Lt. Comdr. Farnsworth, on January 24, 1938, wrote a confidential memorandum to the Head of the Procurement Division requesting that letters be sent out requesting designs and proposals from various airplane manufactures because the Bureau was interested in procuring two experimental airplanes of the single seat fighter class, one having a single engine, and the other two engines. Type specification for the single engine type was to be Type Specification SD-112—13, and the General Specification SD-24-D. The two engine airplane, was to conform with Type Specification SD-112-14 and General Specification SD-24-D. The proposals were to reach the Bureau not later than 11 April 1938, and the letter requesting bids was sent out 1 February 1938, by confidential letter Aer-PR-BA, VF.
On account of this active interest, on 1 February 1938, another request was made for designs and informal proposals for (1) a single engine fighter designed around the Allison mechanically supercharged engine, and (2) a twin engine fighter weighing less than 9000 pounds. The letter of 1 February 1938 set up the competition and bids were opened on 11 April 1938. At this time five airplane companies submitted ten designs, and in addition, both Grumman and Curtiss submitted two designs and an alternate in the twin engine field.
The following companies participated: Vought, Brewster, Grumman, Bell, and Curtiss.
One of Vought's proposals, called the Vought B proposal, introduced the gull wing and laid the foundation for the development of the present Corsair fighter. This Vought design was considered an experimental project that would need exhaustive wind tunnel and engine tests because of its unconventional design and also because of the then existing status of the 2800 engine. However, in view of the fact that the Vought design could, if the necessity arose, incorporate the R-2600 engine as an alternate, the plane appeared to show considerable promise. Thus, out of this competition came the XF4U-1, the Vought "B" proposal. As outlined in the proposal, the weight would be 6584 pounds. It is interesting to note that the F4U-1 of 1944 has a gross weight of 12,700 pounds, yet in spite of the doubling of the weight, there has been an increase of 80 mph speed over the 356 mph originally calculated. The Pratt and Whitney R-2800 two stage engine was finally incorporated in the plane to give it its added performance.
The other design favorably acted on by Class Desk A in conjunction with the other offices of the Bureau of Aeronautics was the proposal submitted by Grumman for a twin engine fighter which became the XF5F-1 (specification SD-112-14). This twin engined monoplane was powered by two Pratt and Whitney R-1535-96 engines capable of developing a total of 1500 horsepower at 9500 ft. With the addition of two-stage equipment it was expected that the engines would develop this horsepower at 17500 ft.
In this design competition, there was a third design award to Bell. The contractor's proposal was similar to an Army aproject nearing completion. It was felt, however, that with the expected advance in the rating of the Allison engine, that this plane would give the Navy a more modern airplane with outstanding performance. With the expected rating of 1150 horsepower at 15,000 feet, it was felt that an attractive design could be developed around the liquid cooled engine, A contract was therefore let for the XFL-1 airplane. As 1938 drew to a close it was very strongly felt that the Navy needed this Bell fighter in order to round out its fighter program and have one light weight fighter. This, however, depended on the outcome of the Allison engine rating (V-1710), for if 1150 horsepower could be attained then a VMax of 347 mph at 12,000 feet could be reached.
The weight of the fighters showed a marked increase in this competition. Existing Navy fighters weighed around 4,000 pounds, for example the F3F-1 weighed 4100 pounds, the F3F-2, 4400 pounds, the XF2A-1, 4800 pounds, and the XF4F-2, 5100 pounds. The new designs jumped to weights around 9000 pounds.
