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). It was evaluated by the United States Army Air Force in 1942 as the XBT-17.
The X-90 was a low-wing cantilever monoplane with two-seats in tandem under an enclosed canopy. It had a fixed conventional landing gear and was powered by a 2250NaN0 Lycoming R-680 engine and first flew in 1940. It had wooden wings and a steel tube forward fuselage in order to minimize use of aluminum.[1] In 1942 the aircraft was re-engined with a 4500NaN0 Pratt & Whitney R-985 engine and redesignated the Model X-91. The X-91 was evaluated by the United States Army Air Force as the XBT-17 but no more were built.
According to Edward H. Phillips, "At that time, worries at the War Department about a shortage of strategic materials such as aluminum alloy were rampant. The wood/metal composite construction of the proposed monoplane, which required more raw materials than the biplane trainers on an aircraft-by-aircraft basis, was a major factor in the Air Corps' decision not to place the XBT-17 into production, according to a Boeing technical report."[2]