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)
{{airtemp
|plane or copter?=plane |jet or prop?=prop
|crew=5 |length main=48 ft 10 in |length alt=14.9 m |span main=74 ft 8 in |span alt=22.8 m |height main=15 ft 9 in |height alt=4.8 m |area main=1,145 ft² |area alt=106.4 m² |empty weight main=7,951 lb |empty weight alt=3,607 kg |loaded weight main=12,952 lb |loaded weight alt=5,875 kg |max takeoff weight main= lb |max takeoff weight alt= kg
|number of props=2 |engine (prop)=Pratt & Whitney R-1860-7 |type of prop=radial engines |power main=575 hp |power alt=429 kW
|max speed main=130 mph |max speed alt=110 kt, 210 km/h |cruise speed main=103 mph |cruise speed alt=90 kt, 167 km/h |range main=850 mi |range alt=760 nm, 1,400 km |ceiling main=14,000 ft |ceiling alt=4,300 m |climb rate main=580 ft/min |climb rate alt=30 m/s |loading main=11.31 lb/ft² |loading alt=55.22 kg/m² |power/mass main=0.0888 hp/lb |power/mass alt=146 W/kg
|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
- Photograph
- USAF Museum article on B-4
- USAF Museum article on LB-13
Related content
{{aircontent
|related=
|similar aircraft=
|sequence=
- LB-series: LB-10 - LB-11 - XLB-12 - LB-13 - LB-14
- B-series: XB-1 - B-2 - B-3 - B-4 - B-5 - B-6 - Y1B-7
|lists=
}}