Sikorsky H-19 Hopalong

Helicopters are normally considered short-range aircraft, but in the 1950s the U.S. Air Force wanted test its new Sikorsky S-55 (H-19 Chickasaw) on long-range flights.  In 1952, a pair of Chickasaws flew from Massachusetts to Scotland in five stages, completing the first trans-Atlantic helicopter flight.  One of the helicopters, Hopalong, is displayed with its engine compartment open at the National Museum of the United States Air Force (Wright-Patterson AFB, Dayton, Ohio).