Boeing-Stearman Model X-91

Role Training monoplane
National origin United States
Manufacturer Stearman Aircraft
First flight 1940
Number built 1

The Stearman XBT-17 was a prototype 1940s American two-seat low-wing monoplane primary trainer designed and built by Stearman Aircraft (as the Model X-90).[1] It was evaluated by the United States Army Air Force in 1942 as the XBT-17.[2]

Design and development

The X-90 was a low-wing cantilever monoplane with two-seats in tandem under an enclosed canopy.[1] It had a fixed Conventional landing gear and was powered by a 225 hp (168 kW) Lycoming R-680 engine and first flew in 1940.[1] It had wooden wings and a steel tube forward fuselage in order minimise use of aluminium.[3] In 1942 the aircraft was re-engined with a 450 hp (336 kW) Pratt & Whitney R-985 engine and re-designated the Model X-91.[1] The X-91 was evaluated by the United States Army Air Force as the XBT-17 but no more were built.[1][2]


Stearman X-90
Prototype basic trainer with a 225 hp (168 kW) Lycoming R-680 engine. [1]
Stearman X-91
The X-90 re-engined with a 450 hp (336 kW) Pratt & Whitney R-985 engine for USAAF evaluation.[1]
Stearman XBT-17
United States Army Air Force designation for the X-91.[2]

Specifications (XBT-17)

Data from [4]

General characteristics
  • Crew: 2
  • Length: 27 ft 9 in (8.46 m)
  • Wingspan: 35 ft 9 in (10.90 m)
  • Wing area: 200 sq ft (19 m2)
  • Empty weight: 3,080 lb (1,397 kg)
  • Gross weight: 4,150 lb (1,882 kg)
  • Powerplant: 1 × Pratt & Whitney R-985-AN-1 , 450 hp (340 kW)


  • Maximum speed: 190 mph (306 km/h; 165 kn)
  • Cruise speed: 160 mph (139 kn; 257 km/h)
  • Service ceiling: 20,000 ft (6,096 m)
  • Rate of climb: 1,300 ft/min (6.6 m/s)

See also

Aviation portal

Related lists



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