Originally Posted by onehundred80

I am no expert but the SC does not have to rotate fir the engine to run.
There is clearance between the main body bores and the rotors and clearance between the rotor spirals.
The rotors spin due to the air being drawn between these clearances, the rotors are windmilling due to the air passing by them.
You can stop the rotors spinning by stopping the black portion of the clutch carefully and the engine will not hesitate.
If the clearances were not there the SC would be wrecked when the faces touched, this would occur when a bearing or bearings were too worn to maintain the clearances.