Grumman S2F/S-2 Tracker Monograph

Finally (it's been a work-in-progress for a long time). It's currently being printed and should be on Steve Ginter's website (http://www.ginterbooks.com/NAVAL/NAVAL.htm) shortly. My coauthor, Bob Kowalski, was one of the earliest Navy S2F pilots; I got to sit in one with my mother about that same time.

  And in 1993, I got to fly one, courtesy of what is now Cascade Aerospace.

I can assure you that there's stuff in this monograph that you haven't seen before.

In summary:
The Grumman S2F (S-2) was developed to meet a specific mission requirement, carrier-based antisubmarine warfare. It proved to be so useful and adaptable that it is still in military and civil service more than 60 years after it first flew in December 1952. Richly illustrated and personalized by Tracker pilots and crewmen anecdotes, Grumman S2F/S-2 Tracker describes its evolution from initial requirement to eventual replacement including unsuccessful Grumman proposals for improved versions. Its service in foreign militaries and adaptation to wildfire control are also summarized along with descriptions of the Carrier On-board Delivery (COD) and Airborne Early Warning (AEW) variants.

A-6 "Iron Hand" Conversions

Operation Iron Hand was a belated endeavor to deal proactively with Surface to Air Missile (SAM) sites during the Vietnam War. Although construction of the sites was no secret, attacking them was not allowed by the Department of Defense until Navy and Air Force airplanes started being shot down. The first USAF mission in late July 1965 was a total failure, with six of the 46 F-105s being shot down by conventional antiaircraft gun batteries in what turned out to be a strike on a well-protected but SAM-less site.

There were basically three ways to deal with SAMs: evade them; electronically jam or mislead the tracking radar and guidance signals; and destroy the sites. Evading them was iffy and required a visual sighting soon enough to do so. Jamming or misleading the tracking and guidance was only somewhat effective. Destroying the sites with conventional attacks was problematic because they were heavily defended with an array of radar-directed and barrage-type antiaircraft guns.

Another method of destroying the SAM capability was the use of an Anti-Radiation Missile (ARM), which was fired well outside of the SAM site's conventional AAA defenses, homed in on its tracking radar, and destroyed it. The Navy had already developed an ARM using its Sparrow missile combined with a radar-homing seeker. This was designated the AGM-45 Shrike and was usually fired from the Douglas A-4 Skyhawk.

These Navy missions received the nickname Iron Hand after the original operation. (The corresponding USAF aircraft were known as Wild Weasels.)

The only problem was, the Shrike's range was significantly less than that of the Russian SA-2 SAM, making an Iron Hand attack too much of a fair fight. The next ARM was therefore a modification of a big Navy ship-launched Surface-to-Air Missile, which resulted in the AGM-78 Standard ARM. Since it weighed almost 1,400 lbs, it had to be carried by the Grumman A-6 Intruder.

Rick Morgan has written two posts which describe the history of the various A-6 "Iron Hand" derivatives:

http://rickmorganbooks.com/a-6b-standard-arm.html

http://rickmorganbooks.com/a-6e-anawg-21.html

Training the Right Stuff

Mark Frankel and I have written a book on the development and operational history of U. S. Air Force and Navy jet trainers.

It will be available in May 2016. For more information, see:

http://www.schifferbooks.com/training-the-right-stuff-the-aircraft-that-produced-americas-jet-pilots-5914.html

Republic R-46?

Okay - it's a bogus designation, based on the Navy practice of designating a research aircraft with its identifier for the manufacturer and the manufacturer's model number of the design, e.g. Douglas D-558-1 Skystreak. (Also see http://thanlont.blogspot.com/2010/07/navy-research-aircraft-designations.html) In this case, it was Republic's AP-46, the Air Force's XF-84H informally known as Thunderscreech, a flying test bed for supersonic propellers. While the model number is correct, an R for Republic is conjecture on my part. Neither it nor its predecessor, Seversky, was apparently ever assigned a manufacturer's designation by the Navy.*

I first read of the Navy's prospective involvement in the program in the 3 May 1954 issue of Aviation week, which stated that the XF-84H was to fly in August. It also stated "the Air Force will use the plane to check supersonic propeller characteristics" and, of more interest to me, after being "fitted with another type Aeroproducts propeller, it will also undergo Navy carrier trials".

As it happened, it didn't fly until July 1955 and there was no Navy testing. In fact, there was very little Air Force testing, since the two XF-84Hs only flew a total of 12 times, making precautionary landings on 11 of those occasions. As a test-pilot friend of mine once noted, it doesn't take long to take a close look at a hot horseshoe.

I had assumed that the Navy's interest in the airplane, if true, had been as a backup for the Douglas A2D Skyshark, which was powered by the same Allison T40 turboprop engine.

However, the timing was way off, the XA2D having first flown in May 1950. Also, its engine was more or less unsatisfactory from the get-go, suggesting that the Navy's backup for the A2D, if it had one, would have used a different one.

I just now took another look at the XF-84H program since Steve Ginter has released the latest in his excellent series of monographs on Navy and Air Force aircraft.

To order from Steve (he makes a few more bucks that way) see http://www.ginterbooks.com/AIRFORCE/AFL219.htm

There aren't many details about the Navy's involvement, but by happenstance, John M. Leonard updated his fascinating online article (http://www.enginehistory.org/Allison/XF-84Propulsion.html) about the XF-84H propulsion system for the latest issue of the American Aviation History Society Journal (Fall 2015). If you're not a member, you should be. This issue alone is worth the price of a year's subscription.

He describes what little is known about the Navy involvement, which was basically the funding of design and whirl test of an Aeroproducts six-bladed, two-row propeller beginning in late 1949 or early 1950. This is a picture from his AAHS article:

The aft (bottom, as depicted here) propeller is obscured in this picture. The propellers were nine feet in diameter and separated by about 18 inches longitudinally. The aft propeller was offset by 15 degrees and, surprisingly, given the amount of torque involved, rotated in the same direction. I assume that the shock waves from the front propeller dictated this configuration.

In the late 1940s and early 1950s, the Navy was interested in a supersonic propeller in order to get more range and endurance from a fighter with with jet performance, not to mention the takeoff and wave-off benefits of the propeller.

As far as I know, the Navy never got as far as assigning a Bureau Number to its AP-46, which would have been the third one built. Instead, the Air Force reportedly agreed to install the Navy gearbox and propeller in the second XF-84H after its initial flight test. That, of course, didn't happen.

* Seversky did propose a carrier-based variant of its P-35 to the Navy in 1937 and furnished one, free of charge, for an evaluation that included the Brewster F2A Buffalo and the Grumman F4F Wildcat. Seversky promoted it as "NF-1", signifying Navy fighter number one, but it was civil registered and as far as I know, not assigned a Bureau Number or Navy designation. For one thing, it was on loan from Seversky and not owned by the Navy. The Navy reportedly referred to it as the XFN-1. This is possible—albeit only informally since the designation had previously been assigned to a Naval Aircraft Factory fighter, BuNo A8978, several years before and the Navy rarely reused a designation even when, as in this case, the NAF design wasn't built. According to several websites, the P-35 evaluated by the Navy was modified by the Naval Aircraft Factory and therefore designated XFN-1; I suspect that this is a conflation of the two designations leading to an erroneous conclusion. For one thing, the Grumman XF4F-3 was assigned BuNo 0383 and the Brewster XF2A-1, 0451. If the NAF did modify the P-35 and it was assigned a BuNo, it would have almost certainly been higher than 0451, not 1,400 BuNos lower in the previous A series.

Carrier-Based Airplane Self-Boarding

Mark Nankivil passed along the following from Jack Abercrombie:

While watching the Banshee at  https://www.youtube.com/watch?v=khVPlD2rNfc, which shows a ground crewman exiting on the right side. the question occurred to me—on which side of most top-entrance jet aircraft are built-in steps, left or right? And what about external, crew chief erected boarding ladders?

Which got me to thinking. It turns out that carrier-based propeller-driven fighters tended to have the boarding provisions on both sides of the fuselage, like the F6F Hellcat.

These big engines needed to be warmed up. This allowed a crew chief to do so if desired and then climb out of the cockpit on one side while the pilot climbed in from the other.

The F4U Corsair had a similar arrangement, but eventually the boarding provisions on the right side were somewhat more user friendly than the ones on the left, as with this F4U-5P that had a boarding step extending out from the fuselage.

 The earliest jets were a mixed bag. The FH-1 had boarding steps on the right side but not on the left.

Note that there was a non-skid patch on the nose landing-gear door for the first step with the left foot.

The FJ-1 had boarding steps on both sides (there was also a door that opened on the left side as there was on the right).

Since boarding provisions were heavy and jets didn't need to be warmed up, my guess is that it was quickly determined that only access was required from only one side. But which side?

The F6U Pirate was boarded from the left side.

But the F3D was boarded from the right.

As was the XF2D-1 as Jack noted:

(Note that the landing gear door was not used as a step.)

However, the production F2H was boarded only from the left, with the gear door again serving for the first step.

 The F9F Panther was also boarded from the left side, which was now standard.

With the advent of bigger jets with a nose-high stance for low-speed lift like the F7U-1 Cutlass, providing for self-boarding began to be a challenge.

Ladders were still anathema on the carrier, but widely used ashore.

There were only two exceptions to the self-board requirement. One was the A4D Skyhawk. Self-boarding was one of many things left off in the pursuit of minimum empty weight (also see http://thanlont.blogspot.com/2011/09/self-boarding-for-douglas-skyhawk.html). The other was the F4D Skyray. In the latter case, both the mockup and the prototypes featured self-boarding from the left side.

However, by the time the XF4D was ready for at-sea carrier qualification, it had more of a nose-up stance and a ladder (mounted on the left side) was needed to reach the cockpit.

Somehow Douglas convinced the Navy to forego F4D self-boarding, probably because its contemporary, the A4D, didn't have self-boarding and used a similar ladder, (different than the one shown above) that could be attached only to the left side of the fuselage.

Similarly, the F3H Demon, which was delivered with self-boarding capability (see http://thanlont.blogspot.com/2009/06/self-boarding.html for the XF3H and http://thanlont.blogspot.com/2008/05/i-had-hoped-to-find-picture-like-this.html for the F3H), was allowed to have ladders even aboard carriers as was the F7U-3, which probably avoided several broken bones or worse (note that the F7U-1 steps have become pegs with a giant step required from the engine nacelle to the first peg and another from the second peg to the cockpit).

Why access from the left side? My guess is that given the primitive fuel controls of the first jet engines, a pilot's first start or two during his initial checkout in jets needed to be demonstrated and/or closely monitored in order to avoid overtemping the engine. Since the throttle was on the left side of the cockpit, the instruction by an experienced pilot or crew chief needed to be from the left side of the airplane. 

Carriers and Tricycles

Except for a few very early biplanes, for many years airplanes had tail wheels, not nose wheels, even though the latter made landings less likely to result in excursions off the runway or worse. The reasons were compelling. A nose gear was more likely to break during a landing (or even a takeoff) in the former pastures that were used for landing fields, it was heavier than a tail wheel, and before the adoption of retractable landing gear, resulted in more drag in cruise flight.

However, paved runways eventually became the rule rather than the exception. Retractable landing gear made the nose-landing-gear drag penalty disappear. The nose landing gear arrangement also became of benefit during the takeoff roll of a multi-engine airplane: in the event of an engine failure, the pilot was more likely to be able to keep the airplane headed down the runway if it had a nose wheel to help resist the turning moment. In fact, it was more widely incorporated on early bombers like the B-24, B-25, B-26 etc. than fighters. (One exception was the P-38 but the configuration of the former wasn't really suitable for a tail wheel and it was also multi-engined.)

Another exception was the Bell P-39. It's unique inline arrangement of cannon, cockpit, and engine provided room for a nose gear and the need for nondisposable weight up front for balance reasons.

The Navy's preference for a tail-wheel configuration was so strong, that when it agreed to consider a carrier-based variant of the Army's new fighter, it insisted on it. The resulting Bell FL-1 became a taildragger.

For more on the brief history of the XFL-1 Aerobonita (as well as a summary of the history of the development of—and the engine manufacturer's struggle for supremacy between—the air-cooled versus liquid-cooled airplane engine and the Navy's ongoing interest in the liquid-cooled engine) see my monograph;

It is available from Steve Ginter here: http://www.ginterbooks.com/NAVAL/NF81.htm

The Navy didn't completely forswear the nose-wheel configuration any more than they did the liquid-cooled engine. In August 1939, they went to the trouble of converting a Lockheed Junior to have a nose gear (it was fixed and the main landing gear had to be moved aft as well) and conducting successful at-sea trials aboard Lexington (CV-2).

Douglas won contracts during World War II for two single-engine carrier-based attack planes with nose landing gears, the SB2D and TB2D:

 

My guess is that the advantage was that heavy bombs and torpedoes didn't have to be positioned at an angle to be attached to the airplanes. A small quantity of BTDs,  a development of the SB2D, were built for evaluation. Douglas quickly replaced it with an all-new design with a tail wheel, the BT2D, which became the AD Skyraider.

The Ryan FR-1 also needed a nose wheel because it had a jet engine in the tail. From time to time, it was a poster child for the benefit of not having a nose landing gear during a carrier landing (as well as proper location of the attach point for the tailhook).

Nevertheless, the nose wheel configuration also went to sea on the Grumman F7F Tigercat, albeit rarely and not without incident:

The F7F's main contribution to carrier-based aviation was the need for the development of a crash barrier that was compatible with airplanes with nose landing gears. See http://thanlont.blogspot.com/2010/10/barriers-and-barricades-one-more-time.html

Jets, of course, all but had to have a nose landing gear for various reasons. There were a few exceptions early on, even one that was carrier based, the Supermarine Attacker.

For more on twin-engine carrier-based airplanes with nose landing gears, see http://thanlont.blogspot.com/2010/11/one-if-by-land-two-if-by-sea.html

TailDragger Transition

Mark Frankel and I are in the process of finishing up our book on U.S. Air Force and U.S. Navy trainers, Training the Right Stuff. It will be published by Schiffer in the spring.

One major feature of the new post-World War II trainers was that they had nose wheels (tricycle landing gear) rather than tail wheels (taildraggers). Landing an airplane with a tricycle landing gear was a lot less likely to be dramatic because it was directionally stable. A taildragger was not, some more inclined to swap ends than others, but none that didn't bear watching, particularly in a crosswind. There were other advantages to the tricycle landing gear, such as being able to see where you were going when taxiing or beginning a takeoff. (For more on tail draggers and in particular the "ground loop", see http://thanlont.blogspot.com/2014/10/tricycles-are-for-kids.html

One shortcoming of an all-tricycle training fleet was that there were still taildraggers in use. However, most had dual control or dual-control variants, including the P-51 Mustang. And transitioning to a taildragger was somewhat easier if you already knew how to land. In the military, if an aviator had gotten that far, he would be less likely to be off optimal (airspeed, rate of descent, and alignment with respect to crosswind and runway) on short final and quicker to correct a problem like a swerve or a bounce.

What hadn't occurred to me, but did to Frank Williamson, was how did a Navy pilot go from the tricycle-gear T-28 into the AD Skyraider? The Navy didn't have any with dual controls (the Air Force did later on, since the AD-5 had dual-control provisions). The answer was advanced training at Navy squadron VT-30 at Corpus Christi.

Richard Adams via Phillip Friddell

Walt Fink was one of the aviators to do so:

Been there and done that in July 1962. Skyraider "Fam" at VT-30 consisted of five AD-6 (single-seat, because that's all we had—no Fat Spads) "flights"—that in quotation marks because on the first one, we didn't ever get airborne. It was a ground exercise to acquaint us with the taildragger mentality but we prepared for it like we were going flying, with all our gear, complete pre-flight briefing, complete pre-flight of the airplane, etc. After engine start, our instructor led us from the VT-30 line to the run-up area. We followed along, spreading the wings. Once there, we went through all the checks of prop, mags, hydraulics and such. Then he led us on a taxi-around tour of NAS Corpus Christi, looking not unlike elephants on parade, so we could get a feel for what it was like with the tail wheel locked and then unlocked, making turns, etc.

The final part of that first "flight" was that each of us taxied  onto the runway and when we got permission for "takeoff", we held the brakes, stick full back, and ran the R-3350 up to 30" of manifold pressure. Then we released the brakes and without adding power, got a little feel for how much right rudder it took to keep the nose pointed straight down the runway. I don't remember how fast we actually got—enough to get the tail light, anyhow—before we aborted the takeoff and discovered how much left rudder it took to maintain directional control. Then we taxied back to the line, folded the wings, and went through the shutdown procedures. We probably spent 45 minutes or so from start to finish.

Our first real flight was the next day and lasted about two hours, terminating in one landing. The following day, FAM-2 was spent on landing practice: my logbook shows I made 11 landings that consisted of 10 touch-and-goes and one full stop. The third flight was the same and the fourth one was six touch-and-goes and a full stop. The airplane was a beautiful flying machine but it took a little getting used to landing and directional control. By the way, we three-pointed the landings; the bird was heavy enough that it stayed where it was planted.

That was it for "basic fam" but of course we learned a little more with each successive flight. Those four Fam flights were followed by two formation hops, three Tac/Acro flights, and then we got into weapons delivery, day and night navigation, night formation, instruments, and finally FCLP (Field Carrier Landing Practice) and CQ (Carrier Qualification at sea). Total AD flights in my logbook at VT-30 were 44 with no incompletes or repeats.

Robert Hansen also went through the transition: I remember adding power and when the tail lifted off the runway, we cut power. That was an exciting point because you had to change rudder to account for the change in torque. Sometimes it was very colorful and there was an occasional "ground loop". When the flight returned from the first airborne flight, instructors were known to line the windows to watch the "first" landings, which also were colorful at times.