The Keystone LB-10 was a conversion of the last production LB-6 (S/N 29-27). The double vertical stabilizers of the LB-6 were removed and replaced with a single tail. Although the tail assembly was of modern design, the Army Air Corps general staff continued to prefer the biplane bomber over monoplane types and fabric and wood types over the all-metal aircraft, which wouldn't be accepted until production orders for the Martin B-10 came in 1933.
The basic LB-10 design would form the basis for the last of the biplane bombers used by the Army. The Keystone B-3, -4, -5 and -6 series aircraft were all essentially improved versions of the LB-10 with engines being the major difference between types.
Last LB-6, new tail assembly
TECHNICAL NOTES: Armament: Five .30-cal. machine guns and 2,500 lbs. of bombs Engines: Two Wright R-1750-1 Cyclone radials of 525 hp each Top speed: 116 mph at sea level Cruising speed: 93 mph Service ceiling: 13,440 ft. Range: 352 miles with full bomb load Span: 75 ft. 0 in. Length: 49 ft. 3 in. Height: 15 ft. 6 in. Weight: 13,285 lbs. gross Crew: Five