Vought UO-3 / FU-2

In the mid-twenties, there was a major thrust to operate single-place, fighter-type aircraft from the catapult-equipped ships. 

As a result, final development of the UO series brought an order on June 20, 1926, for 20 single-seat UO-3 airplanes with the Wright Whirlwind 220-hp J-5 engine. 

These were catapult-launched, floatplane fighters armed with 7.62-mm, forward-firing, machine guns. 

Before delivery in 1927, they were re-designated by the Navy as FU-1 to more accurately describe their mission. 

The standard observation two-seater UO was converted to a single seater and stiffened up to withstand the additional loads, including improved wings and a revised vertical tail. 

It also incorporated the first service application of supercharging. 

These aircraft used the Rootees model 3 supercharger capable of maintaining sea level pressures at the carburettor to the critical altitude of 15,000 feet. 

These aircraft were the last wood and wire design emanating from World War I that were bought for the U.S. military. 

They went to service simultaneously with the larger Boeing Packard FB-5. 

This was a single seater with a 600-hp, water-cooled engine. 

The squadron equipped with the Vought FU’s came into daily competition with this FB-5 squadron.

It was a striking fact that anywhere above 10,000 feet the little FU was superior in speed, manoeuvrability, and climb to its competitor, which had approximately three times its sea-level horsepower. 

Here again the influence of wing loading and supercharging on altitude performance were demonstrated in actual service. 

VF-2, calling themselves the “Big Apes,” was the only squadron to receive the FU-1. 

In due course, eighteen of the FU-1’s were converted to two-seat FU-2’s, performing utility and training duties when new fighters appeared on the horizon in 1928 Many of these excellent and well-built aircraft were serving in secondary roles into the early 1930’s.

When two new carriers, the U.S.S Lexington and USS. Saratoga, came onto the scene, the “battleship fighter” concept was dropped, and the FU’s were modified to two-seat trainers as FU-2’s. 

This rounded out their service in fleet support and training duty. 

By 1933, the Navy UO/FU’s were retired, with the last Coast Guard UO-4 phasing out in 1935.





28 ft 4.5 in (8.65 m)


34 ft 4 in (10.47 m)


10 ft 2 in (3.10 m)

Wing area

270 sq ft (25.1 m2)


Navy N-9

Empty weight

2,074 lb (943 kg)

Gross weight

2,774 lb (1,260 kg)


1× Wright J-5 Whirlwind 9 cylinder air cooled radial engine, 220 hp (164 kW)


Maximum speed

106 kn (122 mph, 196 km/h) at sea level


357 nmi (410 mi, 660 km)

Service ceiling

26,500 ft (8,080 m)

Wing loading

10.3 lb/sq ft (50.2 kg/m2)


0.079 hp/lb (0.13 kW/kg)

Climb to 5,000 ft (1,520 m)

5 minutes



2 x .30 in machine guns.


Share on facebook