Hughes XF-11

infobox Aircraft
name = XF-11
type = Reconnaissance
manufacturer = Hughes



caption =
designer = Howard Hughes
first flight = 7 July 1946
introduced =
retired =
produced =
number built = 2
status = Cancelled due to oil leak resulting in crash
unit cost =
primary user = U.S. Army Air Force (intended)
more users =
developed from =
variants with their own articles = 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.

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 [ Winchester 2005, p. 222. ] . 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.

Operational history

The first prototype, tail number 44-70155, piloted by Hughes, crashed on 7 July 1946 while on its maiden flight. [ [http://www.check-six.com/Crash_Sites/XF-11_crash_site.htm Crash of the XF-11] ] 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. Winchester 2005, p. 223. ] 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. [ [http://www.check-six.com/Crash_Sites/XF-11_crash_site.htm XF-11 Crash site] ]

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. 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.

pecifications (XF-11)

aircraft specifications
plane or copter?=plane
jet or prop?=prop
ref=
crew=two, pilot and navigator/photographer
capacity=
payload main=
payload alt=
length main= 65 ft 5 in
length alt= 19.94 m
span main= 101 ft 4 in
span alt= 30.89 m
height main= 23 ft 2 in
height alt= 7.06 m
area main= 983 ft²
area alt= 91.3 m²
airfoil=
empty weight main= 37,100 lb
empty weight alt= 16,800 kg
loaded weight main=
loaded weight alt=
useful load main=
useful load alt=
max takeoff weight main= 58,300 lb
max takeoff weight alt= 26,400 kg
more general=
engine (prop)= Pratt & Whitney R-4360-31 radial
type of prop=
number of props=2
power main= 3,000 hp
power alt= 2,240 kW
power original=
max speed main= 450 mph
max speed alt= 720 km/h
cruise speed main=
cruise speed alt=
stall speed main=
stall speed alt=
never exceed speed main=
never exceed speed alt=
range main= 5,000 miles
range alt=8,000 km
ceiling main= 44,000 ft
ceiling alt= 13,415 m
climb rate main=
climb rate alt=
loading main=
loading alt=
thrust/weight=
power/mass main=
power/mass alt=
more performance=
armament=
avionics=

ee also

aircontent

related=
*Hughes XP-73
*Hughes XA-37

similar aircraft=
*P-38 Lightning
*XF-12 Rainbow
*F-15 Reporter

lists=
*List of military aircraft of the United States

see also=

References

Notes

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.

External links

* [http://www.check-six.com/Crash_Sites/XF-11_crash_site.htm Check-Six.com - The Crash of the XF-11] - Numerous details and photos of the crash
* [http://www.library.unlv.edu/hughes/pages/XF11_first.html UNLV Library Archive - Hughes' account of the crash]