# Brushless motor prop calculator for diy quadcopter

About brushless motor prop calculator for quadcopter, Generally you will get suggested prop value in brushless motor specification, motor and prop are very closely related. Here is some calculators about RPM & Thrust & load weight and a simple example of its applications are given, if you want to know please go ahead.

RPM=KV * V

For example,If you have 900kV motor and 4S lipo battery to supply power, RPM of of brushless motor at NO LOAD would be

900 x 14.8(4S battery) = 13320 RPM.

Payload Capacity + The weight of the craft itself = Thrust * Hover Throttle %

For example,If you choose 3s Lipo battery to supply power.your propos is 10*5 and throttle is 75%.The weight of the craft itself is 1000g,if you want to build your qucopter which can load 1211G.Then

1211G + 1000G = Thrust *75%

Thrust = 2948 and you have to choose brushless motor which thrust is more than 737 (2948/ 4),such as MT2312-960KV Motor.

Payload Capacity = ( Motor thrust * Number of motors * Hover Throttle %) –The weight of the craft itself.

For example,you have to check this post:Simple formula about quadcopter weight calculator ,.Keep in mind that the weight of the craft itself is including all parts of your quadcopter such as brushless motor, brushless esc,battery,etc.

As we see above our brushless 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 10×3.8 and 10×6. 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 10×3.8 prop our quad will climb in the air at 5.7 m/sec, while with 10×6 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 quadcopter?

Generally you will get suggested prop value in brushless 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 13×3.8 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 quadcopter you should go with low pitch prop if you need more stability and less vibrations.

### Conclusion

Yes,all above brushless motor prop calculator for quadcopter are often asked by some beginners ,In fact these calculator is very very complex,but I think that it is less practical for the complex calculator,so I only tell you sample methods. Build your own quadcopter,One thing is much more improtant is that how to choose and balance all the parts ?Maybe this post will help you.components of quadcopter what parts combination will work with each otherIf you have more story about quadcopter,share here to us.

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