A General Electric F404 military turbofan was used as the basis of the GE36. The F404 mixed exhaust stream discharged through a seven-stage low pressure (LP) turbine, where each stator ring was 'unearthed' and free to move in the opposite direction to that of the rotors. One set of open rotor, variable pitch, fan blades was connected to the LP turbine rotor system, while the other set was connected to the contra-rotating LP turbine stators. The scimitar shape of the fan rotor blades enabled high flight speeds (about Mach 0.75) to be obtained. GE used a low speed, (effectively) 14 stage, LP turbine, rather than a conventional high speed LP turbine and reduction gearbox, to drive the fan rotor blades.
Although the engine demonstrated an extremely low specific fuel consumption, cabin noise levels were a problem, even though the engines were mounted at the rear of the test aircraft. However, the noise was not considered an insurmountable problem. The downfall of this engine at the time was economic conditions (mostly a major drop in oil prices) post OPEC oil embargo; and at least the perceived public perception of the external fan blades being too much like “old and slow” prop planes. Even though these engines never made it past development and prototype testing, the technology lives on and is currently being used in engines (General Electric GE90 & General Electric GEnx) that power the Boeing 747, Boeing 777, and Boeing 787 Dreamliner.