Some of the MTH helicopter cars work very well and will send the copter
up 10-15 feet and others will just fall off the car. There is friction between the drive in the car and the copter drive that holds the copter in place until the power is
removed from the car motor. As the car motor slows down and the copter rotor keeps spinning, the friction is released and the copter goes up. The friction release and
rotor speed is very critical for good operation. If the copter does not work than
a little silicone on the drive may make it work better.
ElectricRR makes a board to control the helicopter car. There is a time control for the
motor power so the copter will not hit a low roof.