Graviman,
The point is that to control the prop velocity the worm gear has to react large torques. Since Power=Torque x Rot_Vel this means that whenever the worm is "controlling" the speed a lot of engine power is wasted
I partially agree with what you are saying. In addition, I think that you will agree with the following;
For the power to be wasted there must be sliding friction. The only location of sliding friction in the powertrain is between the worm & gear, in the Speed Controller.
During slow flight and hover the worm & gear are not turning, therefor there is no power loss due to friction.
During cruise, the propeller is consuming all the power on that side of the differential. The worm is not resisting the gear, therefor there is no power loss due to friction.
IMO, the power loss due to friction will only take place during forward speeds between transition and cruise. I am currently trying to calculate the power loss
here. It is looking like the power loss may be a curve; from 0% at transition, up to 13%, and then back down to 0% at cruise. This is not particularly attractive and requires more thinking.
Flight Safety,
What you say is correct, however there is an alternative to the wings of a compound helicopter. This alternative is the use of large chord rotor blades.
Here is an example and
here is an explanation
Dave