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#RC Airplane Series-6
In this article, we are going to learn to do the ESC Calculations. Also, we are going to study about the control systems connections (basically, how are the electronics are connected to each other) !!
Topics Covered :
- What is ESC ?
- How to choose a ESC ?
- How to connect all the electronic components?
- Use of Y-junction (optional)
1. What is ESC ?
ESC stands for Electronic Speed Controller. It’s job is to provide set appropriate voltage across the BLDC motor according to the throttle given on the transmitter.
- For example, Suppose, I give 25% throttle, so, to get the speed corresponding to 25% throttle, what should be voltage applied across the motor –> this is the job of ESC ! (speed is controlled by controlling current)
- The main thing to understand is that, we will be controlling the voltage across the motor with the help of ESC. We are already aware of the motor kV relation :
- So according to the relation, Varying the voltage will vary the RPM of the motor, which will result in speed variation as well !!
From the example itself, we can understand that choosing a proper ESC is very much crucial so that everything is under control and also safe at the same time
Wiring connections for ESC :
Fig. Wiring Connections of ESC
2. How to choose ESC ?
Let’s undertand the procedure using an example !
Suppose, we finally choose the motor for our model:
A2212 10T 1400kV motor
Step-1 : Find out the maximum current which the current draws. If this value is not directly given, it can be calculated from the relation
P = V x I
(‘P’ is max. power of motor, ‘V’ is the nominal voltage of our battery used and ‘I’ is the max current from motor)
Step-2 : But we should choose an ESC such that this maximum current value should just be 75% of the actual ESC current which we will be buying. (Read it again !). We call this current as ‘Actual ESC Current’
This implies that we need an ESC which has a rating of 20.25 A. But in reality, there is no such ESC with this current rating being manufactured. So we need to go with an ESC which has a bigger value than 20.25
We can go with 30A ESC or an 40A ESC would also be perfect !!
3. Connections of all Electronics
Now, by this article 6 of RC Airplane Series, we already got to know about all the basic electronic requirements for an RC Airplane. Let’s list it down :
- Motor and Propeller
- LiPo Battery
- ESC (Electronic Speed Controller)
- Receiver (On board)
- Transmitter (Not on board)
- 4 Servos (1 for each ailerons, 1 for elevator, 1 for rudder)
In this example, let’s say we are using a 6 channel transmitter and receiver
- Usually in most of the cases, we have to attach the connectors to the 2 wires assigned for battery in ESC. For this, we can use XT60 connector which is very commonly used as well. They come in a set of a female and male connector. The female one is to be attached to the ESC while the male one is to be attached to the battery
For more clarity on above figure, you can also refer to the diagram below
4. Why Y-junction wire for ailerons ? (optional)
- If you look into the connection diagram carefully, we can see that the servos attached to the 2 ailerons are connected to a Y-junction wire. This then goes onto connect to the receiver and it uses just one channel on the receiver for 2 servos !!
The reason behind us doing this thing can be learnt from the article – RC Airplane Series-2 : ‘Understanding Control Surfaces’
- In the above article, mainly focus on the ailerons part in order to understand the reasoning behind Y-junction cable. In short, we can summarize it as :
In order to get a roll, making the ailerons deflect in opposite sense helps even more. For example, if we need to take right roll, then on giving just one stimulus through transmitter, the right aileron will deflect upwards while at the same time, the left aileron also deflects downwards
One Advantage and One Disadvantage !
Advantage :
- We can get a better roll due to 2 ailerons moving in opposite sense and everything is completed by using just 1 channel
Disadvantage :
- We can’t make the ailerons to be used as flaps since they will always move in opposite sense. (i.e. flaperons is not possible)
Conclusion :
- So in this RC Airplane-6, we have learnt to do the ESC Calculations. Similar stuff is used while drone designing as well since it also includes BLDC motors whose speed needs to be controlled.
- Here, we have completed the basic designing of RC Airplane. Hope you enjoyed the Series and got to learn something new through this. But again reminding you, this was just the Basics !!
RC Airplane Series (All previous Articles)
- Part-1 : What’s in the Wings !
- Part-2 : Understanding the control surfaces !
- Part-3 : Designing your Airplane !!
- Part-4 : Motor and Propeller Selection
- Part-5 : How to choose LiPo Battery ?
Any suggestions from your side are welcomed !!
Keep Learning !!
All the Best !!
