How to choose an electric motor for a heli?

Just got into the hobby and was curios how to choose an electrical motor for a heli.

Do you choose KV based on the total weight?
Pinion based on max Apms that motor can draw at a set blade size?
How to chose the battery (voltage) for the motor and the cell size (ex: 5S vs 6S for E-smart) ?

any advice or links are appreciated
thanks

Hey, Well when I started out I used the internet. You didnt say what heli it was for???

Do google searches for that type of heli and style of fly'n. Forums have the best info.

There are a lot of smart and helpfull guys on this paticular forum so if you tell us a little more about the heli and your fly'n preferences, you will get a lot of good info.

Your question as it is would take awhile to explain. So narrow it down a little and let the magic happen...

Yea I kinda started poking around the net for the answers. A few sites that I found interesting:

“Brushless Systems: Understanding Them and How They Work” http://www.rchelimag.com/pages/howto.php?howto=28&page=1

“What does KV mean?” http://www.flyelectric.com/ans.kv.html


I started looking into the motor choosing issue when I got a 400X Extreme Brushless motor as a replacement for my crappy brushed 400 on the Honey Bee King 2. Since it was the only suggestion on the site for a replacement, I got it without thinking too much if anyone else did any test on it. Now to think about it, a 4000KV motor seems a bit high for this size heli.

I went up from original 9T to 11T pinion only to notice that Esky 24A ESC burning hot, my 25C 2000mAh battery last only for few minutes and also warm to the touch.

If time permits I’ll test the 400X motor with a Watt meter to get the actual Amp draw for range of pinions (9T to 13T), and a digital scale to get the heli weight and static thrust.

Maybe after some pocking I’ll find a right motor KV-pinion-blades combo without burning anything up.

For honey bee king I suggest using esky 3900kv motor. As I know it is direct fit, cheaper than extreme motor, and really powerful

Thats the one I use on my King!!! It smokes!!! Very powerful!!! I'd recomend it to anybody!!