Ryan YO-51 Dragonfly

The Ryan YO-51 Dragonfly was an observation aircraft designed and built by Ryan Aeronautical for the United States Army Air Corps (USAAC). A single-engined parasol wing monoplane, it was designed for optimum STOL capability, but although three prototypes proved highly successful in testing, the Stinson YO-49 was judged superior and no production contract was placed.

YO-51 Dragonfly
General information
Type	Army observation and liaison
Manufacturer	Ryan Aeronautical
Primary user	United States Army Air Corps
Number built	3
History
First flight	1940

Design

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 parasol monoplane 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]

Operational history

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]

Specifications

YO-51 on the ground

Data from Donald 1997^[3]

General characteristics

• Crew: two (pilot and observer)
• Length: 35 ft 6 in (10.82 m)
• Wingspan: 52 ft (16 m)
• Height: 11 ft 1 in (3.38 m)
• Gross weight: 4,206 lb (1,908 kg)
• Powerplant: 1 × Pratt & Whitney R-985-21 Wasp Junior radial, 440 hp (330 kW)

Performance

• Maximum speed: 129 mph (208 km/h, 112 kn)
• Cruise speed: 107 mph (172 km/h, 93 kn)
• Stall speed: 30 mph (48 km/h, 26 kn)

Armament

• None

See also

Aircraft of comparable role, configuration, and era

• Bellanca YO-50
• Fieseler Fi 156 Storch
• Henschel Hs 126
• Kokusai Ki-76
• Polikarpov Po-2
• Repülőgépgyár_Levente_II
• Stinson L-1 Vigilant

Related lists

• List of military aircraft of the United States