Keystone LB-8 in flight. In this photograph, Maj. Hugh J. Knerr, commanding officer of the 2nd Bomb Group, Langley Field, Va., leads a flight of 19 bombers on their way to exercises in California. (U.S. Air Force photo)
The Keystone LB-8 was the 17th Keystone LB-7 (S/N 29-9) re-engined with Pratt & Whitney GR-1860-3 radial engines of 550 hp each. The LB-8 had slightly better performance than the original LB-7 but never entered production.
The most significant feature tested on the LB-8 was the geared engine (2:1 ratio), which was designed to allow more efficient propeller operation combined with better engine performance.
17th LB-7 with new engines
TECHNICAL NOTES: Armament: Five .30-cal. machine guns and 2,000 lbs. of bombs Engines: Two Pratt & Whitney R-1860-3 radials of 550 hp each Top speed: 126 mph at sea level Cruising speed: 100 mph Service ceiling: 16,800 ft. Span: 75 ft. 0 in. Length: 49 ft. 3 in. Height: 18 ft. 1 in. Weight: 13,745 lbs. gross Crew: Five