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Old Nov 06, 2012, 04:21 PM
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我爱飞行 . . . I love flying
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South Africa, GP, Pretoria
Joined Jul 2003
424 Posts
Originally Posted by crashawk View Post
I learned a lot from a couple of local manufacturers, working for one winding motors and the other (castle creations) answered a lot of questions from me as several of their employees fly locally, some even in our indoor club for a long time. (and I allways bugged them for all the info I could) I used to build motors just to test what I learned. built a cdrom motor that did 350 watts on 4 cells turning a 3 inch prop 36000 rpm, scared the bejesus out of me and my brother and sounded like a freight train. (was told that was impossible) also built an outrunner from the blower motor from a semi-truck. 5 inches across the bell and our largest prop (24x12) was nowhere near big enough to tax it. at 3500 watts it ran colder than the ambient air temp producing over 25 pounds of thrust. still have it but can't afford to do anything with it for now. had to start over from scratch on everything due to a fire and still havent started building motors again, just wasn't enough insurance to replace all the parts, pieces and tools I had before the fire. been flying since 1988 and doing electric planes since 1990, started flying brushless motors and lipo batts around 10 or 12 years ago and pretty much went electric on everything about then. before the fire had around 65 or 70 planes all with motors I built in them from 4 ounce micro planes to 6 pound warbirds. lost over a hundred planes in the fire and 60 kits and half a chord of balsa wood. I don't throw anything out here unless I got it from a reliable source and checked it out myself. my chances of "coming around" are nill, lol, too set in my ways after all these years.


I was just trying to help. There is no need to try and convince me of your experience in aeromodelling and building electric motors.

At the risk of sounding vain, I can mention that I started flying models in 1961 and have been flying electric since 1995. I have also been building, modifying, testing and reviewing electric motors for the past 14 years. But all that means nothing if one can't show some kind of understanding of the subject.

Being able to calculate the amount of heat generated (copper loss) is much more important than knowing Ohms Law (volts x amps = Watts), for the simple reason that an electric motor is only limited by the amount of heat it generates and that it can safely dissipate. Input Watts has absolutely nothing to do with this. If you haven't come across this kind of reasoning yet, maybe this is your chance to gain some insight in the workings of electric motors.

With all respect, this thread is about designing, building and winding motors. I was under the impression that you're here to learn, but I must have been mistaken. If you can't (or don't want to try) understand the very simple formula for calculating copper loss (heat), then I suggest that you rather read the more general threads on electric models.

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