The Stearman Model 6 Cloudboy was a 1930s
American training biplane designed and built by the
Stearman Aircraft Company of Wichita, Kansas.
History
The Cloudboy was designed as a commercial or military trainer. Due to economic pressure during the
Great Depression, only a few aircraft were built.
Three civil models were built, followed by four similar aircraft for evaluation by the
United States Army Air Corps. Designated YPT-9 by the Army, it failed to gain any orders. All models went through a number of engine changes (resulting in new designations for both the military and civil aircraft).[1]
Variants
Model 6A Cloudboy
Initial civil production with a 165 hp (123 kW)
Wright J-6 Whirlwind 5 engine, three built.
Model 6C Cloudboy
Re-engined with a 300 hp (220 kW)
Wright J-6-9 Whirlwind (R-975-1), also designated YBT-3.
Re-engined with a 165 hp (123 kW)
Continental A70 engine, also designated YBT-9A.
Model 6H Cloudboy
Re-engined with a 170 hp (130 kW)
Kinner YR-720A engine, also designated YBT-9C.
Model 6L Cloudboy
Re-engined with a 200 hp (150 kW)
Lycoming R-680-3 engine, also designated YBT-9B
Model 6P Cloudboy
One 6F re-engined with 1 220 hp (160 kW)
Wright J-5 engine
YPT-9
Military production variant of the Model 6A with a 165 hp (123 kW)
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).
YPT-9A
One YPT-9 re-engined with a 165 hp (123 kW)
Continental A70 (YR-545-1) engine, later converted to YPT-9B.
YPT-9B
One YPT-9 and one YPT-9A re-engined with a 200 hp (150 kW)
Lycoming R-680-3 engine.
YPT-9C
YBT-3 re-engined with a 170 hp (130 kW)
Kinner YR-720A engine.
YBT-3
One YPT-9 re-engined with a 300 hp (220 kW)
Wright J-6-9 Whirlwind, later converted to a YPT-9C.
A primary trainer derived from the 6A for evaluation at
Wright Field. Formed the origins of the Stearman NS and PT-13 for the US Navy and USAAC respectively.
6004 – YPT-9B on display at the
Yanks Air Museum in
Chino, California. It was previously owned by the Boeing School of Aeronautics and was acquired by the museum in 1987.[6][7]