Hughes XF-11
| Hughes XF-11 | |
|---|---|
 Second prototype of the XF-11 on a test flight in 1947 |
|
| Type: | Photo reconnaissance |
| Design country: | |
| Manufacturer: | |
| First flight: |
April 15, 1946 |
| Commissioning: |
Never put into service |
| Production time: |
Was never mass-produced |
| Number of pieces: |
2 |
The Hughes XF-11 was a twin-engine long-range reconnaissance aircraft . The letter “F” in the designation stands for the order designation Photographic Reconnaissance, which was used from 1930 to 1947 and must not be confused with the type designation for fighter later used by the USAF .
history
The XF-11 was designed by the US billionaire Howard Hughes . The internal designation was Hughes D-5 , because it represents a direct further development on the basis of the Hughes D-2, from which the design with a double tail unit was also adopted. The US Air Force initially ordered 98 machines of this type for use as photo reconnaissance. At the end of the Second World War , however, this order was withdrawn, so that only two prototypes were built, the first of which took off on its maiden flight on April 15, 1946, but crashed and burned out on July 7 of the same year. Hughes, who piloted the plane, was seriously injured in the accident.
On April 5, 1947, after Hughes' recovery, the second prototype started, this time with conventional four-blade propellers , while the first version was provided with two counter-rotating propellers per engine. However, since the stability at low speed left a lot to be desired and a comparable and cheaper aircraft was available with the Boeing RB-50 , the Air Force decided not to further develop the XF-11 for reasons of cost.
construction
The XF-11 was a two-seater cantilevered shoulder wing with a double tail girder . In contrast to the Hughes D-2, the XF-11 (D-5) was made of duralumin using the conventional half-shell construction. In accordance with its intended role as a high-flying reconnaissance aircraft, it was given wings with a high aspect ratio and a relatively small profile thickness . These also housed the four fuel tanks with a total capacity of 7968 liters. In addition, two drop-off 1136-liter additional tanks could be attached to the external load carriers under the outer wings. The hydraulically operated landing flaps could be extended up to 40 ° (landing configuration) and reached almost the entire span. In addition to the landing flaps, the landing gear and brakes were also operated hydraulically. A hydraulic system with 1250–1500 psi (86–103 bar ) operating pressure and an electrically operated (pump drive) emergency system were available for this. Roll spoilers were used for steering around the longitudinal axis , while the very small ailerons were only used to support and simulate the steering pressure ( steering feel ). The centrally arranged fuselage was designed as a pressurized cabin . By means of bleed air from the turbochargers of the engines, a cabin height (pressure equivalent) of 3200 m up to an altitude of 10,200 m could be maintained. There were a total of four cameras in the bow of the fuselage, three of them in a trimetrogonal arrangement. In the left tail girder, four more cameras were located directly behind the landing gear well. The two engines in the front ends of the tail boom each consisted of a Pratt & Whitney R-4360-31 and two parallel-connected GE -BH-1 turbochargers with intercoolers . This design enabled a drive power of 2237 kW (3000 bhp ) at an altitude of up to 12,000 m. An oil tank in each tail boom with 265 liters each ensured a sufficient supply of lubricating oil even on long flights. In the first prototype, hydraulically adjustable counter-rotating eight-blade propellers from Hamilton-Standard were used as propellers . These propellers were still untested and a leak in the rear propeller of the right engine led to the crash of the first prototype on July 7, 1946 . Therefore, the second prototype (serial number: 44-70156) was equipped with R-4360-37 engines and electrically adjustable four-blade propellers from Curtiss-Electric (C644S-B).
Technical specifications
| Parameter | Data |
|---|---|
| crew | 2 (pilot, navigator / photographer) |
| length | 19.94 m |
| span | 30.91 m |
| height | 7.09 m |
| Wing area | 91.32 m² |
| Wing extension | 10.5 |
| Empty mass | 17,820 kg |
| max | 27,216 kg |
| Fuel capacity | 7968 l (internal) + 2272 l (external) (Avgas 100/130 octane) |
| Fuel consumption | 757-2771 l / h |
| drive | 2 × 28-cylinder quadruple radial engine Pratt & Whitney R-4360-31 (-37) each 3000 bhp (2237 kW) starting power at 2700 rpm and 1.8 bar boost pressure |
| Takeoff route | 287–770 m (concrete track, no wind) |
| Landing route | 527–799 m (concrete track, no wind) |
| max | 16.8 m / s near the ground, 11 m / s at 10,058 m at 17,962 kg take-off mass |
| Marching speed | 439–491 km / h at 10,058 m |
| max. continuous speed | 674 km / h at 10,058 m |
| Top speed | 725 km / h at 10,058 m (475 km / h near the ground) |
| max | 13,415 m |
| Range | 5584 km (at 491 km / h in 9144 m) |
See also
literature
- Charles Barton: Howard Hughes and the 10,000 ft. Split-S . Air Classics Vol. 18 No. 8, 1982.
- Jim Winchester: Concept Aircraft: Prototypes, X-Planes and Experimental Aircraft . Thunder Bay Press, Kent 2005, ISBN 978-1-59223-480-6 .
Web links
Individual evidence
- ^ Graham White: R-4360 Pratt & Whitney's Major Miracle . ISBN 978-1-58007-173-4 , pp. 337-344 .
- ↑ US Army Air Force / Periscope Film LLC (ed.): Hughes XF-11 Pilots Flight Operating Instructions . Periscope Film LLC, ISBN 978-1-935327-79-0 .