If you buy something like a Futaba Skysport, you will get a 4 - channel transmitter and a 7 - channel receiver. But, that is not the issue. Using 5 servos in this case means that there will be 2 servos for the ailerons. You can connect both servos with a Y - connector and plug it into the receiver and still only be using 4 channels of the receiver. If you get a computer radio, it will allow you to use 5 channels of the receiver but that will be extra expense to accomplish the same task.