In 1965 Bell Aerosystems concluded a new contract with the Defense Advanced Research Projects Agency (DARPA) to develop a jet pack with a turbojet engine. This project was called the "Jet Flying Belt", or simply the "Jet Belt". Wendell Moore and John K. Hulbert, a specialist in gas turbines, worked to design a new turbojet pack. Williams Research Corporation (now Williams International) in Walled Lake, Michigan, designed and built a new turbojet engine to Bell's specifications in 1969. It was called the WR19, had a rated thrust of and weighed . The Jet Belt first flew free on 7 April 1969 at the Niagara Falls Municipal Airport. Pilot Robert Courter flew about in a circle at an altitude of , reaching a speed of . The following flights were longer, up to 5 minutes. Theoretically, this new pack could fly for 25 minutes at velocities up to .