The XB-10 was initially the Martin Model 123 (or XB-907) and featured three open cockpits, retractable landing gear and Townend ring engine cowlings. The Model 123 had a top speed of 197 mph -- faster than pursuit aircraft in service at the time!
The aircraft was returned to Martin in mid-1932 for several modifications designed to make the basic aircraft even better. First, the front gunner's compartment was covered with an enclosed full-rotating dome turret, the first on a U.S. bomber. Next, original engines were replaced by more powerful versions, and the ring cowls were replaced with full engine cowlings giving the aircraft improved streamlining. Finally, the wing span was increased by more than eight feet. The new aircraft was redesignated XB-907A and then XB-10 by the U.S. Army Air Corps and given the serial number 33-139.
The basic design of the Martin B-10 began a revolution in U.S. bomber design and made all existing bombers in Army inventory completely obsolete. The all-metal monoplane with enclosed cockpits and gun turrets, retractable landing gear and speed-enhancing features like full engine cowlings would set a design standard for decades to come. The Glenn L. Martin Co. was awarded the Collier Trophy in 1932 for the XB-10. In fact, the B-10 was so fast it would take pursuit plane designers another three years to produce an aircraft significantly faster than the production B-10.
Type
Number built/
converted
Remarks
XB-10
1
Martin Model 123; XB-907A
TECHNICAL NOTES: Armament: Three .30-cal. Browning machine guns and 2,260 lbs. of bombs Engines: Two Wright R-1820-19 radials of 675 hp each Maximum speed: 207 mph at 6000 ft. Cruising speed: 170 mph Range: 600 miles with full armament load Service ceiling: 21,000 ft. Span: 70 ft. 7 in. Length: 45 ft. Height: 10 ft. 4 in. Weight: 12,560 lbs. gross Crew: Four Serial number: 33-139