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Keystone B-4
| B-4 | |
|---|---|
| Keystone Y1B-4 (S/N 30-281). | |
| Type | Light bomber |
| Manufacturer | Keystone |
| Primary user | United States Army Air Corps |
| Number built | 5 Y1B-4 + 25 B-4A |
| Developed from | Keystone B-3 |
The Keystone B-4 was a biplane bomber developed for the United States Army Air Corps.
Design and development
Originally ordered by the United States Army Air Corps as the LB-13 (light bomber), when the LB- designation was dropped in 1930, the first five planes were redesignated Y1B-4. (The Y1B- designation indicates funding outside the the normal annual appropriation.)
The first B-3A (S/N 30-281) was converted to Y1B-4 configuration with the addition of more powerful R-1860-7 radial engines and low pressure tires. Because of more powerful engines, the performance of the Y1B-4 was a slight improvement on the B-3. 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.
Operational history
The B-4 was the last Keystone model ordered by the U.S. Army in late 1931. These aircraft were used primarily as observation and reconnaissance aircraft as early as 1934 when the Martin B-10B became operational. Some remained in service into the early 1940s.
Variants
- LB-13
- Seven aircraft ordered but delivered as the Y1B-4 and Y1B-6 with different engine installations.
- Y1B-4
- Five pre-production aircraft, as the LB-10 but with two 575hp (429kW) R-1860-7 engines.
- B-4A
- Production version of the Y1B-4, 25 built.
Operators
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 weight: 7,951 lb (3,607 kg)
- Loaded weight: 12,952 lb (5,875 kg)
- Max takeoff weight: lb (kg)
- Powerplant: 2× Pratt & Whitney R-1860-7 radials, 575 hp (429 kW) each
Performance
- Maximum speed: 130 mph (110 kn, 210 km/h)
- Cruise speed: 103 mph (90 kn, 167 km/h)
- Range: 850 mi (760 NM, 1,400 km)
- Service ceiling: 14,000 ft (4,300 m)
- Rate of climb: 580 ft/min (30 m/s)
- Wing loading: 11.31 lb/ft² (55.22 kg/m²)
- Power/mass: 0.0888 hp/lb (146 W/kg)
Armament
- Guns: 3× .30 (7.62 mm) Browning machineguns
- 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
See also
Related development
Related lists
Lists relating to aviation | |
|---|---|
| General | Timeline of aviation · Aircraft · Aircraft manufacturers · Aircraft engines · Aircraft engine manufacturers · Airports · Airlines |
| Military | Air forces · Aircraft weapons · Missiles · Unmanned aerial vehicles (UAVs) · Experimental aircraft |
| Notable incidents and accidents | Military aviation · Airliners · General aviation · Famous aviation-related deaths |
| Records | Flight airspeed record · Flight distance record · Flight altitude record · Flight endurance record · Most produced aircraft |
Lists relating to aviation | |
|---|---|
| General | Timeline of aviation · Aircraft · Aircraft manufacturers · Aircraft engines · Aircraft engine manufacturers · Airports · Airlines |
| Military | Air forces · Aircraft weapons · Missiles · Unmanned aerial vehicles (UAVs) · Experimental aircraft |
| Notable incidents and accidents | Military aviation · Airliners · General aviation · Famous aviation-related deaths |
| Records | Flight airspeed record · Flight distance record · Flight altitude record · Flight endurance record · Most produced aircraft |
| This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Keystone B-4". |
