Motors: The electric motor itself is of primary importance. There are different types, such as simple ferrite magnet motors; the more sophisticated cobalt (samarium cobalt) magnet motors; and the highly efficient, long-lasting, expensive brushless motors.

After selecting the type of motor, your next concern is to size it so that it is capable of flying a model aircraft of a particular weight. In this case the choice has been made for you. Another consideration is running the motor direct drive (with the propeller attached directly to the motor shaft) or through a gear-reduction drive that can add an advantage to the power output.

Since this is a beginners' article I've selected a basic ferrite motor known in the generic sense as a Speed 400. These come in three different windings designated by voltage. This project will use the 6-volt winding. The motor can be obtained from many sources.

This size motor is capable of flying a model with a total flying weight of roughly 10-18 ounces. It can accomplish this using a direct-drive propeller, so for this first try we will not use a gear-drive assembly. Be advised for the future that a gear drive will allow you to fly heavier-weight models and/or it can extend the flying time of a model flown on direct drive. 

My choice of direct drive was to keep it simple and inexpensive. A Speed 400 motor costs approximately $15. It is a sealed can. When you eventually burn out the brushes, you throw out the motor and buy another!

The motor will have two terminals, and they are polarized (positive and negative). Most have a red dot or mark indicating the positive terminal. For our beginner's package, a wire has already been attached to each terminal. The connectors applied to the wire ends are the popular Anderson Power Pole (APP) variety. There are many popular connectors available, but I felt that the APP were best for this application. These connectors have already been attached for you.

Almost any brushed electric motor will generate some form of electrical noise which could conceivably feed back into the RC system. To suppress this brush noise, one or more bypass capacitors are added. Generally, one capacitor goes from each terminal to the case, which is like a ground connection. In this case, the motor selected has the capacitors installed inside the motor can, so nothing else is necessary.

When you start your motor the first time, the wind created by the propeller should blow toward the rear of the model. If it blows forward, it means that the motor polarity has been reversed and the propeller is turning in the wrong direction. That shouldn't happen in this instance since the work has been done for you. Be advised for the future that if the propwash blows forward, reverse or swap the motor terminal connections.

The motor shaft protrudes from the front of the motor. Some direct-drive propellers are simply pressed onto the motor shaft. I'm not in favor of that approach, so I specified the use of a propeller adapter. The adapter is slipped onto the motor shaft. A collet-type device essentially clamps to the motor shaft as you tighten the adapter. I found the adapter already installed on my motor shaft; you might find the same.

Once the adapter is in place, put the propeller on, followed by a propeller washer then the nut. Tighten the nut, and you are set. The propeller of choice for this project is a Gunther 5 x 4 white plastic. You will likely have to drill the center shaft hole somewhat to fit on the adapter shaft. Next month I'll write about how to install this motor on your aircraft.