Keystone B-4

Keystone B-4

Description
Rôle	Light bomber
Crew	Five
First Flight
Entered Service	1932
Manufacturer	Keystone Aircraft Corporation
Number built	5 Y1B-4, 25 B-4A
Dimensions
Length	48 ft 10 in	14.9 m
Wingspan	74 ft 8 in	22.7 m
Height	15 ft 9 in	4.8 m
Wing area	ft²	m²
Weights
Empty	lb	kg
Loaded	13,000 lb	5,897 kg
Maximum takeoff	lb	kg
Capacity
Powerplant
Engines	Pratt & Whitney R-1860;-7 radials (2)
Power	575hp	kW
Performance
Maximum speed (sea level)	130 mph	209.2 km/h
Cruising speed	103 mph	165.7 km/h
Combat range	850 miles	1,367 km
Ferry range	miles	km
Service ceiling	14,000 ft	4,267 m
Rate of climb	ft/min	m/min
Wing loading	lb/ft²	kg/m²
Power/Mass	hp/lb	kW/kg
Armament
Guns	Browning.30-calibre machine guns (3)
Bombs	2,500lb

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The Keystone B-4 was a biplane bomber originally ordered by the US Army as the LB-13. When the LB- designation was dropped in 1930, the first five planes were renamed Y1B-4s (the last two of the seven were named Y1B-6s).

Because of more powerful engines, the performance of the Y1B-4 was a slight improvement on the B-3, but the planes were overall nearly identical.

In 1932, the army ordered 25 improved Y1B-4s as the Keystone B-4A. This production version (along with the B-6) was the last biplane bomber ordered from Keystone Aircraft

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Designation Series	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