Vought V - 173 The Vought V - 173 " Flying Pancake " designed by Charles H . Zimmerman was an American experimental test aircraft built as part of the Vought XF5U " Flying Flapjack " World War II United States Navy fighter aircraft program . Both aircraft featured an unorthodox " all - wing " design consisting of a flat , somewhat disk - shaped body ( hence its name ) serving as the lifting surface . Two piston engines buried in the body drove propellers located on the leading edge at the wingtips . Design and development . In the 1930s , Charles Zimmerman was a noted aeronautical engineer who advocated the concept of " discoidal " aircraft , the so - called " Zimmer ' s Skimmers " and worked on a variety of projects on his own and with the Vought company . After testing using scale models , including a remotely controlled , electrically powered large scale model , designated the Vought V - 162 , the US Navy approached Zimmerman and offered to fund further development . Data and concept documentation was given to the Navy in 1939 , with wind tunnel tests on full scale models being completed in 1940 - 1941 . The original prototype , designated the V - 173 ( " Flying Pancake " ) , was built of wood and canvas and featured a conventional , fully symmetrical aerofoil section ( NACA 0015 ) . Designed as a " proof - of - concept " prototype , the initial configuration V - 173 was built as a lightweight test model powered by two 80 hp ( 60 kW ) 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 . The disc wing design featured a low aspect ratio that overcame the built - in disadvantages of induced drag created at the wingtips with the large propellers actively cancelling the drag - causing tip vortices . The propellers were arranged to rotate in the opposite direction to the tip vortices , allowing the aircraft to fly with a much smaller wing area . The small wing provided high maneuverability with greater structural strength . In January 1942 , BuAer requested a proposal for two prototype aircraft of an experimental version of the V - 173 , known as the VS - 135 . The development version , the Vought XF5U - 1 , was a larger aircraft with all - metal construction , and was almost five times heavier . Operational history . The first flight of the V - 173 was on 23 November 1942 with Vought Chief Test Pilot Boone Guyton at the controls . The aircraft ' s most significant problem concerned its complicated gearbox that routed power from the engines to its two long propeller shafts . The gearbox produced unacceptable amounts of vibration in ground testing , delaying the aircraft ' s first test flight for months . Flight testing of the V - 173 went on through 1942 and 1943 with 190 flights , resulting in reports of " flying saucers " ( unlikely usage , because the term was coined on June 24 , 1947 by Kenneth Arnold ) 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 . 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 . 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 . The V - 173 is now part of the Smithsonian collection at the Paul E . Garber Preservation , Restoration , and Storage Facility in Silver Hill , Maryland . It is currently at the Vought Aircraft plant in Grand Prairie , Texas being restored to go back on display . As of April 2012 it is on loan to the Frontiers of Flight Museum in Dallas , Texas .