rely on its airframe contractors to supply ejection seats when required, its specifications favored the Martin-Baker design philosophy of face-curtain activation of the seat.While it didn't buy Martin-Baker seats for various reasons at the time, it did purchase a trainer/test rig from M-B and required their airplane contractors to furnish seats that were fired with the M-B type face curtain (the Air Force used triggers located on the seat's arm rests).

The man in the fedora is James Martin, later knighted as Sir James, visiting the Philadelphia Navy Yard in August 1946 where the Martin-Baker test rig had been installed.

The early ejection seats were simply bailout assists. Even after features like automatic seat separation were added, a survivable ejection had to be initiated at least 500 feet above the ground, much more if the airplane had a high sink rate. Ejection during takeoff or final approach was not an option.

Martin-Baker was dedicated to improving the seat capability and in the mid-fifties succeeded in qualifying a seat system that resulted from a survivable ejection on the runway at speeds above 100 knots. In 1956, BuAer contracted with Grumman to install the new Mk4 M-B seat in an F9F-8T for a demonstration. Flying Officer Sidney Hughes, RAF, successfully ejected from it at Patuxent River in August 1957 while on the runway at 120 kts.

This successful demonstration resulted in a Navy contract with Martin-Baker for the Mk5 seat, which was a strengthened version of the Mk 4 from a crashworthiness standpoint. (An actuator loop was also added at the front of the seat pan to expedite ejection if required, such as an emergency during catapult launch, or when g-levels made reaching the face-curtain loops difficult.) Most in-service Navy fighters with ejection seats were changed over to the new seat, either in production or as a retrofit. It took a few years because each installation had to be developed and certified by Martin-Baker. The seats were somewhat tailored to each aircraft type, with specific identifiers in some cases, e.g. H5 for the F4H, F5 for the F8U, and P5 for the F4D (shown here).

The change over appears to have begun with the single and two-seat F9F Cougars in the training command. The first F9F-8T ejection on Martin-Baker seats was in September 1958. The first Cougar ejection was in November.

Martin-baker seats were installed in F3H BuNos 146709-146740 at the factory. The first ejections using a Martin-Baker seat from the F3H reportedly occurred in March 1958 with the last in a McDonnell seat in November 1960.

The F-4 Phantom first flew with a McDonnell seat but it was quickly supplanted by the M-B Mk 5 seat in production, probably in 1960 with the second block of production airplanes.

Vought was reluctant to admit that the M-B seat was better than its own (although they did install a M-B seat in the third F8U-3 which flew in late 1958). Its seat was a modification of the Douglas Escapac seat which also provided survivable ejection on takeoff and approach. However resistance was futile. M-B Mk-F5s were installed in F8U-2s toward the end of their production run. (Contrary to some reports, a cockpit console width change was not required, only different rails and catapult fittings plus stiffening of the bulkhead.)

LTjg John T. Kryway cut it a bit fine but survived after his hard landing on FDR in October 1961 necessitated jettisoning his F8U-1:

The FJ-4s appear to have begun to be switched over in early 1961 at the first or second major overhaul after late 1960. The first reported ejection using the Martin-Baker seat was in September 1961. If you don't have a photo of the specific aircraft being modeled, the best bet is the original seat. The earliest example that I found of a MB seat is VA-144's 3rd deployment, November 1961 to May 1962. However, there is a picture of a reserve FJ-4B dated July 1963 with the original seat.

No M-B seats appear to have been installed in F4Ds during production at Douglas, but most survivors were eventually converted to the Mk-P5 during overhaul.

One notable exception to the changeout was the F11F Tiger. A quantity of 201 seats was procured for the Tigers but they were not installed, with the exception of two F11Fs subsequently pulled out of long-term storage for an in-flight thrust reverser program.

Martin-Baker demonstrated its zero-zero seat in 1961, with the Navy procuring it in 1965 as the Mk7. The performance increase was accomplished by the addition of a rocket. The Mk 5 seat reportedly could be modified to the Mk 7.

The Mk5 and Mk7 seats are easily differentiated by the parachute housing. On the Mk5, the parachute was enclosed in a horseshoe-shaped fabric casing that was housed in a black-painted metal shell on the upper seat back. (See the F4D P5 picture above.) On the Mk7, the parachute was enclosed in a green composite horseshoe-shaped shell mounted on the upper seat back.

The changeover to the Mk 7 seat began in early 1968. The first F-4Js were produced with Mk 5 seats and then retrofitted, as were F-4Bs. (The last RF-4Bs were also reportedly delivered initially with the Mk 7.) The F-8J conversions from F-8Es included the installation of the F7 seat. The Hs (rebuilt F-8Ds) after mid 68, and all Ks (rebuilt F-8Cs) and Ls (rebuilt F-8Bs) models were also delivered with the F7 seat.

The Conception of the F8F Bearcat

2011-02-04T23:56:00.004-05:00

The interweb would have you believe that the F8F Bearcat resulted from a Grumman evaluation of the Focke-Wulf Fw 190 accomplished in early 1943, possibly even at Grumman's facility at Bethpage on Long Island, New York.

There is a report of a captured FW 190 arriving at Wright Field, Ohio in August 1943. However, it seems very unlikely that it would have passed through Bethpage first for an evaluation by a Navy contractor, although I'm sure that it would have been a closely held secret if it did.

As best I can determine, the F8F originated with a memo from Roy Grumman to Chief Engineer Bill Schwendler dated 28 July 1943 requesting a predesign of a small fighter built around the most powerful R-2800 engine available and providing some additional guidelines. It was reportedly the result of previous discussions between those two dating back to at least late 1942.

A predesign drawing by Dick Hutto dated 20 August 1943 indicates that the basic size and shape, including a bubble canopy, of the Grumman G-58 were well established by then.

The story that seems more credible (and supported by contemporaneous documentation) is that Grumman's Bob Hall and Bud Gilles went to England in September 1943 to fly a captured Fw 190. I haven't seen Hall's report, but they were undoubtedly impressed by its speed and maneuverability. It seems likely that they would have returned to Bethpage with the intent to match, if not exceed, its performance and handling qualities with the new Grumman fighter.

It therefore seems almost certain that the basic philosophy that shaped the F8F was not this flight evaluation but the result of 1942 combat experience in the Pacific vis-a-vis the Mitsubishi Zero and the need for a small fighter that had better performance than the F4F Wildcat to operate from the small decks of the newly created escort carriers.

The Navy ordered prototypes of the G-58 in November 1943 and designated it the F8F. The first one flew only nine months later, in August 1944. Deliveries of the first production aircraft were made in February 1945.

However, the first air group equipped with F8Fs arrived in the Pacific just days too late to participate in the war. (In fact, it was first Navy carrier-based aircraft initiated after Pearl Harbor to get that far; most were canceled before reaching fleet squadrons.) Within a few years, it was supplanted by jet fighters and relegated to a training role.

The F-111B versus the F-14A, One More Time

2011-01-27T19:53:00.004-05:00

I recently had the incentive to revisit this diatribe in the process of responding to a request from another author about the F-111B program. As before, this assessment was made using the respective Standard Aircraft Characteristics charts, the F-111B’s dated 1 July 1967 and the F-14A’s, dated April 1977. While the argument can be made that the F-111B SAC did not reflect its final weight, I believe that that same argument can be made concerning the one used for the F-14A, so it’s at least a pretty close apples-to-apples comparison. Note: In the following discussion, the F-14A is penalized with the weight of an internal gun and ammunition whereas the F-111B is penalized with the weight of the original Airborne Missile Control System (AMCS) design, roughly the same.

Much has been made of how terribly overweight the F-111B turned out. And it was, compared to a totally unrealistic specification. Many think that the F-14A was far lighter than the F-111B, primarily because most comparisons neglect to do so using the F-111B’s design mission for both aircraft. The F-14A is still lighter, of course, because the Navy changed its requirements so that it would be. Deleted were the escape capsule, bomb bay, and swiveling wing pylon stations among other things. The Hughes Airborne Missile Control System, given a few more years of development, was lighter. The structure was designed for 6.5 gs at 49,548 lbs, about 10,000 pounds less than the F-111B’s design gross weight at that g level. In effect, the six Phoenixes and 3,800 lbs of fuel were treated as an overload for the design of the F-14A structure. At combat weight (13,800 lbs fuel and six Phoenix missiles) the F-111B therefore had a load limit of 5.8 g and the F-14A (12,000 lbs of fuel and six Phoenix missiles), a lower (but not particularly constraining) 5.2 g. The result, however, is a somewhat lower structural weight for the F-14A.

According to the F-111B SAC, when it was loaded with full internal fuel and six Phoenixes, it weighed 77,566 lbs and required 11 knots wind-over-deck on a tropical day for launch; the F-14A, not surprisingly, weighed almost 7,000 lbs less but, surprisingly, required 16 knots wind-over-deck. However, at its takeoff gross weight the F-111B was carrying 3,000 lbs more fuel than the F-14, making the difference in takeoff gross weight for the same fuel and weapons load only 3,866 lbs, or 5%, not exactly the amount or percentage difference that most would have guessed given all the negative publicity garnered by the “Sea Pig.” With that additional fuel, the F-111B could loiter on station for 1.5 hours with the combat fuel allowance assuming an acceleration to 1.5 Mach; the F-14A with the two external tanks of overload fuel, and with the same combat Mach number (one has to read the SACs very closely), could only loiter for 1.1 hours.

As for landing, they were both heavy. In fact, the maximum arrested landing weight limit of the F-14A precluded it from landing back aboard with all six Phoenixes, whereas the F-111B had a 5,000 lb margin, all fuel, between its maximum landing weight and the landing weight with the standard landing fuel load of 2,417 lbs of fuel and six Phoenix (56,980 lbs). One does not need to be a Naval Aviator to appreciate being able to land with three times the required fuel. On a tropical day at the standard weight, the F-111B needed 15 knots wind-over-deck for landing; the F-14AA could only land with five Phoenix, and even then needed 17 knots wind-over-deck at its maximum landing weight of 51,830 lbs. The F-111B was also less of an handful following an engine failure since its engines were not as widely separated as the F-14A’s.

This is not to say that the Navy didn’t do the right thing in getting the F-111B program cancelled and replacing it with the more versatile F-14, particularly since the Hughes AMCS wasn’t ready for prime time. However, with respect to its Fleet Air Defense design mission, it got an airplane that could not loiter as long or land with its full complement of missiles, had a higher stall speed at a lower weight, required more wind-over-deck for takeoffs and landings, and was more difficult to bring aboard with two engines running, not to mention with one inoperative.

So which is the real "Sea Pig" then?

My answer is neither of the above. The F-111B could do, pretty much, the Phoenix-based Fleet Air Defense mission that it was intended to do while weighted down with Air Force low-level supersonic mission and other requirements. The F-14 could not do the FAD mission quite as well - but well enough if needs be - and it did the carrier Navy’s other, equally important, fighter missions much better.

Updates to Prior Posts

2011-01-19T19:18:00.000-05:00

11 January 2011: Expanded discussion of nuclear weapon delivery technique, "Not Doing It Right", posted 5 June 2008.

The Gift That Keeps On Giving - Final Chapter

2011-01-19T19:17:00.003-05:00

The Supreme Court has heard arguments on the dispute over who owes who how much in the settlement of the 1988 contract between the Navy and its contractors, General Dynamics and McDonnell Douglas (now Boeing), to develop the A-12 Avenger. See Here for the New York Times report. The decision is expected this summer.

For my prior blogs on this long running, multimillion-dollar gift to the legal profession over a multibillion-dollar claim and counterclaim, see here , here, here, and here.

Catapult Development

2011-01-19T15:41:00.002-05:00

The basic concept of the aircraft carrier catapult hasn't changed much over the years. The airplane is fitted with something to hook it to the catapult and something to hold it back under full throttle until the catapult is activated. The hold back is designed to break (or nowadays release) when the airplane is being pulled forward at a force somewhat greater than that provided by full power and the catapult shuttle being pulled forward to tighten the hookup. However, the details have changed significantly.

Before World War II, although carriers were fitted with catapults, takeoffs were usually accomplished by a deck run rather a catapult launch. It was quicker and to a small extent safer since catapult failures were not unknown. However, as airplanes got heavier, requiring more distance to take off, and more of them were crowded on deck, resulting in less distance for a takeoff run, the catapult launch became more the rule than the exception.

The catapult bridle (two attach points on the aircraft) or pendant (one attach point) was considered disposable. It simply dropped from the aircraft and fell into the sea off the bow after the launch. It's not clear whether there was an alternative hookup during the war which retained the bridle/pendant on deck.

However, at some point the bridle/pendant was retained on deck by means of a heavy elastic strap that was attached to both the bridle/pendant and the catapult shuttle. After a certain number of launches or visible damage, the bridle/pendants were disposed of, either by a launch without a retainer when it was one launch short of the limit or being dropped over the side if damaged. This is an S2F which used a pendant.

It appears that there was little commonality among aircraft with respect to launch gear, including hold backs, particularly the strength of the "weak links" that broke when the catapult fired.

My guess is that pendants were more desirable than bridles from the deck crew's standpoint because they were lighter but bridles may have been necessary on some airplanes to accommodate a slightly off-center lineup.

Still later, somewhat after the introduction of the angled deck and the steam catapult, "bridle catchers" were added ahead of the catapult on some carriers. It appears that on those carriers without bridle catchers, the previous practice of using elastic straps to retain the bridle/pendant on deck was no longer used and it was disposed of with each launch.

The bridle arrester lanyards were attached to the bridle and a track on the deck parallel to the catapult track.

The bridle rig wound up on the bridle catcher following launch and were retrieved with the shuttle.

The bridle/pendant hookup process was somewhat labor-intensive, time-consuming, and dangerous. It also relied on the skill of the catapult crew for a proper hookup. In this case, the sailors who are going to hook up the hold back are lying on the deck. The bridle is lying on the deck already looped around the shuttle.

The solution was the integration of the launch and hold back hardware on the nose landing gear. Beginning with the Grumman E-2 Hawkeye, all new carrier-based airplanes were to be designed with this capability. The first at-sea E-2 launch was accomplished on 19 December 1962 from Enterprise, the first carrier equipped with the nose tow capability.

The holdback is now reusable, although a specific one is required for each aircraft and are color coded accordingly.

Note that only one sailer is required in close proximity to the aircraft using the nose tow concept.

The Truculent(?) Turtle

2011-01-02T19:34:00.013-05:00

An acquaintance recently asked me why the Lockheed P2V-1 Neptune that set a distance record in late 1946 was called the Truculent Turtle when the name on its nose was just "The Turtle". Moreover, the cartoon character on the nose, a turtle smoking a pipe and pedaling the propeller-driven equivalent of a unicycle, was anything but truculent.

In many places (copies of the Wikipedia entry), the interweb incorrectly states that "With time, the aircraft has come to be called 'Truculent Turtle'..." In fact, in press releases before the flight, the Navy was already referring to it as The Truculent Turtle as evidenced by a New York Times article dated the day that the flight began.

The name The Turtle and the cartoon character doubtless originated with the Navy/Lockheed plan, "Operation Turtle," to counter the publicity being garnered by the Army Air Force with long-range B-29 StratoFortress flights, one setting the long-distance record in November 1945. The Navy was concerned that the President and Congress might well overvalue the Army's ability to deliver the newly demonstrated atomic bomb and underfund the Navy's ship and airplane programs. "Turtle" was probably used by the engineers in recognition of the fact that the maximum-range cruise speed of a propeller-driven airplane, even high performance fighters, is slower than most people would think, only about 150 knots or 170 mph. They can cruise at higher speeds, of course, but not go as far.

The addition of Truculent was probably belated recognition that The Turtle did not convey the impression of long-range weapon delivery capability that the Navy wished to make with this record-setting flight even though this was not its stated purpose.

It was, no question, a publicity stunt. Few if any airplanes were as modified for speed records as The Turtle was for the distance record. Lockheed removed as much equipment as possible to minimize the empty weight and parasite drag and then added as many fuel tanks as there was space available until the aircraft gross weight was almost 50% greater than the maximum allowed operationally. In addition to new tip tanks, there were additional tanks in the outboard wing panels, the forward fuselage, and the aft fuselage. The standard internal fuel capacity of the P2V-1, not counting auxiliary tanks in the bomb bay, was 2,350 gallons. The Turtle's fuel capacity, including bomb bay tanks, was 8,541 gallons, well over than three times more.

Hal Andrews collection via Jim Sullivan (The lower radome was removed prior to the record flight and the tip tanks were dropped when empty.)

In order to accommodate an engine failure shortly after takeoff, a fuel jettison capability was developed to fairly quickly reduce the airplane's weight. The tip tanks were simply dropped. The fuselage tanks were ganged to a dump station manned by one of the relief pilots during the takeoff. In theory, once the P2V had climbed to 1,000 feet above the ground, he could empty those tanks while maintaining the center of gravity within an acceptable range and thereby reduce the gross weight to that permitting a climb before they lost more than 800 feet.

Even a new, well-broken-in piston engine burns oil. The engine oil capacity was therefore increased by 64 gallons. The oil in the tank added in the nose wheel well was pumped manually as required to one or the other of the standard 78-gallon tanks located in each engine nacelle.

Four JATO bottles were added for the takeoff. These minimized both the length of the takeoff roll and the time it would take to reach the minimum single-engine control speed. Another change was the substitution of heavier duty main landing gear tires because of the higher takeoff speed required at the higher gross weight. The resulting takeoff roll was 4,700 feet on a 6,000-foot long runway. (The normal takeoff distance was less than half that.)

JATO Takeoff Test at Lockheed Burbank

The takeoff from Perth, on the west coast of Australia, was made at dusk local time. One reason given was the desire to begin at night to allow celestial navigation. However, as plane commander CDR Thomas D. Davies admitted to the press before takeoff, a far more important consideration was minimization of the level of turbulence likely to be encountered. At its design gross weight of 54,000 pounds, the P2V was designed for a limit load factor of 2.6. At a takeoff weight of 85,500 pounds, the structure was theoretically capable of being loaded to only 1.64 gs before being damaged. Of course, catastrophic failure of the structure was not supposed to occur before a 50% higher load was encountered, with the likelihood that it would sustain even more than that, but it was best to avoid turbulent conditions until some fuel had been burned off.

It would take almost 60 hours to burn this much fuel at the maximum range cruise speed. To reduce weight, the crew therefore consisted of only four pilots instead of the regular crew of eight, with two resting and two flying at any given time. The flight was not uneventful. The crew had to deal with bad weather crossing the equator northeast of Australia, turbulence and icing in the western US, and unexpected headwinds. The stated destination prior to takeoff was Seattle, Washington*, which would have set the record, but it seems clear that they intended to fly as far as they could, preferably all the way to Washington, D.C. However, after reviewing their fuel status and approaching Columbus, Ohio they prudently decided to land there after 55 hours in the air rather than pressing on to Anacostia where officials and family were waiting. That would set the record at 11,236 statue miles, almost halfway around the world.

New York Times

The flight had the hoped-for impact and specific comparison with the Army Air Force B-29 flights. On 2 October 1946, a New York Times editorial stated "The 7,916-mile record that it shattered was that made by the Army's Boeing Super-Fortress Dreamboat. A plane like the P2V can carry an atomic warhead from any point on the earth's surface to a point half-way round the globe."

Of course, the Times neglected to note that delivering a bomb to a target 12,000 miles away would be a one-way trip for a P2V, it couldn't be a very big bomb (the crew debated the last-minute addition of a 37-pound kangaroo), and the enemy would have a couple of days to get ready...

*Seattle, Washington was on the great circle route to Washington, D.C. as shown here.

The great circle route is the shortest distance between two points on the globe, which does not appear as a straight line here because it is the depiction of the globe with a Mercator projection. However, winds aloft might (and did) dictate a deviation from this line, which on a long flight is established by a concept called pressure pattern flying (feel free to Google that). Moreover, the reported weather in Seattle dictated a mid-flight deviation to the south as shown on the map of the actual route of flight.

And Now For Something Completely Different

2010-12-29T19:59:00.013-05:00

This is yet another work in progress. There's a lot of conflicting information about the Piasecki HRP on the interweb although it's mostly just the details. I'm still doing fact checking and any documentation from contemporaneous sources would be very much appreciated.

The Coast Guard was responsible for helicopter development during World War II. One of their concerns was the rescue of the crew from a ship that had been sunk by German submarines off the U.S. east coast. Existing helicopters were too small to carry more than one or two rescuees. The Coast Guard wanted one that could carry eight in addition to a crew of two.

At the time, based on experience with autogiros, it was believed that the empty weight of a single rotor helicopter as a percentage of gross weight would increase with rotor diameter so quickly that large single rotor helicopters would have no payload capability. Frank Piasecki, a young engineer who had just flown his first helicopter, convinced the Coast Guard and the Navy that the answer was a single-engine, tandem-rotor helicopter. He got a contract for a prototype in February 1944.

The first flight of what was designated the XHRP-X, Bureau Number (BuNo) 37968, was made in March 1945, little more than a year after go-ahead. It was powered by a 450-hp Continental R-975 radial engine and subsequently referred to as the Dogship at Piasecki. Unique features in addition to the tandem rotors were the castering wheels intended to minimize side loads in a touchdown with sideward motion; the pilot sitting aft of the front pylon (the copilot sat directly behind him); and the bottom of the forward fuselage being "skinned" with clear plexiglass panels for downward vision. Unlike subsequent tandem-rotor helicopters, the rotors did not overlap.

The XHRP-X was featured in this late 1945 newsreel as the "World's Largest Helicopter!". Following its successful development and demonstration, Piasecki received a production order for 10 HRP-1s in June 1946 and another 10 in April 1947.

The Dogship is currently stored at the Smithsonian's Paul E. Garber Preservation, Restoration, and Storage Facility located at Silver Hill, Maryland.

A second prototype, with a more powerful P&W R-1340 engine and probably assigned BuNo 37969, followed with a first flight in March 1947. It had a modified aft fuselage without as much side area, possibly to reduce weight. Stability problems resulted in the addition of a small horizontal stabilizer and vertical fins.

The first production HRP-1 flew in September 1947 and was delivered later that year. The last of the total order of 20 was delivered in 1949. These were initially used by the Marine Corps to develop tactics for vertical assault and by the Coast Guard for its ongoing helicopter search and rescue development.

The surviving HRPs were then used by the Navy for the development of dipping sonar and airborne minesweeping. Eventually a portion of the small fleet was acquired by civil operators from military surplus.

The first production HRP-1, BuNo 111809, that was at the New England Air Museum is currently being restored at Piasecki Aircraft Corporation in Essington, Pennsylvania for eventual display at the American Helicopter Museum in West Chester, Pennsylvania.

The HRP-2 utilized the same drive train and engine as the HRP-1 in an all-metal fuselage. The pilot and copilot now set side by side ahead of the front rotor mast. First flight was on 10 November 1949. Only five were produced. They were initially used by the Marines along with the HRP-1s and then all of the -2s were assigned to the Coast Guard. It was clear that they were underpowered with the same 600-hp engine installed in the HRP-1.

At least one surplus HRP-2 was procured and operated by Rick Helicopters, then the largest civil operator of rotorcraft, in the 1950s.

The Air Force and subsequently the Army recognized the value of the basic design for their emerging helicopter missions, however, and ordered modified versions of the HRP-2 as the H-21 with more powerful Wright engines with up to 1,425 horsepower.

The Davis Barrier, One More Time

2010-12-10T22:43:00.006-05:00

For background and other information on the Davis barrier, see the following entries.
22 September 2008
1 October 2008
26 September 2009
4 October 2010
One of these days, I'll combine all this into one entry.

The FJ-2 and -3 Furies had a retractable barrier pickup device located aft of the nose gear wheel well. This insured that the activated barrier cable did not fall back down before it engaged the airplane's main landing gear struts. (It was subsequently removed from at least the -3s when the angled deck eliminated the need for the Davis barrier.)

There is a similar, albeit non-retractable, device on the belly of the Grumman S2F. I had assumed that it performed the same function, but it turns out that it corrected a different problem related to the Davis barrier function.

The initial S2F Davis barrier qualification at Naval Air Material Center (NAMC) had actually been accomplished with an F7F that had been modified with tubing shaped to simulate the S2F-1 belly. Surplus F7Fs were plentiful and surplus S2Fs, not. Moreover, in the interest of minimizing cost, nose-high, off-center, and lifter strap run-down by a dual nose wheel landing gear (the F7F had a single nose wheel) were not evaluated.

In early 1954, during one of the first S2F squadron carrier qualification periods aboard Siboney (CVE-112), a pilot failed to lower his tail hook, which wasn’t noticed by anyone on the LSO platform as it should have been. This guaranteed a trip into the barriers. The airplane also engaged nose high, which didn’t help matters. Things went badly after that. The cables didn't engage the left main landing gear as they should have. The nose gear failed when the airplane pitched down and the right wing was torn off when the airplane was yanked violently around by the engagement of only one landing gear strut by the barrier cable.

S2F-1 BuNo 129146 was therefore assigned to NAMC to provide a more representative test article for a series of more comprehensive tests. It was catapulted, unmanned, into a Davis barrier at speeds from 35 to 70 knots in five-knot increments. Normal, nose-high, and nose-low engagements were made as well as at 17 feet off of centerline. A total of 129 shots were accomplished between 30 May and 23 November 1954 to develop a configuration that provided a higher likelihood of a benign barrier encounter.

One of the problems encountered was that on a nose gear with two wheels, a lifter strap could conceivably be caught between them, preventing the lifting of the barrier cables. The S2F also had a relatively short wheelbase and a wide tread, which meant the cable might not always rise high enough across the width of the tread in time to engage both landing gear struts. If only one strut was engaged, a violent yaw resulted as it had in the Siboney incident.

S2F changes established during the testing included the addition of four pairs of small detents on a strengthened nose wheel door so the actuator strap would not slip down, affecting the rise of the barrier cable. The nose gear strut torque arms were modified and the tow fitting between the wheels was extended forward to reduce the likelihood that a lifter strap would be trapped between the nose wheels. A slanted fairing was also added ahead of the catapult hook so there was less likelihood that the cable would be deflected downward and not engage the main gear struts.

Most importantly, a cable scoop, the “Fosdick,” was added on the bottom of the fuselage. Unlike the one on the FJ-2/3, it was not just there to keep the barrier cable up off the deck. It was primarily there to reduce the drag loads of the barrier cables on the landing gear and the violent yaw that would result if only one main landing gear was engaged by the cables, assuming that the cable scoop was engaged as well.

Here is an early S2F, flying with one engine shut down and the propeller feathered. Note that the only protuberances on the belly ahead of the retractable radar dome are two radio antennas and the catapult hook.

This is the belly of the S2F after the addition of the detents on the nose gear door, the fairing ahead of the catapult hook, and the cable scoop.

The existing main landing gear "scoops" were also modified to be more effective at diverting the cables onto the struts.

Steve Ginter is working on an S2F-1 monograph for publication in his Naval Fighters series.

Once Upon A Time

2010-12-08T18:01:00.005-05:00

I rediscovered an interesting report in the Vought archives this week, Notes on Comparison of Carrier and Land-based Fighter Airplanes Incorporating Folding Wingtips dated 21 March 1952 and authored by John H. Quinn Jr. I had previously copied it from the George Spangenberg collection in the National Archives but hadn't taken the time to examine it closely.

The folding wingtips aspect of it was only of passing interest to me because it was never incorporated on a produced design, at least not for the original purpose, which was to provide a high aspect ratio wing for cruise flight with the wingtips lowered and a low aspect ratio wing for combat maneuvering with the wing tips raised as shown in the following artists concept.

Vought submitted an unsolicited informal proposal to the Navy for the V-381 which incorporated the feature in September 1952. The Navy passed, having already given Douglas a contract for the A4D Skyhawk.

The report, however, addressed a more pressing issue, which was the Navy's need to achieve performance parity with land-based jet fighters. Three predesigns were accomplished for the study: a carrier-based airplane designed to the existing limitations, a land-based airplane, and a carrier-based airplane taking advantage of relaxation of the existing limitations.

"It was assumed the airplanes were powered with a single J67W-1 engine... and were designed to combat radius of 600 nautical miles, approximately." The J67 was the designation of the Curtiss-Wright license-built Bristol Aero Engines Olympus; it was projected to provide 21,500 lbs of thrust. The mission radius was, of course, selected to highlight the cruise benefit of the folding wingtip feature.

At the time, carrier airplanes had to be designed for launch from the existing hydraulic catapults and recovery using the Mk 7 arresting gear; tactical airplanes, as opposed to the big nuclear bombers, could not be any longer than 56 feet (for straight spotting on Essex-class elevators) or taller than 17 feet and more than 24.4* feet wide when folded. (The folded height and width were Essex-class hangar deck constraints.)

Although there was no dimensional restriction on the land-based airplane, it was required to operate from a 5,000-ft runway with the takeoff roll not to exceed 3,000 feet. (Sounds short, but according to the F-100A Standard Aircraft Characteristics chart, it had a ground roll of 2,970 feet at its maximum gross weight of 29,000 lbs.) It was also required to have a combat ceiling of 55,000 feet as another constraint on wing loading. (The F-100A was bit short on that and woefully short of the range, not having folding wingtips.)

Because of the lift and size limitations imposed by the existing carrier-basing ground rules, the first carrier-based design was predicted to be 200 knots slower than the land-based one at 35,000 feet, about Mach 1.7 and 2.0 respectively. Analysis indicated that only two of the carrier-basing imposed constraints, takeoff wing loading and overall length, were the cause of the difference. The newly invented steam catapult was projected to eliminate the wing loading penalty; diagonal spotting was suggested to allow for more length and provide a better fineness ratio for less drag. The result was parity of performance with land-based airplanes. (It was recognized that the longer airplane would result in fewer being accommodated aboard, a shortcoming for carrier-basing.)

Navy Length and Wing Area Constrained

Air Force Land-Based

Navy Diagonal Spotting and High Wing Loading

As it happened, the F8U-1 achieved parity (even superiority) with the F-100, also powered by the P&W J57, based on the benefit of the steam catapult alone. (It was just within the 56-foot length limit.) The F8U-3 exceeded 56 feet in length by a little less than three feet but it had Mach 2 performance in part due to the rediscovery of the area rule by Whitcomb in 1952; it too had performance parity with the land-based J75-powered fighters.

*The maximum folded width was in the process of being increased to 27.5 feet, in part perhaps to allow the Douglas A4D Skyhawk to go below without having to fold its wings.

F-111B Colossal Weight Improvement Program

2010-11-19T18:30:00.001-05:00

This assessment is based almost entirely on a 1/50th scale model in the Grumman History Archives on Long Island.

The empty weight proposed for the F-111 was even more optimistic than usual in winner-take-all paper competitions. As is customary, Grumman and General Dynamics initiated a two-pronged F-111B weight reduction study effort, the Super Weight Improvement Program and the Colossal Weight Improvement Program, even before first flight. Roughly speaking, the ground rules for the SWIP were to reduce the weight but not significantly depart from the design and mission requirements. The CWIP allowed a great deal more flexibility, basically tossing out anything imposed only by the Air Force low-altitude strike mission and preferences like the crew escape capsule.

For the CWIP configuration, Grumman engineers deleted the bomb bay and escape capsule and reduced the volume required for the main landing gear by not allowing for the large low-flotation tires required for operation from unprepared fields. That enabled them to shorten the forward fuselage by about five feet. The shorter forward fuselage presumably allowed them to delete the ventral fins, with the original vertical fin now adequate for directional stability even at high angles of attack. However, the horizontal stabilizers were slightly increased in size, presumably for improved low-speed handling qualities for the carrier approach.

All six Phoenix missiles were now carried on the fuselage, four semi-submerged and two on short pylons on the lower sides of the fuselage. This arrangement eliminated both the wing pylons and swivel mechanisms required to keep the missiles aligned when the wings were swept. I haven't yet found any information on the main landing gear configuration change required by putting two missiles on the centerline of the belly, but presumably it resembled that on either the Grumman F11F Tiger or the North American A3J Vigilante.

The center fuselage with the engine inlets and wing mounting structure were basically unchanged except for the main landing gear bay. The wings were also unchanged. The engines appear to have been moved forward by about two feet to restore the center of gravity after the nose was shortened.

Although the canopy appears to be bulged upwards, my preliminary assessment is that the visibility over the nose was no better than it was on the original F-111B, which was determined to be unsatisfactory. However, the lower weight would have resulted in a lower angle of attack for the same lift, possibly providing the same over-the-nose visibility improvement as the raised cockpit that was eventually required.

The government program team elected to incorporate most if not all of the SWIP changes in the 12th F-111A and the 4th F-111B. The CWIP specification changes stayed on the drawing board until Grumman was able to apply them to what became the F-14.

One if by Land, Two if by Sea

2010-11-04T19:37:00.008-04:00

“One if by land, and two if by sea.” That line from Longfellow’s poem commemorating Paul Revere’s famous ride in 1775 was one of the justifications used by the Navy in 1976 to select the twin-engine McDonnell F-18 over the single-engine F-16 for its VFAX program. Some viewed it as dissembling on the Navy's part since the desirability, much less necessity, for twin-engine carrier-based aircraft had not been very evident up until then. In fact, although single-engine airplanes were in the minority in the air wings at the time, that was a relatively recent change from past practice. A year earlier there was still an air wing aboard Hancock (CV-19) that was almost entirely comprised of single-engine aircraft. Now, of course, there are no single-engine airplanes in the carrier air wings.

The major benefit of twins, the capability to return to base after an engine failure, was initially problematic for a carrier-based airplane. The pilots approached power-on in level flight at the lowest safe speed and minimum altitude, cutting the engine just when the airplane would settle onto the deck. This was essentially the same technique used for a short-field landing ashore, where it assured a touchdown very close to the approach end of the runway, allowing the maximum distance for stopping.

The pilot of a twin-engine propeller-driven airplane with one engine inoperative had to take into account the minimum control speed in that situation. Since the engines were almost always placed out on the wing, when one failed the other produced a significant turning moment which had to be counteracted by the rudder. Since rudder effectiveness varied with airspeed, at some point the pilot could no longer stop the airplane from turning with the engine at full power. What’s worse, the turning generated a roll because of the difference in the lift on the wing on the outside of the turn versus the one moving slower on the inside. Since the ailerons also lost effectiveness with decreasing airspeed, a loss of control in roll would result as well if the engine power was not immediately reduced.

Unfortunately, the minimum-control speed at the power required to climb with the gear and flaps down was almost certainly higher than the required approach speed dictated by arresting gear, which made a successful wave-off an iffy proposition.

The tyranny of minimum-control speed was also imposed on an airplane taking off, but it was more draconian at sea than ashore. If the pilot taking off from a runway lost an engine while still below minimum-control speed, he would simply close the throttle on the good engine and reject the takeoff. The outcome varied with the length of the runway and if it came to that, the landscape beyond its end, but was rarely as dire as faced by the pilot of an airplane less than one hundred feet above the sea after being launched from an aircraft carrier at less than the minimum-control speed with full power on the operating engine. If he reduced power on it engine to maintain control, he almost certainly would not have enough for level flight, much less to climb or accelerate to a speed at which he could use all the power available.

Having a second engine was therefore not as good a deal for a pilot flying from an aircraft carrier as it was for one flying from an airport. Although it enabled one to divert to a land base or get back to friendly ships and ditch if an engine was lost in flight, it doubled the risk of an engine failure during a critical, albeit short, time during takeoff and landing. Twin-engine airplanes also tended to be bigger than singles whereas compactness was a virtue on an aircraft carrier.

Nevertheless, there were benefits beyond the ability to continue flight after an engine failure. The easy way to improve the performance of fighter airplanes is to incorporate more powerful engines in new or existing designs. Increasing power in piston engines basically meant adding more and/or bigger cylinders and supercharging. By the late 1930s, the engine manufacturers were beginning to approach the limits of existing technology and incremental horsepower increases were resulting in increasingly smaller increases in speed and greater engine complexity. The obvious next step was the twin-engine fighter, a doubling of power available without requiring the time and expense of a new engine development.

The U.S. Navy solicited proposals for a twin-engine carrier-based fighter in 1937 but none of the submittals were deemed to be acceptable. In 1938, the Navy had Lockheed modify an Electra Junior to have a fixed tricycle landing gear and tail hook. It was designated XJO-3 and delivered in October 1938. On 30 August 1939, Navy pilots made 11 takeoffs and landings from Lexington (CV-2) to evaluate it from both twin engine and tricycle landing gear standpoints.

In parallel with this research program, the 1938 competition for a new fighter was opened to both single and twin-engine designs. This time, the Grumman design number G-34 was considered worthy of evaluation by the Navy as the XF5F along with single-engine designs from Vought, the XF4U-1 powered by the big new P&W R-2800; and Bell, offering a derivative of the Army Air Forces P-39, the XFL-1.

The XF5F, probably in consideration of the one-engine-inoperative requirement, had the engines mounted as far inboard as possible and twin vertical fins, one in each engine’s slipstream. One-engine-inoperative wave offs were evaluated at altitude: "(A wave-off) might be accomplished (on one engine) provided the airspeed is about 80 knots or more and no more the 1/2 power on the operative engine were used." The "proper" approach speed based on stall speed, however, was defined as about 74 knots.

In spite of having as much or a little more installed horsepower than the XF4U, the XF5F was slower and couldn’t climb as high although its rate of climb through 20,000 feet was essentially the same. As a result, the Navy elected to proceed with the F4U for development and production. Nevertheless, the Bureau of Aeronautics continued to be interested in a twin-engine carrier-based fighter. On 30 June 1941, Grumman received a contract for the two XF6Fs and two XF7Fs. The F7F program suffered from the priority on F6F Hellcat development but the prototype Tigercat finally flew for the first time on 3 November 1943.

As soon as Grumman test pilots flew the XF7F-1, they realized that it did not have a big enough fin and rudder for an acceptable minimum control speed in the event of an engine failure on takeoff or a wave-off. Design of a bigger fin and rudder was initiated and introduced on the F7F-3. Although all models of the F7F were carrier qualified, the likelihood of and/or concern about a successful single-engine wave-off must have been low as there was no description of the technique for a single-engine carrier landing in the flight manual. In any event, the Tigercat never deployed with an air group on a carrier, probably due to its size as much as anything else.

One of the Navy’s first carrier-based jets, the McDonnell FD-1 Phantom was a twin, mainly because the Westinghouse-provided engine wasn’t very big. It grew to become the F2H Banshee, the first twin-engine airplane to regularly deploy on carriers. Two of its contemporaries, the Douglas F3D Skyknight and the North American AJ Savage, were also multi-engined. The AJ had three engines, two turning propellers and a jet. Like the F7F Tigercat, the Skynight was primarily operated by the Marines and made very few deployments. The Savage did deploy because of its critical mission of long-range nuclear strike, but because of its size, it generally was held in readiness at nearby Naval air stations during a carrier’s deployment. These jets were less limited from a minimum control speed standpoint in the event of a one-engine-inoperative situation than previous twin-engine propeller-driven airplanes because the engines were located close to the centerline; the AJs were slightly better off if one of its piston engines failed because the jet engine was located on its centerline.

However, North American was concerned about minimum control speed as evidenced by the size of the AJ’s original fin and rudder, made even bigger because carrier basing necessitated a fairly short airplane. Unfortunately, the rudder proved to be too big for high speed flight and resulted in a fatal accident when it broke the tail off in a flight test maneuver. The empennage was redesigned to increase the size of the fin, reduce the size of the rudder, and delete the dihedral in the horizontal stabilizer.

The lack of U.S. Navy concern about engine failures in the late 1940s was evident by the initiation of single-engine airplane programs, the Douglas F4D Skyray and the McDonnell F3H Demon, to replace the twin-engine all-weather Banshee. It was still true in 1958, when the Navy had to choose between the single-engine Vought F8U-3 and the twin-engine McDonnell F4H. The safety record of twin versus single-engine airplanes was examined and determined to not be a deciding factor. In fact, the only twin-engine airplane in the deployed carrier air groups at the time was the Douglas A3D Skywarrior, which had two engines because it was too big to be powered by only one. The F4H was selected because it had a dedicated radar operator, not because it had two engines.

The Navy did regularly deploy one twin-engine propeller-driven airplane at sea for more than two decades beginning in the mid-1950s on axial deck carriers, in part because Grumman had learned a lot about operating twin-engine airplanes from aircraft carriers with the F7F program. Its S2F (S-2) was as short-coupled as carrier airplanes get, so in order to size the rudder both for the single engine takeoff and wave-off condition and—relatively speaking—high-speed flight, it had a two-piece rudder. Up and away, the forward portion of the rudder was just used for directional trim and only the aft portion of the rudder moved with the rudder pedals. For takeoffs and landings, the forward and aft portions of the rudder could be selected to move as a unit, doubling the width of the rudder and reducing the S2F's minimum control speed to one suitable for carrier launches and wave-offs.

The introduction of steam catapults, angled decks, and descending, constant angle of attack approaches also reduced the degree of difficulty of one-engine-inoperative takeoffs and landings. By the time Grumman engineers designed the F-14, they felt confident enough in their handling qualities analysis to widely separate its engines to provide a "tunnel" where two of the big Phoenix missiles could be carried.

However, minimum control speed would still prove fatal to the unwary: Hultgreen Crash

Finally, click HERE for a great tale of how a second engine and a naval aviator saved an airplane...

Blog Index

2010-10-04T15:02:00.000-04:00

See July 2010 for an index of blog entries 1-99.

Barriers and Barricades, One More Time

2010-10-04T13:54:00.010-04:00

I recently read an excellent history of a carrier-based airplane but noted that the author, in the captions, did not bother to differentiate between barriers and barricades. It is a minor quibble, but the nomenclature is specific and illustrates a two-step set of changes to carrier-deck equipment forced by the introduction of jet airplanes, one element of which was retained on angled-deck carriers.

Barrier

Davis Barrier

Barricade

The original barrier was introduced at the very beginning of carrier operations to stop an airplane when its tail hook had missed all the arresting wires. First one steel cable and then two were strung across the deck about three feet high at each barrier station. They were attached to stanchions which could be folded down to place the cables on the deck so airplanes could taxi past the barriers. An operator was stationed at each barrier to raise and lower it.

The steel cable barriers were very effective.

Unfortunately, the original barriers were not safe to use to stop airplanes with nose landing gears and to some extent, with twin-engine airplanes. The steel cables would wipe out the nose landing gear, raising the potential for the cables on the next barrier forward to slice the canopy off the airplane, and with it the pilot's head.

There was also the potential on a twin-engine propeller-driven airplane for the nose gear to pull the cable forward, allowing a propeller to hit it an angle and cut it, rather than skip off of it and past it. A tightly stretched steel cable when cut could wreak all kinds of havoc.

The Davis barrier solved those problems by having the cables laying flat on the deck. A canvas strap was strung across the deck about three feet up using the same stanchions used for the original barrier. When the airplanes nose gear hit the horizontal strap, vertical straps between it and the cables pulled them up off the deck to engage the main landing gear, thereby stopping the airplane. There were about six or so barriers on a carrier, so some were rigged for props and some for jets. They could also be reconfigured or replaced fairly quickly. Four barriers are shown in this picture, two prop (lying on the deck) and two jet/AJ (Davis), one that has been activated but didn't snag the main landing gear because the jet had hooked a late wire so was going too slowly (barrier operators were cautioned not to drop their barriers too quickly) and the other in the ready position.

The Davis barrier worked fine after some development, although it was recognized that if the airplane were going too fast when it hit the Davis barrier, the cables might not be pulled up high enough, fast enough so they didn't get above the main landing gear tires and snag the landing gear struts before the main landing gear had passed by. There was also a problem with the steel cables being cut by airplane appendages at the higher landing speed of jets as well as pilots defeating the purpose of the barrier with a late and unsuccessful wave off as pictured above. After a few incidents in the fleet with jets not being stopped by the Davis barrier, a really big canvas net hung from scaled-up barrier stanchions was introduced as the last-chance layer of protection for the men and aircraft forward of the landing area. This was the barricade.

With the advent of the angled deck, barriers were no longer required. However, the barricade was still necessary if a jet had a landing gear or tail hook problem and couldn't land ashore. It is only rigged when required and the deck crews periodically practice erecting it on short notice and in only a few minutes.

XF2D-1/F2H-1/F2H-2 Fuel System

2010-09-29T18:38:00.005-04:00

Today I read an article in an English modeling magazine by a well-known aviation history author who repeated the error that the F2H-2 fuselage was longer than the F2H-1's, whereas the length increase actually occurred between the XF2D-1 and the F2D-1 (F2H-1). I decided to fix that on Wikipedia as a public service. In the process of doing so, I also fact-checked statements about the fuel capacities of the three airplanes. That's when I discovered that I had only resolved part of the length error that continues to be promulgated.

At the time of the XF2D-1 mockup review, its Standard Aircraft Characteristics (SAC) chart dated 1 May 1945 lists the fuel capacity as 510 gallons internal plus a 345 gallon external tank. Unfortunately, there were no drawings on this SAC chart. However, the length was given as 38' 9.5". The external tank was probably similar to the one provided for the FD-1 (FH-1) as shown here in November 1948.

A month later, an addendum page was added providing the "effect of mock-up changes on XF2D-1 preliminary data sheets dated 1 May 1945": "Subsequent to the distribution of the XF2D-1 data sheets, mock-up board recommendations revised the fuel system to eliminate the external droppable tank and provide instead an increase in internal protected fuel capacity from 510 to 847 gallons."

The XF2D-1 SAC chart dated 1 June 1946 shows an overall length of 38' 11.5", an increase of only two inches. The total internal-fuel capacity shown is the required 848 gallons, including the two tanks in the stub wings that presumably was 90 gallons of the more than 300-gallon increase required. I would guess that the fuselage was deepened from the mock-up configuration to provide most of the rest.

Note that there are three large fuselage tanks, again similar to the FD/FH fuel system configuration.

According to the SAC charts, the F2H-1 internal fuel capacity was increased by only 29 gallons over that of the XF2D-1. What's a little confusing is that the 1 April 1948 F2H-1 SAC chart page for Armament & Tanks is identical to the one above for the XF2D, almost certainly an error in compiling the SAC chart since the correct fuel quantity of 877 gallons is listed on its Page 1. (Each tank has a small but different capacity, with the largest difference being the aft tank at 223 gallons instead of 198.) Another oddity is that this SAC chart lists 200-gallon tip tanks for the F2H-1, whereas it's clear from the Pilot's Handbook for the F2H-1 dated 1 October 1949 and the F2H-2 SAC dated 1 November 1949 that the F2H-1 did not have provisions for tip tanks. Note that the F2H-2 SAC page for Armament & Tanks once again uses the XF2D artwork although it has been updated to show the -2 tip tanks and label each fuselage fuel tank with its correct volume without changing the size or shape of the tanks from the original XF2D illustration.

Not withstanding all that, the revelation to me is that the increase in fuel system capacity does not account for all or even most of the fuselage length increase ahead of the engine inlets between the prototype XF2D and the production F2D (F2H). A net increase of 31 gallons in the three fuselage tanks (the wing stub tanks were reduced in capacity by one gallon each) requires a net increase in length of the tanks of only about five inches, not 12. The remainder may have resulted from the need for additional interior volume for equipment and/or the desire to increase the fineness ratio of the fuselage and canopy to reduce drag. A center-of-gravity correction can't be ruled out, either.

A-12, The Gift That Keeps On Giving, IV

2010-09-28T23:50:00.002-04:00

The Supreme Court has agreed to hear part of the A-12 appeal by Boeing and General Dynamics. (See here, here, and here for the background; the case status is provided here.) Note that they are limiting their review to the Fifth Amendment issues and not reviewing the termination for default issue.

Sep 28 2010 Petition GRANTED limited to Question 2 presented by the petition. The petition for a writ of certiorari in No. 09-1298 is granted limited to Question 1 presented by the petition. The cases are consolidated and a total of one hour is allotted for oral argument.

09-1302 BOEING COMPANY V. UNITED STATES
DECISION BELOW: 567 F.3d 1340
LOWER COURT CASE NUMBER: 2007-5111, 2007-5131
QUESTION PRESENTED:
1. Whether the Due Process Clause of the Fifth Amendment permits an appellate court to adopt a new legal rule, inconsistent with its own prior ruling in the same case, and then apply it retroactively to the record established in the trial court pursuant to the prior ruling, without remanding to afford the parties the opportunity to prove their case under the new rule. 2. Whether the Due Process Clause of the Fifth Amendment permits the Government to maintain a claim while simultaneously asserting the state secrets privilege to bar presentation of a prima facie valid defense to that claim. 3. Whether the Government may terminate a government contract for default on the ground that a contractor has failed to make adequate progress toward timely completion of that contract where the Government has not set a valid deadline for completing the contract.
CONSOLIDATED WITH 09-1298 FOR ONE HOUR ORAL ARGUMENT
09-1298 LIMITED TO QUESTION 1
09-1302 LIMITED TO QUESTION 2
CERT. GRANTED 9/28/2010

The 27 Charlie

2010-09-05T17:05:00.008-04:00

Some ship guys who know a lot about aircraft carriers don’t know all that much about carrier-based airplanes. Similarly, some carrier-based airplane enthusiasts are likely to be equally ignorant about aircraft carriers in spite of their best efforts, as in my case.

For example, I have sometimes referred to any angled-deck Essex/Ticonderoga-class* carrier as a 27 Charlie. The nickname comes from the SCB (Ship Characteristic Board) design number for a set of Essex-class carrier modifications that began to be defined in the late 1940s, when the Navy realized that a major upgrade program was needed to allow them to operate jets, which had to be launched and recovered at higher speeds, and larger attack aircraft.

While doing some fact checking for my Skyhawk book for Specialty Press, including trying to figure out why a hangar-deck illustration appeared to show two starboard deck edge elevators on an Essex-class carrier (see here), I discovered that I was in error. As it turns out, the SCB 27 modifications added more powerful catapults and arresting gear, a reinforced flight deck, larger centerline elevators with additional lift capability, a new island, and an increase in the aviation gasoline storage capacity, among other things, but not the angled deck or starboard deck edge elevator. The first nine modified were 27As with the new H-8 hydraulic catapult and the final six were 27Cs (hence the Charley nickname) with the even newer and more powerful C-11 steam catapult, the most significant difference between the two upgrades. The nine 27As and three of the six 27Cs were completed and placed into service as axial deck carriers; the addition of the angled deck was accomplished in a subsequent overhaul period. (Only one SCB 27 carrier, Lake Champlain, did not eventually receive the angled deck.)

Not, strictly speaking, a 27 Charlie (Kearsarge)

A 27 Charlie (Ticonderoga)

(Note that the shape of the forward elevator and the aft location of the starboard elevator mark it as a 27 Charlie but an Essex-class carrier with a rectangular forward elevator and the starboard elevator located more forward might also be one of the 27 Charlies.)

In short, of the 15 (including Antietam) Essex/Ticonderoga-class carriers with angled decks, there were only six 27 Charlies: Intrepid (CVA-11), Ticonderoga (CVA-14), Lexington (CVA-16), Hancock (CVA-19), Bon Homme Richard (CVA-31), and Shangri La (CVA-38).

The last three (Intrepid, Ticonderoga, and Hancock) of the six 27Cs modification were completed with the angled flight deck, so-called hurricane bow, and a starboard deck edge elevator replacing the aft centerline elevator. These modifications were the major part of SCB 125, which was then applied all but two of the carriers updated by SCB 27A and 27C. (These three were also unique in that the starboard deck edge elevator was located farther aft than on the other three 27Cs or any of the 27As subsequently modified in accordance with SCB 125, hence the hangar deck illustration mentioned above showing two locations for that elevator.)

The 27 Charlies are also distinguished by a 70-foot long forward elevator. However, the three modified at Puget Sound (Lexington, Hancock, and Shangri La) were originally completed with the standard SCB 27 54-foot forward elevator for some reason, with the 70-foot version being retrofitted at some point.

More than half of the angled-deck Essex-class carriers were therefore 27 Alphas plus the SCB 125 changes. One, Antietam (CVA-36), was neither a 27A or C but it was modified with an angled deck for an evaluation, which resulted in SCB 125. The starboard deck edge elevator was not incorporated. Antietam was eventually relegated to a training role.

Strictly speaking, it is not even correct that all angle-deck carriers with steam catapults were 27 Charlies. The first carrier to be modified in accordance with SCB 27A, Oriskany (CVA-34), had its hydraulic catapults replaced with steam catapults in the late 1950s when the angled deck was finally added to it. This was the unique SCB 125A configuration. From a capability standpoint, it was equivalent to the other 27 Charlies.

For much, much more on the subject of the development and description of U.S. Navy aircraft carriers, I recommend Dr. Norman Friedman's excellent U.S. Aircraft Carriers: An Illustrated Design History, Naval Institute Press, 1983, ISBN 0-87021-739-9.

* The most significant difference between the so-called Essex and Ticonderoga classes, if I understand correctly, is that the Ticonderoga-class had the upper part of the bow extended slightly to accommodate a second quad 40 mm cannon emplacement just in front of and below the flight deck. This gives rise to the categorization of short hull (Essex) versus long hull (Ticonderoga) ships; they were the same length at the waterline and the flight decks were essentially the same size.

The Best F8U-3 Monograph Now Available

2010-08-11T15:00:00.002-04:00

Not too bold a claim, since as far as I know, it's the only one. However, it's got a lot of stuff in it on the F8U-3 and the Grumman D-118 that I'm sure you've not seen as well as coverage of the fly-off between the F8U-3 and the F4H. You can order it from Steve Ginter here or from Sprue Brothers here.

No matter how long I procrastinate before turning in a manuscript and illustrations, something always shows up after it's too late to include. In this case, the go-to guy for F3D stuff, Paul Bless, sent me an email with the following additional information:

I believe that the heads-up display in the F8U-3 was one of the first in a combat aircraft. It was developed by the Autonetics Division of North American Aviation and test flown in F3D-2M BuNo 127028, which was assigned to the Dallas BAR (Bureau of Aeronautic Representative) in 1956 through about 1960 when it was transferred back to Point Mugu.

VX Squadrons

2010-07-23T15:06:00.005-04:00

The history of Navy VX development/evaluation squadrons is complicated and inadequately documented but I've attempted to summarize it. An example of complication is VX-3. In its first (and brief) incarnation, it existed to evaluate helicopters and develop operational procedures for them.

The aircraft evaluated by the second VX-3 couldn't have been more different, although it even used the same tail code initially.

VX-3 was one of four new air development squadrons (VX) that the Navy formed in 1946 to develop and evaluate aircraft tactics and techniques as directed by a command that was a consolidation of fleet units doing development work. (In December 1947 this command was designated the Operational Development Force.) Other squadrons were subsequently added. In 1969, the surviving Air Development Squadrons became Air Test and Evaluation Squadrons.

The first VX squadrons had two-letter tail codes with the first letter being X. In 1957, the first letter of the east-coast-based VX squadrons was changed from X to J.

VX-1 (XA/JA) Anti-Submarine Warfare: VX-1 was originally an Aircraft Experimental and Development Squadron established at NAS Anacostia in Washington D.C. on 13 August 1942. A detachment for aircraft antisubmarine warfare development was established at NAS Quonset Point, Rhode Island on 1 April 1943. This detachment was the basis for the next VX-1, which was commissioned on 15 March 1946 and moved to Boca Chica Field, NAS Key West, Florida. VX-1 relocated to NAS Patuxent River in September 1973 and is the only one of the original four VX squadrons still in existence.

VX-2 (XB/JB) Drone Controller/Guided Missile Development: Established at NAS Chincoteague, Virginia in 1946 from elements of Task Group 1.6. VX-2 was disestablished circa 1958.

VX-3 (XC) Helicopter Development: Established at NAS New York on 1 July 1946 and moved to NAS Lakehurst. It apparently didn't take long to sort things out because the first VX-3 was disestablished on 1 April 1948. Its personnel and aircraft were assigned to one of two utility helicopter squadrons HU-1 (UP) and HU-2 (UR) located on the west coast and east coast respectively.

VX-3 (XC/JC) was reincarnated in November 1948 at NAS Atlantic City to accomplish development and evaluation of jet fighter tactics and procedures. It was formed by merging VF-1L and VA-1L of Light Carrier Air Group 1L. VX-3 was relocated to NAS Oceana, Virginia before NAS Atlantic City was decommissioned in July 1958. It was disestablished on 1 March 1960.

VX-4 (XD) Airborne Early Warning Development was established with the personnel and aircraft of VPB-101 on 15 May 1946 at Floyd Bennett Field, New York, flying PB-1Ws (B-17Gs with APS-20 air search radar installed in place of the bomb bay). The squadron made the first hurricane surveillance flight using radar in September 1946. It relocated to NAS Quonset Point, Rhode Island, in September 1946. It subsequently moved to NAS Patuxent River in July 1948 and was reportedly redesignated as Airborne Early Warning Squadron 2 (VW-2) in June 1952.

VX-4 (XF) Air-Launched Guided-Missile Development: Established 15 September 1952 at Point Mugu, California. It was disestablished on 30 September 1994 as part of the consolidation with VX-5 to form VX-9.

VX-5 (XE) was commissioned on 18 June 1951 at NAS Moffett Field, California. The squadron was initially assigned the development and evaluation of aircraft tactics and techniques for delivery of special weapons (nukes) from AD Skyraiders in all-weather conditions. In July 1956 VX-5 moved to the Naval Air Facility, China Lake, CA, since much of their test effort had involved use of the ranges and instrumentation facilities there. Semi-permanent detachments were located at several other bases Over the years, VX-5 maintained detachments at other Navy bases, e.g. at NAS Whidbey Island, WA to monitor EA-6B developments. VX-5 was formally disestablished on 29 April 1994 as part of the consolidation with VX-4 to form VX-9.

VX-6 (XD/JD) Antarctic Program Support: Established at NAS Patuxent River, Maryland on 17 January 1955 and subsequently relocated to NAS Quonset Point from which it deployed to the Antarctic from October to February each year. It was redesignated as VXE-6 in January 1969. Before Quonset Point was closed in 1974, the squadron was relocated to Naval Air Weapons Stations Point Mugu, California, where it was disestablished on 27 March 1999. (At some point, possibly associated with the move to the west coast, the tail code became XD again.)

VX-7 I haven't found anything on a squadron operating as VX-7.

VX-8 (JB) The Oceanographic Airborne Survey Unit was established on 1 July 1965 at NAS Patuxent River. It was redesignated VX-8 on 1 July 1967 and became the Oceanographic Development Squadron, VXN-8, on 1 January 1969. It was disestablished on 1 October 1993.

VX-9 (XE) was formed at China Lake from the consolidation of VX-4 and VX-5 directed by the CNO in June 1993 as a cost reduction measure. It was established on 30 September 1994. It evaluates strike warfare airplanes, weapons, and tactics, to include electronic countermeasures, from an operational standpoint.

HMX-1 was established in on 1 December 1947 at MCAS Quantico, Virginia for the development of amphibious assault via vertical envelopment. In September 1957, it acquired the additional role of presidential transportation via helicopter.

In early 2002, only three "X" squadrons remained: VX-1, VX-9, and HMX-1. Five more were added on 1 May 2002 as a result of redesignations of existing units:

   The aircraft test and evaluation squadrons at Patuxent River were redesignated as VX squadrons;

      VX-20 (Force) Naval Force Warfare Aircraft Text Squadron (VP, VS, VAW, VX, VR, and VT aircraft)

      HX-21 Naval Rotary Wing Aircraft Test Squadron (for some reason, this squadron does not mark their aircraft with a tail code)

      VX-23 (SD) Naval Strike Aircraft Test Squadron

   Two existing Naval Weapons Test Squadrons were also redesignated:

      VX-30 (BH) Naval Weapons Test Squadron at Point Mugu

      VX-31 (DD) Naval Weapons Test Squadron at NWAS China Lake

Navy Research Aircraft Designations

2010-07-20T21:34:00.002-04:00

In addition to its descriptive designation system for operational aircraft, the Navy had one for research aircraft, at least following World War II. It evolved to be the combination of the Navy’s letter for the manufacturer and the manufacturer’s internal design number for the project.

One of the first Navy research aircraft was the concept demonstrator for the Vought F5U program. The Navy designated it V-173, the Vought model number, and it was so marked along with the assigned Bureau Number (BuNo). The V-173 apparently predated the formal adoption of the research aircraft designation convention because U was the Navy’s letter for Vought, not V.

The Navy's next research aircraft program was initiated in 1945 with Douglas for high-speed research aircraft. This was intended to be a three-phase effort, with the first phase being design, manufacture. and flight test of a set of transonic jet airplanes; the second, modification of two of the six Phase 1 airplanes with auxiliary rocket engines for higher speed; and the third, a mockup of an operational jet fighter. Early on, Douglas and the Navy tore up the original plan. The first phase resulted in three D-558-1 identical straight-wing Skystreaks. The second phase was an all-new swept-wing aircraft. It received the designation D-558-2 and a different popular name, Skyrocket. Note that its Douglas model number was almost certainly not 558. The third phase of the contract was cancelled.*

The next Navy research aircraft program resulted in two Bell P-63s modified with swept wings in early 1946. These were designated L-39-1 and L-39-2, with L being the Navy’s letter for Bell and 39 in this case being the Bell design number for the proposal. (Design numbers were assigned by Bell engineering independently of model numbers, which were assigned by management). As it happened, Bell never assigned a model number to the Navy’s L-39. However, at least one of Bell’s L-39 flight test reports began with 33, which was the model number of the early P-63s.

The Navy bought three of the Kaman synchropter model 225s for evaluation in 1950, assigned them BuNos, and gave them the designation K-225, which also was the Kaman designation.

In January 1951, Convair received a contract for two experimental jet fighter seaplanes, which the Navy designated Y2-2. This is the cleanest example of the convention, since Y was the Navy’s letter for Convair and 2-2 was Convair’s model number. These were redesignated XF2Y-1 later that year.

The Navy contracted with Kaman for a tiltwing STOL ground test article (half of the wing, one engine, nacelle, and prop) as the K-16 in 1956. In January 1958, this contract was amended to add the design and manufacture of the K-16B, which consisted of the K-16 wing and a Grumman JRF fuselage. It never flew but was tested in the NASA Ames 40X80 wind tunnel in late 1962. A K-16C proposal with a Kaman HU2K helicopter uselage and fixed wing aircraft empennage did not result in a contract.

The Goodyear Inflatoplane was evaluated at NATC circa 1959/1960 in an Office of Naval Research Program. Five Goodyear GA-468s were reportedly acquired by the Navy for test but I don’t know if it ever got a BuNo or a Navy designation.

* The cancellation of the third phase of the Navy/Douglas high-speed research program did not preclude the uninformed from subsequently applying the designation D-558-3 to a follow-on study accomplished by Douglas for the Navy, the Models 671, as well as to its proposal for the Air Force/NASA/Navy X-15 program, the Model 684. It was, in effect, a retroactive nickname, one not used by Douglas at the time, much less the Navy.

D-671 D-684

Index for Entries 1-99

2010-07-19T16:10:00.009-04:00

For the hundredth post on this blog, I decided to create an index of blogs 1-99, since I have trouble remembering what I’ve done and some of the entry titles aren’t very helpful. I've added links for your convenience. Note that the titles here may differ from the blog entry.

For a more modeler-oriented blog, see Tailhook Topics.

Launch
   Real Men Don’t Need Catapults (F4D) 3 November 2008
   Hangar Deck Catapult 17 November 2008
   Hydraulic vs. Steam (F4D) 10 January 2009
   Nose Gear Launch Bar 27 April 2009
   Bridal Launch (F2H/A3J) 28 April 2009
   High Angle of Attack (F7U-1) 27 May 2009
Landing
   Davis Barrier Development 22 September 2008
   Davis Barrier Redux 1 October 2008
   Barrier Cable Pickup (XFJ-2) 26 September 2009
   Most Accurate Aviation Movie Ever? 10 November 2008
   Ramp Strikes 20 April 2009
   The Tail Hook (F11F) 20 September 2009
   Landing Stress (F8U) 3 October 2009
   LSO
   The Tail Hook (FR-1/XF4D) 12 October 2009
   The Tail Hook (F7U-1) 14 October 2009
   Vertical Fin Markings 10 December 2009
   Beware of Propellers 21 January 2010
Spot Factor and Folding
   Wing Folding (F4F) 13 March 2010
   A-7 Vertical Fin Modification 18 June 2009
   A-6 Folding Horizontal Tail 19 June 2009
   Spot Factor Summary (V-383) 22 June 2009
   A4D Wing Span 28 June 2009
   XF3H Angled on Elevator 30 June 2009
   Hangar Deck Height
       AJ Savage 13 March 2010
       F9F Panther 21 March 2010
   Maximum Folded Wing Span 11 July 2010
   Folded Wing Span History 14 July 2010
   Hangar Deck Folded Width Constraint 2 July 2009
   SCB 27C Forward Elevator I 5 March 2010
   SCB 27C Forward Elevator II 9 March 2010
Weapons
   Not Doing It Right (Idiot Loop) 5 June 2008
   Antiaircraft Bombs 20 June 2008
   Torpedo Attack Geometry 24 July 2008
   Torpedos (Tailhook Topics)
   TDN/TDR Control Plane 19 September 2008
   Folding Fin Air-to-Air Rockets
      XF4D/XF3H 12 June 2009
      F8U 20 December 2008
      A4D 11 June 2009
   AD-4N with torpedo 15 March 2009
   Nuclear Weapons (F2H) 4 November 2009
   Laser Guided Bombs 7 September 2009
Air Group Composition
   Saratoga (CV-3) 1930s 26 March 2009
   Midway August 1952 (F7U-3/XFJ-2) 26 February 2010
   Lake Champlain 1954/5 (VC squadrons) 29 November 2009
   Hornet 1957 23 March 2009
   Saratoga January 1958 4 December 2008
   Forrestal 1960 (F8U-2/A3J/F4H) 12 April 2009
Other
   Area Rule (F11F/F8U) 15 February 2009
   Boundary Layer Control 12 December 2009
   Turboprop Fighters (A2D) 9 February 2009
   General Purpose Fighter (F3H) 2 June 2009
   Self Boarding
       XF3H 2 June 2009
      Production F3H 21 May 2008
   1946 Long Range Escort 20 April 2010
   1948 Jet Bomber Competition 24 December 2008
   RATs
       F8U 26 January 2009
       XF4H 2 February 2009
   Akron and Macon 19 July 2009
   Strike from the Sea
      Errata I 31 July 2009
      Errata II 9 August 2009
   Unpainted Finish 20 December 2009
   V for Volplane? 4 April 2010
Engines
   Supercharging Makes a Difference 25 May 2008
   The Navy and Liquid Cooled Engines 10 June 2008
   Turbofan Engines (F-111B) 8 March 2009
Specific Airplanes
   Bell HSL Monograph Announcement 19 May 2008
   Bell XFL-1
      Carrier Suitability Evaluation 4 July 2008
      Monograph Announcement 6 September 2008
   Douglas “D-558-3” 20 May 2008
   Douglas AD Longevity 21 May 2008
   Douglas A4D
      With A3D Pathfinder 4 April 2009
      All-Weather (A4D-2N) 6 April 2009
      Book Announcement 27 June 2010
      Why 27 ft 6 inch Wing Span 11 July 2010
   General Dynamics A-12
      Lawsuit Status I 3 June 2009
      Lawsuit Status II 27 November 2009
      Lawsuit Status III 12 July 2010
   Grumman WF-2 Prototype 10 July 2008
   Grumman F10F
      Flight Controls 19 January 2009
      Variable Incidence Wing 14 July 2009
   Grumman Single Seat A-6 [VA(L) competition]
      Mockup 23 August 2008
      Artists Concept 14 June 2009
A-6 Folding Horizontal Tail 19 June 2009
   Grumman F12F 16 September 2008
   Grumman F-111B
      Monograph Announcement 19 May 2008
      Carrier Trials 3 March 2009
Engine Inlets 8 March 2009
   Martin Model 245 Long-Range Bomber 17 July 2008
   Martin Model 246 Attack Airplane 2 August 2008
   McDonnell F2H Banshee Misstatements 29 December 2008
   McDonnell F4H (F-4)
      Engine Selection 9 September 2009
      Lift Improvements 20 November 2008
   FJ-4/F8U (Navy Day Fighter Specification) 20 October 2008
   North American FJ-5 Monograph 6 December 2008
   Vought XF4U-1 (400 mph?) 10 October 2008
   Vought AU-1 20 March 2009
   Vought F7U-1 16 December 2008
   Vought General Purpose F8U 31 October 2008
   Vought F8U-3 15 December 2008
   Vought Attack Crusader (A-7) 17 August 2008
   Vought A-7 27 August 2009

Fitting In III

2010-07-14T11:55:00.002-04:00

One of the interesting aspects of the maximum folded span of 27 feet six inches that set the wing span of the Skyhawk was that it was two feet less only a few years earlier.

I haven't made a complete review of folded spans but of the early jets, the biggest by far (not counting the FJ-1 and F6U that did not have folding wings but were to use a retractable nose gear feature to reduce the spot factor) was the Douglas F3D Skynight. Its mockup review was in April 1946 and the folded span appears to have been somewhat more than 26 feet. If this was a problem, it wasn't significant enough to be mentioned as a concern. The folded span was measured on the XF3D-1 at 26 feet seven inches and shown on the F3D-2 SAC as 26 feet 10 inches.

The XA2D-1 folded span was 25 feet six inches from the September 1947 mockup review through the production aircraft. (The AD's folded span was 24 feet.)

The Navy's report on the F4D mockup review held in March 1949 mentions that the folding scheme had originally been to manually fold the outboard four feet of each wing downward. Assuming that the wing span at the time was the same as the XF4D's, that would have resulted in a folded width of 25 feet six inches. "However, in later design studies it became apparent that the wing break would have to run diagonally instead of fore and aft. This necessitates wing folding upward. It was thought that manual folding would be unsatisfactory from an operational viewpoint, therefore power folding is required." There is no concern expressed that the folded span would be 26 feet two inches with the slats open.

By the July 1949 mockup review of the McDonnell XF3H Demon, a limit has been established. "The Board requested the contractor to study the feasibility of providing manual instead of power wing folding. The unfolded span is not a limiting factor on carrier elevator and folding would be required primarily to permit passing of aircraft on CV-9 hangar decks. Since other operational considerations such as spotting on the flight deck did not appear to be seriously affected, the Board was of the opinion that the substantial weight saved by manual wing folding would be highly desirable in an interceptor. In addition, the contractor was asked to move the wing fold outboard, but under no circumstance is folded span to be greater than 25' 4" (max allowable to permit passing of aircraft on hangar deck)."

My current guess is that there were pressures to move the wing-fold joint outboard (lower loads on the fold joint and therefore somewhat reduced weight, for one thing). Since the pinch point on the hangar deck could be avoided by foresight in positioning aircraft, the new limit of 27 feet six inches was probably established in 1952 by the longer elevators being introduced on the Essex-class carriers modified in accordance with SCB 27A that were beginning to appear in 1950 and 1951. As shown in previous posts, this folded span permitted two airplanes to be loaded on the longer elevator at the same time.

How to explain the Navy approving a folded span of 28 feet five inches for the F5D at its mockup review in 1953? Perhaps because Douglas fit two in...

A-12, The Gift That Keeps On Giving III

2010-07-12T20:10:00.002-04:00

Again, the gift is one to lawyers. When I last posted on this (27 November 2009), Boeing and General Dynamics had lost a request for a rehearing by the U.S. Court of Appeals for the Federal Circuit of its decision sustaining the government's default termination of the A-12 program. At that time, Boeing and GD announced that they would take the case to the Supreme Court.

As it turns out, you don't actually get to argue a case before the Supreme Court just because you want to. What you do is petition the Court to hear your case and the judges decide if it's worthy of their review. The Court turns down most petitions although there are reasons why it might find this one interesting, according to the contractors' lawyers anyway. (The Court might also not hear it but kick it back for the rehearing that Boeing and General Dynamics were denied.)

In Boeing's 2009 annual report, it said that it would file a Petition for Writ of Certiorari to the Court on or before March 24, 2010. As it turns out, you can look up the status of cases on the Court's docket. Boeing did file on 23 April. The United States government was to respond on 27 May. It did not however, requesting and receiving extensions on roughly a month-by-month basis. The latest response date is 20 August.

If the Supreme Court decides not to hear the case, Boeing and General Dynamics each have to pay about $1.5 billion in unliquidated progress payments and interest on the payments. On the other hand, if the Court does hear the case and decides that the U.S. Court of Federal Claims got it right in March 1998, then they each get almost $600 million.

If you want to follow all this excitement on your own, go Here.

Fitting In II

2010-07-11T19:22:00.000-04:00

I still haven't found out what set the maximum folded span at 27' 6" in the early 1950s. Before then, folded spans for the jets varied somewhat but were almost always less than 27 feet. Exceptions were the big strategic bombers (the AJ, A2J, A3D, and A3J) as well as the Douglas F5D, which had a folded span of 28' 5". I had thought that it might have been set by a pinch point in the middle bay of the Essex-class carrier hangar deck:

However, if that pinch point dictated the width that allowed an airplane to be towed past another one that was parked to one side there, then the maximum folded span would be about 25 feet—which perhaps not coincidentally, was the wing span of the first predesign sketch of what became the A4D—not 27' 6".

The Navy's contractors paid close attention to the size constraints. As previously noted, the McDonnell XF3H-1 was 59' 4" long, which maximized its fineness ratio but required it to be carefully positioned at an angle on the forward elevator of the Essex-class carrier. The Navy did not like that.

As a result, the F4H was initially 56 feet long, giving 1 foot of clearance at the nose and tail so it did not have to be angled. (Note that the folded span is 27' 6" inches!)

Of course, the F4H nose got two feet longer with the introduction of the bigger radar dish during development but it turned out not to matter, because the Phantom was never deployed on the Essex-class carriers.

As an indication of the attention that the contractors paid to spotting in predesign, here are two pages from Vought's 1952 proposal for what became the F8U Crusader. The V-383, which was powered by the Pratt & Whitney J57, has a folded span of only 22' 6", but was more than 54 feet long, so only 25 could be accommodated on the forward or aft 200 feet of an Essex-class carrier compared to 27 of the slightly smaller and lighter V-384s, which was powered by the Wright J65. Note that two V-383s can be positioned on the forward elevator without being angled.

For some reason, the shorter V-384 had a greater folded span. However, because it was slightly smaller overall, a slightly different spotting arrangement (three versus four abreast) resulted in an increase of two airplanes that could be parked in the 200 foot by 96 foot area. The greater folded span did require the V-384 to be angled on the elevator if two were to ride it at the same time.

Why 27 feet 6 inches? Redux

2010-07-11T09:55:00.004-04:00

In my 28 June 2009 post, I speculated that the A4D's span was set by the 58-ft length of the Essex-class forward elevator after the angled-deck conversion. Too conveniently, 27.5 feet times two plus one-foot clearance between the aircraft and the edge of the elevator equaled 58 feet. What I didn't realize was that the forward elevator was only open to the hangar deck on its aft side, the narrower one, so the Skyhawks loaded athwartships couldn't be moved unless the wheels were on dollies.

The correct loading is shown here and I've also revised the June post.

However, even before I realized my blunder with respect to access to the hangar, I had been bothered as to why the 58-foot long elevator was used as the criteria, since it was the biggest centerline elevator, introduced with the SCB 27A change. Most were smaller. The centerline elevators on the Essex before conversion were 48 feet by 44 feet; those on the Midway class before conversion had a maximum dimension of 54 feet. It turned out that the 27 feet 6 inches was consistent with the original Essex elevators when the aircraft were positioned athwartships and headed at each other. (This was probably established before the slats were reintroduced in the configuration, but since they were easily stowed, the lack of one-foot clearance with the slats extended was not a problem.)

Of course, the Skyhawks still had to be positioned fore and aft on the forward elevator and angled for loading and unloading, but they fit. Note that angling was undesirable because of the extra time it took for positioning and the added risk of a crunch...

A-4s Forever!

2010-06-27T06:50:00.000-04:00

I'm almost done with my next book, Scooter, for Specialty Press. It's a history of the development, production, and usage of the A4D (A-4) Skyhawk. Because of the time it takes to convert a manuscript and 400 illustrations into a handsome hard-cover book, it won't be available until early next year. However, here is one of those illustrations to provide you with an idea of the breadth and depth of coverage:

Oh, Never Mind...

2010-04-20T01:03:00.000-04:00

In 1946, both the Air Force and the Navy realized that they needed to develop long-range escort fighters to protect the strategic bombers in the next war, if it came to that. Neither service was actually successful in that regard, but the Air Force's efforts to develop parasite fighters (the McDonnell F-85) and long-range fighters (the McDonnell F-88 and Lockheed F-90) are well known and documented. Not so the Navy's. I had only heard about studies but seen nothing specific until diligent researcher Ryan Crierie found two Curtiss-Wright proposals in George Spangenberg's papers at the National Archives.

I'm still a little fuzzy on the details, but it appears that the Navy issued OS-112 to define the requirements for a carrier-based fighter to accompany its planned force of long-range, carrier-based, atomic bombers. The most significant number was the combat radius: 1,200 nautical miles, roughly twice that of existing carrier-based fighters. As envisioned by Curtiss-Wright, it was to be a big airplane with a four-man crew. The armament consisted of a forward and aft facing radar-directed turrets. The large pods on the wing tips were not fuel tanks, but housed search radars, one covering the upper hemisphere and the other the lower. (An alternate approach had one covering the right hemisphere and the other the left.)

The crew consisted of a pilot and copilot and two gunners, one facing aft and one forward across from each other in a compartment aft of the cockpit. Presumably the copilot was there as a relief pilot, since the mission time was over six hours for the jet version and almost eight hours for the turboprop. (As it happened, all the Navy's strategic bombers were single-piloted, with the crew consisting of a bombardier and a third man whose duties varied over time and with the aircraft type.)

The artist's concept above is the Curtiss Wright 551, which was powered by four Westinghouse J46 engines with afterburners and had a takeoff gross weight of 68,500 pounds. The turboprop version, the 538, was powered by two Allison T40s and only weighed 51,000 pounds. By way of comparison, the biggest Navy carrier-based jet fighter at the time, the Douglas two-seat F3D Skynight, weighed about half that and had a combat range, not radius, of 1,200 nautical miles. (It was actually used to escort Air Force B-29s on night missions during the Korean War.)

The operational concept appears to have been that the crew of the escort "fighter" would detect the approaching enemy interceptors with its search radars, get into position to block them from approaching the bombers, and shoot them down when they came within range of either the forward or aft turrets.

After a review of the proposals and a rethink, the Navy decided to send its bombers out on their own, protected only by speed in the case of the AJ Savage, the placeholder for the A2J and A3D that were both designed with tail turrets.

What does the "V" stand for?

2010-04-04T20:31:00.008-04:00

If you look closely at the above picture (click on it to make it bigger), you'll note that the KA-6D tanker is assigned to squadron VA-165 and the F-4J, VF-96. The A is short for Attack and the F, Fighter. So what's with the V?

The V means that it's a fixed-wing heavier-than-air squadron (as opposed to H for a rotary wing, i.e. helicopter, heavier-than-air squadron). Why V? It turns out that not even the Navy knows for sure, although its historians think it might have represented volplane, a French word for an aircraft sustained in the air by lifting surfaces as opposed to a bag of a gas that is lighter than air. In the beginning, since the usage predates helicopters by more than 20 years, it stood for heavier-than-air, period, with the designation for lighter-than-air being Z. It seems very likely that the Z is based on Zeppelin, the name of the Count who pioneered rigid airships before World War I, although the Navy applied it to non-rigid as well as rigid airships. See: http://www.history.navy.mil/avh-1910/APP16.PDF

My understanding is that the designations first appeared in General Order No. 541 (see http://www.history.navy.mil/danfs/genord_541.htm) approved by the Secretary of the Navy on 17 July 1920. It provided two-letter (and in some cases, three-letter) designations for all the Navy's ships and airplanes. The first letter of the ship designation was its basic type, e.g. battleship, cruiser, destroyer, submarine, etc. The second letter was a modifier as to class within that type, e.g. a light cruiser was designated CL and a battle cruiser, CC. The aircraft carrier, the first of which was in the process of being converted from a collier (AC), was considered to be a type of cruiser, probably by default since it resembled any of the other six types even less. For some reason, an ordinary cruiser was a CA, which eliminated the use of A for aeroplane for the aircraft carrier, which was designated CV. Almost every letter in the alphabet was used for the second letter in the various designations, most being logical like SF for Fleet Submarine. V, whether for volplane or not, was probably as good as any other letter available once A was not.

Heavier-than-air airplane designations were to begin with V as well, with the secondary letters been F for fighting, O for observation, S for scouting, P for patrol, and T for torpedo and bombing. As it turned out, however, the V system was used to designate squadrons as shown above rather than airplane types, whereas ships were identified by the two-letter designation and sequential numbers, e.g. CV-1 was Langley, CV-2 was Lexington, and so forth.

Your guess is as good as mine as to why a battle cruiser wasn't a CB and an ordinary cruiser a CC (a battleship was a BB, a destroyer a DD, and a submarine an SS, for example), making CA available for the aircraft carrier. Better, actually, since I don't have one...

Missed it by That Much V

2010-03-21T09:35:00.009-04:00

The wings on the Grumman XF9F-2 Panther were oriented straight up when folded.

The folded configuration—with the fold joint well inboard—utilized all the hangar deck height to maximize the number of airplanes that could be parked on deck and in the hangar.

Unfortunately, the Panther—like all the early carrier-based jets—proved to not have enough endurance, so permanently mounted tip tanks were added to increase the fuel capacity. Since the hangar height limit had already been reached and there were disadvantages to under-slung tanks and folding the wings past vertical, the wing fold angle had to be reduced to provide the requisite clearance.

Tip tanks were added to the McDonnell F2H-2 Banshee for the same reason. In this case there was still overhead clearance available so the wing fold remained the same. However, the wing fold mechanism and structure hadn't been designed for the weight of wing-tip mounted fuel, so the tip tanks had to be empty when the wings were being folded and spread. If tip tank fuel was needed, which it almost always was, the F2Hs had to be spotted for launch with the wings spread, taking up scarce deck space. Although the F9F now took up more deck space when folded than originally planned, it didn't have this constraint so the tip tanks could be fueled when the wings were folded.

The Hell It Won't Fit II

2010-03-13T12:42:00.000-05:00

As carrier-based airplanes got bigger, folding became more necessary. The basic size limitations were the length and width of the inline elevators and the height and width of the openings from the deck-edge elevators to the hangar deck.

Early on, hangar heights varied somewhat. Beginning with the Essex-class carriers and continued in the Midway-class, the height became standardized at 17' 6", which set the maximum height above deck of the folded wing tips. When the much bigger multi-engine nuclear-strike airplanes were added to the carrier's air groups, the vertical fin had to be folded as well. The first of these was the North American AJ Savage.

In the original layout, the tips of the folded vertical fin, the horizon stabilizers, the folded wing, and the propellers were all about 16 feet above the deck, well within the hangar overhead height limit. (A clearance of about a foot was desired to accommodate variations in the airplane's "sit" caused by flat tires, shock strut pressure, fuel and bomb load, etc.) However, tip tanks had to be added to the design to address a deficiency in range, resulting in a significant reduction in clearance, as depicted in the drawing above and the picture below.

Sailors are positioned on the wings to insure that the tip tanks will clear the opening to the hangar deck. Also noteworthy in the picture:
- To minimize weight, power folding was not incorporated. In order to fold the wings and vertical fin, hinges with a hydraulic actuator had to be bolted to the wings and a manually operated screw-jack actuator had to bolted to the tail. Note the ladder which was hung on the aft fuselage to provide access to the fin for the latter installation.
- Sailors with chocks are poised to place them athwart the wheels if necessary to stop the aircraft in place.
- Two tow tractors are ganged together to provide the horsepower to pull the big Savage into the hangar bay.

In any event, the AJs were rarely folded, much less taken to the hangar deck. The process of folding the airplane was determined in Board of Inspection and Survey trials to take 16 minutes with a four-man, well-trained crew, on land, with negligible wind. The time increased significantly when it had to be accomplished a pitching, windy deck. As a result, a Savage was only folded and taken below when it suffered an unfixable casualty and needed to be gotten out of the way. (Note that the tip tanks have been removed.)

Snapshot of A Transition II

2010-03-12T17:05:00.005-05:00

Somewhere in the Pacific early in World War II, a Grumman F4F Wildcat is on the elevator of an aircraft carrier with three Douglas TBD Devastators on deck behind it. The big three-man TBD torpedo bomber has power-folding wings to increase the number that can be accommodated aboard, the first U.S. Navy carrier-based monoplane to be so configured. Like almost every other carrier-based airplane up until the start of the war, this model of the Wildcat, the -3, does not have folding wings. The F4F-4 will, like almost every carrier-based airplane the Navy procures thereafter with one famous exception.

The folding wing meant more than doubling the number of Wildcats that could be stowed aboard. Although it looks like the fold joint must be double hinged, the outboard wing panel actually pivoted on a single axis tilted aft and outboard. The concept was famously developed at Grumman by using a drafting eraser for the inboard wing stub and a bent paper clip simulating the pivot axis and outboard wing panel.

The crank handle did not fold the wing. It pulled the pin that locked the wing in the flight position and extended the wing lock indicator to the unlocked position.

The U.S. carrier Navy was about to be devastated by the TBD losses at Midway. Its withdrawal from combat use in favor of the faster Grumman TBF Avenger torpedo bomber was already a foregone conclusion, however. It was a sad end for an airplane that only five years earlier was the most technically advanced airplane in the Navy's carrier-based arsenal.

The Chief is striding past an arresting cable that has been temporarily repositioned to allow the inline elevator to be used. Note how much smaller in diameter the cable was when airplanes weighed much less than 10,000 pounds on landing and stalled at 70 knots or less.

It is likely that this is the forward elevator on a Yorktown-class carrier (Yorktown/Enterprise/Hornet). Early on, some carriers had a second set of arresting gear for over-the-bow recoveries in the event that an airplane had to be landed with the deck configured for launch, the aft end of the deck had suffered combat damage, or its inline elevator had suffered a casualty while not full up. (Presumably, the Wildcat pilot here is making a message drop.)

The over-the-bow recovery capability, like non-folding wings, would soon disappear from the carriers.

Procrustes at BuAer

2010-03-09T10:44:00.007-05:00

BuShips and BuAer were independent kingdoms in the Navy. While BuShips cooperated and coordinated with BuAer and the Chief of Naval Operations ruled them both, once the constraints were agreed to and the ships built or altered accordingly, BuAer's aircraft manufacturers had to design their airplanes within those constraints of hangar deck height, elevator dimensions, catapult and arresting gear capability, etc. Although bigger and more capable was usually reflected in a new class of ships, after the Korean War most of the Essex-class carriers received major upgrades to be able to handle larger and heavier airplanes.

As it happened, BuAer almost invariably required new aircraft to operate from the smallest carriers then in the fleet. Because of austerity measures, however, before or shortly after these aircraft arrived in the fleet, the carriers for which the new aircraft were constrained to be compatible had sometimes been decommissioned or were about to be. In a few cases, a new airplane never deployed from the smaller, less capable carriers that it had been designed to operate from even though they remained in service. For example, the McDonnell F4H Phantom specification incorporated the limitations of the Essex-class carrier and one set of carrier trials were accomplished on Intrepid, but the Phantom was never deployed on one.

That led me to revisit the SCB-125 forward elevator extension on the Essex-class carrier described in my prior post. While the A3D wasn't even close to fitting on this elevator and the other carrier-based fighters and attack aircraft didn't need the added length per se, there was one mid-1950s new program that did, the North American A3J Vigilante. Its folded width was 42 feet, providing the requisite one-foot clearance on each side. With the radome and tail folded, it was actually a bit shorter at 65 feet and a few inches than absolutely necessary. (The nose looks a little odd because the radome has been tilted upward into the folded position.)

There's a chicken and egg element to this theory, since I'm not sure of the relative timing of the SCB 125 elevator change and the A3J design freeze. In any event, unlike the A3D which it was intended to replace, the A3J never flew to or from an Essex-class carrier.