Heres one to get the brain working.

Heres one to get the brain working.
Does any one know the rpm of the main motor when the throttle stick is full on?
I'm not on about the head speed just the motor.

Also is there a difference between fixed pitch and collective,
and brushed and brushless?

not sure about the motor rpm but the pitch of FP's main blades cannont be adjusted (fixed) where as you can change a CP's blade pitch. And because brushless mototrs have no brushes they last much longer and are more powerful. You can also get brushless motors that are almost completely sealed, good for rc cars.

The typical RPM on a 370 carbon brushed motor is about 2,000rpm/Kv. So, the max RPM at 7.4v is (7.4 x 2,000=14,800 RPM).