Stearman Model 6 Cloudboy was a 1930s American training biplane designed and built by the Stearman Aircraft Company of Wichita, Kansas.
The Cloudboy was designed as a commercial or military trainer. It was a two-seat biplane with tandem open-cockpits and powered by nose-mounted 165 hp (123 kW)
Wright J-6 Whirlwind 5 engine. It had a fixed tailwheel landing gear. The aircraft was only built in small numbers due to the American economic climate in the early 1930s. Three civil aircraft were built followed by four similar aircraft for evaluation by the United States Army Air Corps. Designated the YPT-9 by the Army it failed to gain any orders. With only a few aircraft built they all went through a number of engine changes resulting in new designations for both the military and civil aircraft.
Model 6A Cloudboy
Initial civil production with a 165hp (123kW) Wright J-6 Whirlwind 5 engine, three built.
Model 6C Cloudboy
Re-engined with a 300hp (224kW) Wright J-6-9 Whirlwind (R-975-1), also designated YBT-3.
Model 6D Cloudboy
Re-engined with a 300hp (224kW) Pratt & Whitney Wasp Junior, also designated YBT-5
Model 6F Cloudboy
Re-engined with a 165hp (123kW) Continental A70 engine., also designated YBT-9A.
Model 6H Cloudboy
Re-engined with a 170hp (127kW) Kinner YR-720A engine, also designated YBT-9C.
Model 6L Cloudboy
Re-engined with a 200hp (149kW) Lycoming R-680-3 engine, also designated YBT-9B
Model 6P Cloudboy
One 6F re-engined with 1 220hp Wright J-5 engine
Military production variant of the Model 6A with a 165hp (123kW) Wright J-6 Whirlwind 5 engine, four built (one converted to YPT-9A, one to YPT-9B, one to YBT-3 and one YBT-5).
One YPT-9 re-engined with a 165hp (123kW) Continental A70 (YR-545-1) engine, later converted to YPT-9B.
One YPT-9 and one YPT-9A re-engined with a 200hp (149kW) Lycoming R-680-3 engine.
YBT-3 re-engined with a 170hp (127kW) Kinner YR-720A engine.
One YBT-9 re-engined with a 300hp (224kW) Wright J-6-9 Whirlwind, later converted to a YPT-9C.
One YBT-9 re-engined with a 300hp (224kW) Pratt & Whitney Wasp Junior engine.
A primary trainer derived fron the 6A for evaluation at Wright Field. Formed the origins of the Stearman NS and PT-13 for the US Navy and USAAC respectively.
Alternative company designation for the XPT-943.
United States Army Air Corps
Specifications (YPT-9B) Edit Data from United States Military Aircraft since 1909 
Length: 24 ft 8 in (7.52 m)
Wingspan: 32 ft 0 in (9.76 m)
Height: 9 ft 7 in (2.92 m)
Wing area: 272 ft 2 (25.3 m 2)
Gross weight: 2,814 lb (1,279 kg)
Powerplant: 1 × Lycoming R-680-3, 200 hp (149 kW) each
Maximum speed: 135 mph (217 km/h)
Range: 490 miles (789 km)
Service ceiling: 17,000 ft (5,183 m)
Rate of climb: 1,050 ft/min (5.3 m/s)
↑ Swanborough and Bowers 1963, p. 441.
Andrade, John (1979). U.S.Military Aircraft Designations and Serials since 1909. Midland Counties Publications. ISBN 0-904597-22-9.
Swanborough, F.G; Bowers, Peter M. (1963). United States Military Aircraft since 1909. London: Putnam.
Taylor, Michael J. H. (1989). Jane's Encyclopedia of Aviation. London: Studio Editions.
The Illustrated Encyclopedia of Aircraft (Part Work 1982-1985). Orbis Publishing. pp. 2958.
External links Edit