Keystone B-3

The Keystone B-3A was a bomber aircraft developed for the United States Army Air Corps in the late 1920s.

Keystone B-3
Class Aircraft
Type Bomber
Manufacturer Keystone Aircraft
Origin United States of America
Country Name Origin Year
United States of America 1929
Country Name Operational Year Retirement Year
Philippines View
United States of America View
ManufacturerName Production From Production To Quantity
Keystone Aircraft View

It was originally ordered as the LB-10A (a single-tail modification of the Keystone LB-6), but the Army dropped the LB- 'light bomber' designation in 1930.

Although the performance of the B-3A was hardly better than that of the bombers flown at the end of World War I, it had come a long way. In terms of its safety, it was far superior to its oldest predecessors.

The B-3A was the last biplane operated by the US Army; it remained in service until 1940. A few years after it was first produced, the introduction of all-metal monoplanes rendered it almost completely obsolete.

Role Light bomber
Manufacturer Keystone Aircraft
Primary user United States Army Air Corps
Number built 63 B-3A/B-5
Variants Keystone B-4
Keystone B-5
Keystone B-6

General characteristics

  • Crew: 5
  • Length: 48 ft 10 in (14.9 m)
  • Wingspan: 74 ft 8 in (22.8 m)
  • Height: 15 ft 9 in (4.8 m)
  • Wing area: 1,145 ft² (106.4 m²)
  • Empty weight: 7,705 lb (3,495 kg)
  • Loaded weight: 12,952 lb (5,875 kg)
  • Max. takeoff weight: lb (kg)
  • Powerplant: 2 × Pratt & Whitney R-1690-3 radial engines, 525 hp (392 kW) each


  • Maximum speed: 114 mph (98 kn, 183 km/h)
  • Cruise speed: 98 mph (85 kn, 158 km/h)
  • Range: 860 mi (760 nmi, 1,400 km)
  • Service ceiling: 12,700 ft (3,870 m)
  • Rate of climb: 530 ft/min (2.7 m/s)
  • Wing loading: 11.31 lb/ft² (55.42 kg/m²)
  • Power/mass: 0.0811 hp/lb (133 W/kg)


  • Guns: 3 × .30 in (7.62 mm) machine guns
  • Bombs: 2,500 lb (1,100 kg); 4,000 lb (1,800 kg) on short runs

End notes