Introduction to RC Plane Electronics

Oct 07

Introduction to RC Plane Electronics

In the previous post, I described to you the Radio or transmitter, and gave you a basic idea about the different “channels”. (See: Getting to know the “Radio” in Radio Control). In this post I would like to give you a basic idea about how the radio “communicates” with your airplane, and how the “electronics” are set up. There is a lot more in-depth information about each component that I will cover in later posts.

 

The main parts consist of:

  1. Battery
  2. Electronic Speed Control (ESC)
  3. Motor
  4. Receiver
  5. Servos (Number depends on the “channels”)
Let us now take a look at each component separately.
Battery
The most commonly used and popular batteries for electric aircraft are the LiPo Batteries or Lithium-Polymer batteries. They are lighter and provide much more capacity and voltage compared to the Nickel-cadmium (Ni-Cd) and Nickel-metal-hydride (NiMH) batteries. The LiPo batteries require special chargers and some amount of care to get a long life out of them.
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Electronic Speed Control (ESC)
The ESC regulates the speed of the motor. The ESC is plugged into the receiver’s throttle channel and connected between the motor and battery pack. The Battery Eliminator Circuit (BEC) is a built-in feature that allows the ESC to power both the motor and the radio’s receiver with the same battery pack. When the voltage gets too low, the BEC circuit cuts the motor power and keeps the receiver operating properly so the pilot can land the plane.
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Motor
The most popular type of motor being used for model airplanes today is the Brushless Outrunner Motor. They provide a greater power-to-weight ratio, but cost a little bit more than the traditional brushed motors. Outrunner motors produce a lower rpm, but produce more torque and can drive their propellers directly. This eliminates the weight and complexity of a gear box. The size of the motor is determined by the weight of your model airplane, which determines the size of the propeller. In essence, you need to choose a motor that will be able to generate the required rpm for the propeller. (Note: If this confusing, do not worry, it gets easier to understand when you start building your plane!)
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Receiver
The receiver is one component which you really cannot choose. It comes along with the radio, and works only with that particular radio on a certain pre-defined frequency. It is connected directly to the “servos”, and has a thin single wire antenna that extends outside the airplane. The receiver gets signals from the transmitter when you move a stick/control. These signals are then passed through to the servos, or ESC, which respond appropriately.
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Servos
The number of servos varies according to the number of channels that the radio has and the model airplane requires. For example, a 3 channel airplane will have 2 servos, one servo connected to the rudder, and one connected to the elevator (P.S. The third channel is for the throttle or ESC). A servo consists of a set of gears that are directly linked to a “servo horn” or “arm”, located at the top of the servo body. The horn/arm connects directly to the control surface (rudder, elevator, etc) of the airplane via a rigid or flexible rod. When the receiver picks up a signal from the transmitter/radio, that signal is sent to the appropriate servo which causes the arm to either push or pull the rod, thus moving the corresponding control surface.
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So…that was a primer into the world of RC electronics. This is the basic stuff that you need to know before you fly your first RC airplane. There is a lot of technical details regarding each of these components that you will eventually learn as you progress. Let’s be satisfied with these “appetizers” for the time being.
We are slowly getting towards the point where we start “building” our first model airplane. So, as always, stay tuned and “keep you eye to the skies”!!

 

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22 comments

  1. Robin Davies /

    I have just come back to RC gliding after 35 years away from it!! I have purchased a Parkzone Radian glider with 2.4 sPEKTRUM 5e tx/ AR500 rx & LiPo 1300mAh 11.1V battery but haven’t aatempted to fly it yet. I will of course use an instructor to help me get back the feel of RC flying!!.The RC electrics article really helped me understand the basic electronics set up in an electric glider. Thank you for taking the time to write it for people like me. It is much appreciated. However I am still a bit confused regarding the rx/servo battery theory. I take it I can pretty much buy any matching 11.1 voltage output battery ( as supplied with the glider ) as a spare but does the mAh have to be the same 1300 or can it be more or less to give longer or less flying time.I can see that the weight will also be less on the lower amp hour batteries and more on the higher ones. Can the battery have a higher max current output than the fitted ESC or will that short the ESC? Any further detail on the batteries and their relation to the ESC one can use etc would be very helpful.

    Also I take it with a 2.4ghz TX I will be able to bind it to several different RXs in the future to be able to fly say 2 or 3 different gliders in a day. Is this in fact the case?

    I sam trying to get up to speed with understanding the whole new technology since my bungee and hand launch days in South Africa and have to admit I am a bit daunted by all the different equipment!!

    Robin

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