The Stearman XA-21 (Model X-100) was a competitor in a United States Army Air Corps competition for a twin-engined attack aircraft which (after redesigns) led to the Douglas A-20 Havoc, Martin A-22 Maryland and North American B-25 Mitchell.
The X-100, designated XA-21 following purchase by the Army Air Corps, was a twin-engined high-winged monoplane of all-metal construction.[1] Its initial design featured an unusual "stepless cockpit" arrangement, much like those on most German World War II bombers designed during the war years from the He 111P onwards, with a streamlined, well-framed greenhouse canopy enclosing both the pilot and bombardier stations.[2]
The XA-21 was first tested with the streamlined cockpit but this configuration was found to restrict the pilot's forward vision, and the aircraft was rebuilt with a conventional (stepped) nose and cockpit structure.[3] Although this change in the cockpit did not significantly affect performance, the XA-21 was not ordered into production.'
The sole XA-21 had serial number 40-191.[4]
United States