Quadcopter 101:Theory to Practical

Introduction: Quadcopter 101:Theory to Practical

Greetings fellow Instructables Readers,Makers,Geeks,Hobbyists,Electronics Enthusiasts and Beginners;

If you have a curiosity and enthusiasm to get your 'creation' up in the air or have a thirst for knowledge about Quadcopters: What Are These Things? How Do They Work? How Can I Make One?, then you have come to the right place.

This Instructable Will Have 3 Parts To It:

  1. The Theory

    > What is A quadcopter?

    > How Does a Quadcopter Work?

  2. Being Practical !

    > How Can I Make a Quadcopter?

    > Troubleshooting

    > First Flight !

  3. Extra Help and Modifications

Why make a Quadcopter When You Can Just Buy One?

Agreed, that it is easier, cheaper and probably better to just waltz into your favorite online store and 'Add to Cart' but, a great man once said; "What I Cannot Create, I Do Not Understand". That great man was Richard Feynman.

Note: Though I have tried my best to cover everything, Quadcopters, Multirotors in general, is a vast field and there are some specific things which I might have missed out on, that are just beyond the scope of this instructable

Step 1: Safety Is No.1 Priority!

"The evil that is in the world almost always comes of ignorance, and good intentions may do as much harm as malevolence if they lack understanding."

Keeping That In Mind;

“The true method of knowledge is experiment.” — William Blake

Not to Intimidate you or scare you in any way, but before we get into quadcopters and things that fly, you should be aware about the various consequences and mishaps that could happen if you dont follow the proper procedures.

Some Basic Things To Keep In Mind Are:

  • Always make sure that it is legal to fly a quadcopter in the area that you live in.{For Example: It is not legal to fly a 'personal'/'hommeade'-Drone/Quadcopter/Unmanned Aerial Vehicle}
  • Keep your Quadcopter in your direct Line Of Sight (LOS). while flying it, since you dont want it bumping into a human with its razor sharp propellors spinning at 10000+ RPM :p
  • Do not fly over 400 feet above the ground and avoid manned aircraft.
  • Do Not Fly your Quadcopter within 5 miles of an Airport.

  • Don't do anything that might cause people to think you are intruding on their privacy.

  • Always REMOVE the propellors when the quadcopter is hooked up to a computer while the battery is plugged in or BAD things will Happen!

If you are a complete beginner, contact someone who can help you out and under whose supervision you can work.If for any reason you cant find such a person with knowledge in te specific field, feel free to contact me:



Step 2: The Theory

What Is A Quadcopter ?

It is an unmanned helicopter having four motors, each fixed with a propellor.

Quadcopters are also called multirotors, due to them having 4 or more small rotors instead of one like the traditional helicopter. Some models have more than 4 rotors and are called multirotors. As a general rule, the more rotors a drone has, the stronger and more stable it becomes.

How does a Quadcopter Work?

Basically, the quadcopter moves by the action of YAW,ROLL and PITCH.

A quad copter can control it’s roll and pitch rotation by speeding up two motors on one side and slowing down the other two. So for example if the quad copter wanted to roll left it would speed up motors on the right side of the frame and slow down the two on the left. Similarly if it wants to rotate forward it speeds up the back two motors and slows down the front two.

The copter turns (aka “yaw”) left or right by speeding up two motors that are diagonally across from each other, and slowing down the other two. Horizontal motion is accomplished by temporarily speeding up/slowing down some motors so that the vehicle is leaning in the direction of desired travel and increasing the overall thrust of all motors so the vehicle shoots forward. Generally the more the vehicle leans, the faster it travels. Altitude is controlled by speeding up or slowing down all motors at the same time.

Checkout The Video For an Even More Better Explanation On How Quadcopters Fly!

For those on the Instructables Mobile App, you can view the video HERE

Step 3: Being Practical: Making a Quadcopter

Before we jump into making a quadcopter, you need to decide on what purpose your multirotor is going to serve.These can be:

  • General Flying/Getting Started {Recommended For Beginners}
  • Racing Quadcopter {For amatuers who want to try out their skills at the drone grand prix}
  • Aerial Photoggraphy/Surveillance {Those of You Who Want to Take Beautiful panaromic/cinematic shts of Nature and its mesmerix=zig beauty}
  • FPV-First Person View{Basically, flying by seeing the live feed from your multirotor throgh a lcd screen/ FPV goggles}
  • Heavy Weight Lifting/Transportation{To transport a small packages to your friends, like your own mini 'PRIME air' service!)

In this instructables, I wil be helping you make a quadcopter for general flying since it is fun to fly, easy to make and also doesn't take away your whole year's allowance :p

To buy all the materials, You can use websites (these ship worldwide) such as:

For those Living In India:

The Most Basic Materials Required To Build A Quadcopter Are:

  • Frame{Either a Kit, a Prebuilt or Custom}
  • 4* Brushless Motors
  • 4*ESC's
  • 4*Propellors
  • 1*Power Distribution Board{PDB} [Many Frames either come with one or have an integerated PDB]
  • 1*Flight Controller


  • Heat Shrink Tubing-Various Sizes
  • Cable Ties/Nylon Ties/Zipties
  • Small Nuts n Bolts

Some Basic Tools Are Also Required:

  • Soldering Iron and Solder
  • Wire Cutter/Stripper
  • Pliers>Normal and Nose Pliers
  • Tape
  • Screw Driver

Step 4: Being Practical:Choosing the RIGHT Materials


One of the most important part of multirotor is its frame because it supports motors and other electronics and prevents them from vibrations. You can either make one yourself or buy a premade kit.I prefer the premade frame Kits since the holes for everything are drilled precisely and everything lines up correctly.

FC(Flight Controller)

There are many FCs out now in the RC world. Some of them are KK, MultiWii, Ardupilot, Naza, Naze, Rabbit, WKM and many other. Advanced FCs have more features and advanced sensors like gyro, accelerometer, sonar, GPS, Magnetometer.For my quadcopter, i am using the CC3D Flight Controller.


One of the important part of multirotor is its motor. It's a part of power system. Infact whole power system depends on selection of motor so you should be very careful while selecting motor. Brushless motors are the common choice for multirotors.There are certain specifications which you need to llok out for in order to chose one that will work for your application.


Max current(A)

Shaft dia




Suggested prop

For multirotor application 600-1200kV motors are good. Below 600kV even better. Low kV means you can swing big prop. Big prop means it can move more air and you will get more thrust.

kV = RPM/V

If you have 600kV motor and 3S battery to supply power, RPM of of motor at NO LOAD would be

600 x 11.1(3S battery) = 6660 RPM.

Max current rating is another important factor while selecting motor. Selection of ESC and battery depends on this value

Now we are coming to the thrust. In most cases you will see value of the thrust motor can produce with suggested prop on the website. If you remember we learned that to lift 1000 grams quadcopter we need total 2000grams of thrust. And quadcopter has 4 motors, so each motor should be able to produce at least 500grams of thrust to satisfy our need.

4 motors x 500grams thrust = 2000grams thrust.

One more thing is Watt.

Watt = V(Voltage) x I (Ampere)

More Watt more power so you should also consider that while selecting motor.

But when it comes to selecting motor you will notice that there are many options available for motor selection and it's really confusing, so which motor is best for multirotor application? Well you should consider few more things other than specifications. Some of them are

Motor Mount: Well motor mount is one more important factor you should keep in mind while selecting motor for your multirotor. Motor mount comes under tensile force especially when you are swinging big prop and if motor is not fitted properly it might come off during flight and i am sure nobody wants to see such things happen. So make sure that motor you are purchasing has good mount that can hold motor properly under heavy load and same way you can fit that mount easily on the frame.If you are buying a frame kit, then theres a good chance that the motor mounts will be built right into it.


Specifications of prop are easy to understand and they are dialmeter and pitch.Generally we see prop with the specification of

9x5 {0905}

10x3.8 {103.8}

10x4.5 {1045}

First value is diameter of prop and second value is pitch. Both are in inches.

Diameter: Virtual circle that prop generates.

Pitch: Amount of travel per revolution.

As we see above our motor runs at 6660 RPM at NO LOAD. But when you mount prop on it, RPM will be reduced. Here we will take example of two props 10x3.8 and 10x6. When you mount 10 inch diameter prop RPM of motor will be reduced to 3600 RPM (Revolutions Per Minute).

60 Revolutions Per Second.

Our 1st prop has 3.8 inch pitch. Means per revolution it will travel 3.8inch. So

60 x 3.8 = 228 Inch/Sec = 5.7 m/sec

For 2nd prop, it has 6 inch pitch.

60 x 6 = 360 Inch/Sec = 9.1 m/sec

So we can say if we have 10x3.8 prop our quad will climb in the air at 5.7 m/sec, while with 10x6 prop climb rate will be incread to 9.1 m/sec.

Bigger dia prop can produce more thrust.

So which prop is best for our multirotor?

Generally you will get suggested prop value in motor specification, so you should go with it and buy 1-2 pair extra. But what if prop value is not given. You will see kind of table with different props, Volts, Amp, Thrust and Efficiency. Here you will have to try trial and error method. But it doesn't mean you swing 13x3.8 prop on 1700kV motor.

Lower kV motor can deal with bigger prop. With increasing kV value size of prop will be decreased. So you will have to keep this in mind. For multirotor you should go with low pitch prop if you need more stability and less vibrations.

ESC(Electronic Speed Controller)

ESC supplies power from battery but not constant, it varies according to input signal. ESC also has BEC(Battery Eliminated Circuit). BEC is nothing but 5V output from ESC that can power up receiver, servomotor(for camera gimbal) and FC. You only need to keep in mind that Ampere rating of ESC should be higher than max amp rating of motor. For example the motor we selected draws maximum 15Amp so your ESC rating should be higher than 15amp. Say 18-20Amp.Here is simple forumla:

ESC = 1.2-1.5 x max amp rating of motor

1.2-1.5 x 15 = 18-22.5A

For My Quadcopter, Here Is the List Of Parts That I Used:

  • 4*1000kv Motors(generic)
  • 1* CC3d Flight Controller
  • 1*Q450 Frame(450mm)
  • 4*30amp DYS ESC's
  • 4*1045 Propellors
  • 1*2200mAh 20C 3S LiPo Battery(generic)
  • 1* Fly Sky FS-IA6 Transmitter/Receiver (6Ch)

Step 5: Being Practical:The Actual Build

Unfortunately, I will not be able to go into how to build an actual quadcopter since there are plenty of tutorials on the internet for just doing that. Watching these will help you understand the actual process a lot better than just the text. Here are some great ones I scavenged out while building my own quadcopter:

Step 6: The Final Product

After reading this Instructable, I hope that you have learnt something new and have been able to use that knowledge to make your own quadcopter.

Now, even if you have followed all the steps and built a quadcopter, you still might encounter some problems. If No, then that’s great. Happy Flying! Or maybe your quadcopter beeps but is not flying. In that case, I recommend that you do not get disheartened and rather look for the source of the error.

When I first made a quadcopter, everything was working properly, the motors were spinning, buzzers were beeping, but it was not flying. I got really upset but then I carefully observed it and found out that one of the motors was spinning in the wrong direction! Yes I know what you are thinking, such a silly error, yet a drastic effect!

If you still face any problems which don’t seem to go away, feel free to ask me by dropping a comment here and I will reply to it as soon as possible. Alternately, you can also contact me through my mail: hrithikbansal70@gmail.com

If you like what I am doing, you might be interested in other projects I have built. Check them out: www.hrithikbansal.com

Note: Some of the pictures used have been obtained from the internet. The owner can contact me if they feel that their content should not be displayed here. I do not intend to infringe/plagiarize anybody else’s property.

Thank You!

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