A General Electric F404 military turbofan was used as the basis for the GE36. The F404 mixed exhaust stream discharged through a turbine which drove two counter rotating stages of 10 and 8 fan blades each (originally 8 and 8). The scimitar shape of the fan rotor blades enabled high flight speeds (about Mach 0.75) to be obtained. The power turbine was a seven-stage (initially 6-stage) turbine plus inlet and outlet guide vanes. The fourteen turbine blade rows rotated alternate rows in opposite directions. Each stage was a pair of rotors (there were no stators). The counter-rotating turbine ran at half the rpm of a conventional turbine so did not require a reduction gearbox to drive the fan.
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 carbon composite fan blade 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.