Boeing 74 / 77 / F3B-1
The XF3B-1 (Model 74) was built by Boeing as a private venture and externally resembled closely the F2B-1, but had provision for a single central float with outboard stabilising floats. Powered by a 425hp Pratt & Whitney R-1340 Wasp, it was flown for the first time on 2 March 1927 as a float seaplane.
Showing no significant advance over the F2B-1, the XF3B-1 was returned to Boeing by the US Navy and completely rebuilt (as the Model 77), a redesigned undercarriage, wing and tail being introduced. In this new form the fighter proved successful and was the basis of an order from the US Navy for 73 production examples as F3B-1s. The F3B-1 was of mixed construction with wooden wings, a steel-tube fuselage and fabric skinning, but the ailerons and tail surfaces were of semi-monocoque all-metal construction with corrugated covering. Armament comprised two synchronised 7.62mm machine guns and provision was made for five 11kg bombs to be carried.
The first flight of the rebuilt XF3B-1 took place on 3 February 1928, and the first production F3B-1, powered by an R-1340-B Wasp, was delivered to the US Navy on 23 November 1928.
Engine: Pratt & Whitney R-1340-B Wasp
Take-off weight: 1336 kg / 2945 lb
Empty weight: 988 kg / 2178 lb
Wingspan 10.06 m / 33 ft 0 in
Length: 7.56 m / 24 ft 10 in
Height: 2.79 m / 9 ft 2 in
Wing area: 25.55 sq.m / 275.02 sq ft
Max. speed: 253 km/h / 157 mph
Range: 547 km / 340 miles