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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 |
TheHughes XH-17 "Flying Crane" was the firsthelicopter project for thehelicopter division ofHughes 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.
The XH-17 was a heavy-liftrotorcraft 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 aNorth American B-25 Mitchell and the rear wheels from aDouglas C-54 Skymaster. The fuel tank was a bomb bay-mounted unit from aBoeing B-29 Superfortress. The cockpit was from aWaco CG-15 military glider and the tail rotor from aSikorsky H-19 Chickasaw was used for yaw control.
In the late 1940s,Hughes developed an interest in helicopters. In August 1947, helicopter manufacturerKellett 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. TwoGeneral Electric J35turbojet engines were used, sendingbleed air up through the rotor hub. The blades were hollow, and the hot compressed air traveled through the blades totip 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, littletorque compensation was required, mostly due to friction in the main rotor bearing. Thus, the XH-17 had a very smalltail rotor compared to its main rotor. This drive system was inefficient, limiting the test aircraft to a range of only 40 miles (64 km).
TheXH-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.
Data from McDonnell Douglas aircraft since 1920 Vol.2[1]
General characteristics
Performance
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