The Keystone LB-10 was the direct predecessor of the Keystone B-3A Panther and the series of biplane bombers that followed, and was the last entry in the LB Light Bomber series to be ordered into production. Only one LB-10 would be completed before the order was changed to one for the same number of B-3As, using a different engine.
The single LB-10 was produced by modifying the last production LB-6. It received a new tail, with a single vertical control service, and was powered by two Wright R-1750-1 Cyclone engines, the same engines as used in the LB-6. The main difference in performance was the increase in bomb load from 2,000lb to 2,500lb.
Keystone received an order for 63 LB-10As, but before any were built the LB Light Bombardment series was abandoned in favour of the B (Bombardment) series. The first LB-10As would be delivered as Keystone B-3A Panthers, powered by Pratt & Whitney engines.
Engine: Wright R-1750-1 Cyclone
Length: 49ft 3in
Height: 15ft 6in
Gross Weight: 13,285lb
Maximum Speed: 116 mph at sea level
Cruising Speed: 93mph
Range: 352 miles with full bomb load
Guns: Five 0.30in machine guns
Bomb load: 2,500lb