Choosing the best quadcopter motors is critical if you are serious about performance. Without the right motors, nothing else will matter much. Your drone will simply not perform as it should. You might try options like rewiring, using a different set of blades, replacing the flight controller board or maybe even tinker with the frame.
If your motor selection for your quadcopter is not right, your multicopter will not perform well. Motors have a huge impact on how the craft performs – perhaps a lot more than any other part or accessory.
Another reason why you will want to be careful in selecting the right motors for your quad is the cost. Motors can be pretty expensive – especially the brushless ones. Some of the specifications listed may sound complex – but don’t worry. This page will explain all of the complex sounding stuff and make the task of choosing the right motors that fit your budget easy and fun!
These Are The Best Quadcopter Motors
Parrot AR Drone 2.0 Motor and Controller
Hobbypower A2212 1000kv Brushless Motor
4pcs EMAX RS2205 2300KV Brushless Motor
Here’s a list of features you would want to look for in motors for your quadcopter or multicopter …
The Ultimate Quadcopter Motors Buying Guide
Clockwise and Anticlockwise
It is best to choose motors that can rotate both clockwise and counter clockwise. Quadcopters have 4 motors – and for the highest stability, two of these rotate clockwise while the other two rotate counter clockwise. You can buy motors that are either clockwise or anti clockwise only, but that would make the craft a lot harder to fly.
Sure, there are algorithms that can take care of the resulting instability for you, but these models would be really hard to keep in the air if you are relatively inexperienced and choose to fly in the manual mode.
- How many poles?
You would need to have some understanding of what pole count of a motor is, but you would not want to fuss about this. While a motor’s pole count does make a difference, you do not have to worry too much about it because all of the intricacies are handled by the electronics.
A motor with a higher pole count requires more voltage and produces more torque – or lift. But it also will have a lower rpm or revolutions per minute. You will want to use larger blades with these motors.
A motor with a lower pole count has more rpm and requires less voltage, but the corresponding output torque – or lifting power – is also lower. The propeller blades also have to be correspondingly smaller as well. These motors will not be able to handle larger propellers.
Quadcopters generally use higher pole count motors – outrunners – so that they can avoid using a gearbox. High pole count motors output a high torque – and this means a gearbox will not be necessary to increase the torque.
- Kv value or RPM/volt
This is a critical number you would need to pay attention to. As the number of poles in a electric motor increases, it’s Kv value – or RPM/volt – drops.
You would want to note that Kv here does *not* mean kilo volt. Instead, it’s a constant that tells you the RPM of the motor when a potential difference of 1V is applied with no load whatsoever. The Kv value is critical when you want to calculate the load a motor will be able to carry.
Note : The notation is Kv and not kV. kV means kilo volt and is entirely different from Kv we are talking about here.
A motor with a 1000 Kv rating rotates at a speed of 1000 rpm when 1 volt is applied at no load. If it happens to be a 12V motor, then it will rotate at a speed of 12,000 rpm at 12 V under zero load.
Here’s another example : A 1000 Kv motor has a maximum rpm of 20,000 and is rated at 120 watt. The maximum voltage you will be able to apply to this motor will be 20000/1000 = 20 V. The amperes it draws will be 120/20 = 6 amps.
Another 4000 Kv motor has a maximum rpm of 40,000 and is rated at 120 watt. The maximum voltage you can apply will be 40000/4000 = 10 V. At maximum load, the maximum current this motor can draw will be = 120/10 = 12 amps.
Another 4000 Kv motor has a maximum rpm of 40,000 and is rated at 120 watt. The maximum voltage you can apply will be 40000/4000 = 10 V. At maximum load, the maximum current this motor can draw will be = 120/10 = 12 amps.
How does Kv value matter?
With a drop in Kv value, the torque produced by the motor increases. More torque means more acceleration, and more lifting power. Conversely, motors with higher Kv value produce less torque.
For motors with higher Kv value, you will have to choose smaller propellers. With smaller propellers, you can achieve higher speeds, but efficiency will be lower.
On the other hand, motors with lower Kv value can handle larger propellers that can lift more weight, use less electrical current, are more stable – but have lower speeds.
If all of this sounds a bit confusing, this is what you will want to remember :
A higher pole count motor will have lower Kv value, can output more power and has less rpm.
More power = larger propellers, more lift, higher acceleration.
A lower pole count motor will have higher Kv value, outputs less power, but has more rpm.
Less power = smaller propellers, less lift and less acceleration, but higher speeds (because the RPM – revolutions per minute – is higher)
What pole count works best in your case? To answer that, you will have to do quite a bit of testing and see what works in your case. You would want to check out this article on how to test quadcopter motors.
Some people believe that a powerful engine has less torque, and while this is not entirely true, it is not entirely wrong. If the power is constant (e.g. using the same battery), the maximum current is limited, so it can be assumed that a motor with low RMS power can develop more torque. However, if the power is infinite, the motor KV has little relationship to torque until you reach the current limit of the motor and controller and burns out.
Torque is a double edged weapon.
A high torque motor provides faster shifting speeds, faster response and movements, less propeller wash and quicker response. A high-torque engine is also sharper and more robotic, while a low-torque engine is generally smoother and gentler. The choice depends on your flying style and personal preference, and high torque is not always better.
Power to Weight Ratio
You want to use a motor with a very good power to weight ratio. A motor with a power to weight ratio of 1 will be able to lift just its own weight – useless to be used for pretty much anything. On the other hand, a motor with a power to weight ratio of 5 will be able to lift five times its own weight.
In general, you will want to use powerful but light motors.
Before you buy the motors, it will be essential that you calculate the lifting capacity of your drone. And you should choose the motors such that the quadcopter and the payload hovers at around 50% throttle.
You should not choose motors that need to run at full power just to hover with the payload. That would mean the motors are getting pushed beyond their capacity and they most certainly will not last as long as they otherwise could. And that would also mean shorter flight times and less than satisfactory performance.
But you know what, doing those calculations is certainly not a walk in the park. More so if you are just starting out and do not yet have a sound understanding of all the factors that influence the performance of a quadcopter – and there are a lot many factors that need to be accounted for.
Factors like the frame size, atmospheric pressure and temperature, diameter of your propellers, resistance of the battery, motor, controller and many more. If you do not take into account all of the factors while designing your drone, you will end up with less than desirable flight times and lifting ability.
The dimensions of the parts to be used are indicated in that order. 1. Frame size 2. Propeller size 3.Engine size.
Once we know the size of the frame layer, we can estimate the size of the motor to be used. The frame size limits the size of the props. And each propeller size requires a different speed motor to provide efficient thrust, so this will affect the KV of the motor.
It must also be ensured that the motor is capable of generating sufficient torque to turn the selected propeller, and here the stator size is important. In general, larger stator size and higher RMS means higher current consumption.
Here’s one good way to understand how all of these influence your quad’c performance – play around with this excellent calculator and see what the key parameters will be at full throttle. Do this long enough and you will get an intuitive understanding of what your motor’s key parameters should be.
As a rule of thumb, if you are designing a drone for longer flight times, the thrust should be 2 times total weight. But for aerobatics, thrust should be 3 to 4 times weight.
For long flight times : thrust = 2 x weight
For aerobatics : thrust = 4 x weight
Thrust also depends on the propellers you use. Larger propellers generate more thrust. A 12″ propeller generates significantly more thrust than a 10″ propeller.
If are really serious about calculating values like motor efficiency and thrust, you will want to take a look at this piece of software.
Total weight and size of the frame
The total weight of the quadcopter should include all parts and hardware: Chassis, FC, ESC, motors, props, RX, antenna, LiPo, screws, screw connections, cooling system, VTX, ESC, GoPro, battery unit, wires and more.
It is better to overestimate the weight and get extra power than to underestimate the weight and have launch problems. It is also a good idea to add 10-20 grams to compensate for cables, buzzers, hinges, etc.
If you know the dimensions of the frame, you can determine the maximum allowable size of the mount.
Motor Type : Disc or Barrel?
Brushless motors – the kind that’s recommended for use with quadcopters if you are really serious about performance – come in two types.
- Disc : Shaped like a disc, is lighter and generates a higher torque as it has a higher number of windings.
- Barrel : Shaped like a barrel, is heavier and produces less torque.
But disc motors are also more expensive – which explains why they are not so commonly used.
In general, disc motors have more poles and lower Kv value. They can power larger propellers, consume less battery power, are more responsive, have reduced vibrations and noise – and are excellent for long, stable flights.
But disc motors can also be more expensive. Even small ones can cost $10 to $30 more than comparable sized barrel motors. And a quadcopter requires 4 such motors. Disc motors are really only for the professional hobbyists – like those who are into aerial photography or videography. These are generally not suited for folks just getting their feet wet and testing the waters.
An electronic speed controller (ESC) is required to control the brushless motor. Unlike a brushed motor, which has only two wires, an AC motor has three wires and can be connected to the controller in any order. If you change two of the three wires, you simply change the direction of rotation of the motor. In the ESC configuration, the direction of motor rotation can also be reversed.
Energy consumption of a brushless motor depends on the payload. The motors draw as much current from the batteries as their load.
Brushless motors can deliver more power than motors with the same size brushes because they are much more efficient and can handle these large loads electrically and mechanically.
They are essentially permanent magnet synchronous motors (PMSM). When they are driven by three-phase AC, they are called PMAC motors; when they are driven by switched three-phase DC, they are called BLDC motors.
In mobile applications like RC cars, we have to use them as BLDC because AC cannot be stored. DC can be stored in batteries. An electronic speed controller (ESC) must be used to convert a simple zero-phase DC to three-phase AC.
The durability of brushless motors is a lot higher than that of brushed motors. Moving parts are limited to the permanent magnet rotor and the bearings that support it. Brushed motors have lots of parts in contrast. Maintenance is also easier as a brushless motor contains fewer parts.
Propeller Motor Combination
This is perhaps the most important part of it all. Some people actually say you do not start by choosing the motors first and then suit it with a propeller – you do it the other way around. Choose the propellers you want to use, and then go about finding a motor that works well with it.
Larger propellers generate more thrust, have higher acceleration and result in stable slights. Shorter ones have a lot of speed and are great for acrobatics.
To start with, you would need to decide what exactly you are designing the quad for …
If you are into acrobatics, you will need small propellers – under 8 inches.
But if you are into something like aerial real estate photography, your quadcopter will carry much heavier payloads like a gimbal mounted FPV camera and so you will need much larger propellers – more than 12 inches.
It’s really, really hard to design a quadcopter that does great acrobatics and carries a heavy, gimbal mounted camera 🙂
There are essentially two numbers you will have to pay attention to when choosing propellers – diameter and pitch.
- Diameter : Larger diameter propellers generate more thrust, smaller diameter propellers generate less thrust.
- Pitch : This is the distance traveled for a single complete revolution. Lower the pitch, more the torque. Lower pitch propellers also have a lot less turbulence, can carry heavier loads and result in lower power consumption and longer flight times. On the other hand, higher pitch propellers are generally used mainly for acrobatics and racing.
Ideally, you would want the pitch to be less than 5. If you use propellers with too high a pitch, your drone will start wobbling a lot and unless you are an experienced pilot, you can have trouble even controlling it.
Quadcopters are mostly designed to hover – and to achieve that, you will need propellers with smaller pitch.
In practice, it’s very hard to find specifications for the vast majority of RC motors on the market. You will be hard pressed to find torque curves for a motor of your choice and work out the math. It rarely works that way in the “real world”.
Other motor performance factors
Many characteristics of quadcopter engines are not specified by the manufacturers and can only be determined by more precise engineering tests.
Torque is the force that turns the propeller and determines how fast the engine can increase and decrease speed. In other words, how easily the motor moves the rotors, propeller and especially the air masses.
Torque has a significant impact on the performance of the quadcopter, especially on its accuracy and responsiveness in flight. An engine with high torque responds faster by shifting gears faster. With higher torque, the deflection of the propeller can be less.
High torque also means you can use a heavier propeller (at the expense of more power). If a low torque motor drives a propeller that is too heavy for it (called an overloaded propeller), the motor cannot produce enough power to spin at the required speed, resulting in inefficiency and overheating.
One disadvantage of high-torque motors, however, is vibration. High torque motors change speeds so rapidly that they can amplify errors (in the PID loop) and cause vibrations that are difficult to eliminate even with PID adjustments, especially along the deflection axis.
Motor response times also depend on torque, with high-torque motors usually having shorter response times. A simple way to measure response time is the time it takes the engine to reach maximum speed 0.
Response time is highly dependent on the weight and pitch angle of the selected propeller. Remember that it is also affected by weather conditions. For example, at lower altitudes the air is denser, which means that the propeller has to move more air molecules to create thrust.
At higher altitudes, the propeller spins faster and responds faster to changes in gases, but the overall thrust is less because there are fewer air molecules acting on the propeller.
Temperature affects brushless motors because the magnetic field of the magnets used in our motors is weaker at high temperatures and demagnetizes faster as the motor heats up, which affects the life of the motor.
If the engine is run too long and the throttle is fully depressed, the engine can overheat. This reduces the efficiency of the engine and alternator over time. Engine design that promotes cooling is often synonymous with long life. Provided, of course, that you don't destroy it first.
Vibrations caused by the motor can have an unpleasant effect on the performance of the quadcopter.
If the engine is poorly balanced or poorly built, vibrations can occur that can affect the PID controller. Since the frequency of vibration can vary depending on the throttle position, this can make it very difficult to tune the quadcopter.
A vibrating motor also produces more electrical noise than a quiet running motor. This electrical noise can affect the gyroscopic sensors, further reducing flight performance, and can also affect the quality of FPV video if the FPV system is powered by the same battery as the engine and electrical bells.
Many people have successfully installed engines and flight controllers to reduce vibrations and have had good experiences.
Remember that damaged, bent and unbalanced propellers can also cause problematic vibrations.
Quadcopter Drone Motors - FAQs
How do I choose the right ESC for my brushless motor?
The ESC you choose depends on the KV rating of the motor. The ESC controls the RPM of the motor. It uses the signal received from the radio transmitter to control the servos which control the motors' RPM.
You will need to know the amperage (A) and the voltage (V) of the motor. Here's a thumb rule - choose a ESC whose amperage is at least thirty percent more than your motor's peak amperage rating.
For instance, if your motor's peak amperage rating is 30A, your ESC's peak amperage rating needs to be 40A. This will keep the ESC from over heating when peak current is being drawn. If the ESC overheats, it will shut down, and your drone will crash.
It should be able to handle the voltage required by the motor. If the motor operates at 14.8V and the ESC cannot handle more than 9V, the ESC will fail.
There are two types of ESCs - ones that comes with a Battery Eliminator Circuit, and ones that do not include a BEC.
The name BEC is a carry over from the nitro days where a separate battery would be needed to power all of the electronics, the receiver and to run the servos. So there would be two onboard batteries.
The BEC eliminates the need to have a separate battery for the onboard electronics - so your drone needs only one battery insteda of two.
The battery eliminator circuit is also sometimes called SBECs, UBECs, LBECs. These are some of the different types of BECs.
SBECs are switching BECs.
UBECs are Universal BECs.
LBECs are Linear BECs.
The vast majority of ESCs today have inbuilt BECs. ESCs step down the voltage from your battery so that the on-board electronics can be safely powered up and operated.
You would want to know the specifications of the BEC on the ESC, and the specifications of each of the electronic components on your drone - and whether the two are compatible with each other.
If the output voltage of the BEC is too low, that would mean your motors will not be able to run at the maximum speed it is capable of.
If the output voltage of the BEC is too high, you might end up burning the servos and the receiver.
On some ESCs, the output voltage is adjustable. So you will be able to adjust the output voltage to match the input voltage of other on board electronic components.
Standalone BECs are available as well. So these would sit separately and would not be on your ESC. These are used only in certain applications - typically when the current required is more as is in the case of relatively large RC quadcopter drones and planes that use much larger servo motors.
The output voltage on standalone BECs is usually adjustable.
A standalone BEC also insures that your drone does not crash in case the ESC fails.
Opto ESCs - or optoisolator ESCs - do not come with a ESC. You will need to use a standalone BEC when you use one of these.
If you choose to use a separate BEC with an ESC that already has a BEC, then you will need to disconnect the built in BEC on your ESC. Else you will end up increasing the output voltage - and this may damage a lot of your on board electronics including the servo motors and receiver.
Before you route the current to the rest of your on board electronics through the ESC, you would always want to check the output voltage and make sure it's not too high or too low.
There's one other thing you would want to keep in mind. Certain servo motors can pull a lot of current. These can end up overwhelming the BEC and the ESC may shut down momentarily. These are called brownouts.
During a brownout, you can lose control of your drone - and there's no output from the ESC to power up either the motors or the receiver.
You can reduce the chances of a brownout by using what are called 'glitch busters'. These are essentially capacitors that you can plug into any spare channel on your receiver. So when there's excess current being fed into the transmitter, the capacitor will keep the receiver from being shut down.
How do I choose a drone motor?
There are a few things you would want to pay attention to when choosing a motor. A good drone motor should have a high quality air suction system and a cooling system.
1. The size: If you take a look at a motor, you will see four digit numbers like 2204, 1806, 1306, 1105 and more. The first two digits tell you the diameter of the motor.
So a motor with 2204 on it is 22 mm in diameter, a motor with 1106 on it is 11 mm in diameter and so on.
The size of a motor indicates how much load it will be able to lift.
The next two digits tell you how tall the stator is. The stator is the stationary part of a motor. So in a 2204 motor, the stator is 4 mm high.
Motors which are bigger - have a greater diameter and a higher stator - can lift a lot more load than motors with smaller diameters and stators. You will be able to use larger propellers with bigger motors. If you use a larger propeller with a smaller motor, you will possibly end up burning the motor.
You would need to choose a motor of the appropriate size based on the size of the frame you are using.
2. The KV rating: On a motor, you will also see a KV rating. This number tells you how many thousand times the motor spins per volt in a single minute. You would not want to confuse this with the RPM of the motor.
The KV rating lets you know how fast the motor will spin depending on the input voltage from the ESC.
So a 3100 KV will spin 3100 times per volt per minute. If you supply 6 volts to it, it will spin 3100 x 6 = 25800 times in a minute.
Smaller motors tend to have much higher KV ratings than larger motors. This is because it's a lot easier for these to spin faster.
Now, higher KV ratings do not mean these motors will be able to lift larger loads. It just means they will be able to spin smaller propellers a lot faster. If you were to use a larger prop on a small motor with a high KV rating, the motor will be overloaded - or over propped - and will get damaged.
Likewise, if you were to use a smaller propeller on a larger motor with a lower KV rating, you will be under-loading the motor. It will be under propped as some people refer to this situation.
So when you choose a motor, you will need to know what size propeller you are going to use - and choose a motor with the right KV rating.
3. The weight of the motor: It's essential that you measure the weight of the motors you are using. A 2206 motor may weigh 30 g while a 1106 motor may weight just around 10 to 12g. You are going to be using four to six motors on your drone - and so the weight used gets multiplied.
4. Its amperage rating: The propellers you use determine the current your motors require. If you use large propellers then the motors will pull in a lot more amperes. The more current the motors draw, the hotter they will tend to get.
If your motors draw too much current, then that would mean the motors will get damaged. So you will want to know what's the amperage rating - or the maximum amperes the motor can handle. And you would want to choose the right sized propellers.
5. The efficiency rating: The more efficient a motor is, the more load it can lift while drawing less current. In other words, it can generate the same amount of thrust for less amperes.
Two motors can be of the same exact size - but one might be more efficient than the other. So it will be able to generate the same amount of thrust as the other motor - while needing less current to do so.
Using efficient motors would mean your flight times will be longer - as the motors draw less power. So if you are into drone photography, efficiency would be very important.
In racing drones, speed is more important than flight times - so efficiency is less important.
How much does a drone motor cost?
The cost depends on the size of the motor, the KV rating and the efficiency. You will need to choose a motor based on the frame you are using - and the propellers you want to use.
That said, the cost for a set of four motors can range from $40 to $1000. The more expensive motors are typically used on much larger, professional drones.
Which KV motor for drone?
Some people struggle with KV rating because they think KV stands for Kilo Volt. But that's not what it means in this context.
'K' here stands for thousands rotations per minute.
So a motor with a rating of 1400KV rotates 1400 times per minute for every volt applied. If you apply 1 volt, it will rotate 1400 times per minute; Apply 2 volts and it will rotate 2800 times per minute and so on. This rating is not 100% accurate - but it's close to being accurate. If you use a tachometer, you could get a more precise estimate of what the KV of a motor actually is.
Further, after mounting a propeller, the RPM does fall as there will be air resistance. Larger propellers should always be paired with low KV motors and smaller propellers should be paired with high KV motors.
You would want to choose a motor based on the size of the frame and propellers you are using.
Does higher KV mean faster motor?
Yes. KV is the RPM per voltage. So a higher KV rating means the motor will have a higher rotations per minute per volt supplied.
Which essentially means a motor with a higher KV rating will spin faster.
Does lower KV mean more torque?
A motor's KV rating does not have any bearing on the torque it's capable of generating.
What is T in brushless motor?
The 'T' indicates the number of turns. This is the number of times the wire has been wound around the stator. Lower the number of turns, faster will the motor spin. It will have a much higher RPM.
For instance, a 3.5T motor will have have a RPM of 10,500; A 7.5T motor will have a RPM of 5800 and a 17.5T motor will have a RPM of 2200.