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Boeing Y1B-9
| Boeing YB-9/Y1B-9 | |
|---|---|
| Y1B-9 test flight, 1932. | |
| Type | Bomber aircraft |
| Manufacturer | Boeing |
| Maiden flight | 1931-04-29 |
| Retired | 1934 |
| Status | No surviving examples |
| Primary user | United States Army Air Corps |
| Produced | 1930-1933 |
| Number built | 7 |
The Boeing B-9 was the first all-metal monoplane bomber designed for the United States Army Air Corps. The first service model, dubbed the YB-9, was originally tested and developed by Boeing as XB-901 and first flew on April 29, 1931. The YB-9 was an enlarged alteration of Boeing's Model 200 Commercial Transport. The Pratt & Whitney R-1830-13 radial engines used on the YB-9 gave it a top speed of 163 mph (262 km/h).
The second test model, named the Y1B-9 (Y1B- indicating funding outside normal fiscal year procurement), used liquid-cooled Curtiss V-1570-29 'Conqueror' engines. The increased power from these engines, combined with increased streamlining of the engine nacelles, increased its top speed to 173 mph (278 km/h). With the exception of the B-2 Condor, liquid-cooled engines were never used on production bombers for the United States military. The air-cooled radial engine was simpler and more reliable than the liquid-cooled engine, and less vulnerable to enemy damage.
The Y1B-9A was an improved version of the YB-9, featuring more powerful engines and a redesigned vertical stabiliser. Utilising two Pratt & Whitney R-1860-11 'Hornets', the plane was faster than any contemporary Pursuit aircraft. The Y1B-9 was the first closed-cockpit plane flown by the Army. Its high speeds made open cockpits extremely impractical. Five were ordered by the Army in September 1931.
Specifications (Y1B-9A)
General characteristics
- Crew: 4
- Length: 51 ft 6 in (15.7 m)
- Wingspan: 76 ft 10 in (23.4 m)
- Height: 12 ft 8 in (3.86 m)
- Wing area: 954 ft² (88.6 m²)
- Empty weight: 8,941 lb (4,056 kg)
- Loaded weight: 13,932 lb (6,320 kg)
- Max takeoff weight: 14,320 lb (6,500 kg)
- Powerplant: 2× Pratt & Whitney R-1860-11 "Hornet" radial engine, 600 hp (450 kW) each
Performance
- Maximum speed: 188 mph (163 knots, 302 km/h)
- Cruise speed: 165 mph (143 knots, 265 km/h)
- Range: 540 mi (470 nm, 870 km)
- Service ceiling: 20,750 ft (6,325 m)
- Wing loading: 14.6 lb/ft² (71.3 kg/m²)
- Power/mass: 0.0861 hp/lb (142 W/kg)
Armament
- Guns: 2× .30 in (7.26 mm) Browning machine guns
- Bombs: 2,200 lb (1,000 kg) bombs
References
- Alain Pelletier (2002). "End of the Dinosaurs: Boeing's B-9, Breaking the Bomber Mold". Air Enthusiast 101.
- Wagner, Ray (1982). American Combat Planes. New York: Doubleday. ISBN 0-930083-17-2.
- Jones, Lloyd (1974). U. S. Bombers. Fallbrook: Aero. ISBN 0-8168-9126-5.
- Boeing B-9. Encyclopedia of American Aircraft. Retrieved on April 10, 2005.
- Boeing Y1B-9. USAF Museum. Retrieved on August 1, 2004.
Related content
Related development
Comparable aircraft
Designation sequence
- U.S. Military: B-6 - Y1B-7 - XB-8 - Y1B-9 - B-10 - YB-11 - B-12
- Boeing: 200 - 202 - 214 - 215 - 221 - 246 - 247 - 248 - 264 … 281 - 294 - 299 - 300 - 314 - 316 - 341
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