Hughes XH-17 "Flying Crane" was a massive experimental heavy-lift helicopter developed by the Hughes Aircraft Company in the early 1950s. It is most famous for holding the world record for the largest rotor system ever flown, featuring a two-bladed main rotor with a diameter of 134 feet (41 meters). Key Characteristics Design Purpose: Built for the U.S. Air Force to test the feasibility of lifting immense loads, such as tanks and artillery, by straddling them with its tall, spindly landing gear.