The Helicopter With The Largest-Ever Rotor System.
Known as "The Flying Crane," the Hughes XH-17 is one of the most interesting aircraft projects in history. The heavy-lift chopper was the first helicopter project taken on by the Culver City, California-headquartered Hughes Aircraft Company, run by the famed aviation Howard Hughes. It boasted a twin-bladed main rotor with a diameter of 40.81m, far larger than a conventional helicopter and almost double that of a conventional heavy-lifter.
Following the end of World War II, the United States Air Force wanted a helicopter that could transport a weight of up to 4535kgs. The initial contract to design the heavy-lift helicopter was given to the Kellett Aircraft Corporation of Upper Darby, Pennsylvania. If the Army Air Force approved the design, the next step would be building a prototype.
By the late summer of 1947, the XH-17 design had progressed well enough for the green light to be given for a test rig of the helicopter's rotor system. Kellett was having financial difficulties and tried to save money by using components taken from other aircraft. However, unable to shake off its money troubles, the building of the XH-17 was sold to the Hughes Aircraft company with the Air Force's blessing.
Hughes employed many of Kellett's engineers and relocated them to California to continue with the project. Work on the XH-17 resumed in March 1949, and Hughes, just like Kellett, used parts from other planes. The cockpit was taken from the Waco CG-15 glider, and the landing gear came from a North American B-25 Mitchell bomber. The helicopter's rear landing gear came from a Douglas C-54 Skymaster, and the fuel tank from a Boeing B-29 Superfortress.
In the summer of 1952, the helicopter was complete and ready for flight testing. It completed its first flight in September 1952, when test pilot Gale Moore hovered the chopper by just one foot - however, the controls were reportedly far more erratic and sensitive than planned, with the first flight almost ending in disaster before touching down hard.
It had a planned top speed of 144km/h (but only ever managed 113km/h) and a small range of only 48 kilometers, mainly because of the high fuel burn of the two General Electric engines. The two-bladed main rotors were a foot thick and 147cm wide, weighed 2268kgs. These blades were so cumbersome that they had a fatigue life of just 10 hours - when turning, the noise was so loud that it could be heard from eight miles away.
The XH-17 flew in 1953 at a gross weight in excess of 23000kg. 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.