Sikorsky H-19 Chickasaw

The Sikorsky H-19 Chickasaw, company model S-55, was a piston-engined utility helicopter that Sikorsky developed privately, without government sponsorship, and first flew as the YH-19 on 10 November 1949. Its radial engine sat in the nose and drove a single fully articulated main rotor above the cabin, a layout that held the centre of gravity steady as loads changed without ballast and gave the helicopter a bulbous-nosed look. The Army and Air Force used it, the Navy and Coast Guard as the HO4S and the Marines as the HRS, and Westland built it in Britain as the Whirlwind. It led directly to the larger H-34 and proved popular with civil operators.