Hughes XF-11
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| XF-11 | |
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| Type | Reconnaissance |
| Manufacturer | Hughes |
| Designed by | Howard Hughes |
| Maiden flight | 7 July 1946 |
| Status | Cancelled due to oil leak resulting in crash |
| Primary user | U.S. Army Air Force (intended) |
| Number built | 2 |
The Hughes XF-11 was a prototype military reconnaissance aircraft, designed and flown by Howard Hughes for the United States Army Air Force. Despite promise, the XF-11 suffered a crash that nearly killed Hughes. The program never recovered from this setback.
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[edit] Design and development
The aircraft was designed to meet the same requirements as the Republic XF-12. Specifications called for a fast, long ranging photo-reconnaissance aircraft. Said to be a scaled-up version of the earlier Hughes D-2, the final design was similar in general appearance to the World War II Lockheed P-38 Lightning [1]. It was a tricycle-gear, twin-engine, twin-boom all-metal monoplane with a pressurized central crew nacelle, with a much larger span and much higher aspect ratio than the P-38's wing.
The XF-11 used Pratt & Whitney R-4360-31 28-cylinder radial engines with twin four-bladed, controllable-pitch propellers at the front of each engine. The propeller design was unusual in that the propellers on each engine were contra-rotating propellers, which can increase performance and stability, but increase mechanical complexity.
The Army originally ordered 100 of them for photo reconnaissance. The order was cancelled following the end of World War II, leaving Hughes with two prototypes.
[edit] Operational history
The first prototype, tail number 44-70155, piloted by Hughes, crashed on 7 July 1946 while on its maiden flight.[2] An oil leak caused the right-hand propeller controls to lose their effectiveness and the rear propeller subsequently reversed its pitch, disrupting that engine's thrust which made the aircraft yaw hard to the right.[3] Rather than feathering the propeller Hughes elected to make an emergency landing on the Los Angeles Country Club's golf course, but about 300 yards short of the course, the aircraft suddenly lost altitude and clipped three houses. The third house was completely destroyed by the fire resulting from the crash and Hughes was nearly killed. [4]
The second prototype was fitted with conventional propellers and flown on 5 April 1947, after Hughes had recuperated from his injuries. This test flight was uneventful and the aircraft proved to be stable and controllable at high speed. However, it lacked low-speed stability as the ailerons were ineffective at low altitudes, and when the Air Force evaluated it against the XF-12, testing revealed the XF-11 was harder to fly and maintain, and projected to be twice as expensive to build. [3]A small production order for the XF-12 went out but the USAF chose the RB-50 Superfortress instead, which had similar long-range photo-reconnaissance capability and was available for much less cost.
[edit] Specifications (XF-11)
General characteristics
- Crew: two, pilot and navigator/photographer
- Length: 65 ft 5 in (19.94 m)
- Wingspan: 101 ft 4 in (30.89 m)
- Height: 23 ft 2 in (7.06 m)
- Wing area: 983 ft² (91.3 m²)
- Empty weight: 37,100 lb (16,800 kg)
- Max takeoff weight: 58,300 lb (26,400 kg)
- Powerplant: 2× Pratt & Whitney R-4360-31 radial, 3,000 hp (2,240 kW) each
Performance
- Maximum speed: 450 mph (720 km/h)
- Range: 5,000 miles (8,000 km)
- Service ceiling 44,000 ft (13,415 m)
[edit] See also
Related development
Comparable aircraft
Related lists
[edit] References
[edit] Notes
- ^ Winchester 2005, p. 222.
- ^ Crash of the XF-11
- ^ a b Winchester 2005, p. 223.
- ^ XF-11 Crash site
[edit] Bibliography
- Barton, Charles. "Howard Hughes and the 10,000 ft. Split-S." Air Classics, Vol. 18, no. 8, August 1982.
- Winchester, Jim. "Hughes XF-11." Concept Aircraft: Prototypes, X-Planes and Experimental Aircraft. Kent, UK: Grange Books plc., 2005. ISBN 1-84013-309-2.
[edit] External links
- Check-Six.com - The Crash of the XF-11 - Numerous details and photos of the crash
- UNLV Library Archive - Hughes' account of the crash
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