The Vought V-173 "Flying Pancake" was an American experimental test aircraft built as part of the

Vought XF5U The Vought XF5U "Flying Flapjack" was an experimental U.S. Navy fighter aircraft designed by Charles H. Zimmerman for Vought during World War II. This unorthodox design consisted of a flat, somewhat disc-shaped body (hence its name) serving as ...

program during

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposing ...

. Both the V-173 and the XF5U featured an unorthodox "all-wing" design consisting of flat, somewhat disk-shaped bodies (hence the 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 H. Zimmerman was a noted aeronautical engineer who advocated the concept of "discoidal" aircraft, the so-called "Zimmer Skimmer" and worked on a variety of projects on his own and with the

Vought Vought was the name of several related American aerospace firms. These have included, in the past, Lewis and Vought Corporation, Chance Vought, Vought-Sikorsky, LTV Aerospace (part of Ling-Temco-Vought), Vought Aircraft Companies, and Vought Ai ...

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 An airfoil (American English) or aerofoil (British English) is the cross-sectional shape of an object whose motion through a gas is capable of generating significant lift, such as a wing, a sail, or the blades of propeller, rotor, or turbine. ...

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 The Vought F4U Corsair is an American fighter aircraft which saw service primarily in World War II and the Korean War. Designed and initially manufactured by Chance Vought, the Corsair was soon in great demand; additional production contracts ...

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. Vought V

The disc wing design featured a low aspect ratio that overcame the built-in disadvantages of

induced drag In aerodynamics, lift-induced drag, induced drag, vortex drag, or sometimes drag due to lift, is an aerodynamic drag force that occurs whenever a moving object redirects the airflow coming at it. This drag force occurs in airplanes due to wings or ...

created at the wingtips with the large propellers actively canceling 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. The empennage consisted of two vertical fins with rudders, all-moving stabilizers with anti-servo tabs, and two large elevator/trim surfaces on either side of centerline on the trailing edge of the wing planform. V-173 Clearly Showing All-Flying Tail with Anti-Servo tabs

V-173 Clearly Showing All-Flying Tail with Anti-Servo tabs

Zimmerman chose to include the all-moving stabilizer design because he realized that the increased drag, prop wash, and large wing area would make the aircraft difficult to control at low speeds. Wind tunnel tests would prove that this was a success to an extent. The aircraft would prove to require a lot of force to control at low speeds during in-flight testing but the tail design would prove to make the aircraft controllable. In January 1942,

BuAer The Bureau of Aeronautics (BuAer) was the U.S. Navy's material-support organization for naval aviation from 1921 to 1959. The bureau had "cognizance" (''i.e.'', responsibility) for the design, procurement, and support of naval aircraft and relate ...

requested a proposal for two prototype aircraft of an experimental version of the V-173, known as the VS-135. The development version, the

-1, was a larger aircraft with all-metal construction, and was almost five times heavier.Winchester ''Concept Planes'' 2005, p. 247. Although a prototype was constructed, it only performed brief hops on the runway, it never entered true controlled flight.

Operational history

The first flight of the V-173 was on 23 November 1942 with Vought Chief Test Pilot

Boone Guyton Boone Tarleton Guyton United States Navy, (September 4, 1913 – April 4, 1996) was a naval aviator, experimental test pilot, author and businessman. In a flying career spanning the biplane era through the jet age, Guyton was perhaps best known fo ...

at the controls. The aircraft's most significant problem concerned its complicated

gearbox Propulsion transmission is the mode of transmitting and controlling propulsion power of a machine. The term ''transmission'' properly refers to the whole drivetrain, including clutch, gearbox, prop shaft (for rear-wheel drive vehicles), differe ...

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. This contributed to the aircraft feeling much too heavy when maneuvering for its light weight. In addition to this on the first few flights, the pilot was never able to achieve enough speed to achieve the correct amount of airflow over the control surfaces to pull the aircraft into level flight. The test pilot Guyton discussed these issues with Zimmerman and they worked to eliminate these issues. In addition to this Guyton commented that the cockpit design was poor. He explained that in addition to the poor comfort the pilot had limited to no use for the clear bottom panels of the cockpit. He explained that the pilot sat too high in the cockpit to effectively use these lower panels for takeoff or landing. Flight testing of the V-173 went on through 1942 and 1943 with 190 flights, resulting in reports of

UFO An unidentified flying object (UFO), more recently renamed by US officials as a UAP (unidentified aerial phenomenon), is any perceived aerial phenomenon that cannot be immediately identified or explained. On investigation, most UFOs are id ...

s from surprised Connecticut locals.

Charles Lindbergh Charles Augustus Lindbergh (February 4, 1902 – August 26, 1974) was an American aviator, military officer, author, inventor, and activist. On May 20–21, 1927, Lindbergh made the first nonstop flight from New York City to Paris, a distance o ...

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 A lifting body is a fixed-wing aircraft or spacecraft configuration in which the body itself produces lift. In contrast to a flying wing, which is a wing with minimal or no conventional fuselage, a lifting body can be thought of as a fuselage ...

. 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.Guyton 1991, p. 29. 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.

Aircraft on display

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 The Smithsonian Institution ( ), or simply the Smithsonian, is a group of museums and education and research centers, the largest such complex in the world, created by the U.S. government "for the increase and diffusion of knowledge". Founded ...

to the Frontiers of Flight Museum in Dallas, Texas.

Specifications (V-173)

References

;Notes ;Bibliography * Chant, Christopher. ''Fantastic Aircraft''. New York: Gallery Books, 1984. . * Ginter, Steve. ''Chance Vought V-173 and XFU-1 Flying Pancakes (Naval Fighters Number Twenty-one)''. Simi Valley, CA: Steve Ginter Publishing, 1992. . * Guyton, Boone T. "The Flight That Must Not Fail, In the Strangest Flying Machine of All - The V-173." ''The Hook - Journal of Carrier Aviation'' Vol. 19, no. 4, Winter 1991. . * Guyton, Boone and Paul Marcus. "The Ups and Downs of The Flying Pancake." ''True'', July 1951. Vol. 29, no. 170. * Guyton, Boone T. ''Whistling Death: The Test Pilot's Story of the F4U Corsair''. Atglen, PA: Schiffer Publishing Ltd., 1996. . * Jerram, Michael E. ''Incredible Flying machines: An Anthology of Eccentric Aircraft''. New York: Exeter Books, 1980. . * Pearson, Gregory. "Vought's Flying Disc." ''Wings'' Vol. 32, no. 1, February 2002. * Schoeni, Art. "The Flying Pancakes." ''Aeroplane Monthly'' Part 1 Vol. 3, no. 11, November 1975, Part II, Vol. 3. no. 12, December 1975. * Schoeni, Art. "The Flying Pancakes." ''Air Classics'' Vol. 11, no. 8, August 1975. * Winchester, Jim. ""Vought XFU-1." ''Concept Aircraft: Prototypes, X-Planes and Experimental Aircraft''. Kent, UK: Grange Books plc., 2005. . * Winchester, Jim. "Vought V-173 and XFU-1 'Flapjack' (1942)". ''X-Planes and Prototypes''. London: Amber Books Ltd., 2005. .

External links