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-   -   power output (https://www.rc-monster.com/forum/showthread.php?t=5011)

jollyjumper 01.11.2007 12:47 PM

i have yet another question.
if you want to crawl or so, would your best bet be running a 90/1 reduction or so and 20k rpm or run around 15/1 and only a few 1000 rpm's?

MetalMan 01.11.2007 05:11 PM

Good question! My reasoning tells me 1000 RPM and 15:1 would be better.

jollyjumper 01.11.2007 05:27 PM

wouldnt it have a huge lack of torque?

BrianG 01.11.2007 05:31 PM

Electric motors have max torque right at 1rpm. The problem with running at slow rpms with a sensorless brushless motor is maybe a little cogging since there are less rpms for the controller to sense.

jollyjumper 01.11.2007 05:37 PM

thanks.
also, what would happen if you stall a 2 pole inrunner?

Aragon 01.11.2007 05:40 PM

Gearing down allows you to increase torque. By running the motor at a high RPM and gearing down further, you are increasing the amount of torque available at the wheels.

My vote would be 20k RPM for max torque, but 1k RPM might provide enough torque for the job and be more efficient.

BrianG 01.11.2007 05:46 PM

Quote:

Originally Posted by jollyjumper
thanks.
also, what would happen if you stall a 2 pole inrunner?

Lots of cogging, lots of current (no back-EMF to impede current flow), and possibly a blown controller if it doesn't know how to deal with that condition properly.

I tend to lean towards the higher rpm choice and gear down. Very slow speeds will be smoother.

jollyjumper 01.11.2007 05:47 PM

darn, dangerous huh?!?
or would a crawler be better with brushed motor?:032:

BrianG 01.11.2007 05:49 PM

At the risk of being flamed, I would say yes. Or maybe a sensored brushless motor...

jollyjumper 01.11.2007 05:51 PM

or an outrunner maybe?!?
but i know squat about outrunners, anyone got links?

coolhandcountry 01.11.2007 06:08 PM

I done some reading on the out runner in a crawler.
The man ran a mamba 25 esc in it with a little aevox motor.
He compared the combo to the power of a 55t lathe motor.
It was on rccrawler but not sure where.
I will be playing with different combos before long. I hope to know more.

MetalMan 01.11.2007 10:35 PM

I made my post based on the brushed motors that are more popular (55t lathe motors). With sensorless motors I agree that the higher RPM would be a better choice.

Aragon 01.12.2007 05:32 AM

Quote:

Originally Posted by jollyjumper
or an outrunner maybe?!?
but i know squat about outrunners, anyone got links?

I think an Outrunner would be much better suited. Main downside of them is keeping dirt out, but in a crawler I would guess that is not a problem.

jollyjumper 01.12.2007 08:09 AM

i found good ones, hyperion z30 serie.
what does this mean; 12 Statoren (CNC gefertigt) und 14 Magneten?
does it mean 12 poles?

jollyjumper 01.18.2007 02:33 PM

hehehe, i'm bringing this up again.
this time, for your pleasure, with more questions.:D
let novak hv 4.5 in a monster you need to run 25/1 or so, right.
so it runs 40mph and does 70k rpm, and doesnt run to hot. ok?!?
why on earth wouldnt this work with lehner or so other high-end BL without heat problems? :032:


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