Brushed motors - RC Groups
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Dec 21, 2001, 05:05 PM
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motorhead's Avatar

Brushed motors

I have a 17 turn single in my elmh and it is dieing a quick death. I have gone through 3 pairs of brushes at about 8 flights each. I just got a set of hard brushes. We will see how long they last. When I was installing the hard brushes I took a good look at the comm and it looks like the trailing edge of the com pad is getting eaten away. I would love to go to brushless but cannot afford it right now. What am I doing wrong with my motor? My set up is:
17t motor
8 cell CP1700
13t pinion
4 deg pitch
Carona blades

The motor problems were the same when I had the normal blades.

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Dec 22, 2001, 06:19 AM
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I think everyone who uses ferrite motors in a heli has problems. Mine lasted about 10-15 flights in a Whisper. You might want to try a cobalt motor as a better option. I've used the Astro 05 which was a bit slow and the 035 which is just about right. The heat doesn't bother them and the com and brushes last forever.
Dec 22, 2001, 10:28 AM
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all you can do is try to reduce your current draw....... Try moving to 6 degree grips, or one 4 and one 6. When I was flying my LMH, I was using a 17T motor, and 11T pinion. I was also using only 6 Cell 1700's. My brushes would last about 40 flights before they would need to be changed. Have you measured your current draw at hover???? I used to pull about 17 amps at hover. With only 4 degrees of pitch, and a 13t pinion you must be pulling over 20. I have heard that the 19turn motors hold up better with larger pinions because they have more of the low end torque need for the larger pinions.... Hope this helps
Dec 22, 2001, 11:39 AM
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Which 17t motor? I suspect that the motor construction matters.

Greg in Minneapolis.
Dec 22, 2001, 04:36 PM
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motorhead's Avatar
I just switched to a 9 tooth pinion and 6 degrees on the pitch. I got a 4:58 flight indoors hovering about 4' high. The battery took a 1.7 AH charge so I think that the average current is about 20 A. It has been my longest hover so far but the motor was getting hot at the end of the flight. I am charging now and will try the same thing with 5 deg pitch. I tried 4 degrees to start with but it would barely hover.

Tried the 5 degree pitch. I did not notice any change in duration or motor temp.

Last edited by motorhead; Dec 22, 2001 at 05:35 PM.
Dec 22, 2001, 05:25 PM
Registered User
I tried several motors of various turns this summer in my LMH. At least a couple of them were 17 turn motors. The only one that worked well was the Kyosho Atomic Force... I suspect because of the oversized commutator and brushes. None of the other motors worked as well... and some didn't work well at all.

I have used two combos I consider successful in my LMH... the 1010/2Y and the Atomic Force. I understand that Lite Machines is using a motor sourced from another maker... and that another person who posts here has had good luck with a Trinity motor, I don't remember which one. I'd put them on the short list too.

Not knowing what motor your using, this may not apply, but just using a 17 turn motor does not guarentee success with the LMH... it needs to be a certain 17 turn motor, my recommendation is the Atomic Force. If, for example, you were using one of the other 17 turn motors I tried this summer, you would not like it.

I'm up to about 75 flights on my Atomic Force on the original brushes... down to about 1/2 gone... and it only gets warm, so I can do back to back flights. The rest of my setup is a 13t pinion and 4-4 grips.

Greg in Minneapolis

P.S. I agree with what Andrew said about ferrite motors except for some of the newer motors... they are much better (in my experience) than motors of 2-3 years ago and better than even some brushless combos (not all).
Last edited by gstew; Dec 22, 2001 at 05:29 PM.
Dec 22, 2001, 05:38 PM
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motorhead's Avatar
I will keep playing with this one but might get the atomic force in a couple of months. Does the atomic force use vertical or horizontal brushes?
Dec 22, 2001, 08:20 PM
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JIMJAM's Avatar
I would take the advice of GSTEW. A long time ago, I pulled out all my brush motors from cars, planes,boats and even and submarine and tried just about everything from a modified 8t single to a 22t stocker. I ended up in a no win situation. The hotter the motor, the better the power,the quicker they ate brushes and comms. The milder the motor,the less performance if at all but the brushes lasted. The only brush motor I had any luck with was a 17t modified with an aluminum endbell designed for speed boats. But at $75 whats the point. Even if brushless motors werent any more powerful and times were the same as brush motors, just the fact that I dont have to worry about all that other crap makes it worthwhile to me.
Dec 22, 2001, 11:22 PM
Our Daddy and Heli Junkie
Fred Bronk's Avatar

Buy once, Buy Right!

Listen to the guys who have done it. You can pay in installments, trying different motors, or go Brushless now.

Dec 22, 2001, 11:58 PM
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BEC's Avatar
Originally posted by motorhead
I will keep playing with this one but might get the atomic force in a couple of months. Does the atomic force use vertical or horizontal brushes?
Neither. The brushes in this family of Kyosho motors (and the similar MEC motors) are 5mm square.
Dec 23, 2001, 12:49 AM
Registered User
I talked with a Lite Machines Tech Support person the other day and asked him how many turns their Corona stock brushed motor (the Electro-Fusion 7 cell motor) has, and he didn't know! He said "it's a modified motor made by Reedy, probably an 11 Double," but he wasn't sure of the exact motor spec. Strange, I would think a Tech Support person at Lite Machines should know . They probably tried different com sizes and brushes, etc., to get the best result, so buying a motor from Reedy with the same turns may not get the same results, but it seems silly to me that he wouldn't know the stock motor spec.

So being the fool I am, I ordered one. LOL! Oh, and extra brushes too. It's my first heli so I'm going to try their stock setup and see what results come of it. I bought the Castle Speed controller on sale for $37 and I already have a few Trinity modified motors and a com lathe, so I'll just eat some brushes while I learn to hover this beast.

He did say the stock pinion is 9 tooth, so atleast I got something for the toll call .


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