McDonnell XHJH Whirlaway

The McDonnell XHJH Whirlaway, also called the McDonnell Model 37, was an experimental twin-rotor helicopter that McDonnell Aircraft built for the United States Navy, which wanted a large rescue helicopter with room for ten occupants. It was designed as the XHJD-1 and redesignated XHJH-1 shortly after it flew. It was derived from the Platt-LePage XR-1, a company in which James McDonnell had invested and which he took over in June 1944, and it first flew about two months later. Two side-by-side rotors of roughly 46 feet turned in opposite directions at the ends of pylon wings, each driven by its own 450 horsepower Pratt and Whitney Wasp Junior radial engine. It was the largest helicopter of its time and the first successful twin-engined twin-rotor helicopter in the world. Only one was built, and it is held by the National Air and Space Museum.