Applications

What is a machine? – 3 idiots machine definition breakdown

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What is a machine - definition breakdown

One of my favourite scenes from the ‘3 Idiots’ movie is when Rancho is asked about the definition of ‘Machine’ by his Professor. We all know and love Rancho’s simplified version of the ‘3 idiots’ machine definition, but the professor didn’t seem to appreciate it. Instead, he was much more impressed by Chatur’s definition, which many of us, if not all, skipped over. In this blog, I will simplify the 3 Idiots machine definition for you.

Rancho character in 3 idiots movie
Rancho
Chatur character in 3 idiots movie
Chatur
Table Of Contents
  1. 3 idiots machine Definition:

Of course, it’s not a great idea to mug up things without understanding (we have already discussed this point in Understanding Projectile Motion), but the definition of a machine that he gives is also quite impressive. It goes something like this:

If you are interested, you can watch 3 idiots on Amazon Prime by clicking HERE

3 idiots machine Definition:

“Machines are any combination of bodies so connected that their relative motions are constrained and by which means, force and motion may be transmitted and modified as a screw and its nut, or a lever arranged to turn about a fulcrum or a pulley about its pivot, etc. especially, a construction, more or less complex consisting of a combination of moving parts, or simple mechanical elements as wheels, levers, cams etc.”

In today’s blog, we will be breaking this definition down with the help of a very simple example, which most of us (from PCM or PCB background) have studied, i.e., the Atwood machine – the simplest pulley-block system.

Let’s divide the 3 idiots machine definition into parts and try to get this thing sorted out quickly :

1st part – “Machines are any combination of bodies so connected that their relative motions are constrained.“

Look at bodies 1 and 2. Both the masses are so connected that their motions are dependent on one another. That’s what we call – ‘the relative motion is constrained.’

We can write the constraint relation for the displacement between the two masses for this case as :

*Refer to this article for a detailed discussion on writing constrained relations: Click Here

It shows that if 1 comes down by ‘x’ metres, then 2 has to move up by ‘x’ metres. It’s all constrained!

This article discusses the 3-idiots machine definition, and the figure represents the simple Atwood machine

2nd part – “and by which means, force and motion may be transmitted.“

The gravitational force on 1 (m1*g) is transmitted through the string to affect the motion of 2.

Also, if 1 and 2 are of the same mass, they don’t have any acceleration, but in case the masses are different, the accelerations of 1 and 2 get modified.

We write the FBD (free body diagram) equation for each body as :

This article discusses about the 3-idiots machine definition, and the figure represents the FBD or the free body diagram for the Atwood system

3rd part – “as a screw and its nut, or a lever arranged to turn about a fulcrum or a pulley about its pivot, etc.“

This part explains various examples of simple machines (screw-nut, lever, pulley).

Here, in these examples, we have a pulley as a simple machine component as a part of this whole system.

This article discusses about the 3-idiots machine definition, and the figure represents the Pulley assembly and how it works

4th part – “especially, a construction, more or less complex, consisting of a combination of moving parts, or simple mechanical elements, such as wheels, levers, cams, etc.“

Compared to a simple machine like a pulley, we can say that the Atwood machine system arrangement would come under a complex combination that has many moving parts in it, such as :

  • Masses
  • String
  • Pulley
The system consists of pulley, sting and masses

This was a short and fun kind of post explaining the famous 3 idiots machine definition, just to make sure that all of the 3 idiots movie lovers can now break down this definition the next time they watch the movie! My aim was to explain this thing in the simplest way possible.

Also, I would like to add that just memorizing blindly doesn’t make any sense, but understanding the definition would really help us to make our grip on the concepts much better. I would also be quite impressed if Chatur had the understanding of this beautiful definition. But sadly, the character ‘Chatur’ doesn’t seem to be interested in all this 🙁

Keep Learning!

 

Why is Multigrade Engine Oil So Important?

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We all have seen engine oil somewhere or other, and most commonly at the mechanic’s shop. Have you ever wondered what this 5W-30 is written on? Well, that’s what we are going to find out through this article.

Table Of Contents
  1. 1. Short Introduction to Viscosity
  2. 2. Temperature effect on Viscosity
  3. 3. Need for Multigrade Engine Oil
  4. FAQ section

1. Short Introduction to Viscosity

Let’s say you have water flowing over a flat plate. For sure, it’s not going to move freely. But why do we say that? The answer to this is: Viscosity. In simpler words, there is a kind of internal friction among the moving layers of the fluid. This resistance doesn’t let the fluid flow freely over the plate.

Introduction to viscosity

You can say that: ‘Friction loves keeping all the layers together’. In technical terms, we say: “Friction opposes relative motion”. Having this understanding, consider layer number 2. 

  • Layer 3 moves at a faster speed (v+dv) than Layer 2. Hence, the viscous force on the lower layer of 3 acts in such a way that it gets slowed down. 
  • Layer 1 moves at a slower speed (v-dv) than Layer 2. Hence, the viscous force on the upper layer of 1 acts in such a way that it gets faster.
Introduction to viscosity - this figure tells that the fluid layers offer resistance to the adjacent faster-moving layer

This fluid property of trying to keep and move the fluid ‘together’ is known as Viscosity.

The thing that separates the low viscous fluid from the highly viscous fluid is the amount of ‘strictness’ that the fluid shows for keeping them together.

Honey - very viscous fluid
Honey
Water - Less viscous
Water
  • For example, water is less viscous than honey because water doesn’t care much about keeping the layers moving together. While Honey is like a much ‘strict master’ who wants all of these layers to be united/together

Technical Definition for Viscosity –
The measure of resistance to relative motion within the fluid is called viscosity.

2. Temperature effect on Viscosity

Effect of temperature on viscosity - this is useful for the explanation of multigrade engine oil
Effect of Temperature

Temperature does have an effect on the viscosity of the fluid.

  • In the case of a liquid, the molecules are bonded by weak chemical bonds. 
  • On increasing the temperature, you are actually providing enough thermal energy to the molecules that they break the bonds and become free. This causes the viscosity of fluid to decrease as there is no more dependency of fluid layers on one another because of moving apart. We say the fluid becomes thinner.
  • While at much lower temperatures, the fluid tends to become thicker.

3. Need for Multigrade Engine Oil

We all would agree that an engine is nothing but a machine, and we know that in the case of a machine used in machining operations, there are many parts that require grease for proper functioning.

Similarly, Engine Oil is used to ensure that there is proper lubrication among the contact parts, i.e., with engine oil, we ensure there is no wear and tear among the interacting parts. 

engine oil pack with its rating printed on it

3.1 What happens if oil is too thin or too thick?

  • If the oil you use is too thin, it will just flow out of the surfaces very quickly, and hence won’t be of any help

If the oil is too thick, a lot of power would go into just moving the parts through your ‘thick’ oil

Engine oil is being used as a lubricant for machine parts

3.2 Effect of Temperature on Engine Oil

So, knowing this, we choose a motor oil with a given viscosity. Now, consider 2 cases :

  • Case 1: I use this oil on peak summer days
  • Case 2: I use this oil in peak winters

We have already discussed the effect of temperature on the viscosity. An oil with given viscosity would become thinner in peak summer and thicker in peak winter.

SOLUTION :
To overcome this, earlier people used a 30-weight motor oil (already thicker) in summers, so that it thins out and reach required value because of high temperature, while they used a 5-weight motor oil (already thin) in winters, so that it thickens to reach the required value in peak winters due to low temperature.

BUT Now, we have come up with something even better, known as ‘Multigrade Engine Oil‘. 

The speciality of this oil is that it can maintain a constant value of viscosity over a wide range of temperatures. Hence, we no longer have to change our oil from season to season. 

  • The key feature of multigrade oils is their ability to remain fluid when cold and provide adequate viscosity at higher temperatures.

3.3 How to interpret the rating?

5W-30 means 5 weight in winter and 30 weight in summer. Hence, the viscous nature remains maintained. Now, you know the reason behind 5W-30. Similarly, we also have 10W-40 and many more combinations available in the market

FAQ section

How to interface RGB Led with Arduino?

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Everyone likes colourful LEDs, don’t they? And what if I tell you that we can get all the 3 primary colours (red, green, and blue) in a single LED? Exciting, isn’t it? Here’s where RGB LED comes into the picture. Let’s see how to interface an RGB led with Arduino.

RGB, as we all know, stands for :

  • Red
  • Green
  • Blue

They are one of the primary colours which can be mixed in different proportions to result in various colours.

Table Of Contents
  1. 1. Problem Statement 
  2. 2. How does an RGB LED work?
  3. 3. Components Required
  4. 4. Pinouts and Circuit Diagram
  5. 5. Explanation and Code
  6. 6. Assignment:
  7. Conclusion:

1. Problem Statement 

  • We need to create a message for our loved ones, but NOT as a direct text message. When I say loved one, it can be your mother, father, sister, or just anyone whom you love and want to express your feelings to! 
  • This has to be done with the RGB LED, Arduino, etc. Frame your own way of conveying your message to the person with the help of the components discussed

*Hint for the Solution: For this project, we will be showing ‘143’ with the help of an RGB LED

2. How does an RGB LED work?

  • As we know, red, Green and Blue are one of the primary colours that can be used to obtain different colours.
  • This is done using different compositions or ratios of the 3 colours during mixing.
  • And how does mixing happen? The answer is that – It just happens under one LED –> This makes the colours get mixed

The best analogy is the painting palette, which we normally use in our drawing classes. Consider having the smaller version of the paints. So, how did you use to obtain different colours? –> By mixing those available colours in different ratios!

Just 6 colours of poster paints
Drawing Palette
  • The given below are some of the shades which you can make with the help of RGB combinations : 
Photo Credits: https://en.wiktionary.org/

Also, different shades of the colours can be obtained by varying the intensity of the RGB colours

3. Components Required

  • Arduino Uno
  • RGB LED x1
  • Resistors (220 ohms) x3
  • Jumper Wires

4. Pinouts and Circuit Diagram

The RGB LED has 4 pins –

  • RED
  • BLUE
  • GREEN
  • GND

Always check the pin name associated with the pin. The pin order might change from manufacturer to manufacturer!

Important:

Treat each of the colour pins as a separate LED. Only then can you control each colour on the LED individually.

  • This implies that you will need a separate resistor to protect each of the 3 LEDs – Therefore, we choose three 220 ohms resistors

Schematic Diagram on TinkerCad:

Pin Connections:

5. Explanation and Code

So, as discussed in our Problem Statement, we are going to code our LED such that it somehow conveys the message ‘143’ (A modern way to say “I love you“). This is how it can be done :

Table for understanding the output of the code
  • If you look into the Pinouts Section above, you will notice that the Pins 5, 6, and 9 have a ‘~’ type of symbol adjacent to them on the Arduino Board. This symbol represents that the Pin is a PWM pin.
  • PWM stands for Pulse Width Modulation
  • It’s a kind of additional Superpower which is given to a digital pin to process the data differently if needed. We will be discussing this in detail in upcoming Articles. 
  • For now Let’s take a small example and have an idea about PWM in Layman’s terms.

We know that Digital Pins have only 2 signals – ‘1’ and ‘0’ –> i.e. It’s either ON or it’s OFF, respectively. This case is like a switch that we use to turn ON and turn OFF the fan. 

                                                                                   Fig. For Digital Pins without PWM

BUT Now, PWM is like adding a Regulator besides the switch (it’s just an addition to what we had before). This will allow us to vary and control the speed of the fan as well.

                                                                                   Fig. For Digital Pins with PWM

Code:

The code for the Main Project can be found in the attached GitHub File. The comments will guide you to understand the reasoning for that particular section of code.

You can directly just copy and paste the code given below:

/*
-----------------------------------------------------------
Website: www.physicsandelectronics.com
Refer Article for in-Depth Explanation about this Project & Explore More

Main Project : RGB LED interfacing with Arduino
Instagram : @physics_and_electronics
Youtube Channel : Physics And Electronics - Saurabh Salvi

**Main Code for the Project**
-----------------------------------------------------------
*/

//Declaring pins for each colour on RGB led (All are PWM pins)
int red = 5;      
int green = 6;
int blue = 9;

void setup() {
  // put your setup code here, to run once:
  // All pins are set as OUTPUT
  pinMode(red, OUTPUT);
  pinMode(green, OUTPUT);
  pinMode(blue, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
//Blink Red Colour once
ledColour(255, 0, 0);  //Keeping only RED colour for 1000ms
delay(1000);
ledColour(0, 0,0);      //Keeping LED off for 800ms (For a pause)
delay(800);

//Blinking the Green Colour 4 times
for(int i=0; i<=3; i++){
  ledColour(0, 255, 0);
  delay(1000);
  ledColour(0, 0,0);
  delay(200);
}
ledColour(0, 0, 0);
delay(800);

//Blinking the Blue Colour 3 times
for(int i=0; i<=2; i++){
  ledColour(0, 0, 255);
  delay(1000);
  ledColour(0, 0,0);
  delay(200);
}

//Keeping White COlour
ledColour(0, 0, 0);
delay(1000);
ledColour(255, 255, 255);
delay(5000);
}

//defining a function for colour selection on RGB Led 
void ledColour(int redVal, int greenVal, int blueVal){

  analogWrite(red, redVal); 
  analogWrite(green, greenVal);
  analogWrite(blue, blueVal);

}

6. Assignment:

Problem Statement:

You need to design a police siren with flashing alternating red and blue lights. You are free to design your own concept, but please try to stick to these two colors.

Components to be used:

  • RGB LED x2
  • Arduino Uno
  • Breadboard
  • Resistors*
  • Wires

*Decide the resistance value yourself. If you want a reference, you can read the related article by clicking HERE

Make the Project in TinkerCad or any other Simulation Software which supports Arduino

For Submission/Doubts: You can send me an email at: connect@physicsandelectronics.com

Conclusion:

So, through this Mini Arduino Project-2, we learnt to interface an RGB LED with Arduino and also learnt some basic working of the same. As discussed, we will be looking into PWM signals in a lot more detail in upcoming articles.

  • Don’t forget to attempt the Assignment Problem. It will allow you to apply the knowledge you gained in the article (Information + Arduino Code) 

Keep Learning!

Arrow Indicator Circuit – Arduino Project

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This project mainly aims to cover a part of the basics regarding Arduino IDE and Interfacing of Arduino with other components. Let’s get straight into building this project!

This Arduino project will help you get a clear understanding of the complete methodology to be carried out in order to deal with any project based on this microcontroller.

Table Of Contents
  1. 1. Description of the Project
  2. 2. Components Needed for this Arduino Project
  3. 3. Understanding and Procedure
  4. 4. Explanation of Code:
  5. Conclusion:

1. Description of the Project

Problem Statement :

Our main objective for the project is to make an Arrow Keypad-like thing in order to control the LEDs. The LEDs indicate the direction corresponding to the button that we pressed on the keypad

Fig.1 Arrow Keypad
Fig.2 LED pattern that would appear when the corresponding button is pressed

2. Components Needed for this Arduino Project

  • Arduino Uno
  • Breadboard
  • 4 Red LEDs 
  • 4 Push Buttons
  • 4 Resistors  (220 ohms)
  • Jumper Wires

Reference Article Alert!

How to check the resistance value of your resistor? – Refer to this Article: Dealing with Resistors

3. Understanding and Procedure

3.1 Understanding

Note that there are no connections among the LEDs. 

  • Each LED is separately connected to the Arduino
  • Similarly, each push button is also connected separately to the Arduino Board
  • But the connection between the two (LED and pushbuttons) is done through Arduino. That’s the job of a Microcontroller –> ‘To connect the things as instructed in code.’
Fig. Each LED and each pushbutton is connected separately

We will see how to connect each component with Arduino

3.1.1 Single LED Connections:

  • The adjacent circuit diagram shows the connections that are to be made to control the LED with the help of Arduino
  • The diagram has been prepared with the help of TinkerCad (Simulation Software)

Code for the Blinking of LED can be found below.

/*
-----------------------------------------------------------
Website: www.physicsandelectronics.com


Main Project : Arrow Indicator Circuit - Arduino Project

Sub-Code : Blinking of LED
Objective : To understand the controlling of LED with Arduino

-----------------------------------------------------------
*/


int led = 3; //Assigning pin number 3 for LED

void setup()
{
  pinMode(led, OUTPUT); //LED will be acting as OUTPUT
}

void loop()
{
  //Code to blink LED
  
  digitalWrite(led, HIGH); //Turning ON led 
  delay(2000);			   //Keeping it ON for 2 seconds
  digitalWrite(led, LOW);  //Turning OFF led 
  delay(2000);			   //Keeping it OFF for 2 seconds
}

3.1.2 Single Push Button Connections:

  • The pushbutton serves as an INPUT for most of the time.
  • It gives a value of 0 or LOW when not pressed and gives a value of 1 or HIGH when pressed.
  • There is another way to connect a pushbutton, i.e., by adding a Pull-up Resistor.  

Code for understanding single push button connections is given below. You can directly copy and paste it into your Arduino IDE

/*
-----------------------------------------------------------
Website: www.physicsandelectronics.com


Main Project : Arrow Indicator Circuit - Arduino Project

Sub-Code : Interfacing of Push Button with Arduino
Objective : To know when is the button pressed and when it is not 

-----------------------------------------------------------
*/

int button =7;
int buttonState;

void setup() {
  // put your setup code here, to run once:
pinMode(button, INPUT); //keeping button as INPUT
Serial.begin(9600); // Because we need Serial Monitor
}

void loop() {
  // put your main code here, to run repeatedly:
buttonState = digitalRead(button); // buttonState stores 1 if button is pressed and 0 if not pressed
Serial.println(buttonState);  //Shows the state of button on Serial monitor
}

3.1.3 LED + Push Button:

  • Now that we have learnt to interface the button and LED separately, it’s time to interface them with Arduino at once.
  • Check the code. The comments will guide you to understand the idea behind each line

Code for the ‘controlling LED with Push Button’ is given below. You can directly copy and paste it into your Arduino IDE

/*
-----------------------------------------------------------
Website: www.physicsandelectronics.com


Main Project : Arrow Indicator Circuit - Arduino Project

Sub-Code : Controlling LED with Push Button
Objective : To control LED by Push Button through Arduino 

-----------------------------------------------------------
*/


int led = 8; //Assigning pin number 8 for LED
int pushButton = 7; //Assigning pin number 7 for push button
int buttonState ; //this variable will help us to know whether button is pressed or not

void setup()
{
  pinMode(led, OUTPUT); //LED will be acting as OUTPUT
  pinMode(pushButton, INPUT); //Push Button will act as input
}

void loop()
{
  //Code to control LED with Push Button
  
  
  buttonState = digitalRead(pushButton); //Read the value you are getting from push Button
  
  if(buttonState == 1){ //if button has been pressed
  
    digitalWrite(led, HIGH); // turn the LED ON
  }
  else{
  	digitalWrite(led, LOW); // keep the LED OFF
  }
 }

3.2 Procedure

After Being Comfortable with the above three mini-projects, the main project is very easy to do, as we have done the same thing, but now, it has to be done multiple times.

Step-1:

We need the LED matrix type setup to be in a square shape (diamond shape). So accordingly, we arranged to set up the LEDs and corresponding resistors to protect those LEDs

Reference Article:

How to choose the correct Resistor for a specific coloured LED? – Refer to the Article: Dealing with Resistors

You will learn that –> It is safe to use a higher resistance resistor than the required value. So we go for 220 ohms.

Connect the LEDs as learnt in Section 3.1

Step-2:

  • Attach the 4 Push Buttons to the breadboard in a keypad fashion. 
  • The connections of each button have to be done with Arduino as explained in Section 3.2

Overall Diagram in TinkerCad can be shown as:

The same thing in Reality looks something like:

4. Explanation of Code:

Copy and paste the complete code given below into your Arduino IDE

/*
-----------------------------------------------------------
Website: www.physicsandelectronics.com


Main Project : Arrow Indicator Circuit - Arduino Project

**Main Code for the Project**
-----------------------------------------------------------
*/



int led12 = 2;  //led in row=1 ; column=2
int led21 = 3;	//led in row=2 ; column=1
int led23 = 5;  //led in row=2 ; column=3
int led32 = 6;  //led in row=3 ; column=2

int fwd = 7;	//button for forward 
int right = 8;  //button for right 
int left = 10;  //button for left
int back = 9;   //button for back 

int fwdVal;   //Variable to store the state of fwd button (1 when pressed and 0 when not pressed) 
int rightVal; //Variable to store the state of right button (1 when pressed and 0 when not pressed) 
int leftVal;  //Variable to store the state of left button (1 when pressed and 0 when not pressed) 
int backVal;  //Variable to store the state of back button (1 when pressed and 0 when not pressed) 

void setup()
{
  //keeping leds as OUTPUT
  pinMode(led12, OUTPUT);
  pinMode(led21, OUTPUT);
  pinMode(led23, OUTPUT);
  pinMode(led32, OUTPUT);
  
  //Switches will act as INPUT
  pinMode(fwd, INPUT);
  pinMode(right, INPUT);
  pinMode(left, INPUT);
  pinMode(back, INPUT);

  Serial.begin(9600); //Serial monitor to keep a record of what's happening
}

void loop()
{
  //Checking the situation/state of push buttons
  fwdVal = digitalRead(fwd);
  rightVal = digitalRead(right);
  leftVal = digitalRead(left);
  backVal = digitalRead(back);
    
     Serial.println(fwdVal);

  /*Controlling LEDs in order to represent forward sign if forward button is pressed*/
  
  if(fwdVal == 1){
  	digitalWrite(led12, HIGH);
  	digitalWrite(led21, HIGH);
  	digitalWrite(led23, HIGH);
  	digitalWrite(led32, LOW);
    
  }

 
  /*Controlling LEDs in order to represent backward sign if backward button is pressed*/ 
  
  else if(backVal == 1){
    digitalWrite(led12, LOW);
  	digitalWrite(led21, HIGH);
  	digitalWrite(led23, HIGH);
  	digitalWrite(led32, HIGH);
  }
  
  /*Controlling LEDs in order to represent left sign if left button is pressed*/
  
  else if(leftVal == 1){
    digitalWrite(led12, HIGH);
  	digitalWrite(led21, HIGH);
  	digitalWrite(led23, LOW);
  	digitalWrite(led32, HIGH);
  }
  
  /*Controlling LEDs in order to represent right sign if right button is pressed*/
  
  else if(rightVal == 1){
    digitalWrite(led12, HIGH);
  	digitalWrite(led21, LOW);
  	digitalWrite(led23, HIGH);
  	digitalWrite(led32, HIGH);
  }
  
  //If no button is pressed, then keep all leds OFF
  else{
    digitalWrite(led12, LOW);
  	digitalWrite(led21, LOW);
  	digitalWrite(led23, LOW);
  	digitalWrite(led32, LOW);
  }
  
}
  • We are using some kind of nomenclature here in order to properly keep track of which LED we are talking about or which button we are referring to.

Below is the attached file for Code Explanation. This will exactly give you an idea of the flow that the project code has in it.

Code Explanation - Main Arduino Project

Actual Execution:

When forward key is pressed:

When the left key is pressed:

When the right key is pressed:

When the back key is pressed :

Conclusion:

So, with this, we have learnt to do the basic interfacing of the components with Arduino. There’s still a lot to learn about Arduino. Many sensors can be used for different projects. 

This Article was all about keeping it as basic as possible so that it is more interesting for people/students to read and see

Keep Learning!

How to choose the correct Electronic Speed Controller (ESC)? – Part 6

by

RC Airplane Series – Part 6

In this article, we will learn how to perform ESC Calculations. Also, we are going to study the control systems connections (basically, how the electronics are connected)!

Table Of Contents
  1. 1. What is an Electronic Speed Controller (ESC)?
  2. 2. How to choose an appropriate ESC?
  3. 3. Connections of all of the RC Electronics involved
  4. 4. Why use Y-junction wire for ailerons?
  5. Conclusion:

1. What is an Electronic Speed Controller (ESC)?

electronic speed controller

ESC stands for Electronic Speed Controller. Its job is to provide a 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 the voltage applied across the motor -> this is the job of the 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 the ESC. We are already aware of the motor kV relation:

motor kV=RPM of motorVoltage across the motor\text{motor } kV = \frac{\text{RPM of motor}}{\text{Voltage across the motor}}

  • 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 crucial so that everything is under control and also safe at the same time. 

Wiring connections for ESC:

Wiring Connections of electronic speed controller
Fig. Wiring Connections of ESC

2. How to choose an appropriate ESC?

Let’s understand the procedure using an example!

Suppose we finally choose the motor for our model: 

A2212 10T 1400kV BLDC motor

BLDC motor

Step-1: Find out the maximum current that the current draws. If this value is not directly given, it can be calculated from the relation.

 P=V×IP = V \times I

(‘P’ is max. power of motor, ‘V’ is the nominal voltage of our battery used, and ‘I’ is the max current from the motor.

From the datasheet:

In our case, the maximum power of the motor is 180W, and we consider that we are using a 3S LiPo battery, which gives us 11.1 V voltage

P=V×IP = V \times I

180W=(11.1V)×I180\,W = (11.1\,V)\times I

I=16.2AI = 16.2\,A

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 ‘Actual ESC Current.’

Calculating 80% of ‘Actual ESC Current’ (this value needs to be on the ESC we would be finally buying) would give us the ‘Maximum motor current.’

80% of Actual ESC Current=Max motor Current80\% \text{ of Actual ESC Current} = \text{Max motor Current}

75100×Actual ESC current=16.2A\frac{75}{100} \times \text{Actual ESC current} = 16.2\,A

Actual ESC current=20.25A\text{Actual ESC current} = 20.25\,A

This implies that we need an ESC that 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 that has a bigger value than 20.25

We can go with a 30A ESC or a 40A ESC, which would also be perfect in our case.

3. Connections of all of the RC Electronics involved

Now, by this article 6 of the RC Airplane Series, we already 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 aileron, 1 for elevator, 1 for rudder) 

In this example, let’s say we are using a 6-channel transmitter and receiver.

The schematic explains the connections to be made

  • Usually, in most of the cases, we have to attach the connectors to the 2 wires assigned for the battery in the ESC. For this, we can use the XT60 connector, which is very commonly used as well. They come in a set of female and male connectors. 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 the above figure, you can also refer to the diagram below.

The figure explains the wiring connections to be made between various components involved in making an RC Airplane

4. Why use Y-junction wire for ailerons?

Y-junction wire

  • 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 on to 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, the focus is on the aileron part to understand the reasoning behind the Y-junction cable. In short, we can summarize it as follows: 

To get a roll, having the ailerons deflect in the opposite sense helps even more. For example, if we need to take the right roll, then on giving just one stimulus through the 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 the opposite sense. (i.e., flaperons are 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 design of the 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)

Any suggestions from your side are welcome!

Keep Learning

All the Best

How to Choose a Correct LiPo Battery? – Part 5

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RC Airplane Series – Part 5

LiPo battery

In this article, we are going to learn about the correct battery selection for our RC Airplane Project. This step is very crucial as the battery is going to be serving as the powerhouse for the entire set of electronic components on the plane. 

I will be covering some examples as well for your clarity. So, without any further delay, let’s straightaway start with the topic

Table Of Contents
  1. Why choose LiPo Battery?
  2. Battery Specifications:
  3. Voltage of LiPo battery:
  4. Capacity of Battery:
  5. 'C' Rating / Discharge Rate:
  6. Flight Time Calculations :
  7. Detailed Example for Battery Selection
  8. Conclusion

Why choose LiPo Battery?

Among so many batteries, when it comes to the electronic projects (especially RC aircrafts), we directly choose LiPo over others. 

LiPo stands for Lithium Polymer batteries. These are known for their ‘High Energy Density‘. 

mass density = mass/volume and similarly, energy density = energy/volume

By comparing the definitions, we can see that, if more mass is accumulated in lesser volume, we term that substance as highly dense substance. Similarly, if given energy can be stored in a lesser volume, we term the substance as the one having ‘high energy density’ !

Battery Specifications:

When it comes to LiPo batteries, we have 3 main parameters which we need to check in order to select the right LiPo for our project. Those are :

  • Number of cells (Voltage of the battery (in volts))
  • Capacity (in mAh)
  • ‘C’ rating/discharge rate
The chart shows various battery parameters like Number of cells, capacity, and C Rating

Voltage of LiPo battery:

A battery is a combination of cells. So basically, to calculate the total voltage of the battery, we need to know the voltage of a single cell. 

Thumb rule:

  • The voltage of the cell in a LiPo battery should not go below 3.3V, and also should not cross 4V, as in both cases it might damage the cell and hence the battery
  • So, we decide a term called ‘Nominal Voltage‘. This is basically an approx. The average value of the max and min voltages. In the case of LiPo, we take it as 3.7 V. For batteries, we always consider the nominal voltage
LiPo Battery with '3S' highlighted

‘S’ represents the number of cells

Based on the S number, we calculate the total voltage of battery.

For example, the above battery is ‘3S’ which implies that it has 3 cells in it. Therefore,

Battery Voltage=(S number)×(Nom. Voltage of a cell)\text{Battery Voltage} = (\text{S number}) \times (\text{Nom. Voltage of a cell})

Battery Voltage=3×3.7=11.1V\text{Battery Voltage} = 3 \times 3.7 = 11.1\,V

Suppose, we select a model for our BLDC motor : DYS D2826-10 1400KV Outrunner Brushless Motor

Now, we need to correctly choose our motor based on the motor suggested specifications or check datasheet

Specifications of BLDC Motor
from Robu.in

Now, selecting 2s LiPo or 3s LiPo depends on your model and requirements. The more voltage you apply, the more RPM you will get for the same given motor by the relation :

kV=RPM of motorNominal Voltage of BatterykV = \frac{\text{RPM of motor}}{\text{Nominal Voltage of Battery}}

Capacity of Battery:

The Capacity of Battery gives you an idea of the time in which the battery will get drained off. The unit of Capacity for LiPo is ‘mAh’. It stands for milli-Amp hours.

We try to understand the same with an example. Suppose I have a battery of 4200 mAh. 

  • It implies that my battery will get drained off completely if I keep drawing 4.2 A from the battery continuously for 1hr.
  • Now, from the same battery, if I draw only 2.1 A (less than 4.2 A), then the battery will drain off after 2 hrs ; giving me more usage time. 
  • It’s Pretty Obvious that if you draw less current, the battery will allow more usage time.
LiPo battery with its Capacity value encircled

For RC Airplanes, Capacity plays an important role for determining the flight time (time for which the plane will fly).

We will discuss about Flight time in coming section below

‘C’ Rating / Discharge Rate:

This thing is nothing but a simple multiplier. It is used to know the actual strength of our battery. This value helps us to calculate the maximum current (continuous and burst) which the battery can provide safely. 

Formulation : 

Maximum continuous discharge current=Capacity×C rating\text{Maximum continuous discharge current} = \text{Capacity} \times \text{C rating}

Maximum burst discharge current=Capacity×burst C rating\text{Maximum burst discharge current} = \text{Capacity} \times \text{burst C rating}

LiPo battery with its C Rating encircled

Some times, we need some more current than the maximum continuous current value as well. So in that case, the burst continuous current comes into picture. It shows that the battery can provide some extra amount of current as well if required though only for a short interval of time.  

Usually, on batteries, only continuous discharge rate is given. For burst rate, we need to check the battery specifications on websites

For example, 

My battery has specifications 2200 mAh, 11.1V and  I want to decide the appropriate C rating to be chosen. I also know that the maximum current requirement for all my electronic components (majorly motor) is 20 A.

Solution :

So, I need a battery which must have the strength/ability to continuously providing 20A (though its not always needed). By the above formula,

We get,   

20=2.2×(C rating)20 = 2.2 \times (\text{C rating})     

C rating=9.1C\text{C rating} = 9.1\,C

So now, anything more than 9.1 C (like 10C, 15C, etc) is absolutely fine BUT less than 9.1 C is NOT OK !!

Flight Time Calculations :

A very important concept and is crucial especially for competitions were time constraints are there. As discussed in Capacity sub-section above, this concept is a lot dependent on the Capacity of battery. 

Note the step-by-step procedure :

Step-by-step procedure for calculating flight time
Flight Time Calculations Flow (Text)
  1. Calculate/Find the maximum current drawn by the motor. This is called the Motor Amps.
  2. Add current contributions of other electronic components (receiver, ESC electronics, etc.). These are usually not significant, so this step is optional.
  3. Find the Battery Amps from the capacity value.
    Example:
    If the battery capacity is 5200 mAh, then Battery Amps = 5.2 A.
  4. Formula for flight time is given below:

Flight Time (in minutes)=Battery AmpsMotor Amps×60\text{Flight Time (in minutes)} = \frac{\text{Battery Amps}}{\text{Motor Amps}} \times 60

After completing all the steps, we get a flight time value. But once this flight time is completed for an RC plane, the battery will be completely drained, and WE DON’T WANT THIS !!

  • It is always advisable for LiPo batteries to keep atleast 25 % remaining (i.e. use only 75 % of the battery). So if only 75 % of the battery is to be used, then we will obviously get only 75 % of our calculated flight time. This will be our min. actual flight time. It can be more than this but not less, since we calculated this value based on the ‘Max.’ current from motor.

Detailed Example for Battery Selection

The document below is a short example designed to get you more clarity on the theory part. Do go through the document once you have gone through the article completely. Keep both, this article and the example, side-by-side, and then learn and analyze how it’s done.

RC-Airplane-Series-5-Example

RC Airplane Series – All Articles  (You are at Part – 5 !)

Conclusion

From this article, we got to learn about the procedure to select the correct LiPo battery for our project. In the next upcoming articles, we will cover the ESC calculations and also learn about the thrust test. Till then, Enjoy Learning !!

All the Best !!

How to Select Motor & Propeller for RC Aircraft? – Part 4

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RC Airplane Series – Part 4

Now, we enter into the electronics side of the RC Airplane. In this article, we discuss ‘How shall we exactly choose a motor for our RC Airplane ?’. This is one of the very crucial steps because your electric motor and propeller combination in RC Airplane does the work similar to the fan engines in real RC aircraft. This motor + propeller combination is responsible for providing the necessary ‘thrust’ required.

RC Airplane
Table Of Contents
  1. Just to clarify!
  2. 1. Electronic Components for RC Airplane
  3. 2. Deciding the Type of Flight
  4. 3. Choosing the motor
  5. 4. Choosing Appropriate Propeller:
  6. 5. Example:

Just to clarify!

I am sure you will have a question that, if, in the last article, I asked you to refer to a plan from online sources, then why not copy their electronic components as well? 

There’s a problem with that!

Many students/hobbyists aim to participate in various aeromodelling competitions. And when there’s a competition, there are some rules/constraints that we need to follow. Basically, this is where it’s important to know exactly how to model the aircraft (design part + electronics part). Otherwise, if there were no rules, there would be so many resources about ‘How to make an RC airplane?’ So, everyone would copy them.

And apart from this, the joy and the interest which u generate in the field of aeromodelling once you try to understand these concepts is unmatchable.

1. Electronic Components for RC Airplane

  • Motor + Propeller combination
  • ESC (Electronic Speed Controller)
  • Battery
  • Servo motors
  • Receiver
  • Connectors

Here, we are just naming the electronics needed to drive an RC plane. We cover the motor and propeller selection in this post. In the upcoming articles, we start discussing each one in detail. We are going to keep everything to the point, but discuss the important and necessary things in detail.

2. Deciding the Type of Flight

In order to select a motor, we need to first decide the type of flying we need from our plane. 

And based on that, we have a term called ‘Thrust-to-weight’ ratio, also known as ‘TWR’ or ‘T/W’. Based on the type of flying we choose, we need to fix our TWR accordingly. To elaborate,

TWR=ThrustWeight of RC AirplaneTWR = \frac{\text{Thrust}}{\text{Weight of RC Airplane}}

Based on the TWR value, we can categorize flying into 2 types:

  • Controlled and Slow flying (T/W<1)
  • Fast and Aerobatic Flying (T/W>1)
The flowchart explains the 2 types of flying
  • So, the first step for motor selection will be to fix the TWR for your plane.

3. Choosing the motor

We need to follow a specific procedure in order to get therequired motor. Refer to the following flowchart for that :

Step-wise procedure to choose the correct motor for the RC Airplane

Step-1:

In the previous article, we learnt to calculate the ‘model weight’ (i.e., only the design part). Now, we need to first assume the electronic components and calculate the ready-to-fly weight. It means that the plane is fully ready (design + electronics) to fly, and the weight of the plane is then called here as ‘ready-to-fly‘ weight. 

The total weight is the sum of the model weight and the weight of the electronic components. The figure shows the various electronic components like battery, ESC, motor, and servo

Assuming electronic components:

  • Most of the components (motors, ESC, battery, etc) have their weight within a fixed range. And note that, you DON’T have to be very specific and exact for this. We need an approximate weight of the aircraft. 
  • Refer to the product’s website and check the specification section to get the weight
  • This part will become clearer once you have the knowledge of all the components used in an RC plane. I have attached a file below as an example to demonstrate the whole process.

Note: If you are using landing gears for your plane instead of a hand takeoff, you need to include that weight as well.

Step-2:

From the previous section, we have fixed our TWR. Use this value to calculate the thrust. This will be the thrust required to achieve the required TWR for the aircraft.

Step-3:

It is advised to use BLDC (Brushless DC motors) due to : 

  •  High Efficiency
  • Longer Life span
  • Better speed control
  • Prevents overheating
1000 kV BLDC motor

Q. What is meant by the RPM of the motor?

The number of revolutions (one complete circle) that the motor rotates in one minute of time is known as the RRM of the motor. RPM stands for Revolutions per minute. For e.g. 2500 RPM implies the motor rotates 2500 times in one minute. So basically, RPM is the unit of ‘angular velocity.‘ 

Q. What is the kV of the motor?

kV rating of a motor gives the idea of: At what RPM will the motor run when a certain voltage is applied. For e.g. If we have a motor of 1000kV and let’s say the safe operating voltage range is 5V-12V. So if I am operating the motor at 5V, the motor will run at 5000 RPM, while if I operate it at 12V, it will run at 12000 RPM. 

Based on this, we can formulate the kV rating as:

motor kV=Motor RPMNominal Voltagemotor\ kV = \frac{\text{Motor RPM}}{\text{Nominal Voltage}}

How to choose the kV of the motor?

Recall the type of flying that you chose earlier. Generally, for controlled and slow flying, we choose a low kV BLDC motor, which has a range up to 1500 kV, while on the other hand, for Fast and Aerobatic Flying, we choose a high kV BLDC motor that has a range greater than 1700 kV

The flowchart explains which BLDC motor is appropriate based on the type of flying

Now, once the motor kV is fixed, go to the online electronic stores’ website and search for the motors of the calculated kV that are able to provide the required thrust. A thrust value greater than required is OK!

(Look through the specifications/description section of the product’s page for thrust value)

Step-4:

The propeller is another very important factor to consider since this fan-like thing is the most responsible for generating the thrust required for our airplane. Check the datasheet or the recommended propeller size for the selected motor.

4. Choosing Appropriate Propeller:

Working Principle of a Propeller:

The propeller basically ‘pushes’ the air backwards so that the reaction force acts on the propeller, making it move in the forward direction. The working of a propeller is a simple application of Newton’s third law.

The propeller pushes the air backward, which in turn causes the airplane to move forward

Dimensions of Propeller

Diameter: The end-to-end length of the propeller. Mainly responsible for the rotary motion

Pitch: It is the distance covered by the propeller in the forward direction when one revolution is completed. Pitch is mostly responsible for the translatory motion of aircraft. Pitch is connected to the speed of the aircraft.

Notation : Example : 10×4.5 propeller implies diameter = 10 inches and pitch = 4.5 inches

How to select a Propeller?

Again, recall the type of flying chosen for your aircraft. Based on that, we need to fix the size of the propeller. 

propeller selection based on the type of flying

Consider the example below (PDF file) for better understanding. I have discussed a real problem statement, which is generally given in RC Airplane competitions. You can take a similar approach while selecting the motor and propeller for your application

5. Example:

A problem statement has been given (Like a competition), and based on the constraints, the procedure to select a motor has been given. Go through it thoroughly to get a complete understanding. (We are assuming that we chose some plan, and on calculating the model weight of the airplane, it came out to be 250 g.

example-for-motor-1-1

Enjoy Learning!

RC Airplane Series – All Articles  (You are at Part – 4 !)

How to Decide the Dimensions of an RC Airplane – Part 3

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For Best Experience, View on Desktop/Laptop

RC Airplane Series – Part 3

In this article, we are going to discuss about designing the plane and after which in the next article (RC Airplane Series – 4), we discuss how shall we exactly select a motor for our RC Airplane. There is proper procedure for motor selection and is one of the important step in RC airplane designing. 

Table Of Contents
  1. Designing the plane
  2. How to Apply the Theory?
  3. Conclusion

Designing the plane

This RC Airplane Series is going to be for ‘Beginners’ or for the ones who are not much experienced in this field but just want to know the basics of RC Airplane. Due to this reason, we avoid getting into the details of the analysis. The actual Analysis includes a lot more like: Aerofoil selection through XFLR software, ‘Ansys Fluent’ software for model analysis, etc. 

But for now, we keep it very simple

For beginners, a suggestion would be to use online available plans in order to develop your aircrafts. By readymade plans, I mean that , you can get information with figures about the dimensions of fuselage, rudder, elevator, horizontal stabilizer, vertical stabilizer and all…..

How to Apply the Theory?

Let’s take an example for now: 

I have considered this below shown plan as an example. You will get a lot of such similar plans online on various youtube channels and website. 

The one which I am using below is from the website :  https://www.rcpano.net/2020/01/28/fpv-airplane-making-rc-airplane/ . I have modified the plan a bit for simplicity ! And also this website does have a lot of more plans. Do check it out !!

DOWNLOAD

Design Plan example final
  • As shown in the above flowchart, after selecting a plan, we need to choose the material which we are going to use.

In this case, I decided to go with styrofoam and after which I searched for the density of styrofoam on the internet or you can also get it in the ‘specifications’ section from the website page using which you are going to buy it.

The density came out to be 60 g/L.

  • Then, We calculate the mass of the seperate component using the density formula.
  •  For this, first calculate the Area first. Area can be calculated by breaking the figure into simple geometric figures (rectangles, triangles, trapezium, etc) . Then, calculate volume and then calculate mass using density formula.

Conclusion

This was a very short article on the designing of RC Airplane. We will for sure discuss this topic again at an Advanced Level. But for now, for the Beginners stage, lets keep it simple and easy to understand !! After all that’s our main goal.

Enjoy Learning !

RC Airplane Series – All Articles  (You are at Part – 3 !)

How does GPS work? | Working Principle Explained

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In this specific article, we are going to learn about the working of GPS. In the upcoming articles, we will be dealing with the interfacing of the GPS module with the Arduino. I feel that it’s important to know the working of the module which we use in our project instead of just learning about ‘how to make the module throw its data values at us”

GPS stands for Global Positioning System and is mainly used to locate the exact location of the receiver with the help of data which it gives (out of which most important is Longitude and Latitude coordinates)

Table Of Contents
  1. How does GPS locate a position?
  2. How do We Exactly Determine 'd'?

How does GPS locate a position?

The working of the GPS module is based on the communication between the satellites and the GPS receiver module.  For locating the position of a place on earth, we need several parameters like Longitude and Latitude (2-D) and an extra Altitude (for 3-D)

To locate the position, in GPS, we have something known as Trilateration.

In Two-Dimensional Space: 

 we need a total of 2 satellites (say S1 and S2 here). We    are suppose located at point O and we need our location through GPS.

Handmade Diagram to explain 'Trilateration'
Handmade Diagram to explain ‘Trilateration’

                                                                                  

Fig. Determination of position in 2-D

Text version of the above flowchart

Step-1: The distance between the satellite and the GPS receiver (referred as O) is to be calculated. So we get that O is at a distance of d1 from S1.

Step 2: But still, O can be anywhere on the circle-1 with center S1 and radius as d1.

Step 3: Also, the same thing goes with S2, i.e., O can be anywhere on circle 2 as well.

This implies that, O is somewhere on the region common to circle-1 and circle-2. This means it lies in the points of intersection of circle      1  & 2 (here O and P).

To decide between O and P, we take into account the circle-3 which is the earth surface itself. All the 3 circles intersect at O (therefore, P is eliminated) and hence we obtain the position of a GPS receiver in 2-D.

In Three-Dimensional Space: 

We need a total of 3 satellites for locating position of GPS receiver

Here, we need to consider just the spheres instead of circle. 

For quick overview,

Text version of the above flowchart

Step 1: We get 2 spheres of radius d1 and d2. The intersection gives a circle (say C-1). So ‘O’ must lie on the C-1.

Step 2: Now, we have a third satellite, S3; it measures the distance from O as d3. This implies that O lies somewhere on the sphere (of radius d3).

Step 3: So O lies on C-1 as well as on the sphere of radius d3. This means O must be one of the two points of intersection between the sphere of radius d3 and the circle C-1.

Step 4: For the final answer, we take the fourth sphere – Earth itself. The intersection removes the ambiguity and gives the final point as ‘O’,
which is the actual location of the GPS receiver.

But, there exists a problem of time delay, since the satellites have accurate atomic clocks while the GPS receivers uses the clocks which are installed in mobile phones.

But since all the satellites use the same specifications for atomic clock, the ‘time offset’ is the same. Even error of microseconds can give an error in kilometers !! Hence we use fourth satellite (S4).

As we discussed earlier, that we need the distance ‘d’ for locating the positions of satellites. 

How do We Exactly Determine ‘d’?

The ‘radio signal’ which is sent, it carries 2 information:

  • Exact time when it was transmitted (t1)
  • Position of satellite

Now the receiver receives the signal at time t2 (say) :

d=(t1−t2)×cd = (t1 – t2)\times c

where c is the speed of light (3×108m/s)(3 \times 10^{8}\,\text{m/s})

What happens inside the GPS receiver

Components involved in GPS (based on the above flowchart):

Antenna: Receives the signal

Filter: It removes the extra signals that are not needed and only keeps the one that has the GPS-related information.

Decoder: Takes out the information from the signal

Output Display: Displays the position on the device

Keep Learning

Aircraft Control Surfaces | Working Principle Explained – Part 2

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RC Airplane Series – Part 2

In the previous part (RC Airplane Series -1), we learnt about the wings of the aircraft and the reason behind the generation of Lift for the airplane. Now that we have learnt to take the airplane into the air, it’s time to control the aircraft. So, in this part, we are going to learn how the control surfaces are used in order to control the aircraft properly.

Table Of Contents
  1. 1. Classification of Control Surfaces
  2. 2. Dimensions of Movements:
  3. 3. Ailerons:
  4. 4. Elevator:
  5. 5. Rudder:
  6. 6. Flaps:
  7. Conclusion:

1. Classification of Control Surfaces

For the controls part, we have them divided into two parts: Primary and Secondary Control Surfaces

  • Primary: Ailerons, Rudder, Elevator

           (These are the necessary ones! Like Air, Water, and Food for us)

  • Secondary: Flaps 

           (These are the extra ones that help in controlling the aircraft more precisely.) In the Secondary part, we do have some more surfaces, but for basic RC planes, Flaps are enough 

The figure shows the positions of the ailerons and the elevator
Fig. Position of Ailerons and Elevator
The figure shows the position of the rudder
Fig. Position of Rudder

2. Dimensions of Movements:

There are basically 3 axes about which the movement of the aircraft happens :

  • Longitudinal: It goes from the nose to the tail of the aircraft
  • Lateral: It goes from wingtip to wingtip and is perpendicular to the longitudinal axis
  • Vertical: It is mutually perpendicular to both the longitudinal and lateral axes
The figure shows the axes about which an aircraft can exhibit motion, namely, Longitudinal, vertical, and lateral axis

                                                                               Fig. Movements exhibited by an aircraft

  • Pitch: It is the rotational motion of the aircraft about the Lateral Axis (Nose – Up and Down)
  • Roll: Rotation about the longitudinal axis is Roll. During this, the aircraft tilts its wing up and down
  • Yaw: Rotation about the vertical axis is Yaw. Basically, moving right and left in the plane itself
The figure shows the pitch motion
Fig. Representation of Pitch Motion
The figure shows the yaw motion
Fig. Representation of Yaw Motion
The figure shows the roll motion
Fig. Representation of Roll Motion

3. Ailerons:

Ailerons are the control surfaces situated on the wings and are responsible for the ‘Roll’ motion of aircraft.

  • There are mainly 2 types of Ailerons (in Trainer Aircraft mostly): Strip Aileron and Normal Ailerons

Strip Ailerons are the ones that span over the entire half wing and have a width = 1/8 of the chord length

In normal ones, the length = 1/4 of wingspan and are situated towards the wingtip, and have a width = 1/4 of the chord length

Working of Ailerons:

For example, we need our airplane to roll to the right. For this to happen, the Right Wing should be lowered while the Left wing should be lifted (when viewed from the tail)

I will try to explain this in a very simple manner. Just remember that,

“Obstruction causes velocity to decrease.“

(This applies to all control surfaces.)

Right Aileron is raised up while Left Aileron is lowered down.
Fig. Right Aileron is raised up while Left Aileron is lowered down.

  • Now, we want to roll our aircraft towards right. So we control the Aileron with the help of a transmitter (in case of RC Airplane), a steering wheel in case of a real aircraft. 

On giving the signal, the right Aileron is raised while the left Aileron is lowered. For the moment, let’s focus on the Right Aileron. The control surface here has been moved up & now, and this causes Obstruction for the Air.

  • Because of this obstruction, the velocity of air in the upper part decreases, and hence Pressure in the upper part increases. (refer to RC Airplane Series- Part 1) And this causes the Right wing to go down and the left wing goes up, and as an overall effect, we get the Roll towards the right.

4. Elevator:

The elevator is connected to the horizontal stabilizer. The elevator is responsible for controlling the pitch of the Aircraft.

Working of Elevator:

Consider an example where we need to pitch up the plane (make the nose up !). In this case, when the signal is given, the elevator is deflected upwards. Now, again, the air flow in the upper region feels an obstruction, which lowers the velocity of air in the upper region. This causes the Pressure in the upper region to get bigger. 

This results in the ‘pressing‘ of the horizontal stabilizer downwards. Due to this, the nose of the aircraft (front part) rises up.

(Just consider a pencil and hold it somewhere.

Fig. Elevator is deflected upwards

  • The process is the same for all, whether it’s the aileron, elevator, or the rudder

Consider an example of a pencil. Its CG (center of gravity) is marked. So when we apply pressure on the back side (Fig P(a)), the front part (the part which is ahead of CG) rises (which we say here as ‘pitch up’) as it rotates about the lateral axis passing through CG (Fig P(b))

Pressure is applied at the back end of the pencil
Fig. P(a). Pressure is applied at the back end of the pencil
Result of the application of pressure (Nose Rises)
Fig. P(b). Result of the application of pressure (Nose Rises)

5. Rudder:

The rudder is attached to the Vertical stabilizer. It is responsible mainly for the Yaw motion of the aircraft. Basically, Yaw is like moving right and left in your plane itself!

Working of Rudder:

Consider that we need to shift to the left while being in the plane of the aircraft (i.e., just try to give the nose a different direction)

  • When the signal is given such that you want the nose of the airplane to move towards the left, then the rudder also deflects towards the left. Now the rudder acts as an obstruction to the airflow on that side. Hence, velocity decreased. Therefore, pressure increased. The higher pressure causes the front part to move to the left (in the geometric plane)
The figure shows how air flows over the Rudder
Fig. Rudder 

6. Flaps:

Flaps are the Secondary Control Surfaces, which help the pilot to have stronger control and stability over the airplane. Flaps are situated beside the Ailerons. Sometimes, the Ailerons themselves work as Flaps as well (in case of a single servo for each Aileron **). In this case, we call those control surfaces ‘Flaperons’ (Flaps + Ailerons)

You must have heard pilots saying “FLAPS ON!” or “FLAPS DOWN”. This tells that the Flaps are to be deflected downwards. 

Fig. Positioning of Flaps

We are very well aware of the Lift generated because of the Flaps getting deflected downwards. (Same as Ailerons getting deflected downwards) But there is an important factor to consider, which is ‘DRAG.’

DRAG:

There is lift, but there is also DRAG developed due to the downward deflection of flaps. Since, due to this, the contact between the airflow and the surface gets broken.

This Drag causes the wing speed to decrease

  • For Landing, we need the plane to be slow-moving since ofcourse it’s easier to handle a slow-moving car than a fast one. So the drag component takes care of reducing the speed of the aircraft, while on the other hand, we also have the Lift generated, which combinedly gives a slow and controlled descent.
  • From the takeoff point of view, we need Lift to be generated at lower speeds itself, and hence Flaps are essential in this case as well.

Note that: “FLAPS UP” implies the retracting of flaps to the original position (no deflection)

The amount of deflection can be controlled based on the need with the help of the control stick !!

Conclusion:

Through this article, we discussed the control of the Aircraft. Go through it slowly and try to visualize it by yourself. You will definitely get it. In this Series, we will keep going step by step and gradually make the whole basic RC Airplane model. I hope you enjoy this Series.

Keep Learning!

RC Airplane Series – All Articles  (You are at Part – 2 !)