The brainchild of Charles H. Zimmerman, the F5U was intended to perform well as a fighter plane while being able to remain in flight at extremely low airspeed, making it easier to operate from carriers. The F5U's unusual appearance owed to a very low aspect ratio wing without a fuselage, which resulted in something looking like a flying saucer. This shape, combined with powerful engines driving large propellers, could plow through the air at low speed (40 mph!), since the whole airframe is immersed in the prop wash.

The XF5U Flying Pancake was manufactured by Vought. It was a fighter aircraft and the brainchild of Charles Zimmerman during World War II. Its maiden flight was on the 23rd of November 1942 and its production was cancelled on the 17th of March 1947.

The XF5U was the most unusual aircraft designed for the U. S. Navy. It consists of a flat, somewhat disk-shaped body with a very low aspect ratio wing without fuselage that looks like a flying saucer. The Xf5U has two 1,600hp Pratt and Whitney R-2000 radial engines. Its configuration was designed to have a low aspect ratio aircraft that will have a low takeoff and landing speed and high top speed. It can accommodate only one, the pilot; it has a length of 28 ft 7 in; wingspan of 32 ft 6 in; height of 14 ft 9 in; empty weight of 13 107 lb, loaded weight of 16,722 lb. and max takeoff weight of 18,772 lb. It has a maximum speed of 425 mph; range of 1,064 miles; rate of climb 718 ft per minute; and service ceiling of 34,492 ft. It has 6 x .50 machine guns or 4 x 20 mm machine guns or 2 x 1000 lb bombs.

Charles Lindbergh has successfully flown the first flight of the V-173 and he was surprised that it was easy to handle. The aircraft’s main problem was its gearbox which produces unacceptable amounts of vibration. Even the design was really promising. The U.S. Navy came to a point where they had to switch from propeller driven planes to jet propelled planes.