How to Add Air Brakes to RC Foam Airplanes

Draw the outline of the air brake on the top side of the aircraft -- choose an area where the extra weight of the servomotor won't be too destabilizing, and draw a rectangle about the size of a playing card. You need to be as precise as possible -- if your air brake is misshapen or misaligned, it can seriously impact the airworthiness of your RC plane.

Cut through the foam walls of the airplane along the outline you've drawn. Lift the piece of foam away to expose the hollow insides of the model aircraft.

Connect the servomotor to the power pack of the airplane (where the power leads to the servomotors for the other control surfaces plug in) and to the receiver unit for the spare channel of your transmitter.

Test the servomotor by activating the control on your transmitter unit and making sure the servomotor moves across its full range of motion. If it seems to work well, use the low-wattage soldering iron to very carefully solder the connections from the servo to its power and receiver -- be careful that you don't accidentally unsolder other connections or melt the foam of the aircraft.

Turn the servomotor to its default setting -- where it is without any input from the controller. Heat up the hot glue gun and use a small dab to put the servomotor in place inside the hollow of your airplane -- leave the servo arm protruding, because you'll need to secure the air brake to it.

Check the servomotor's position by setting the air brake back in place -- it should rest naturally, directly atop the servomotor arm.

Activate the servomotor using the RC transmitter to bring it to its fully deployed position -- where it will be when you are using the air brake. Carefully fit the air brake atop it, and use the hot glue gun to glue the servo arm to the air brake.