Hughes XH-17

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XH-17 "Flying Crane"

General information
Type	Helicopter
Manufacturer	Hughes Helicopters
Status	Scrapped
Number built	1
History
First flight	23 October 1952
Retired	December 1955

The Hughes XH-17 "Flying Crane" was the first helicopter project for the helicopter division of Hughes Aircraft Company. The XH-17, which had a two-bladed main rotor system with a diameter of 134 feet (41 m), still holds the world record for flying with the largest rotor system. It was capable of flying at a gross weight of more than 50,000 pounds (23,000 kg), but proved too inefficient and cumbersome to be mass-produced beyond the prototype unit.

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 North American B-25 Mitchell and the rear wheels from a Douglas C-54 Skymaster. The fuel tank was a bomb bay-mounted unit from a Boeing B-29 Superfortress. The cockpit was from a Waco CG-15 military glider and the tail rotor from a Sikorsky H-19 Chickasaw 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.

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 main rotor spun at a sedate 88 revolutions per minute, less than half the speed of typical helicopter rotors. Since the rotor was driven at the tips rather than the hub, little torque compensation was required, mostly due to friction in the main rotor bearing. 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 canceled and none were built.

Specifications

Data from McDonnell Douglas aircraft since 1920 Vol.2

General characteristics

Crew: 3 (pilot, mechanic and in-flight test engineer)
Capacity: demonstrated loads up to 10,284 lb (4,665 kg) were carried
Length: 53 ft 3.6 in (16.246 m)
Height: 30 ft 1.2 in (9.174 m)
Empty weight: 28,562 lb (12,956 kg)
Gross weight: 31,270 lb (14,184 kg)
Max takeoff weight: 43,500 lb (19,731 kg)
Fuel capacity: 635 US gal (529 imp gal; 2,404 L) (Boeing B-29 bomb-bay tank)
Powerplant: 2 × General Electric 7E-TG-180-XR-17A gas generators, 3,480 hp (2,600 kW) each combined predicted gas power output, with rotor turning at 88 rpm
Main rotor diameter: 130 ft (40 m)
Main rotor area: 13,274.95 sq ft (1,233.283 m)

Performance

Maximum speed: 90 mph (140 km/h, 78 kn) at 8,000 ft (2,438 m)
Cruise speed: 85 mph (137 km/h, 74 kn)
Range: 30 mi (48 km, 26 nmi) with 10,284 lb (4,665 kg) payload
Service ceiling: 13,100 ft (4,000 m)
Rate of climb: 1,650 ft/min (8.4 m/s)
Disk loading: 2.4 lb/sq ft (12 kg/m)
Power/mass: 0.111 hp/lb (0.182 kW/kg)

References

Francillon, René J. (20 September 1990). McDonnell Douglas aircraft since 1920 Vol.2 (2nd ed.). London: Putnam Aeronautical. pp. 131–135. ISBN 978-0851778280.

External links

"Hughes XH-17". www.1000aircraftphotos.com. Retrieved 14 August 2020.

v t e Hughes Aircraft and Hughes Helicopters
Fixed-wing aircraft	H-1 D-2/XP-73/XA-37 H-4 Hercules (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

United States helicopter designations, Army/Air Force and Tri-Service systems

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

Army/Air Force sequence
(1941–1962)

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
Prefix H-, 1948–1962	H-5 H-6 H-9 H-10 H-11 H-12 H-13 H-13J 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-36 H-37 H-38 H-39 H-40 H-41 H-42 H-43 H-44 H-45

Tri-Service sequence
(1962–present)

1962 redesignations	H-13 H-13F H-13J H-19 H-21 H-23 H-25 H-34 H-37 H-43
New designations	H-46 H-47 H-48 H-49 H-50 H-51 H-52 H-53 CH-53/E/K HH-53/MH-53 H-54 H-55 H-56 H-57 H-58 H-59 H-60 UH-60 SH-60 HH-60 MH-60 H-61 H-62 H-63 H-64 H-65 H-66 H-67 H-68 H-69 H-70 H-71 H-72 H-73
Alternate sequence	H-1 AH-1/J/T/W/Z UH-1/N/Y H-2 G H-3 CH-3/HH-3 SH-3 H-4 H-5 H-6 AH-6 MH-6 OH-6
Non-sequential	H-90 H-92 CH-92/VH-92 H-139

Not assigned

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Design and development

Specifications

See also

References

Further reading

External links