The Boeing XF7B was the first low-wing monoplane with a retractable undercarriage to be tested by the US Navy. The aircraft was developed in response to a US Navy specification of 6 December 1932 for a single-seat fighter. Boeing designed the Model 273, a low-wing monoplane with cantilevered wings, a retractable undercarriage and an enclosed cockpit. It was powered by a 550hp Pratt & Whitney engine. It was similar to the Model 264/ YP-29, and thus shared many features with the earlier P-26 fighter. The XF7B was the first Boeing aircraft to be built with a controllable pitch propeller, the first to get flaps and the first low-wing cantilever monoplane to be submitted to the Navy for use from aircraft carriers.
The aircraft made its maiden flight on 14 September 1933 and was delivered to the Navy test centre at Anacostia on 11 November 1933. After the first set of Navy tests it was returned to Boeing to have split flaps and a longer engine cowling installed. The cockpit canopy was also later removed. Despite the changes the US Navy wasn't interested in the design, considering it to have too high a landing speed for carrier operations as well as suffering from a poor view from the cockpit. The sole prototype was over-stressed in a dive in March 1935 after the windscreen of the open cockpit collapsed. After this incident it was no longer seen as safe to fly, and was scrapped.
Engine: Pratt & Whitney SR-1340-30
Span: 31ft 11in
Length: 27ft 7in
Height: 7ft 5in
Empty Weight: 2,782lb
Loaded Weight: 3,651lb
Maximum Speed: 233mph at 10,000ft
Cruising Speed: 200mph
Climb rate: 3.4min to 5,000ft
Range: 750 miles
Guns: Two 0.3in machine guns Boeing XF7B