How to Choose a Drone Motor & Propeller Size
One of the most posed questions is what motor and propeller size do I use for my Drone or Quadcopter. Well, the answer is not a straight forward simple one but know what all the numbers mean will help. Lets first take a look at the number on a brushless motor.
Brushless Drone Motor Size and kV Numbers
Motor Size - The first numbers on a brushless Drone motor have to do with the rotor size. This is usually a 4 digit number like 2206 or 2306. The first 2 numbers ("22" or "23") tell you the width of the stator in mm. The last 2 digits ("06") tell you the stator height in mm.
The rule of thumb is that a tall stator means the motor provides more power at higher RPMs. A wider stator means the motor produces more torgue at lower RPMs.
On most drone motors out there, they will have a M5 or 5mm shaft. This is the most common shaft size as it allows for a 3", 4", 5" or 6" propeller 99% of the time. Be sure that when you buy propellers, that you are buying ones that match your motor shaft size.
kV Specs - Now the next number of interest on brushless motors is the kV Spec. You will see numbers likes 2300 or 2600, but what the hell do these mean? Well the kV rating on a motor is the number of revolutions per minute the motor will turn when 1 volt of electricity is applied. For example, a 2300kV motor will spin 2300 rpm per 1 volt of electricity.
Typically, the higher the kV, the faster the motor will spin the propeller. The lower the kV, the more torque the motor will have. A good rule of thumb to use when selecting kV and propeller sizes is to go by the below recommendations.
- 2300 kV and less, Use a 6" Propeller
- 2300-2600 kV, Use a 5" Propeller
- 2600 kV and up, Use a 4" Propeller
These numbers are based on the theory that a higher torque / less RPM motor is needed to spin a larger propeller and a higher RPM / less torque motor will spin a smaller propeller better. This all about finding the right balance between RPM and Torque.
Here is a chart that gives an overall idea of what setups will work best based on kV, Prop Size, Motor Sizi, Frame Size and Batteries. As always, if you have questions, please feel free to contact us as Sales@geezdrones.com