I have been working on a jump T/O gyro for some time, we used a laminated steel hub bar so it could be twisted for pitch change using a geared electric motor fed by slip rings. It seems that while it is not legal to change pitch in flight, it is legal to change pitch for flight.

We have had numerous gearbox failures as the drive to the rotor goes up to direct drive the rotor, we calculate it needs about 12 hp, I think that is about 120 foot pounds.
If I ever get back to that project I will try an outboard motor gearbox.
I have a warning on the panel:
PITCH CHANGE IN FLIGHT MAY  VIOLATE REGULATIONS
John Evans



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