“The XH-17 “Flying Crane” 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.
“It 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.”