U.S. Navy Aircraft History

By Tommy H. Thomason

Saturday, December 10, 2016

Horses for Courses: Intruder vs. Buccaneer

If you're familiar with both U.S. Navy and Royal Navy airplane programs from the early 1960s, you may have wondered why the former developed a bigish carrier-based, subsonic, two-seat attack airplane when the latter already had one in development, the Blackburn Buccaneer:
Via Tony Buttler

Certainly the U.S. Navy was paying close attention to the Royal Navy during the early 1950s when the Buccaneer program was initiated, as evidenced by its adoption of the steam catapult, the angled deck, and the mirror-landing system.

The answer is basically requirements. The U.S. Navy wanted a replacement for the obsolescent Douglas AD-5N Skyraider that it and the Marines used for all-weather attack and to a limited extent, antisubmarine warfare.

Some of the requirements overlapped, for example range, payload, carrier-compatibility. However, the Navy wanted to be able to find and accurately bomb a land target while the Brits had in mind a strike against ships at sea or naval bases. As a result, the Buccaneer was optimized for near-sonic speed at sea level for a survivable run-in against a heavily armed target: tandem cockpits, a small radar dish (but adequate to find a big target), an internal bomb bay, a relatively small wing, a retractable inflight refueling probe, and unusually for a subsonic airplane, area ruling. The Intruder, on the other hand, had not one but two radars, side-by-side seating (not a handicap given the size of the nose required for the radars) five stores pylons, a relatively high-aspect-ratio wing (required in part for the Marines desire for short takeoffs and landing ashore), etc. It was definitely not area ruled and its refueling probe was always extended.

For more on the development of U.S. Navy attack airplanes including the A-6, see my book, Strike from the Sea, available from Specialty Press or Amazon (https://www.amazon.com/Strike-Sea-Aircraft-Skyraider-1948-Present/dp/1580071325):

Note that there are other books with the same title...

Friday, September 30, 2016

The Turtle's Takeoff

Great googly moogly...

For a summary description of this Lockheed P2V's record distance flight, see http://thanlont.blogspot.com/2011/01/truculent-turtle.html

I knew the overloaded takeoff from Perth, Australia was a close-run thing, but I just came across this video recently posted by Ken Horner:


Note that for maximum takeoff benefit from JATO, you fire the rockets so that burnout occurs just after liftoff. That is why there is no JATO boost during the first part of the takeoff roll.

In the event of an engine failure at or above 1,000 feet after takeoff, the crew had a fuel-jettison plan (including getting rid of the tip tanks) to get down to a weight that would allow them to climb before they hit the ground. It doesn't look like they got to 1,000 feet for a while...

Thursday, September 29, 2016

How Hard is It to Land on an Aircraft Carrier?

U.S. Navy Mass Communication Specialist 3rd Class Tomas Compian

I was recently asked "How hard is it to land on an aircraft carrier?" I regret to say that I don't know personally. My only pilot experience in that regard is making an approach and landing a Lockheed S-3 in a Navy flight simulator. My only actual carrier landing was as self-loading freight facing backwards in the cabin of a Grumman C-2 Greyhound transport. (I can say in that case there was an unsettling amount of flight control activity and throttle changes on short final before a very firm arrival and impressively short stop.)

However, I have a lot of second-hand knowledge based on reading books/articles, an overnight stay on an aircraft carrier being used for day and night carrier qualifications, listening to naval aviators, etc. The degree of difficulty also depends on the era. In the beginning, landing speeds were much slower and crashes less dramatic, at least as far as the pilots were concerned. As airplanes got bigger and heavier, higher landing speeds were required and crashes became much more colorful. The introduction of jets reached the upper limit of practicality and the Navy was in danger of exceeding it.

The angled deck and the mirror-landing concept were adopted just in time to restore a reasonable amount of repeatability to the landing process. (The fact that carriers were getting bigger and bigger was also beneficial.) The latest automated landing systems now being qualified promise to make the carrier landing a non-event, the equivalent of the self-driving car.

For the time being, however, a carrier landing requires a high degree of precision with potentially fatal consequences for getting it wrong, similar to a high-wire circus act without a net or safety harness. The precision required is akin to flying under a low bridge, a high-risk and foolhardy maneuver. Hitting the bridge, its supports on either side, or the water is likely to be fatal.

The penalty for being too high in the event of a carrier landing is not fatal but means not being able to land on that approach. Another is required, prolonging the time the carrier has to spend on that course and potentially delaying the subsequent launch cycle.

Being a bit too far off to the left or right on a carrier landing is almost as bad as hitting the bridge supports. It risks a crash into parked airplanes on either side of the landing area and/or going off the deck into the water.
 U.S. Navy Mass Communication Specialist 3rd Class Rob Aylward

Being too low is the worst, resulting in a ramp strike. A bit too low might just mean damaging the tail hook, which requires a diversion to a shore base or a landing on the carrier using the barricade which again disrupts carrier operations. Hitting the ramp with the airplane itself is frequently fatal.

How big is the opening? About 20 feet by 20 feet. The target height for the end of the tail hook at the target angle of descent is about 14 feet above the ramp. Being only four feet or so higher means missing the last wire and having to take off again, a bolter.

The width of the opening is constrained by the imperative to keep either wingtip safely distant from the "foul line" that other airplanes and equipment are kept behind. In other words, the naval aviator can touch down as much as 10 feet on either side of the center line as long as the sideward drift, if any, is toward the center line and not away from it.

However, simple passing through the imaginary opening about 20 feet high and 20 feet wide is not sufficient. At that instant the airplane must also be traveling at the target airspeed and with the target rate of descent so as to put the tailhook on the deck between the second and third wires. Being too fast or at too shallow a rate of descent means touching down beyond the last of the four wires and boltering; too high a rate of descent, while insuring that the hook touches the deck before the last wire, risks exceeding the strength of the landing gear.
 The resulting ejection was successful.
 U.S. Navy Photographer's Mate Louis J. Cera

It helps that the target rate of descent, while high—about eight knots or nine miles per hour—is not much more than one third of the demonstrated capability of the landing gear. Landing gear strength is one of several differentiators between airplanes designed for carrier operations versus those that fly from airfields. The stronger landing gear means that the naval aviator does not have to, in fact should not, flare to decrease the rate of descent as part of the landing because not flaring increases touchdown accuracy.

It doesn't help that a lot of time is not allowed to get lined up with the opening and stabilized at the target airspeed and rate of descent. There is often a compelling reason to get all the airplanes aboard in as short a time as possible (for one thing, the carrier has to be headed into the wind for landings and that may very well not be the direction that the battle group needs to go). As a result, the time allotted for the final approach is on 15 to 18 seconds in daytime.

Moreover, unlike an opening under a bridge, the one that the naval aviator must pass through is moving. Even the biggest carriers are affected by stormy or ocean-swell conditions: depending on the sea state, a carrier can move in six different ways—pitch, roll, yaw, heave, sway, and surge—in various combinations. Although the ship movement isn’t quite random, it is not really predictable either. The current big-deck carriers, at least, don’t move quite as much as the smaller ones did.
The rate of change of a big-deck carrier from one extreme to another is also usually relatively slow. Nevertheless, under certain sea conditions, the ramp can move about 20 feet, the height of the imaginary opening, or more in only 10 seconds.

There is also the added degree of difficulty of having to fly "under the bridge" at night from time to time, with only a few lights as guidance as to the location of the opening. As a result, the final approach is then lengthened to about 25 seconds.

For dramatic video of carrier landings under those conditions, watch these:

Although the naval aviator is alone in the cockpit, he or she is assisted by the advice and counsel of a Landing Signal Officer (LSO) standing on the deck who monitors the approach and can often detect an unacceptable trend developing with it or with carrier motion before the aviator does. The LSO's command to abandon the attempt, a wave off, must be complied with.

Tom Wolf in his book, The Right Stuff, observed that test pilots and race car drivers are not preternaturally brave or foolhardy but instead have convinced themselves that they have the skill and knowledge to not crash as opposed to those who have. Prospective naval aviators go through a training program that is designed to instill that level of confidence in them. It also ruthlessly eliminates individuals potentially inadequate to the task. (For more on this, see my book, Training the Right Stuff, HERE.)

The naval aviator prowess at carrier landing continues to be closely monitored during his career by the LSOs, squadron commanders, and the Carrier Wing Commander for poor performance at sea. The result is a very low crash and casualty rate in what is widely regarded as the most demanding aviator skill, the carrier landing.

Friday, July 15, 2016

McDonnell XFD-1 Phantom First Flight - One Engine or Two?

It's widely reported or at least implied that the U.S. Navy's first jet airplane, the twin-engine McDonnell XFD-1 Phantom, made its first flight on 26 January 1945 with only one engine installed. Unfortunately, no picture of that momentous event appears to exist, probably because of wartime secrecy. The following picture is of the second XFD-1, which was used for the at-sea carrier trials (you can just see some of the Davis barrier actuation framework in place ahead of the windscreen), and taken some months later.

My fairly well-informed guess is that this story is apocryphal and resulted from the conflation of two separate events:
1) Early January 1945 high-speed taxi testing at St. Louis with only one engine installed because only one was available. Accomplished prior to an actual up-and-away flight, these are baby steps to evaluate control response, stability (albeit in ground effect), acceleration, braking and steering effectiveness, etc. On at least one of these test runs down the runway the Phantom was briefly airborne, which is not uncommon but certainly does not constitute a flight as it is generally understood.
2) An actual first flight with two engines installed on 26 January 1945.

The single-engine taxi test culminating in a "hop" is documented except for the date. In an article in the September 1946 issue of Aviation, Kendall Perkins (at that time McDonnell's Assistant Chief Engineer) wrote "the first plane, after a number of preliminary tests, made its initial hop (rising a short way off the ground) before the second engine had been installed." In 1981 he gave a presentation on "McDonnell's First Phantom" to the Aeronautical History Society of St. Louis during which he said:

"Well anyway, we flew the airplane in I think it was January of '45, was (sic) the first time. The one interesting, unusual thing about the first flight was that some people didn't even call it a first flight. We took it out of the hangar and we only had one engine at that time. We couldn't get delivery on a second engine, but we were so impatient to get started on taxi testing that we said, well we can taxi it on one engine so we just left a big hole on the other side and taxied it out on the runway and ran it up for a few hundred yards and taxied it back and ran it up a few hundred yards more and it wasn't long before he just took it off the ground. Actually it flew about half way down the runway on just one engine. I don't know whether that a longer flight than the first Wright brothers flight but I suspect it was."

In an undated paper*, "Developmental History of the McDonnell FD-1 or FH-1 Phantom", prepared by the Historian's Office in the Naval Air Systems Command, Washington, D.C. the author(s) wrote:

"(The 19B) engine performed well enough in the October (1944) tests to be delivered to the McDonnell plant, but the XFD-1 needed two engines and only one was on hand; a second was simply unavailable due to technical difficulties. As a result, McDonnell engineers had to be content with installing the single engine and conducting taxi tests at their plant. The second engine finally arrived, and on 26 January 1945 the XFD-1 flew for the first time. The aircraft flew twice that day for a total flight time of 49 minutes."

It seems likely that the author(s) would have used primary sources when writing this paragraph.

An online Phantom summary that doesn't reference primary sources but seems to be credible and provides specific dates: http://tanks45.tripod.com/Jets45/Histories/FH-1/FH-1.htm

In summary, it states that the single-engine "hop" was accomplished on 2 January 1945 with a second engine arriving on 4 January. It was installed for the first flight accomplished by Woodward Burke on 26 January. It also states the flight time on that date as 49 minutes, which is clearly more than a hop.

I'm still hoping that someone comes up with McDonnell test reports from January 1945 that documents whether the up-and-away first flight, as opposed to the "hop", was on one engine or two.

*One of the end notes references a book published in 1972.

Wednesday, July 13, 2016

A History of the Northrop Corporation's Projects

The title and subtitle pretty much summarize the contents in this excellent Specialty Press publication authored by long-time Northrop employee Tony Chong. And a wonderful collection of drawings, illustrations, and pictures it is, tied together with a narrative describing the ups and downs of Northrop over six decades of rapidly changing aerospace technology. Many of the projects described never progressed very far after being created by the predesign group but they provide a comprehensive sense of the company's changing and evolving raison d'etre and business fortunes.

Why recommend this book in a U.S. Navy Aircraft History blog? The answer is that Northrop proposed or considered proposing on Navy programs many times, almost all of which are probably described here. Although Northrop was never successful in that regard, not counting its contribution to the genesis of the F-18, those projects (several of which were new to me) provide a fresh and fascinating look at the Navy's aircraft mission requirements and program competitions over the years.

The book also illustrates the function of an aircraft company's preliminary design department, which is not only to respond to company marketing but also to explore new configurations and concepts for not only existing markets and requirements but those not yet defined or acknowledged. Most go unrequited but the process always has the potential for new business.

Friday, June 24, 2016

Training the Right Stuff

Amazon is shipping my latest book, coauthored with Mark Frankel, now.
"A comprehensive study of the training aircraft used to transition the United States military into the jet age. At the end of World War II, high-performance jets with unfamiliar operating characteristics were replacing propeller-driven airplanes. As accident rates soared, the Air Force and Navy recognized the need to develop new trainers to introduce fledgling as well as experienced pilots to jet flight. The first step occurred in 1948, when a two-seat jet trainer, the T-33, was developed with private funds. It was welcomed by the Air Force and subsequently the Navy, allowing both services to start building modern air arms. Over time other new trainers were developed to serve specific needs while innovations, such as high fidelity simulators, accelerated the process, reduced costs, and increased safety. The evolution continues today with the goal of producing high-quality newly winged aviators for assignment to operational squadrons."