The Boeing XF6B/ XBFB was the last biplane fighter produced by the company, but despite being considered as both a fighter and a fighter-bomber didn't win a production order.
Work on the Model 236 began in 1931. It was designed to use the two-row Twin Wasp Junior engine. The fuselage was all-metal, as was the wing framework, although the wings were fabric covered. It was an equal-span single bay biplane, with equal-chord straight wings of equal size. The lower wing was slightly behind the upper wing. The main wheels were originally carried on two struts, with the first one in a streamlined fairing, but this was later changed to a single fairing for each wheel. It was the last aircraft with a fixed undercarriage to be submitted to the Navy.
The US Navy gave the aircraft the designation XF6B-1. It made its maiden flight on 1 February 1933 with that designation. It was delivered to the Navy on 23 April 1933. On 21 March 1934 the designation was changed to BFB in the new bomber-fighter classification. Although a number of improvements were made to the design during the testing process, biplanes were on their way out by the mid 1930s and the type wasn't ordered into production.
Engine: Pratt & Whitney R-1535 two-row Twin Wasp Junior
Span: 28ft 6in
Length: 22ft 1.5in
Height: 10ft 7in
Empty Weight: 2,288lb
Loaded Weight: 3,704lb
Maximum Speed: 200mph at 6,000ft as fighter, 185mph as bomber
Climb rate: 4.2min to 5,000ft
Ceiling: 24,400ft as fighter, 21,100ft as bomber
Range: 525 miles
Guns: Two 0.3in machine guns
Bomb load: One 500lb bomb, two 115lb bombs