@ Daniel Wilkie

I think you'll find that most choppers operate with a Constant Speed Unit to maintain stable rotor speed in flight.The throttle is necessary for throttling up in the first place from a start or to take off but in flight more throttle would only be needed if climbing or lifting, more energy will be used but without higher velocity of the rotor. A bit like driving a car up a hill at thirty miles an hour compared to driving it on the flat at the same speed, you need more gas to go up the hill at the same speed as you are doing more work. If anybody knows better please post.