The General Electric GE4 turbojet engine was designed in the late 1960s as the powerplant for the Boeing 2707 supersonic transport. The GE4 was a nine-stage, single-shaft, axial-flow turbojet based largely on the General Electric YJ93 which powered the North American XB-70 bomber.[1] The GE4 was the most powerful engine of its era, producing 50000lbf dry, and 65000lbf with afterburner.[2] The Boeing 2707 was cancelled in 1971, putting an end to further work on the GE4.