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


sounds like a great idea.  Instead of a motor for the pitch horn, a magnet as those in the electric door locks might work just as well but much cheaper.  I did the lock on my front gate and found you can get thousands of pounds of force out of a few micro amperes of current depending on the number of rounds on the coil.  A small battery will do it.

Could you send a picture of your rotor head?

Gordon Gao