Vought V-173 Flying Pancake

The Vought V-173 "Flying Pancake" was an American experimental test aircraft built as part of the Vought XF5U "Flying Flapjack program" during World War II.Designed as a "proof-of-concept" prototype, the initial configuration V-173 was built as a lightweight test model powered by two 80 hp Continental A-80 engines turning F4U Corsair propellers. These were replaced by a pair of specially modified 16 ft 6 in three-bladed units. A tall, fixed main undercarriage combined with a small tailwheel gave the aircraft a 22° "nose-high" angle.

Flight testing of the V-173 went on through 1942 and 1943 with 190 flights, resulting in reports of UFOs from surprised Connecticut locals. Charles Lindbergh piloted the V-173 during this time and found it surprisingly easy to handle and exhibiting impressive low-speed capabilities. Both Lindbergh and Guyton found that they were almost unable to stall the aircraft. Guyton was able to keep the aircraft in flight no matter how hard he pulled the stick in low-speed flight ranges at any altitude under 20,000 ft. On one occasion, the V-173 was forced to make an emergency landing on a beach. As the pilot made his final approach, he noticed two bathers directly in his path. The pilot locked the aircraft's brakes on landing, causing the aircraft to flip over onto its back. Remarkably, the airframe proved so strong that neither the plane nor the pilot sustained any significant damage.

 Despite their inability to stall the aircraft they did find low speed handling to be a persistent issue largely due to the shape of the lifting body. They found that the aircraft acted as an airbrake when it was pulled into a high angle of attack. This meant that the control surfaces, the horizontal stabilizers, in particular, would become very hard to operate at low speeds such as stalls, takeoff, and landing.

The developmental V-173 made its last flight 31 March 1947. In 131.8 hours of flying over 190 flights, Zimmerman's theory of a near-vertical takeoff- and landing-capable fighter had been proven.[14] This project would be improved upon including the addition of potential armament with the Chance Vought XF5U. This project would improve on many of the weaknesses discovered during the testing of the V-173 prototype.As of April 2012, after undergoing a long restoration by Vought Aircraft Heritage Foundation volunteers, the V-173 is on loan from the Smithsonian Institution to the Frontiers of Flight Museum in Dallas, Texas.