The joystick controls the throttle setting. The throttle is set higher by "bumping" the joystick to the right. If the joystick is released, the setting remains constant. The throttle indicator beside it was designed and built by a freshman student in my ME 199 class (Way cool!). An electric actuator drives the throttle. A bunch of relays and potentiometers and a voltage regulator drives the electric actuator motor based on inputs from the joystick