Interesting technology.
Seems the traction drive is better suited to variable ratio automotive transmission. No reports of advantage or any use in a helo.
I think I will look more closely at friction drive. Rubber drive wheels. The advantages would be:
1) looser fit is tolerated
2) absorbs torsional vibration from engine
3) open, light frame (no gear case)
4) no clutch needed
5) smooth and quiet
6) easy to inspect
Friction drive is probably only practical for a very low power helo. Even if the transfer efficiency is relatively poor, the cost and simplicity may be more important.
Look at all the problems with the Rotorway drive line... belts, chains, oil leakage, secondary shaft failure...
There must be a better and lighter system for small sport helos.
slowrotor