Keystone B-4
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The Keystone B-4 was a biplane bomber originally ordered by the United States Army Air Corps as the LB-13. When the LB- designation was dropped in 1930, the first five planes were redesignated Y1B-4. (The Y1B- designation indicates that funds for the design did not come from the normal annual funds.)
Because of more powerful engines, the performance of the Y1B-4 was a slight improvement on the B-3, but the only difference between the two planes were their engines. In 1932, the army ordered 25 improved Y1B-4s as the Keystone B-4A. This production version was part of the last biplane bomber order made by the Army Air Corps.
Specifications (B-4A)
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: 7,951 lb (3,607 kg)
- Loaded: 12,952 lb (5,875 kg)
- Maximum takeoff: lb ( kg)
- Powerplant: 2× Pratt & Whitney R-1860-7 of 575 hp (429 kW) each
Performance
- Maximum speed: 130 mph (210 km/h)
- Cruising speed: 103 mph (167 km/h)
- Range: 850 miles (1,400 km)
- Service ceiling: 14,000 ft (4,270 m)
- Rate of climb: 580 ft/min (180 m/min)
- Wing loading: 11.31 lb/ft² (55.22 kg/m²)
- Power/Mass: 0.0888 hp/lb (0.146 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
References and external links
- Encyclopedia of American Aircraft (http://home.att.net/~jbaugher2/b4.html)
- Photograph (http://www.aerofiles.com/keys-b4a.jpg)
- USAF Museum article on B-4 (http://www.wpafb.af.mil/museum/research/bombers/b1-45.htm)
- USAF Museum article on LB-13 (http://www.wpafb.af.mil/museum/research/bombers/b1-33.htm)
Related Content
Related development: Keystone B-3 - Keystone B-5 - Keystone B-6
Comparable aircraft: Keystone B-3 - Keystone B-5 - Keystone B-6
Designation sequence: XB-1 - B-2 - B-3 - B-4 - B-5 - B-6 - Y1B-7
Related Lists: List of military aircraft of the United States - List of bomber aircraft
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