The Boeing F3B (Boeing Model 77) was the third generation of Boeing fighters to see service with the US Navy, and featured new wings, landing gear and tail units.
Work on the aircraft began as a private venture, the Boeing Model 74. This was similar to the Boeing F2B, but was built as a seaplane, with a main central float and wing tip balance floats.
The Model 74 made its maiden flight on 2 March 1927. The aircraft went to the US Navy for trials, where it was given the designation XF3B-1, but its performance wasn't good enough to justify putting it into production. The aircraft was returned to Boeing, where work began on improving the design.
Boeing kept the same Pratt & Whitney R-1340-80 engine as on the Model 74. The fuselage design was the same, although it was extended by two feet (mainly in the nose). Most of the rest of the new Model 77 was new. It had an increased wing span. The upper wing was slightly swept back, the lower wing was un-swept, and with a constant chord. The main landing gear unit and tail units were both redesigned. The main wheels were each carried on three struts with oleo suspension on the main strut. On the prototype a dummy cross-axle linked the wheels. This was designed for use with carrier deck hooks, but was removed on production aircraft.
The Model 77 kept the same basic construction as earlier Boeing fighters, with a welded steel tube fuselage structure, wood wing structure and a fabric covering. The ailerons and tail surfaces were all-metal with a corrugated covering that provided their structural strength. The aircraft was armed with two machine guns and could carry up to five 25lb bombs.
The Model 77 made its maiden flight on 3 February 1928. It performed better in US Navy trials. It was no faster than the Boeing F2B (hardly surprising given that it had the same engine power and was actually a little heavier when fully loaded), but it had a faster rate of climb and range.
The US Navy placed an order for 73 F3B-1s and also paid for the prototype. Deliveries began on 15 August 1928 and ended on 23 November 1928.
The F3F entered service with Squadron VF-2B on USS Langley. It was later used by VB-1B and VF-3B on the Lexington and VB-2B on the Saratoga. Eighteen aircraft were converted to the bomber configuration by Boeing for use with VG-2B. The Navy later added drag reducing Townend-ring cowling to their aircraft.
Engine: Pratt & Whitney R-1340-80 radial pistol engine
Span: 33ft 0in
Length: 24ft 10in
Height: 9ft 2in
Empty Weight: 2,179lb
Maximum Take-off Weight: 2,945lb
Maximum Speed: 157mph at sea level
Cruising Speed: 131mph
Climb rate: 2,020ft/ min
Range: 340 miles
Guns: One 0.3in and one 0.5in fixed forward firing machine gun
Bomb load: Up to five 25lb bombs (total 125lb)