BELL
FL AIRABONITA
by Jack
McKillop
The Bell Aircraft
Corporation was formed in Buffalo, New York, on 10 July 1935 with Lawrence
“Larry” Bell as president. Bell had a long and distinguished career in aviation
having worked for the Glenn L. Martin Company, where he rose to vice-president
and general manager, and the Consolidated Aircraft Corporation, where he became
general manager. By 1935, Reuben Fleet, the founder of Consolidated Aircraft,
had decided to move the company from Buffalo to San Diego, California, and Bell
advised him he wanted to stay in Buffalo and form his own company. Fleet
promised Bell that he would give him sub-contract work to help in establishing
the new company and as promised, Fleet gave Bell orders for over US$900,000
(over US$11 million in year 2001 dollars) for wing panels for PBY-2 and -3
Catalinas, q.v.
These orders gave
the company a chance to get organized but Larry Bell wanted to design and build
aircraft. Robert Woods, the Chief Engineer of Bell Aircraft, had considerable
experience with the liquid-cooled engine and all of Bell’s future piston-engine
aircraft were powered by these engines. Bell’s first opportunity to design a
new aircraft came in 1936 when the U.S. Army Air Corps (USAAC), superseded by
the U.S. Army Air Forces (USAAF) on 20 June 1941, issued an operational
requirement for a long-range escort fighter to protect bombers. Bell’s design,
the Bell Model 1, was accepted and a development contract was signed for one XFM-1
Airacuda on 4 June 1936; this was later followed by a development
contract in May 1938 for thirteen YFM-1s but only nine were built. This
twin-engine aircraft was innovative but its top speed was less than 300 mph
(483 km/h), it had poor performance, and the cost for each aircraft would have
been US$219,000 (US$2.77 million in year 2001 dollars). Accordingly, the
aircraft never went into production.
Bell’s second
design, the Model 2, was a modification of a Consolidated A-11 re-engine with
an Allison liquid-cooled engine. This new aircraft was designated XA-11A but
never went into production.
In March 1937, the
USAAC issued a specification for a new fighter and two months later, Bell
submitted designs for their Models 3 and 4. Both were single-engine fighters
with a tricycle landing gear and a liquid-cooled engine; the difference between
the two was the location of the engine. The Model 3 featured an engine located
ahead of the cockpit while the Model 4 had the engine behind the cockpit. The
Model 4 design was accepted and a development contract for one XP-39 Airacobra
was signed on 7 October 1937.
On 1 January 1938,
the U.S. Navy (USN) issued a specification for a light, high-performance,
carrier-based fighter aircraft to replace the biplane fighters then in service.
Larry Bell was very anxious to obtain a USN contract because there was little
or no profit with development contracts for aircraft like the XFM and XP-39.
This was evident when realizing that the corporate profits for the years 1935
through 1937 were US$49,439 (US$602,915 in year 2001 dollars). Bell, Brewster,
Curtiss, Grumman and Vought submitted proposals for the Navy fighter; some were
single-engine while others were twin-engine. After considering the proposals,
the USN ordered three aircraft, one Bell Model 5 as the XFL-1 Airabonita,
one Grumman Model G-34 as the XF5F-1 Skyrocket and one Vought-Sikorsky
Model V-166B as the XF4U-1 Corsair, q.v.
The contract for one
XFL-1 for testing was signed 8 November 1938 and specified delivery of a single
prototype with 300-days to Naval Air Station (NAS) Anacostia, District of
Columbia; the projected delivery date was 4 September 1939. Like the Model 4,
this aircraft was to be powered by a liquid-cooled engine installed behind the
pilot; the use of the liquid-cooled engine was a gamble
because the USN had banned the storage of highly flammable glycol coolant in
ships in the 1920s. Since the XFL-1 was a navalized version of the Model 4,
many modifications were required before the Model 5 could be used by the USN.
Two of them mandated by the USN were (1) increasing the wing area to permit a
carrier landing speed not to exceed 70 mph (112.7 km/h) and (2) the use of a conventional landing gear and
tailhook rather than the tricycle landing gear of the Models 3 and 4.
One major
modification was the use of a conventional tail wheel, plus a tailhook, instead of the tricycle landing gear of the
Model 4. This required moving the main landing gear forward and attaching it to
the front wing spar requiring a new one-piece wing instead of outer panels
bolted to a center stub. The use of a conventional landing gear and the engine
located far aft provided for center of gravity problems. Consideration was
given to moving the wing 3-inches (7.62 centimeters) aft but this was never
done leading to stability problems described below. Unlike USAAC aircraft, the
wings of the XFL-1 also contained flotation bags, later deleted, that would be
deployed if the aircraft was ditched. Finally, the USN also demanded that ten
small bomb bays, five in each wing, be built into the underside of each wing to
accommodate 5.2 pound (2.36 kilogram) bombs to be dropped over an enemy
aircraft formation.
Other modifications
included strengthening of the entire aircraft for carrier operations, raising
the cockpit to increase visibility, and the inclusion of a small window in the
belly of the aircraft just forward of the wing root to aid in carrier landings.
To increase stability, the wing span, chord, and dihedral of the wing were
increased, the length of the fuselage was reduced, the flaps were enlarged to
reduce stall speed, and the vertical tail surfaces were modified to maintain
longitudinal stability during carrier landings.
As the aircraft was
built, its gross weight increased due to the strengthening required for carrier
operations and an increase in engine weight. The Allison engine was delivered
on 4 January 1940, four months after the aircraft was scheduled for delivery,
and it was found that the long extension propeller shaft and gearbox weighed 25
percent above the original, planned weight. The Navy also insisted on the use
of improved, and heavier, equipment resulting in increased weight. Clearly, a
higher powered engine was called for to compensate for the increased weight but
the design of the airframe precluded the installation of a different power
plant.
PRODUCTION
HISTORY
XFL-1: One Bell Model 5
BUREAU NUMBER
(BuNo)
BuNo 1588
SPECIFICATIONS