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        Brushed motors for helis article in S&E

#1 Fred Bronk May 21, 2001 03:38 AM

Brushed motors for helis article in S&E
 
If you can get a copy of S&E Modeler, the May issue. It has a great article by James Wang on using brushed motors in helis.

Very good reading and informative!!!!!!

#2 gerry schader May 21, 2001 09:27 AM

I have the article and I agree it's VERY good. There is one thing I don't understand however. He states the Voyager stock motor and ESC were made to be used together and the ESC should not be used with any other motor. It is my understanding that a brushed motor ESC can be used with any brushed motor as long as the amp rating is high enough. Anyone have any thoughts on this? Anyone using the Voyager stock ESC with an aftermarket brushed motor?

Gerry

#3 Steph280 May 21, 2001 10:26 AM

I also read that article and wondered about the same thing.

My guess is the Trinity motor he mentioned is a modified motor. And back in my RC car days, modified motors pull more amps than stock ones. And maybe the JR ESC wasn't designed to handle that much amps.

Of course, I still think brushless is the way to go. :-)

#4 Steph280 May 21, 2001 01:43 PM

"That sounds funny..."
There is nothing funny about what I stated. I was simply making a hypothetical guess.

The Trinity motor Mr Wang mentioned in the article is a hot modified motor. Although "Stock" Voyager motor is 12 turns, it MAY not pull as much amp as that particular Trinity will. That's a pretty weak ESC to begin with, Horizon don't even recommend using 9.6 volts with that ESC. Not sure what the amp rating on it is though.

Mr. Wang is a senior engineer at Silkroski helicopters and an accomplished RC heli pilot / writer. I am sure his findings are based on some facts.

#5 ShakyHands May 22, 2001 12:32 AM

That sounds funny...

The "stock" voyager motor is far from a stock rc-car motor. I have heard that the voyager motor is a 13-turn single, which is a fairly Hot modified motor in rc-car terms.
In my particular heli, the current in a hover is just over 20 amps, which I am sure that the voyager ESC can handle.


If that voyager ESC is a PWM-operated controller, there is no reason "I" can think of that would prevent it from working with another motor. One thinkg I can think of is that if one used a milder motor in the voyager, it probally will not fly well, if at all (the voyager is heavy).


#6 Fitz Walker May 22, 2001 12:50 AM

Yes, Mr. Wangs article was pretty interesting. James Wang also writes for several other (glow) heli magazines, by the way.

I'm pretty sure what he meant by the motor controller comment is that if you start using other motors with the stock esc, you may exceed the power handling ability of the esc.

If you are careful and know what you are doing, the stock esc should be ok for some motor experimentation, but if you start using really "hot" (i.e. low turn motors), or more cells you may fry the esc.

-FTZ

#7 jaggies May 31, 2001 05:40 AM

I just tried the stock ESC with a Trinity 13x4 D4 motor with very good results. The specs printed on the can of this motor:

Trinity 13x4
RPM: 39,664
Power: 204.1W
Efficiency: 77.8%
Torque: 220Nmm

I had to reverse the motor per my other post.
I'm still at -35 degrees, which is probably too hot.

I'm using the stock 15T pinion, though I'm thinking I'll try 14T to see if I can drop the temperature a bit.

The JR ESC does run a lot hotter with the Trinity motor than stock, but not unduly so. I ended up installing the heat sync that came with my repaired JR ESC. I also installed the protection diode that came with the ESC. (Anyone know why the stock motor has 2 diodes?)

My 3 flights today were absolutely amazing. Lots of performance. Lots of head speed. Climbs a lot like my Concept 30 gasser!
I got 5:30 minutes of forward flight with a few aggressive climbs thrown in.

The down side is that the motor runs very hot (sorry I didn't take its temperature). It was way too hot to touch for a good 10 minutes after the flight. I had to wait a good half hour between flights for the batteries and motor to cool down.

Has anyone measured current draw of a stock Voyager without blades? I measured 12.6A at full throttle with the Trinity D4. I should have measured this with the stock motor for comparison (and maybe I still will)


--jim



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