The XF5U-1 during testing
Role Fighter
Manufacturer Vought
Designer Charles H. Zimmerman
Status Cancelled 17 March 1947
Primary user United States Navy
Number built 2
Developed from Vought V-173
The Vought XF5U "Flying Flapjack" was an experimental U.S. Navy fighter aircraft designed by Charles H. Zimmerman during World War II. This unorthodox design consisted of a flat, somewhat disc-shaped body (hence its name) serving as the lifting surface.[1] Two piston engines buried in the body drove propellers located on the leading edge at the wingtips.
Design and development:
A developed version of the original V-173 prototype, the XF5U-1 was a larger aircraft. Of all-metal construction, it was almost five times heavier, with two 1,600 hp (1,193 kW) Pratt & Whitney R-2000 radial engines. The configuration was designed to create a low aspect ratio aircraft with low takeoff and landing speeds but high top speed.
Normally, a wing with such a low aspect ratio will suffer from very poor performance due to the degree of induced drag created at the wingtips, as the higher pressure air below spills around the wingtip to the lower-pressure region above. In a conventional aircraft, these wingtip vortices carry a lot of energy with them and hence create drag. The usual approach to reducing these vortices is to build a wing with a high aspect ratio, i.e. one that is long and narrow. However, such wings compromise the maneuverability and roll rate of the aircraft, or present a structural challenge in building them stiff enough. The XF5U attempted to overcome the tip vortex problem using the propellers to actively cancel the drag-causing tip vortices. The propellers are arranged to rotate in the opposite direction to the tip vortices, with the aim of retaining the higher-pressure air below the wing. With this source of drag eliminated, the aircraft would fly with a much smaller wing area, and the small wing would yield high maneuverability with greater structural strength.
The propellers envisioned for the completed fighter were to have a built-in cyclic movement like a helicopter's main rotor, with a very limited ability to tilt up and down to aid the aircraft in maneuvering. An ejection seat was fitted to allow the pilot to clear the massive propellers in the event of an in-flight emergency. Although the prototype was unarmed, a combination of machine gun
eneral characteristics:
Crew: One, pilot
Length: 28 ft 7 in (8.73 m)
Wingspan: 32 ft 6 in (9.91 m)
Height: 14 ft 9 in (4.50 m)
Wing area: 475 ft² (44.2 m²)
Empty weight: 13,107 lb (5,958 kg)
Loaded weight: 16,722 lb (7,600 kg)
Max. takeoff weight: 18,772 lb (8,533 kg)
Powerplant: 2 × Pratt & Whitney R-2000-7 radial engine, 1,350 hp (1,007 kW) each
Performance:
Maximum speed: 413 knots / 475 mph at 28,000 ft (estimated)[8] (765 km/h at 8,534 meters)
Range: 1,064 miles (1,703 km)
Service ceiling: 34,492 ft (10,516 m)
Rate of climb: 3,000 ft/min (914 m/min)
Wing loading: 35 lb/ft² (172 kg/m²)
Power/mass: 0.16 hp/lb (0.27 kW/kg)
Armament:
6 × .50 machine guns or 4 × 20 mm cannon
2 × 1000 lb. bombs
s and cannons would have been installed under the nose.