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Old Nov 06, 2012, 07:45 AM
Jack
USA, ME, Ellsworth
Joined May 2008
17,215 Posts
You've had some interesting experiences, that's for sure. And a lot of fun too I'd have to say.

When I see a spec that lists just Amps or just max and/or continuous Amps, and also says that the motor it OK with a ranges of cells counts like 2S-4S, it always leaves me with some unanswered questions. But if they list the power in Watts, especially of they say if it is a peak or continuous rating, I feel like a know a lot more about the motor's potential.

A lot of the on line sellers are either stupid about electric motors or are just trying to bamboozle potential buyers by just listing the "big numbers". Like the peak Amps from full throttle bursts, little or no mention of Watts, and no mention of it being a peak reading.

HK is especially bad about that. And they are so shallow or ignorant about some of the technical aspects of motors that they even advertise with videos that show them taking the burst readings that they later advertise without any mention of the fact that it was a current reading taken in a 5-10 second burst.

If they are going to give me fragmentary or misleading specs I prefer to see the power rating in Watts. With that, and the weight of the motor, I usually feel like I have a feel for how "optimistic" the reading might be.

Jack
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Old Nov 06, 2012, 01:22 PM
Duh
crashawk's Avatar
grain valley mo, or about 25 minutes east of kansas city
Joined Jan 2004
598 Posts
it's been a great ride Jack, wouldn't trade it for anything (except the fire, I could do with out that).

yes the better manufacturers like to give us a max watts and that's good. just devide the watts they give you by the volts you plan on running it at to get the max amps to watch for on your meter.
and if your full throttle amps exceed your max for your batt or speed control don't think you can use the throttle as a fix, it might not hurt your motor but it won't help your batt and speed control, they are still seeing full throttle amps, just in little pulses instead of constant. either get bigger components of drop your prop size or voltage. have fun everyone.
Jason
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Old Nov 06, 2012, 02:27 PM
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Ron H's Avatar
Bishopville S.C.
Joined May 2003
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Potentially misleading.
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Last edited by Ron H; Nov 07, 2012 at 03:36 PM. Reason: Garbage
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Old Nov 06, 2012, 05:21 PM
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Skylar's Avatar
South Africa, GP, Pretoria
Joined Jul 2003
415 Posts
Quote:
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.

Jason

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.

Regards
Christo
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Old Nov 06, 2012, 06:41 PM
Duh
crashawk's Avatar
grain valley mo, or about 25 minutes east of kansas city
Joined Jan 2004
598 Posts
well Christo, most flyers don't want or need to be able to figure out copper loss, they just need to know what line not to cross current wise so they don't burn up their motor. max amps at specific voltages or max watts is the only options the manufacturers have to give the non-technicol purchaser. I answered the mans question not gave him a formulae to confuse him more. what part of that did you decide I was needing to learn something? did I ask you to help me? and telling me to go away to a simpler thread is like telling me I'm ignorant which is the same as attacking me which if you have read the rules then you know it's not welcome here. if you was over here I'd say lets go flying and forget all this mumbo jumbo, water under the bridge and all, but your half way round the world so I will bid you good day and bother you no more.....................
Jason
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Old Nov 07, 2012, 01:52 PM
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South Africa, GP, Pretoria
Joined Jul 2003
415 Posts
Quote:
Originally Posted by crashawk View Post
well Christo, most flyers don't want or need to be able to figure out copper loss, they just need to know what line not to cross current wise so they don't burn up their motor...
In my opinion, this thread is not aimed at "most flyers". It's for those individuals who are comfortable with, or want to learn about designing and rewinding motors (which is a very small percentage of the general flying public).

Having been a subscribed member of Ron's LRK-Torquemax motor-building group for 10 years, I know how much I appreciated every bit of information that was posted that pertained to motor design and analysis. My posts on this thread were made in the hope that it will benefit someone who might be keen to learn too, and with that I don't necessarily mean you, Jason. There are many lurkers on every thread.

Quote:
...so I will bid you good day and bother you no more.....................
Jason
Let's just agree to disagree then. I'm sure that when Ron finds the time to do some cleaning up on this thread, he'll delete our posts anyway.

@Ron: Sorry for the mess. Please delete any of my posts that you don't find contributory to the general spirit of this FAQ.

Christo
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Old Nov 11, 2012, 06:30 AM
homo ludens modellisticus
Ron van Sommeren's Avatar
The Netherlands, GE, Nijmegen
Joined Feb 2001
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Quote:
Originally Posted by Skylar View Post
... this thread is about designing, building and winding motors. ...
It's an interesting good discussion, not a messy one, don't worry. But this is a FAQ, intended for tips and tricks only. I try to keep it lean and mean and will remove the discussion at some later time.

Power losses are determined by current and rpm, not by power sec.
Copper losses = IČR
Iron losses = hysteris losses + eddy current losses.
Hysteris losses go up linearly with rpm, eddy current losses go up squared with rpm.


Vriendelijke groeten Ron
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Old Dec 17, 2012, 01:12 PM
homo ludens modellisticus
Ron van Sommeren's Avatar
The Netherlands, GE, Nijmegen
Joined Feb 2001
10,923 Posts
Another motor building subforum
www.helifreak.com/forumdisplay.php?f=291

Sensorless field oriented control of brushless permanent magnet synchronous motors
355 pagina's, 8MByte
www.krex.k-state.edu/dspace/bitstream/handle/2097/1507/JamesMevey2009.pdf

Don't use the Acrobat pdf reader, it's 500MB of bloatware, and a security risk as well. Use e.g.
https://en.wikipedia.org/wiki/Sumatra_PDF
https://en.wikipedia.org/wiki/Foxit_Reader
https://en.wikipedia.org/wiki/List_of_PDF_software

Vriendelijke groeten Ron
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Old Dec 21, 2012, 09:15 AM
Aka: Tom Jenkins
ApexAero's Avatar
Palm Beach County, Fl.
Joined Aug 2008
4,507 Posts
Hello all, my name is Tom, I wanted to say thanks to Ron and all here just because of these Electric Threads in RCG. I've been at modeling for quiet a while, first it was the building and designing, then it was learning the In's and outs of 2 stroke R/C engine reworking and tweaking for either Stunt or Speed, then it was Scale Detail added to my skills and flying as fast as I could racing for a spell, poof ten years has gone by, boredom set in.

Well dontcha just know it! Here comes the electric bug whispering on my shoulder, "Hey, you can do this much quieter! And go even faster!" So how you gonna do it? Low and behold there it was gleaming to me off the screen! Electric Motor Design and Construction, hmmm
I'd read of a few guys rewinding motors, I found out about the Power Ditto pages and a thing called F3S and got a new outlook on things, a new direction in the hobby and a way to force myself to step up and just do it! So thank you Ron and the electrically interested members of RCG for the opportunity to learn something new and breath new life into my passion and hobby of Model Aviation. My goal is 250 mph, refining my swept forward design, winding a Croco style motor and vicariously burning a hole through the air. I got back into balsa planes at 33 and just turnd 58.
Enjoy life!
Happy Holidays All
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Old Mar 21, 2013, 10:34 AM
My planes plow into the field
farmertom's Avatar
United States, TN, Taft
Joined Oct 2012
654 Posts
Motor damaged in crash. Can it be repaired?

Well this may be the correct thread
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Old Mar 21, 2013, 10:40 AM
KlonWarz
Joined Dec 2012
455 Posts
Can it be repaired?

Yes! Of course it can!

You have a perfect opportunity to learn, now, since the motor now has no value to you, otherwise!

I am unable to offer specific advice, yet someone will surely come along who has a similar motor... I've used small dental picks to get out retaining rings...

....I was really pleased to see some activity pop back up in this thread!
:-)
rc
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Old Mar 21, 2013, 10:48 AM
Jack
USA, ME, Ellsworth
Joined May 2008
17,215 Posts
Thread has been moved to the more appropriate forum.

My first reply has been copied over to the new/other post.

It can be seen here:

http://www.rcgroups.com/forums/showthread.php?t=1856275

Jack
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Old Mar 21, 2013, 04:28 PM
My planes plow into the field
farmertom's Avatar
United States, TN, Taft
Joined Oct 2012
654 Posts
OK now what

moved this thread to http://www.rcgroups.com/forums/showthread.php?t=1856275
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Old Mar 21, 2013, 07:12 PM
Jack
USA, ME, Ellsworth
Joined May 2008
17,215 Posts
I'll reply over on the other post in the more approriate location, I suggest you edit your post and replace it with a notice here to the effect that the conversation can be continued over there.

Then move your post and photos to the other post...

Jack
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Old Apr 11, 2013, 03:16 AM
Ura
Registered User
Joined Mar 2013
414 Posts
Hey i got little side question plz can some 1 give me help/hint on WHAT MOTORS THIS GUY MIGHT OF USED FOR THIS? im sure he is using similar 3 axis gimbal cheep like alex mos and i want to know what motors he used i know the rewining part will be needed for it. but what motors?
this is the video im refering to
MōVI in Action (Quick Video) (0 min 24 sec)
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