Quadcopter Motors: Understanding The Driving Force of The Drones

Quadcopter motor
Jack Brown
Written by Jack Brown

Drones have become one of the most special possessions these days and more and more people are now spending their time adventuring in this new and exciting world. Flying a drone is indeed one of the best ways to spend your free time or enjoy your job to the max.

However, today we’re not going to discuss drones in general; we are going to focus our attention on a particular piece of the device. Today we’re going to talk about what makes a drone used in aerial photography drone (or a quadcopter) tick: the quadcopter motors.

The motor is positioned immediately under the propeller and controls its rotation and speed. So, for a quadcopter, you will receive 4 motors in the box. That is, if you buy a quadcopter kit or a quad that is not ready to fly out of the box. With complete models, motors are already attached and you don’t have to worry about selecting them.

In the case you are a tinker proper factors should be brought into consideration while choosing the motor for your quadcopter. If you’re interesting in finding more about these motors, continue reading. We searched for the most important details and laid them out for you.

How to choose the best motor for your quadcopter?

Where do you start? While looking for motors for your drone, the first step would be having an idea of the total weight of the copter. Approximate weight estimation can be done by considering all the components of the device. For instance, you could start with the frame of the device you are building.

This will give you an idea of how heavy the other parts should be. If you have a slightly bulky frame, you should opt for the lighter components. You also need to bring into consideration the weight of the prospective camera and gimbal you might be using. After making an estimate of the weight, you can then go ahead and plan on the other aspects of the motor.

Thrust to weight ratio

The one golden rule for choosing your motors – ideally, your drone should be able to hover in midair at about half throttle. This means that when you choose the apt motor for you drone, it should be able to produce 50% more thrust than the multirotor. Your quadcopter motor will have to remain stable and function well even in times of slightly windy conditions.

Disc type motors on the table

Let us give you an example: suppose you have a quadcopter frame with the total weight of components of around 800 grams. In this situation, the quadcopter motor should be efficient enough to produce a thrust of about 400 grams each, or a totally of 1.6 kg on the whole.

If you are considering mini quads, then agility will be the most important feature. For this, you would need motors with high thrust to weight ratios.

On the other hand, if you are keen on drone photography, you could make do with lower thrust to weight ratio since in this case, you would be flying much more gently. This gives you another advantage as well. Since it saves a lot of weight on the frame, you get the option of adding some other components on the drone, like a few extra batteries or a heavier camera.

Efficiency of the motor

Once we are clear about our stand on the thrust to weight ratio, it is now important to move on to the efficiency of the motor. Before we start, what is referred to as the efficiency of the motor? It is nothing but the ratio of the thrust produced to the power used.

The more efficient your motor is, the longer it is likely to fly. That means more the thrust produced by the motor as compared to the power utilized the smoother and longer will be your flight.

Efficiency of the quad motor

Ideally, a motor with an efficiency of 7 or higher might be a good idea. However, there are certain large motors that work with an efficiency of 18! This is especially useful for copters that are used for aerial photography.

On the other hand, if you choose to make your drone do a few acrobatic turns in the air and have agile movements, you might want to opt for a motor with higher RPM. In this case, the efficiency will be slightly reduced.  In nutshell, it entirely depends on your mode of use.

Motor movements

The movement of drones like quadcopters involves the movement of two motors in a clockwise direction while two others move in an anti-clockwise direction. This ensures higher stability of the motors and effectiveness of the device. You might wonder what it might be to purchase motors that move in the same directions.

Drone Motor Movements

As a matter of fact, it is entirely possible to attach 4 motors to your quadcopter, all moving clockwise or anticlockwise. But this would make it rather hard to fly the object. So, for smoother flight characteristics, you need to buy a pair of motors that move clockwise and another pair that moves anticlockwise.

Pole count

Next up is the pole count of the motor. You might have two options in this regard. One, quadcopter motors with a higher pole count. These will require more voltage during its flight, but produce a greater torque. But with these conditions come the lower RPM of the motors. Ideally, it is best to use larger blades with these motor devices.

Diy Drone

On the other hand, you could choose a motor with a lower pole count for achieving a higher RPM. But these devices will then require smaller blades, coming with a smaller torque or lift off the ground. More often than not, quadcopters are seen using motors with higher pole counts in order to eliminate the necessity of a gearbox.

Kv value

The next big question at hand is the Kv value of the motor or the RPM/volts. As we understand from the previous point, the higher the pole count, the lower will be the Kv value. By Kv, we basically refer to a constant that gives us the RPM of the motor, when a potential difference of 1 volt is applied across the motor.

Kv value of quad motor

For instance, a motor with a Kv value of 1000 will refer to 1000 RPM in 1 volt. If the motor is a 12 Volt one, then it is likely to rotate at a speed of 1200 RPM at a voltage of 12 V. When the Kv value decreases, there is an immediate increase in the torque produced by the motor.

This would mean higher acceleration and a more powerful lift. This would indicate that you could include a few heavy equipment including of camera and the likes on the frame and it will give you a good enough lift.

For such high Kv values, you would need smaller propellers, ones that can guarantee you greater speeds, but lower efficiency.

Propeller – motor combination

It is often a common belief that one should choose the propellers first and then go about choosing the motors that work well with them. If you opt for larger propellers, you would be generating more thrust, higher acceleration and more stable flights.

Propeller- motor combination

On the other hand, the shorter propellers come packed with greater speeds and are an excellent choice for mini quads and quad racing where agility is important along with some acrobatic moves. For the first case, you would ideally have to choose propellers around 12 inches in size. These boards will then be able to carry heavy camera equipment and are best suited for aerial photography.

For more acrobatic drones, you would need propellers of about 8 inches or lower. While choosing your propellers that go best with your quadcopter motor, you need to keep in mind two important factors:

  • Diameter: Propellers with larger diameters produce more thrust and thus can alter the thrust to weight ratio of your motor. Just the opposite happens with smaller diameter propellers which generate less thrust.
  • Pitch: The other aspect essential to be kept in mind while choosing a motor based on the propellers is the pitch. This is defined as the distance covered in one rotation of the propeller. The lower the pitch, the higher is the thrust generated. This also means that the flights will be free from turbulence; the motors will be able to carry heavier weights and also have long flight times. Since your drones are mostly intended for hovering in midair, lower pitch propellers will work well with your motors. However, for mini drones with acrobatic movements, you would have to resort to larger pitch propellers.

Types of motors used in quadcopters

Quadcopters generally consume a lot of power, owing to their usage which generally accounts to aerial photography. The motors used in this case are 3 phase brushless DC outrunner motors. These are in use especially because of the performance they deliver. There are two varieties of these motors available in the market: disc and barrel.

Disc type motors

These high power motors are shaped essentially in the form of a disc. More often than not, these motors turn out to be pretty light and thus generate a higher torque during flight. This can also be attributed to the higher number of windings present.

Disc type motors on quadcopter

These also have a higher pole count and thus lower Kv value. This leads to the requirement of larger propellers. Thus, the disc type of motors gives you longer and stable flights with minimal turbulence and noise.

Barrel type motors

These motors work with an action just opposite to that of the disc type. These come in the shape of a barrel, are heavier in structure and generate a lot less torque as compared to its counterpart. These motors, as understood, come with lower pole counts and thus higher Kv value. These lead to agile movements, but the flights are not as stable as the disc type of motors.

But disc quadcopter motors are not so much in use. This can be explained by their high costs.  Add to that, the fact that a quadcopter requires about 4 of these motors to run smoothly. That is why, not too many people invest in the disc type. People who are strong enthusiasts or have taken up aerial photography and videography as a profession or passion tend to go for the disc type of motors.

Barrel type motors

Cutting it short and making the process of selection of drone motors easier for you, hereunder, we are going to present to you some of the drone motors that have been most popular amongst the users.

Best drone motors available in the market today

Parrot AR Drone 2.0 Motor

This motor is specific to Parrot drones but this is one of the most useful devices you will come across. For starters, let us consider the speed of the motor. It comes with a value of 28,000 RPM which is pretty impressive.

This 15 Watt motor has turned out to be an instant hit amongst the users. This kit also comes packed with the flight controller and some metal screws to give you a complete package.

Parrot AR Drone 2.0 Motor

The motor is attached with the electronic controller for facilitating smoother installation processes. With a sleek and compact design, there will be no issues attaching the device on to the copter frame board. That is why it doesn’t take much time to finish off the installations of these drone devices.

Like this great product? Then you can buy it from Amazon.

Emax Mt2213 935kv 2212 Brushless Motor

Talking about brushless motors for quadcopters, here is another product that might interest you. This is a set of four motors with a diameter of about 27.9 mm. When we talk about the thrust, this set is capable of providing a value of 850 grams per volt. Installing these motors is also a pretty simple and easy job.

Emax Mt2213 935kv 2212 Brushless Motor

All you have to do is connect them on to the frame board, check their rotation movements since two motors run in a clockwise direction while two others run in an anticlockwise way. In the case that one motor runs in the wrong direction, you need to flip just two of the three wires and your work is done!

With a decent speed and powerful torque, these motors tend to be quiet and useful, being able to survive a few minor crashes.

If you interested in this product you can check its price on Amazon.

Coolplay® Syma X5 X5C X5C-1 Motor

This is yet another set of useful motors coming packed with a pair capable of moving in the clockwise direction and another pair moving in the anti-clockwise direction. This set is made from plastic gear, giving it the necessary lightweight structure that seems to last long and generate a stable performance.

Coolplay® Syma X5 X5C X5C-1 Motor

The size of these motors is 7 mm x 20 mm and they have a good fit on most copter kit boards. Since the wires are color coded, it is easier to assemble them onto the board.

If you interested in this product you can buy it from Amazon.

HOBBYTIGER 2 Pairs Main Motor Metal for RC Quadcopter Drone

The next one on our list of the most popular drone motors comes from the house of Hobbytiger. These are made with high quality materials with efficient workmanship. These are thus some of the most durable motors that are lightweight in structure and they do not get damaged very easily.

HOBBYTIGER 2 Pairs Main Motor Metal for RC Quadcopter Drone

Available at very reasonable costs, these are thus very easy to purchase and replace on your quad copter board. With colored wires, it is now easier to attach these on to the quadcopter. With stable flight characteristics, these might just be the ideal motors for your drone!

If you interested in this product you can purchase it on Amazon.

Mudder 4 Piece Anti-clockwise and Clockwise Motor

Next up is another set of four motors for drones. As it can be understood, from the whole set, two work in a clockwise direction while two others work in an anticlockwise direction. The motors are made from high quality materials and are designed in a way to reduce the heat generation that will lead to better efficiency of the motors.

Besides, you will also get higher flight times with these devices.

The brass gear makes the motors extremely durable and thus leads to very stable flights. These also come with a very compact design such that the motors can easily fit onto the drone framework. With a diameter of about 7 mm, these will not take up too much space on the quad copter board.

Mudder 4 Piece Anti-clockwise and Clockwise Motor

Each of the four motors is color coded in a certain way that makes installations a lot more convenient. You do not even need to solder the wires since you can just splice them together. There might be some noise because of the metal gear working on the plastic gears, but that is not very prominent.

Like this amazing product? Then you can buy it here.

In conclusion

Choosing the best motor for your drone is not one of the easiest things to do. There are a number of considerations to be made. Also, there are some compromises to be made as well. For instance, it is difficult getting a motor that gives you the swiftest and most agile acrobatic moves while also promising you flight stability and performance.

A higher Kv value in motors gives you higher speeds, but compromises on efficiency. On the other hand, a larger Kv vale motor will make better use of power and give you slower and stable flights. That is why you need to be clear of your purpose of using the drone and choose the motor accordingly.

You’re still confused or in a dilemma? Write to us in comments and we’ll surely help you settle it!

About the author
Jack Brown
Jack Brown

Jack is the Chief Pilot at MyDroneLab.com bringing experience, expertise and knowledge in this quite new industry. He is a graduate of the Drone/UAV Pilot Training Certificate program and member of the Association for Unmanned Vehicle Systems International. Besides having all the necessary technical knowledge when it comes to drones, Jack and his team love to spend the time outside by the ocean, working on new features and teaching others how to pilot these amazing and exciting new robots.

  • Andrew Miller

    Very interesting article, thanks, Jack. Reminds me of my physics course in school. Such methods can be used for attracting kids into science.

  • Thanks for the appreciation Andrew. Definitely!

  • John Whitehouse

    Thank you for this very informative article. I definitely agree that when choosing a motor you should consider its weight and efficiency ratio. A poor motor choice will most definitely lead to poor quadcopter.

    • Thank you for sharing your thoughts with us John.

  • Mike Walker

    The Parrot AR Drone 2.0 Motor is the best on the list in my opinion. Well made, well packaged, and perfectly functional. Priced most modestly. Installation was straight ahead ten minutes procedure. The motor performs well.

    • Jack Brown

      Thank you for sharing your experience with our readers Mike, we appreciate it!

  • Howie McTrevor

    What’s good about the brushless DC motors is that they have a very high power density so it minimizes the weight. They spin very fast but have lesser risks of overheating. They are easy to maneuver because the speed adjusts quickly.

  • Jack Brown

    Yup, the brushless motors are the only way to go if you want a serious drone 😉

  • Pauline Smith

    I admire the Emax Mt2213 935kv 2212 Brushless Motor for its amazing power. It lifts my S500 quad successfully, and my quad can hover around ½ throttle. This motor set comes with 4 CV prop threads. I wish I had purchased another set of two motors that comes with CCW prop threads and the other set of 2 motors with CW prop threads. Nonetheless, there is no major problem with this set. Just monitor the prop nuts frequently to check if they do not fall mid-flight.

    • Jack Brown

      Thank you so much for sharing your experience with these motors! It means a lot to us and our readers!