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

Though the performance of the B-3 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 disbanded by the Army; it remained in service until 1940. A few years after it was first produced, a revolution in airplane design rendered it almost completely obsolete.

Units using the B-3

United States Army Air Corps

• 4th Composite Group
• 6th Composite Group
• 19th Bombardment Group

Specifications (B-3A)

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: 7,705 lb (3,495 kg)
• Loaded: 12,952 lb (5,875 kg)
• Maximum takeoff: lb ( kg)
• Powerplant: 2× Pratt & Whitney R-1690-3 of 525 hp (392 kW) each

Performance

• Maximum speed: 114 mph (183 km/h)
• Cruising speed: 98 mph (158 km/h)
• Range: 860 miles (1,400 km)
• Service ceiling: 12,700 ft (3,870 m)
• Rate of climb: 530 ft/min (160 m/min)
• Wing loading: 11.31 lb/ft² (55.42 kg/m²)
• Power/Mass: 0.0811 hp/lb (0.133 kW/kg)

Armament

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

Links

• Encyclopedia of American Aircraft
• Photograph of B-3 in flight
• USAF Museum article on LB-10
• USAF Museum article on B-3

Related Content

Related development: Keystone B-4 - Keystone B-5 - Keystone B-6

Comparable aircraft: Keystone B-4 - Keystone B-5 - Keystone B-6

Designation sequence: XB-1 - B-2 - B-3 - B-4 - B-5 - B-6

LB-7 - LB-8 - LB-9 - LB-10 - LB-11 - XLB-12 - LB-13

Related Lists: List of military aircraft of the United States - List of bomber aircraft