This thread is privately moderated by Ron van Sommeren, who may elect to delete unwanted replies.
Nov 04, 2012, 04:49 PM
Registered User
Joined Apr 2010
10 Posts
 Thrust vectoring motor mount(suprisingly simple stuff) (1 min 15 sec)
Nov 05, 2012, 12:14 AM

South Africa, GP, Pretoria
Joined Jul 2003
582 Posts
Quote:
 Originally Posted by crashawk most people around here can't use formulas, it's easier to remember what the max watts recomended by the manufacturer is, and most have a max wattage, not max amps since if they rated it at x amps for say, 2 cells someone would try to run it at the same amps on 4 cells and very quickly burn it up. it's all in the watts. lol. either way you look at it though, I still recomend a meter if you are going to experiment. a good way to measure the temp of the stator is a good idea too if you are really going to push it. Jason
Hi Jason

I'm sure it works for you if you are guided by Watts. That is a safe method and there's nothing wrong with that. But... there are some of us who like to push our motors and how do we know what the limit for a motor is? We go by the amps, since amps determines the heat generated in a motor - not Watts! As stated before, the other determining factor is Rm (motor resistance). Finding (or winding) a motor with low Rm is of utmost importance. That is what drives the guys on this forum: http://www.helifreak.com/forumdisplay.php?f=291

These days I often run my motors at double the specified "max Wattage" by using more cells, but staying within the amps limit. Obviously, it often means using a different motor with lower Kv, depending on the cell-count and prop size I want to use.

When I started learning about electric motors, I was also stuck in the "Watts-way of thinking". But fortunately some motor manufacturers stated max amps (not max Watts). That got me thinking and then I finally started understanding how a motor really works. So give it time -You'll come around (hopefully).

Have fun
Christo
 Nov 05, 2012, 11:34 PM Duh grain valley mo, or about 25 minutes east of kansas city Joined Jan 2004 600 Posts [When I started learning about electric motors, I was also stuck in the "Watts-way of thinking". But fortunately some motor manufacturers stated max amps (not max Watts). That got me thinking and then I finally started understanding how a motor really works. So give it time -You'll come around (hopefully). Have fun Christo[/QUOTE] 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.
 Nov 06, 2012, 01:27 PM Night flying Bishopville S.C. Joined May 2003 4,372 Posts Potentially misleading. Last edited by Ron H; Nov 07, 2012 at 02:36 PM. Reason: Garbage
Nov 06, 2012, 04:21 PM

South Africa, GP, Pretoria
Joined Jul 2003
582 Posts
Quote:
 Originally Posted by crashawk 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
 Nov 06, 2012, 05:41 PM Duh grain valley mo, or about 25 minutes east of kansas city Joined Jan 2004 600 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
Nov 07, 2012, 12:52 PM

South Africa, GP, Pretoria
Joined Jul 2003
582 Posts
Quote:
 Originally Posted by crashawk 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
Nov 11, 2012, 05:30 AM
homo ludens modellisticus
Netherlands, GE, Nijmegen
Joined Feb 2001
13,352 Posts
Quote:
 Originally Posted by Skylar ... 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
 Dec 21, 2012, 08:15 AM Aka: Tom Jenkins United States, FL, West Palm Beach Joined Aug 2008 4,677 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
 Mar 21, 2013, 09:34 AM My planes plow into the field United States, TN, Taft Joined Oct 2012 1,068 Posts Motor damaged in crash. Can it be repaired? Well this may be the correct thread Last edited by farmertom; Mar 21, 2013 at 03:18 PM.
 Mar 21, 2013, 09:40 AM KlonWarz Joined Dec 2012 460 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
 Mar 21, 2013, 09:48 AM Jack USA, ME, Ellsworth Joined May 2008 19,247 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 Last edited by jackerbes; Mar 21, 2013 at 06:17 PM.
 Mar 21, 2013, 03:28 PM My planes plow into the field United States, TN, Taft Joined Oct 2012 1,068 Posts OK now what moved this thread to http://www.rcgroups.com/forums/showthread.php?t=1856275 Last edited by farmertom; Mar 21, 2013 at 08:22 PM.