Well honestly speaking, I have experience in RC planes and RC robot cars and not RC helicopters, but I have a lot of useful information to share over here at hubpages, as I have seen a couple of helicopters with engines and electric motors with some of my friends who have build some for their own fun. Would not like to discourage you or doubt your talents, but I feel that they are very difficult to construct as many parts are involved. Also, there is a lot of creativity involved.

A professional helicopter not only involves motors to control them but professionals also use an electronic gyroscope to control the position of the helicopter.

So I will list a few things involved in building a RC heli.

Servomotor used in building remote-controlled helicopters

A servomotor is a motor which has precision control, meaning it rotates through an angle of about 180 degrees or so and has a servo arm on it which is connected to the flap or mechanism which you want to control, for example in R/C planes, the ailerons (hinged control parts attached to wings), rudder, steering mechanism, throttle control of the engine is controlled with the help of the servomotor. A connecting rod similar to a cycle spoke is connected at one end to a servo arm fixed on the shaft of the servomotor and the other end is fixed to the throttle or whatever you want to control

How a servomotor is controlled?

A servomotor is controlled with the help of a 4-channel controller or any controller for that matter. A 4 channel radio comes with a transmitter and a receiver. The receiver should be placed on your RC helicopter, RC plane, RC car, or RC boat and all the servomotors should be connected to the receiver along with the receiver's battery supply.

How rotation of the blades of the RC helicopters is powered?

The rotation of the blades of the helicopter have to be powered either by an engine or with some other electric motor and preferably the motor should be designed for using them in helicopters as they need very high RPM and torque, so try buying some good motor or engine. The engines for helicopters also have to be very good as it should not switch off when in flight or else your helicopter will come down like a dead box......straight down.

You can find several servos available on sale at Ebay and Amazon at low cost.

These are a few things involved in building RC helicopters. For more information, you can google "build RC helicopters". I will come up with my own details in a few days after building one of my own with help of my friends who are very much involved in this, some as a hobby and others as a career. I will then publish the details over here in my upcoming hub. As I want to gain practical knowledge before releasing any useful information. By that time, bye and take care.

My hub on building a remote controlled robo car:

http://hubpages.com/hub/How-to-make-a-Remote-Controlled-Robot-Car