In January 1927 the Chance Vought company produced a single seat fighter version of its mass produced VO 1 shipboard observation aircraft. A two bay biplane, the VO 1 was not entirely suitable as the basis for a competitive fighter, and with only the same engine as before, the 200 hp Wright R 1790 Whirlwind, performance was inadequate. Nevertheless, 20 FU 1 fighters were converted from UO-3 for the US Navy, most of them being central float seaplanes (at least two were fitted with wheels for airfield use).

Despite being pleasant to fly, the FU was really only suitable for training. In their first year, ending in the winter 1928 29, the FU 1s equipped fighter squadron VF 2B aboard the carrier Langley. Thereafter the 18 that survived were converted into FU 2 trainers, still with a fixed Marlin machine gun. They remained in use as trainers and general-purpose aircraft into the 1930s.

Equipped for catapult launch, they were the last fighter so equipped.

FU
Engine: 220hp Wright J-5 (supercharged R-1790)
Span: 10.46 m (34 ft 4 in)
Length: 7.44 m (24 ft 5 in)
Gross weight: 1093 kg (2400 lb)
Useful load: 694 lb
Maximum speed: 236 km/h (147 mph)
Stall: 53 mph
Range: 430 mi
Seats: 1-2