Why brushless (inrunner) motors aren't best for crawling
 

I think this could be the most overlooked and least talked about reason why brushless motors are NOT BEST for crawling, and why they cog.its my understanding that brushless motors have a minimum rpm that coincides with voltage and number of poles. The higher the kv and the lower the number of poles, the higher the minimum rpm will be. Load also has a big play. Brushed motors are less effected by load.

This is why John Holmes is developing a sensored outrunner that has up to 14 poles.

With a set kv, the more poles a motor has, the more torque it has, and also it has the less of a chance to stall between poles because the poles are closer and/or smaller.
Please correct me if I'm wrong. I feel I am starting to really understand brushless motors and would like to help others understand in more detail as well.

Re: Why brushless (inrunner) motors aren't best for crawling
 

I'm running a 890kv, 540 size, outrunner, 12 pole, nonsensored on 9.8 volts(about to be 11.1 3s lipo). This thing is a torque monster! I have never understood why everyone doesn't run an outrunner for crawling. Have run this setup for a couple of years with no problems. An outrunner with a low enough kv. doesn't need to be sensored. Run mine on a Quark procar 33a esc and have not came close to cogging. Have never heard of a Quark procar 33a cogging. My buddies and I have pretty much tried most esc/motor crawling combos between all of us and I have always stuck with my outrunner. As far as brushless inrunners go, I've run them in many touring cars, race trucks and monster/basher trucks with great results, but not so much with crawling or any slow application.

Re: Why brushless (inrunner) motors aren't best for crawling
 

Pics?
You have my interest.
Exactly what motor (brand / model?)

Re: Why brushless (inrunner) motors aren't best for crawling
 

I run a tekin 13.5t brushless SENSORED motor with 13mm torque rotor..smooth as butter no cog..on 3s..MMP esc.

sensorless motors cog/stall..
sensored motors are smoother in lowend control..


I have a HH revolver outrunner I ran for awhile...
just to damn noisy..

Re: Why brushless (inrunner) motors aren't best for crawling
 

So why hasn't his sensorless cogged/stalled in "a couple of years?"

Re: Why brushless (inrunner) motors aren't best for crawling
 

where can we find outrunner's that fit our needs? Do they make outrunners that mount to the output end of the motor?

Re: Why brushless (inrunner) motors aren't best for crawling
 

I've had a sensored 540 inrunner in my Wraith since the beginning. Works perfectly. I had a sensorless 540 in my Exo just to mess with it until the sensored motor showed up and it sucked, but with the sensored motor in there everything is great. I don't see any need to change a thing in either of them.

I ran a couple outrunners for awhile. The startup was hard to get accustomed to. Everything else was there.

Re: Why brushless (inrunner) motors aren't best for crawling
 

like he said..it's an outrunner..not an inrunner.

outrunners generally have more torque less Rpm so stall is less of an issue.

Re: Why brushless (inrunner) motors aren't best for crawling
 

Sensored inrunner..novak ballistic..17.5t
outrunner HH revolver..1000kv

http://i122.photobucket.com/albums/o...0/IMAG1763.jpg

http://i122.photobucket.com/albums/o...0/IMAG1764.jpg

Re: Why brushless (inrunner) motors aren't best for crawling
 

the new Tekin roc motors are designed for crawling..

Tekin -ROC 412 Sensored 4-pole Crawler Motors

http://www.teamtekin.com/graphics/ba...nner_12612.png

Re: Why brushless (inrunner) motors aren't best for crawling
 

So maybe a more accurate way of generalizing (oh that just rolls off the keyboard) would be?

sensorless inrunner motors cog/stall..
sensored motors are smoother in lowend control..
sensorless outrunner motors much less cog /stall

"Smoother", But not as smooth as sensored outruner or brushed. If you can, on a flat surface with 3s compare how slow you can go with that 13.5 and then with a brushed motor. You will see the point Im trying to get across.

What size and kv were you running.

Both scorpions, 22 and 30 series. Iirc 1200kv and 890kv respectively. On 3s and 4s.

Btw not that the startup was cogging, the ramped startup just felt odd.

Re: Why brushless (inrunner) motors aren't best for crawling
 

I understand your point.

it will also depend on how its geared..
if your running 32p gears or 48p.
I can fine tune with gears if my kv is in the right range.

I have been into Rc crawling since '06..
I have ran just about every combo I can.

brushed motors are smoother..no question.

depends on what you call crawling as well..
we talking snails pace or what?

Yes. Sometimes you need that snails pace to get out of a bad spot. When a motor starts at a higher rpm it can be "touchy"or "jumpy" off the line. That could send you into a gate, off the side of a rock, or down a cliff like my wraith did lol.

There is a more "technical" line at my local spot I always can make with my brushed setup. Full confidence! When I went brushless I would make it one out of three times, maybe. It wasn't pretty looking either. There also were lines I just couldn't make. I geared Dow to fix it and there went my wheel speed. Couldn't make the hill climbs I could before. Also still not as slow of a startup speed as brushed.

Re: Why brushless (inrunner) motors aren't best for crawling
 

ESC programming and construction can effect startup as well.

My first attempt at brushless crawling was with an old v1 sidewinder. My latest attempt was with an LT4. They behave way, way differently.

Before you get to excited you do realize how slow that's going to be, right? Snails will yawn.