red_z06
Elite Veteran
Location: Dumont, NJ
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| For non geared application, lower kv means more torque to turn bigger blades/props. A motor with 1000kv may have twice the torque than one with 2000kv. But, 1000kv motor will have 1/2 of the gearing mechanical advantage when compared to 2000kv motor.
For example, 1000kv will require 10:1 gearing for 10x increase in torque at the output. 2000kv will be 20:1 with 20x mechanical leverage. In the end, there will be same available output shaft torque.
In general, higher kv motors have less wind resistance (less loss through winding). But, typically these advantages are too small to be seen by a pilot doing his thing. In reality, it is much more complicated to look at one number (kv, wind resistance etc) to determime.
Good rule to stick to when selecting a motor is so that you can gear up or down by 2 tooth in each direction. When you get a motor that is too fast, you will be able to make it faster (useless) but will not be able to to slow it down due to the physical limitation of the pinion itself. Smallest pinion would have a little more frictional loss than a larger one due to how these gears are cut. I have not seen too many RC manufacturers use involute gear profiles to cut their gears due to cost and simplicity.
In general, 450 class motors use 3.2mm shaft have pinions ranging from 10-20+ teeth. So, selecting a motor that will suit you at 12t minimum will give you a good starting point.
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So, as you go to higher KV (assumtion is same motor size), torque will be less but you get it back due to mechanical advantage with higher gear ratio where you give up the speed for the torque.
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