Pratt & Whitney J57/JT3C family: the J57 military dual-rotor turbojet entered production in 1953, with more than 21,000 built through 1970 and later afterburning versions reaching about 18,000 lbf. It powered aircraft including the B-52, KC-135, F-100, F-101, and F-102. JT3/JT3C is the related commercial designation and remains a distinct civil-derivative boundary rather than a separate military J57 variant.