KV / Gearing choices

[Finnster]

Originally Posted by BrianG

Yeah, a couple places have those calculators, but prop loading is kinda comple and hard to draw parallels to road use, but I see what you're saying.

Did you mean to say "This suggests to me, it is best to run a motor with as low as kv rating as possible..." judging by the rest of the paragraph?

Yeah, the prop loading is imperfect, and it only gives you a fixed point as an output, but I do think it gives some interesting data when it comes to motor load, which we can kinda equate to hard accel or WOT. You can use the max eff point for a given voltage to kinda create a dynamic range, but its "eh".

I was intending to address the question posed by glassDr in previous post.

Basically, if you have a fixed voltage (eg 5S) and are trying to gear to the same speed (prop rpms~=wheel rpms, ie 40mph) is it better to use a lower kv motor and overgear, or a high kv motor and gear lower?

The calc data to me says "lower gear, higher kv" is better. This makes sence to me as well as in my Novak BL example from above as well, that a 8.5 can not be ran as fast as a 5.5 on the same # of cells as after a point the motor becomes overgeared and just becomes hot (data indicates that motor will draw more amps, but eff falls, so output power does not improve.)

=> if you want a truck that does 40 on 14 cells, its more efficient to run a (8)XL and lower the gearing than run a 10xl and gear high.

Obviously there are more factors involved in actual motor selection, but this is what the calc data and my own experience tells me.