HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Apr 11, 2006, 09:57 AM
Registered User
Joined Aug 2005
263 Posts
Discussion
Are curved magnets better than flat?

I have two identical motors here, though one with curved magnets, and the other with flat ones.
Does it equate to a better more powerful motor if they are curved?
I have a feeling the curved magnets belong to the newer model motor, but I cannot be sure.

Any ideas or education on the matter would be appreciated.

Rgds
Aj
world_hobby is offline Find More Posts by world_hobby
Reply With Quote
Sign up now
to remove ads between posts
Old Apr 11, 2006, 10:24 AM
Registered User
Edmonds Wa. (Seattle)
Joined Nov 2003
3,926 Posts
Well I just happen to be just the guy to answer this one for you

having curved magnets will allow you to get the magnets closer to the ends of the stator (de-creasing air gap) and in doing this increase the flux between them. there is no doubt that the curved magnets are better suited for the type application. I built many many motors with 5x5x1 flat magnets and when I received my curved ones and testing them I was shocked at the difference between them. They are both good motors just the one with the curved magnets is a better design.

Thanks,
Scott
Littlescreamers is offline Find More Posts by Littlescreamers
Reply With Quote
Old Apr 11, 2006, 10:24 AM
Registered User
landru's Avatar
Vancouver, Canada
Joined Mar 2003
2,110 Posts
Hi Aj,

All other factors being equal (windings, stator, magnets, airgap, flux ring), the motor with curved magnets will be more powerful than the flat magnet motor—but will have a slightly lower maximum efficiency.

Is that better? Well, since we tend to run our motors well past the point of max efficiency at WOT, I'd say the curved magnet version is better. Likely what you'll get in real life is a higher efficiency—and more power output—with an appropriate prop at WOT.

Or look at it another way: the curved magnet motor will produce more torque for a given amperage.

Or, you could also see it as the curved magnet motor having a lower Kv for the same Rm as the flat magnet motor—with the tradeoff being a higher Io for the curved magnet motor.

Andrew
landru is offline Find More Posts by landru
Reply With Quote
Old Apr 11, 2006, 10:31 AM
Master of 1 point landing
Naperville, IL
Joined Jul 2005
2,841 Posts
Quote:
Originally Posted by Littlescreamers
Well I just happen to be just the guy to answer this one for you

having curved magnets will allow you to get the magnets closer to the ends of the stator (de-creasing air gap) and in doing this increase the flux between them. there is no doubt that the curved magnets are better suited for the type application. I built many many motors with 5x5x1 flat magnets and when I received my curved ones and testing them I was shocked at the difference between them. They are both good motors just the one with the curved magnets is a better design.

Thanks,
Scott
Scott - in your opinion, are the performance gains due to decreased gap or better contact with the bell - or both?
ImaBiggles is offline Find More Posts by ImaBiggles
Reply With Quote
Old Apr 11, 2006, 10:47 AM
Registered User
Edmonds Wa. (Seattle)
Joined Nov 2003
3,926 Posts
I would say both. but I went from a so so flat n45 to a very for sure n50 curved so the cogging was increased ten fold due to the magnets and the fact the I took a bad air gap and took it about a close as I could go. I am very happy with the the gamble to try and see if having the magnets touch! (said it couldn't be done) would change my motors for the better or worse. Well we got the answer and the motor craze is still going. Talking about Curved magnets anyone ever seen my 60deg arc magnets? with a N & S in one magnet? thats right I went a step further and I am not done yet. I have some more magnet news coming.

Thanks
Scott
Littlescreamers is offline Find More Posts by Littlescreamers
Reply With Quote
Old Apr 11, 2006, 10:51 AM
Registered User
Massachusetts
Joined Jan 2006
966 Posts
I like both. And they're about the same if... The equivalent air gap is the same.

But you can get the airgap smaller with the curved magnets which is an advantage for low rpm applications.

And if you need high rpm performance then the airgap needs to be WIDE, so either can be used with equivalent performance.

Newt
INewton is offline Find More Posts by INewton
Reply With Quote
Old Apr 11, 2006, 11:02 AM
Registered User
landru's Avatar
Vancouver, Canada
Joined Mar 2003
2,110 Posts
Quote:
Originally Posted by Littlescreamers
...Well we got the answer and the motor craze is still going. Talking about Curved magnets anyone ever seen my 60deg arc magnets? with a N & S in one magnet? thats right I went a step further and I am not done yet. I have some more magnet news coming.
Scott,

Why do you always drive the discussion towards self-promotion? It's tiresome.

Andrew
landru is offline Find More Posts by landru
Reply With Quote
Old Apr 11, 2006, 11:25 AM
Master of 1 point landing
Naperville, IL
Joined Jul 2005
2,841 Posts
Quote:
Originally Posted by landru
Scott,

Why do you always drive the discussion towards self-promotion? It's tiresome.

Andrew
Now Im all for smacking Scott around once in a while - but Landru - this is Scotts business, griping at him for self promotion that is related to the topic MAY be a bit unfair.
ImaBiggles is offline Find More Posts by ImaBiggles
Reply With Quote
Old Apr 11, 2006, 11:29 AM
Registered User
Joined Aug 2004
734 Posts
Scott,

I have never seen what the big deal is with your 60 degree arc segments. Is there some actual performance enhancement or do they just make manufacturing a little easier. Maybe I'm missing something obvious (or not so obvious) but would you care to enlighten me as to what the advantage is.

Thanks,

Adam
latrans is offline Find More Posts by latrans
Reply With Quote
Old Apr 11, 2006, 11:39 AM
Registered User
landru's Avatar
Vancouver, Canada
Joined Mar 2003
2,110 Posts
What is unfair is for a vendor to divert this thread, or any thread, for self-promotional marketing purposes.

Selling motors may be Scott's business. But this is a discussion forum, not the shopping channel.

Vendors have other established means to promote their products on RCGroups.

Andrew
landru is offline Find More Posts by landru
Reply With Quote
Old Apr 11, 2006, 11:50 AM
Choppa Nutta's Avatar
UK
Joined Jan 2002
1,030 Posts
is it because he's american and thats what americans do ?
but if he has something new, interesting and worthwhile then whats the harm I guess....
Had an idea for a ring magnet where the polar flow is set at a 45deg angle to the tangent place another inside with opposing polarity god knows how one might make it happen though. possible perpetual motion device ?!? thought about tackling it with a series of small magnets arranged in a ring but this would introduce steps to the flow and thus a retardation of rotation, not the smooth magnetic flow desired....
I've seen a design for a magnetic wankel engine that had the magnetics arranged similarly but in a slight spiral formation, most interesting dont know if it worked or not but was thought provoking.....

anyhow, "I'm the greatest, I'm the greatest"
not really, cant resist an oppurtunnity to take the mick
love you all, god bless merry cans
Choppa Nutta is offline Find More Posts by Choppa Nutta
Reply With Quote
Old Apr 11, 2006, 11:53 AM
Registered User
Edmonds Wa. (Seattle)
Joined Nov 2003
3,926 Posts
Quote:
Originally Posted by landru
Scott,

Why do you always drive the discussion towards self-promotion? It's tiresome.
Andrew

Shoot me for being excited about bringing you guys new things? I am not selling these to the public? just something I was trying out. And to answer your ? about better or not? Not really in a performance way but for sure in the building of mass motors. I just wanted to show that i am still thinking out side the box and coming up with new things. I guess I need a break from this site again?



Scott
Littlescreamers is offline Find More Posts by Littlescreamers
Reply With Quote
Old Apr 11, 2006, 12:16 PM
Choppa Nutta's Avatar
UK
Joined Jan 2002
1,030 Posts
no dude don't do it !
I was only being cheeky
your enthusiasm is appreciated
I remember a guy called mario who was much worse for being self promotional but then he had put a lot of effort into what he was doing and you cant blame people for that so "itsa no bigga deal" brush it off and move on...
and post some piccies up of your wierd magnets
Choppa Nutta is offline Find More Posts by Choppa Nutta
Reply With Quote
Old Apr 11, 2006, 12:34 PM
Registered User
Edmonds Wa. (Seattle)
Joined Nov 2003
3,926 Posts
Like this?

Scott
Littlescreamers is offline Find More Posts by Littlescreamers
Reply With Quote
Old Apr 11, 2006, 01:19 PM
Flying motor mount master
fly_boy99's Avatar
San Jose, California, United States
Joined Oct 2004
8,745 Posts
I know of a certain battery vendor which I would love this statement to
apply to but alas it does not...


Quote:
Originally Posted by landru
What is unfair is for a vendor to divert this thread, or any thread, for self-promotional marketing purposes.

Selling motors may be Scott's business. But this is a discussion forum, not the shopping channel.

Vendors have other established means to promote their products on RCGroups.

Andrew
fly_boy99 is offline Find More Posts by fly_boy99
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Hacker A20-20L - Where are the curved magnets? Rotozuk Power Systems 1 Jun 16, 2006 02:21 PM
Are any Channels better than others? Etonic Radios 2 Jan 25, 2004 02:29 PM
Question Are some channels better than others? BuddyO Radios 13 May 21, 2003 12:11 PM
Are small planes better than big planes? gomarpyle Parkflyers 11 Feb 15, 2003 07:14 PM
What are windings and why are fewer windings better than more windings? soholingo Beginner Training Area (Aircraft-Electric) 4 Jan 05, 2002 09:09 PM