How to choose motors for your drone - especially for 7-inch quads

Errata: I forgot to multiply by Pi i stator volume calculations! All values are around 3.14 times to small, but at least I forgot about it everywhere! Pc in video for 6 and 7 inches are swapped, they are fine in the description.
One of the mistakes pilots makes when they build their first drone is they use too small motors. People think that if a motor works fine with 5-inch props, it will work with 7-inch props as well. It's not true. In this longish video, I will tell you how to choose motors for your drone: 5-inch, 6-inch, and 7-inch. We will talk about torque, power, a moment of inertia, what happens when you put a too big propeller on a motor. And finally, some numbers that will help you pick correct motor for propeller size. Both in terms of motor size/stator volume and motor KV.

Stator volume of different motor sizes (all values are divided by Pi, it slipped me and now it's too late to edit. Just do not multiply by Pi :) )

2204 - 484mm^3
2205 - 605mm^3
2207 - 847mm^3
2208 - 968mm^3
2306 - 793mm^3
2406 - 864mm^3
2506 - 937mm^3
2507 - 1093mm^3
2508 - 1250mm^3

Desired stator volume for propeller sizes:
5-inch props - 600mm^3
6-inch props - 700mm^3
7-inch props - 900mm^3

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How to choose KV:
KV = Pc / S

KV - motor KV
Pc - propeller coefficient
S - number of LiPo cells

Pc for different prop sizes:
5-inch props - Pc = 9600
6-inch props - Pc = 7600
7-inch props - Pc = 6400

More about a moment of inertia and KV is here
KV is a lie https://www.youtube.com/watch?v=HpxZh46AANg
Moment of inertia https://www.youtube.com/watch?v=6I1W5-YV6o0

http://fpv-shopping-list.com/

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Recommended hardware:
Frames
Alfa Monster 7 inch http://bit.ly/2Tjd182
AlfaRC Fighter 7 inch https://bit.ly/3gh6J4y

Motors
Avenger v2 2507 http://bit.ly/2XduDUS
XING 2806.5 https://bit.ly/3hNKgfS
iFlight XING 2208 http://bit.ly/2YBlLbO

GPS
Matek M9N-5883 https://bit.ly/2HMZnJS
BN-880 GPS http://bit.ly/2OxW5by

Flight controllers
Matek F722 Wing http://bit.ly/2AzlYCZ
Matek F722 SE http://bit.ly/2r5OAPo
Zeez F7 https://bit.ly/2ZxVSxy
Mamba F405 stack http://bit.ly/2KuIEs6

Cameras
Foxeer CAT http://bit.ly/2XVe5F1
Foxeer Toothless 2 https://bit.ly/36xTkkN
Foxeer T-Rex https://bit.ly/3m8kncN

Arduino compatible boards
Arduino Pro Mini http://bit.ly/2DjkkHZ
ESP32 LORA32 http://bit.ly/2BjG47d

Tools
N1201SA VSWR meter http://bit.ly/2vNifiO
PS-3010DF PSU http://bit.ly/32sEOIl
Uni-T UT210E clamp meter http://bit.ly/2UrCgWV
Uni-T UT373 tachometer http://bit.ly/2BcUNk8

Видео How to choose motors for your drone - especially for 7-inch quads канала Paweł Spychalski