Vought V-173 Flying Pancake Color Photographs

The Vought V-173 was a concept demonstrator designed by aeronautical engineer Charles Zimmerman. It was a lifting body with an unusual circular planform which led to the nickname “Flying Pancake” or “Flying Flapjack”, and several reports of UFO sightings. The U.S. Navy became interested due to the promising characteristics of the design, including its structural strength, maneuverability, and low-speed handling. First flight was on 23NOV42. (NASM, Rudy Arnold Collection)
A major source of drag from a traditional airfoil is due to wingtip vortices generated by higher-pressure air spilling over the ends of the wings. Zimmerman’s design countered this phenomenon by mounting propellers at the extreme forward edges of the body and gearing them so the tops of the propeller discs would rotate outwards. The direction of the prop wash would therefore cancel out the wingtip vortices and increase pressure on the underside of the aircraft’s body, increasing lift and reducing drag. (NASM, Rudy Arnold Collection)
The aircraft was able to fly at very low airspeeds, what would be termed STOL (Short Take-Off and Landing) today. To maintain control at low airspeeds traditional elevators were not used, the entire horizontal tailplane was moveable. Test pilots, including Charles Lindbergh, found the aircraft to be very maneuverable and almost impossible to stall. (NASM, Rudy Arnold Collection)
Because of the nose-high attitude of the aircraft the underside of the nose was extensively glazed. This was not an optimal solution, as pilots still had difficulty seeing the runway due to the approach angles required. Nevertheless, the V-173 proved the viability of the lifting body concept and suitability as a STOL design. It flew for the last time on 31MAR47, after 190 flights. (NASM, Rudy Arnold Collection)
The V-173 is preserved, and is on display at the Frontiers of Flight Museum in Dallas, Texas.
The Navy asked Vought to develop the concept into a prototype fighter aircraft, which resulted in the XF5U. Two were constructed, each using two Pratt & Whitney R-2000 radial engines mounted in the fuselage. The design was promising, but after the war the focus shifted to jet aircraft and the project was cancelled on 17MAR47.