If the motor is mounted on the plane it's fairly easy to restrain the plane. A piece of rope and a screwdriver are all that you need. Tie a piece of rope around the tail of the plane, make sure that it goes around the front of the horizontal and vertical stabilizers, and tie that to the screwdriver. Push the screwdriver into the ground to hold the plane while the motor is running. This will restrain your plane with no problems. Even though the plane is held down, you still want to be careful
around the propeller, see diagram.

Hope this helps

Ken