By Tommy H. Thomason

Wednesday, September 30, 2015

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

2 comments:

Philip Markgraf said...

I find it curious that Douglas made the two tricycle-geared designs (SB2D and TB2D, as you point out) and then returned to the tail-dragger configuration for the AD and the subsequent A2D (which also featured jet-exhausts). I wonder what led to this reversal. Weight and interior volume are both better with the tail-wheel configuration. Or perhaps Heinemann and company did not want to repeat the errors of the SB2D and TB2D.

For those who don't keep the A2D designation right on the top of their heads:
http://www.ginterbooks.com/NAVAL/NF43.htm
https://en.wikipedia.org/wiki/Douglas_A2D_Skyshark

Tailspin said...

In Heinemann's biography written with Rosario Rausa (recommended), he states that the BTD was in danger of losing the BT competition to either the BTM (which became the AM Mauler) or the BTK. At a June 1944 conference with the Navy in Washington, he recommended that further work on the BTD be canceled and the remaining funds be used for a new design. The Navy agreed but required that it still be powered by the R-3350. (The BTM used the R-4360 and the BTK, the R-2800, so the Navy was intent on comparing and contrasting airplanes with these different engines.) Going to a tail-wheel configuration as well as eliminating the bomb bay reduced the weight considerably along with other design changes. As it turned out, at the risk of oversimplifying, the BTM/AM was too big and complicated and the BTK too small and complicated compared to the BT2D.