Originally Posted by trappy
...I can't reach to the throttle fast enough before it hits the ground...
No good to have a simple pressure switch at the grip point which disables the motor?
Thrower holds the plane, disabling motor. Pilot throttles up. Nothing exciting happens. Thrower throws the plane and motor is instant-on.
Failing that -- how about a launch as seen at 0:40 in this vid:
Try to ignore the whole smoking in front of the child thing...