The Attractive Failure
Bell’s Airabonita was a proposed US Navy carrier-borne fighter derivative of the P-39 Airacobra. Malcolm V Lowe examines its unsuccessful development
The US Navy’s search for modern, high-performance pursuit (fighter) types for aircraft carriers was an important American procurement project during the late 1930s. A 1935 requirement initially led to the creation of the ponderous Brewster F2A Buffalo, and eventually the excellent Grumman F4F Wildcat, the purpose being to modernise the fleet’s increasingly antiquated fighter force of colourful, but seriously outdated, biplanes with modern single-engined monoplane fighters. During early 1938, the US Navy’s Bureau of Aeronautics (BoA) requested further proposals, including a challenging demand for a well-armed and (for its time) high-performance carrier-borne naval fighter. Several companies responded to these 1938 parameters, notably Vought, with what eventually became the famous F4U Corsair.
Bell Aircraft Corporation of Buffalo, New York, had no tradition of providing aircraft for naval requirements, unlike Vought. Nevertheless, Bell also responded to the 1938 ‘contest’, with a project that received the in-house designation, Bell Model 5. The firm’s novel approach was to adapt an existing proprietary design, the P-39 Airacobra, to compete for the potentially lucrative US Navy contract. The P-39 was a land-based fighter with a tricycle undercarriage that Bell was developing for the then US Army Air Corps. The tricycle configuration in particular would not work well for aircraft carrier landings, so Bell’s designers reworked the P-39 layout to make the Model 5 more suitable for naval operations. In theory this appeared to be a good idea. However, redesigning an established and carefully formulated blueprint that met the specification of one customer, in order to meet a totally different set of parameters for a different client, proved to be very difficult.
Bell was awarded a contract go-ahead from the US Navy for the construction of a single prototype in November 1938, after Vought received its own go-ahead during June 1938. Bell’s project was officially designated XFL-1, in the US Navy’s laborious nomenclature of the time (X = prototype, F = Fighter, L = Bell). The cost of this one-off aircraft has been quoted as $125,000, although some historians cite a much higher figure.
The single XFL-1 was allocated the designating or serial number of 1588 by the US Navy’s BoA (usually abbreviated as BuNo). The new type was christened Airabonita in Bell’s rather quaint naming process (this name is written as ‘Airbonita’ in some published sources). Bell’s designers worked hard to adapt the P-39 layout for naval use, and eventually numerous changes were made to the Airacobra format.
SIMILAR BUT DIFFERENT
Bell planned to use the same powerplant type for the Airabonita as in the P-39, namely the Allison V-1710 liquid-cooled inline engine. Since the late 1920s the US Navy had tended to employ aircraft with air-cooled radial engines, and the more complicated logistics of maintaining an aircraft powered by a liquid-cooled unit aboard aircraft carriers was obvious. Nonetheless, it was somewhat appropriate that the Allison engine should be the first choice for the Airabonita. Despite the US Navy’s apparent reluctance to employ inline liquid-cooled engines, early in its development the V-1710 had been projected as a power source for US Navy airships. Fitted to the Airabonita was an XV-1710-6, quoted at the time as producing 1,150hp at 9,000ft (2,743m). This was a supercharged, but not turbo-supercharged powerplant. The actual installation was similar to that of the P-39, with the engine mounted roughly amidships behind the cockpit, driving the propeller unit via a long extension shaft and forward-mounted gearbox, allowing for a hollow propeller shaft…
The rest of this article is in the current issue of FlyPast, cover dated January 2019. It’s available in UK shops now or can be purchased via the website – www.flypast.com. Alternatively, you can download a digital edition from www.pocketmags.com – simply search ‘FlyPast’.