Monday, April 6, 2009

Electric RC Jets - Your First Option

We are moving steadily towards our goal of flying an gas rc jet which is not far off as today we are going to have our hands on a regular kind of a remote controlled airplane which will be an electric remote controlled jet. In last post we discussed the start off period for deciding how you should go for selecting your type from RTF (ready to fly), ARTF (almost ready to fly) and the kit (where you actually start to fabricate from scratch). I hope that you must have decided your type of remote controlled airplane and if at all you like to do things with your hands and decided to go for a Kit, by now your first rc plane must have taken some shape and it is very much possible that your rc airplane is now ready to fly and you have tested it. Today we will discuss the two types of power sources available for flying our rc jets. One is electric powered remote controlled jet and the other is called gas remote controlled jet both as their name suggest have different power sources electric powered have electric motor fitted in it and gas one has a gas engine. I will keep my focus to electric remote controlled jets more and in the next post my focus will be gas powered remote controlled jets. But before discussing directly the electric rc jets and the gas ones, I am feeling somewhat a historian today and want to discuss the early hobby models of airplane power sources. Don’t worry, I won’t barrage about it and try to keep it short… here it comes…

Since the flight of the first practical rc airplane, progress with performance depended on technology as like any other field. All remote controlled airplanes require to be constructed of strong but light materials, like their big brothers, the passenger carrying airplanes, and require some kind of power to achieve their quest of flying in the air.

Early form of light weight and very inexpensive power source for model airplanes was twisted rubber bands, now don’t laugh as we could have been the ones living in that era too (lucky us, we are not :) ). As the rc airplane models progress and grew in size, weight and require more power, enabled small gas rc engines to become the preferred means of powering them. Having gas rc airplanes very powerful, these also require a heavy airframe to handle the engine’s vibration. The advantages of gas rc jets and the disadvantages will be discussed in my next post as for this one I just want to focus on an electrical powered airplanes more. Sure we will have to discuss the cons of gas ones to come up with the pros of electrical remote controlled jets.

As I said the gas ones require a heavy and strong airframe to handle the vibrations of the engine, it also requires proper maintenance, cleaning of messy oil leakages and the fuel smell requires handling too. In addition they produce a lot of sound which may be a problem for some of you living in a close neighborhood, though gas one is always required to be flown in a ground or an airfield away from the population. And the main problem which the beginners face is that the gas rc airplane do not come cheap, yes they are costly, one drop on the ground and you will be seeing yourself repairing your gas rc jet, where as electric remote controlled planes are more robust, few drops from quite a height does not shatter them easily. The benefit of electric power is it being cheap, makes them the beginner’s first choice. But there are many other benefits attached with electric remote controlled jet besides being cheap and here they are:

The Advantages of Electric Powered Jets:

We have already discussed that electric driven remote controlled jets are reliable, don’t break easily, their convenience of operation, low maintenance, low vibration, low noise and light on the pocket. However some of you engineer brains might be thinking that where is the aspect of speed in them, which is our main concern since we are only striving to reach our goal of flying a real rc jet, with real turbojet engine and further an rc rocket, if possible. You have very right concerns over speed of electric remote control jets, because we have examples of electric cars that they don’t speed that much so how can an remote controlled jet powered by electric? Well gone are the days of bulky electric batteries which used to hold little amp hour of current, now we have Lithium batteries which are lighter and hold a longer charge for your electric powered planes. The other concern you might have is the power of the electric rc jet motor, as we all know that an remote controlled electric motors cannot beat the gas remote controlled jet engine when it comes to power. Well, cutting the weight in electric rc jet and replacing the brushed motors with brush less motors have enabled electric rc jet to be lighter weight thus enhancing its speed. Let’s see what a brushed and brush less motor has to play in electric rc jets.

In the common brushed motors, sliding contacts are used to provide current to the conductor in the magnetic field so that the conductor can rotate. These sliding contacts most of the times are carbon brushes which are in contact with the conductor of the electric rc jet motor all the time, this contact makes the brushes and conductor to produce heat and wear tear. This causes current losses in the electric rc jet which makes it lose power. With the introduction of brushless motors this loss of power has been taken care of in electric rc jets. The switching of current to the conductor happens electronically in brushless motors by using electronic switches in electric rc jet motors.

Now let’s take a look at the other factor of power saver in electric rc jets which is the battery. Three main kinds of batteries are used in electric rc jets, Lithium Polymer (LiPo), Nicel Cadmium (NiCad) and Nickel Metal Hydride (NiMH). Though three of them are lighter and hold long charge for electric rc jets, LiPo batteries are lighter and hold more charge than the rest of the two.

Electric rc jets come in different shapes and sizes like powered sailplanes, aerobatic models, scale models and ducted fan type. Let’s discuss the types of electric rc jets with respect to the option given to maneuver an electric rc jet, which with respect to radio controls called channels, yes right more channels more options you have to maneuver your electric rc jet.

First we have simple 2 channel electric rc jet, simple and easy, only yaw and pitch controls are available with 2 channel electric rc jet. This one is great for very initial electric rc flights as 2channel electric rc jet comes really cheap. Then we have 3 channel electric rc jet, which gives you controls over yaw, pitch and altitude of your remote controlled jet. The 3 channel is good for occasional flyer who wants a better control over their plane and still keep a not very heavy load on the pocket. Well the 4 channels electric rc jet is what a real enthusiast require, this one offers full control over the yaw, pitch, bank and throttle acceleration.

Okay, enough for today, I will go for gas rc jets in the next post. To conclude this one, I would say that if you are new to flying rc airplanes then electric rc jet is for you after trying out the slower electric pusher airplane and also you should clean your hands on 2 or 3 channels electric rc jets and then spend your hard earned money on 4 channel ones.

Happy flying !!!


No comments:

Post a Comment