From: Joseph F Baugher <jfb@ihlpl.att.com>
Subject: Number Thirty-Nine in the Series--Bell P-39 Airacobra (8 of 9)
Keywords: Naval Airacobras--FL-1 and F2L-1
Organization: AT&T Bell Laboratories -  Naperville, Illinois
Date: Mon, 21 Dec 1992 15:57:56 GMT


From Joseph F Baugher <jfb@ihlpl.att.com>


The XFL-1 Airabonita was an experimental shipboard version of the 
land-based P-39 Airacobra which was developed in parallel with the 
Army version.  However, the Airabonita had the misfortune to be in 
direct competition with the Vought Corsair for Navy orders, and only 
one example was built.  

In February 1938, the US Navy had issued a specification for a 
high-speed, high-altitude fighter.  Bell submitted a navalized version 
of the Airacobra in response to this request.  At the same time, 
Chance Vought submitted a design which was eventually to emerge as the 
superlative F4U Corsair.  A US Navy contract for one XFL-1 prototype 
was placed on November 8, 1938.  The BuAer Number was 1588.  

The XFL-1 differed from its land-based counterpart primarily in having 
underwing radiators and a tailwheel undercarriage.  The main 
undercarriage members were transferred to the front wing spar, and an 
arrester hook was fitted.  The relocation of the main undercarriage 
members to the forward part of the wing necessitated the relocation of 
the wing-root radiators to exterior points under the rear of the 
central section of the wing.  The fuselage was shorter than that of 
the P-39, the vertical tail surfaces were redesigned, and the airframe 
was stressed for carrier operations.  The wing was of larger span with 
greater chord.  The dorsal intake was smaller and shallower than that 
on the YP-39.  Armament was to have been two 0.30-inch machine guns in 
the fuselage nose, plus a 0.50-inch machine gun or a 37-mm cannon 
firing through the propeller hub, although no armament was actually 
ever fitted to the XFL-1 prototype.  

The XFL-1 flew for the first time on May 13, 1940.  It was powered by 
a 1150 hp Allison XV-1710-6, the first in-line engine to be fitted to 
an American naval fighter since 1928.  During tests, the XFL-1 
achieved a maximum speed of 307 mph at sea level, 336 mph at 10,000 
feet, and 322 mph at at 20,000 feet.  Initial climb rate was 2630 feet 
per minute, and an altitude of 20,000 feet could be attained in 9.2 
minutes.  Service ceiling was 30,900 feet.  Weights were 5161 pounds 
empty, 6651 pounds loaded, 7212 pounds maximum.  Dimensions were span 
35 feet 0 inches, length 29 feet 9 1/8 inches, height 12 feet 9 2/3 
inches, wing area 232 square feet.  

Since the use of an in-line, liquid-cooled engine as a powerplant for 
carrier-based aircraft had for many years run counter to Navy 
thinking, the project was regarded with disfavor by many.  
Longitudinal stability proved to be marginal, and the vertical tail 
surfaces were enlarged after a series of wind-tunnel tests.  
Difficulties with the Allison engine delayed delivery of the XFL-1 to 
the Navy until February of 1941.  The XFL-1 failed its carrier 
qualification trials due to problems with the undercarriage.  It was 
returned to the manufacturers in December 1941 for modifications.  
However, shortly afterwards, the superior performance of the F4U 
Corsair against which the Airabonita was competing led the Navy to 
decide that the XFL-1 was unsuitable for further development and the 
project was abandoned with only one example ever being built.  

The Navy later did operate a couple of Airacobras, but they acquired
them directly from the Army and never used them from carriers. 
Towards the end of the war, the US Navy acquired a pair of P-39Qs from 
the Army (Ser No 42-19976 and 20807) for use as target aircraft.  They 
were initially designated XTDL-1, but their designations were later 
changed to F2L-1K.  Their BuAer numbers were 91102 and 91103.  

Sources:

  War Planes of the Second World War, Fighters, Volume Four, William Green,
  Doubleday, 1964.

  The American Fighter, Enzo Anguluci and Peter Bowers, Orion Books, 1987.

  United States Military Aircraft since 1909, Gordon Swanborough and Peter
  M. Bowers, Smithsonian Institution Press, 1989.

  P-39 Airacobra in Action, Ernie McDowell, Squadron/Signal Publications, 
  1980.

  The Calamitous 'Cobra, Air Enthusiast, August 1971.

Joe Baugher       AT&T Bell Laboratories    2000 North Naperville Road 
		  Naperville, Illinois 60566-7033.   (708) 713-4548

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