Bell XFL Airabonita Carrierborne Interceptor
The Bell XFL-1 Airabonita was a failed attempt to convert the land-based Bell P-39 Airacobra into a viable U.S. Navy carrierborne interceptor.
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The XFL "Airabonita" was a Bell Aircraft Company product developed in parallel with the P-39 Airacobra, a land-based USAAF (United States Army Air Forces) design that eventually achieved operational status. In essence, the Airabonita was a "navalized" version of the Airacobra with some navy-induced modifications for operations aboard carriers. Despite the attempt, the Airabonita was plagued by engine and undercarriage issues throughout its development and proved wholly underpowered to most other fighter aircraft of the time. The United States Navy eventually decided on other pursuits and the single $125,000 XFL prototype was inevitably laid to rest.
With its origins in the P-39 army design, the XFL model retained most of the same exterior shape. Intended for use by the United States Navy as an interceptor aircraft, the Airabonita was designed as such, with a conventional undercarriage system (with two main landing gears and a tail wheel) as opposed to the tricycle type offered in the P-39. The air frame was revised and reinforced for the rigors of carrier operations. An arrestor hook was added under the base of the empennage. The Airabonita still retained the automobile-style doors for entry and exit.
The aircraft was to be powered by a single Allison XV-1710-6 12-cylinder Vee liquid-cooled inline engine of 1,150 horsepower. The engine was, as in the P-39, mounted aft of the cockpit and powered a forward-mounted, three-blade propeller via a 10.38 foot shaft running under the cockpit floor. It should be noted that this particular engine lacked the turbo charger as found on the XP-39, already a detrimental fact that would do the system in. The coolant radiators were moved from the wing center section and placed in underwing fairings. Armament would have still revolved around the 37mm Oldsmobile T9 cannon firing through the propeller hub. This cannon could be replaced by a single 12.7mm Browning M2/AN heavy machine gun if desired, potentially saving on critical weight while providing a weapon with a higher rate of fire. Additionally, firepower was to be provided through 2 x 7.62mm (.303 caliber) machine guns mounted in the cowl. By any measure, this arrangement would have been a notch under most formidable armament arrays at the time for even the land-based P-39 utilized more heavy caliber machine guns alongside its cannon armament.
The Airabonita achieved first flight on May 13th, 1940 but faced an uphill battle from the start as deliveries of the Allison engines were delayed for a time. This delay compounded the Airabonita's difficulties when the engines did eventually arrive for the powerplants exhibited issues all their own. The use of the conventional undercarriage also worked against the XFL as problems began to develop during testing. As a result, the system had to be shipped back to Bell Aircraft for further revisions in late 1941. By this time, however, the United States Navy decided to pursue a different direction and cancelled development of the XFL in whole. The single XFL-1 prototype was then used in a series of armament tests until it was eventually scrapped.
Performance specifications listed a top speed of 307 miles per hour with a ceiling of 30,900 feet. A range of 1,072 miles was achievable with a rate-of-climb topping 2,630 feet per minute. By all accounts, the XFL would have been wholly outclassed when one considers the speedy F4U Corsair coming out of development. Even the standard naval F4F Wildcat operated better at altitude than the Airabonita seemingly would have. This particular Allison engine - with its single-speed supercharger - also had a tendency to underperform at altitude as it did in the P-40 Warhawk, P-39 Airacobra and even in the P-38 Lightning - the latter needing exhaust-driven superchargers to have acceptable altitude performance.