Stearman XA-21 Ground Attack Aircraft Prototype
The Stearman XA-21 was a proposed solution to a USAAC requirement for a twin-engined attacker.
Authored By Staff Writer; Content ©www.MilitaryFactory.com
The U.S. Army's road to the classic twin-engined attack aircraft of World War 2 (1939-1945) was a long one and saw many promising (and forgettable) types dropped from contention. This included the overlooked Stearman "XA-21" of which only one was built and failed to impress. The type first flew in 1938 but never materialized beyond its prototype status even after drastic changes had been implemented that included a redesigned nose. The product did, however, provide U.S. Army authorities exposure to twin-engined types (and their inherent strengths and weaknesses) that eventually led the adoption of platforms like the Douglas A-20 "Havoc" and North American B-25 "Mitchell" forms.
The XA-21 began life as the Stearman "Model X-100" and was developed to a standing USAAC ground attacker requirement. The Model X-100 was proposed with its unique nose section that showcased a long "greenhouse-style" canopy over the crew area. A twin-engine configuration was used to power the type (and was required by the USAAC for its new attacker). Three crew operated her various onboard systems and a conventional, single-finned tail unit was used. The wing mainplanes were high-mounted and each carried an engine nacelle. The engine of choice became 2 x Pratt & Whitney R-2180-7 "Twin Hornet" radials outputting at 1,400 horsepower.
Proposed armament included a single Browning 0.30 caliber machine gun in the nose and four additional guns fitted to the wings (two each). Four additional Brownings (0.30 cal) were then installed to face aft and tackle any approaching interceptor. Up to 2,700lb of conventional drop ordnance would be carried to fulfill the bombing requirement.
After the Army acquired the X-100 it was redesignated XA-21 for its test phase. It was quickly found to hold an inherent design flaw - namely its long greenhouse canopy that restricted the pilot's forward vision - this meant poor ground running, take-off, and landing qualities. As such, engineers were forced to completely redesign the nose section and it was then reborn as a "stepped" cockpit approach somewhat reminiscent of the Consolidated B-24 "Liberator" heavy bomber (detailed elsewhere on this site). The XA-21 continued in testing but did not reveal any stunning revelations about her to recommend her for serial production.
This left just the sole prototype form completed.