The design of the YO-51 Dragonfly was typical for aircraft of its type, being optimised for the observation and liaison role, with emphasis on the ability to operate out of the smallest possible airfields.[1] The Dragonfly was a high-wing braced parasolmonoplane with fixed tailwheel landing gear, a two-seat open cockpit, and full-span slots and Fowler flaps for STOL capability.[2] It was powered by a single Pratt & Whitney R-985-21 Wasp Junior radial engine.[3]
At gross weight, the YO-51 could, without flaps, take off after a run of 400 feet, while with full flaps the takeoff run would be only 75 feet, or just four feet more than twice its own length.[4] The Dragonfly was capable of maintaining level flight at speeds as low as 30 miles per hour (48 km/h),[5] and was claimed as being capable of landing in a distance shorter than the length of the aircraft itself.[6]
Nicknamed the "flying motorcycle",[7] three YO-51 aircraft were acquired by the United States Army Air Corps to take part in a fly-off evaluation against the Stinson YO-49 and Bellanca YO-50 to supply a new observation and liaison aircraft for use by the USAAC.[8] The YO-51 was the heaviest of the three aircraft evaluated.[9]
Although the Dragonfly was considered satisfactory during its flight testing,[10] conducted at Wright Field in Ohio,[11] the Stinson machine won the production contract, and no further YO-51s were built.[12]
Adcock, Al (2005). US Liaison Aircraft in action. Aircraft in Action. Vol. 195. Carrollton, TX: Squadron/Signal Publications. ISBN978-0897474870.
Donald, David (1997). Complete Encyclopedia of World Aircraft. London: Orbis Publishing Ltd. ISBN0760705925.
Fowler, Harlan Davey (1948). Fowler Flaps for Airplanes: An engineering handbook. Los Angeles: Wetzel Publishing Co. ASINB0007EA17Q.
Merriam, Ray, ed. (2002). World War II Journal #15: U.S. Military Aircraft of World War II. Bennington, VT: Merriam Press. ISBN1576381676.
Pattillo, Donald M. (2001). Pushing the Envelope: The American Aircraft Industry. Ann Arbor, MI: University of Michigan Press. ISBN978-0472086719.
Penfield, Thomas (1941). Wings for America: Fighting Planes of the U. S. A. Chicago: Rand McNally & Co. ASINB004BVUSC4.
Rowe, Frank Joseph (2006). The Helio Courier Ultra C/stol Aircraft: An Illustrated Developmental History. Jefferson, NC: McFarland & Company. ISBN978-0786422890.
