Hughes XH-17

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The XH-17 "Flying Crane" was the first helicopter project for the helicopter division of Hughes Aircraft. The XH-17, which had a two-bladed main rotor system with a diameter of 134 feet (41 m), was capable of flying at a gross weight of more than 50,000 pounds (23,000 kg).

Design and development

The XH-17 was a heavy-lift rotorcraft that was designed to lift loads in excess of 15 metric tons. To speed construction, parts of the XH-17 were scavenged from other aircraft. The front wheels came from a B-25 Mitchell and the rear wheels from a C-54 Skymaster. The fuel tank was a bomb bay-mounted unit from a B-29 Superfortress. The cockpit was from a Waco CG-15 and the tail rotor from a Sikorsky H-19 was used for yaw control.

In the late 1940s, Hughes developed an interest in helicopters. In August 1947, helicopter manufacturer Kellett sold his design for the giant XH-17 Sky Crane to Hughes, who commissioned the development of the XH-17 Flying Crane research vehicle. In 1948 the XH-17 began to take shape. The giant helicopter was tested in Culver City, California over a three-year period beginning in 1952. The XH-17 flew in 1953 at a gross weight in excess of 50,000 pounds (23,000 kg). It still holds the record for flying with the world's largest rotor system. Only one unit was built, since the aircraft was too cumbersome and inefficient to warrant further development.

Two cars parked beneath the XH-17 give a sense of scale.

The propulsion system was unusual. Two General Electric J35 turbojet engines were used, sending bleed air up through the rotor hub. The blades were hollow, and the hot compressed air traveled through the blades to tip jets where fuel was injected. In flight the rotors spun at a sedate 88 rpm. Since the rotor was driven at the tips rather than the hub, little torque compensation was required. Thus, the XH-17 had a very small tail rotor compared to its main rotor. This drive system was inefficient, limiting the test aircraft to a range of only 40 miles (64 km).

The XH-28 was a derivative, with a maximum weight of 104,000 pounds (47,000 kg). Though a wooden mockup of the design was made, the program was cancelled and none were built.

Specifications

General characteristics

Crew: 3 (pilot, mechanic and in-flight test engineer)
Length: 53 ft 3 in (16.25 m)
Rotor diameter: 129 ft 11 in (39.62 m)
Height: 30 ft 2 in (9.17 m)
Empty weight: 28,563 lb (12,956 kg)
Loaded weight: 31,270 lb (14,184 kg)
Useful load: 10,284 lb (4,665 kg)
Max. takeoff weight: 43,500 lb (19,731 kg)
Powerplant: 2 × General Electric J35 turbojets

Performance

Maximum speed: 90 mph (145 km/h)
Cruise speed: 85 mph (137 km/h)
Range: 40 mi (64 km)
Service ceiling: 13,100 ft (3,995 m)
Rate of climb: 1650 ft/min (8.4 m/s)
Disc loading: 2.34 lb/ft² (11.5 kg/m²)

References

Jim Winchester The World's Worst Aircraft, 2005
Rene J. Francillon McDonnell Douglas Aircraft since 1920: Volume II, 1997

External links

"Giant Jet Helicopter Read For First Flight." Popular Mechanics, August 1952, p. 116.
http://www.1000aircraftphotos.com/Contributions/VanTilborg/3138.htm
http://findarticles.com/p/articles/mi_qa3897/is_200104/ai_n8943768
http://www.flightglobal.com/pdfarchive/view/1956/1956%20-%200015.html

v t e Hughes Aircraft · Hughes Helicopters

Fixed-wing aircraft	H-1 D-2/XP-73/XA-37 H-4 "Spruce Goose" XF-11

Experimental helicopters	XH-17 XV-9

Civil helicopters	269 300 500 530F

Military helicopters	TH-55 OH-6 MH-6 Defender AH-64

Communications satellites	Intelsat I Syncom TDRS GOES

Spacecraft	Surveyor 1 Pioneer Venus

Avionics /Fire control	Hughes MA-1 AWG-9 APG-63 APG-65

Missiles	AIM-54 AIM-120 BGM-71

v t e USAAC/USAAF/USAF/Joint Service Helicopter designations 1941–present

Numerical sequence used by USAAC/USAAF/USAF 1941–present; US Army 1948–1956 and 1962–present; US Navy 1962–present

Main sequence Prefix R-, 1941–1948	R-1 R-2 R-3 R-4 R-5 R-6 R-7 R-8 R-9 R-10 R-11 R-12 R-13 R-14 R-15 R-16

Main sequence Prefix H-, 1948–1962	H-5 H-6 H-9 H-10 H-11 H-12 H-13/J H-15 H-16 H-17 H-18 H-19 H-20 H-21 H-22 H-23 H-24 H-25 H-26 H-27 H-28 H-29 H-30 H-31 H-32 H-33 H-34 H-35 H-36¹ H-37 H-38¹ H-39 H-40 H-41 H-42 H-43 H-44¹ H-45¹

Main joint sequence H- with mission prefix 1962–	OH-13/UH-13J UH-19 CH-21 OH-23 UH-25 CH-34 CH-37 HH-43 CH-46/HH-46/UH-46 CH-47 UH-48 XH-49 QH-50 XH-51 HH-52 CH-53/HH-53/MH-53 CH-54 TH-55 AH-56 TH-57 OH-58 XH-59 UH-60/SH-60/HH-60/HH-60J YUH-61 XCH-62 YAH-63 AH-64 HH-65 RAH-66 TH-67 MH-68 H-69¹ ARH-70 VH-71 UH-72

1962 redesignations reusing old numbers	UH-1/N/Y AH-1/J/T/W/Z SH-2/SH-2G SH-3/CH-3/HH-3 OH-4 OH-5 OH-6/MH-6/AH-6

¹ Not assigned

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Records	Airspeed Altitude Distance Endurance Firsts Large Most-produced aircraft Most-produced rotorcraft

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Hughes XH-17

Design and development

Specifications

See also

References

External links