How do I tell if my brushless motor is up to par? - RC Groups
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May 08, 2002, 07:09 PM
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ferradas's Avatar

How do I tell if my brushless motor is up to par?

I bought a Kontronic Fun 400/42 with a 4:1 gearbox and the Smile 40-6-12 ESC from NSP about 3 weeks ago.

I installed this setup in my Art Hobby Kastor 1.65 glider. I'm using Sanyo 8 600AE's.

I was pretty content with the performance. One day, the carbon boom buckled on the glider and it came down into the brush. A few scrapes here and there but nothing major. When I opened her up, the batteries had slammed forward. The battery caught on the Red battery wire form the ESC and tore it off. The motor itself looks clean, not a scratch on it.

When I got home I decided to solder the red wire back on to the circuit board of the Smile ESC, I noticed that the lead on the wire came apart with a piece of the circuit board. Luckily I was a ble to solder it back on and placed a drop of epoxy on it to reinforce it.

Do you ever crash something and then feel that it's not the same as before? Even though it's performing exactly the same you live with that feeling in the back of your head wondering if it's performing to it's potential, well , this is how I feel about my motor/ESC.

Now my question is.... How do I tell if my motor is putting out what it's supposed to as far as power goes? I don't have a whattmeter but I suppose I can borrow one.

Does anyone know how much RPM I should be turning with my setup? :

Kontronic Fun 400/42
4:1 gearbox
8 600AE's
Graupner Cam 11x8 folding prop

If I rememebr correctly I think my RPM was is the 7,000 range. Is this normal? How else do I check my power?


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May 09, 2002, 03:38 AM
Registered User
Jurgen Heilig's Avatar
Hi Paul,

The performance of your drive system is severely limited by the batteries you use. Motor and controller are good for 40A, while your batteries will start sweating at only 10A. In your case a small Hacker B20 would have been more than adequate. If you have some extra space in your model and a little extra weight is not a problem, try some Sanyo 800AR or CP1300. Jürgen
May 09, 2002, 12:20 PM
Registered User
ferradas's Avatar
Thanks, I was suspecting that the 600AE"S might be a culprit. On this glider it's about all I can fit. Are the 800AE's about the same size? And can they handle alot more current?

The glider climbs alot better on 9 cells. I can get some vertical , then a steady 75-80 degree climb to altitude.

I will make sure my next sailplane has more room for bigger cells.

I just ordered a Bandit from NSP and will be trying the motor in it.
May 12, 2002, 04:28 AM
Flying Free
erashby's Avatar
Jurgen: What BL motor would you recommend to replace a speed 400 for a 2 pound plane on 8 AA cells 1600 MaH NiMH packs? I've been thinking about the AXI outrunner or mini LRK since I want to use a slow flier 9x6 (or there about) size prop.
May 12, 2002, 04:38 AM
Registered User
Jurgen Heilig's Avatar
Depends what kind of plane it is. Glider, sport plane, Aerobatic plane? With your type of cells current should not exceed 10A.
P.S.: So far I haven't used any LRK or "outrunners", but I am pretty sure Hacker would also have a B20 with gearbox to suit your needs.