|Feb 05, 2002, 06:06 PM|
Markle, In. US
Joined Oct 2000
Those LRK motors posted by Ron,to me seem to be the way to go. Low rpm high torque motors. It gets rid of the gearbox. They are a fairly simple design too. Just a matter of finding the right motor to rip the rotor out of. What makes this worse is that is has to be a multiple of 3. I may start looking. Someone on that group made a slow flyer motor that was just over an inch in diameter and probably the same in length. How big is the Astro 010 anyway.
|Feb 05, 2002, 07:14 PM|
Or you can buy the parts:
Pictures/drawing from Kai Huber's site:
|Feb 05, 2002, 07:20 PM|
Why not post all LRK information I have?
The name of these diy brushless outrunner e-motors, “LRK-torquemax”, is the electro-mechanical principle used in these motors: every other stator-tooth is left empty. It was originally developed for magnetic levitation trains! It certainly is not a company or a product.
The original diy construction articles were published in the German quarterly Elektro Modell magazine, issues 2000/4 and 2001/1-2-3, http://www.neckar-verlag.de publishers. Now the construction articles are available on the internet, in English and German, including drawings, pictures and diagrams.
LRK-Torquemax brushless outrunners can be made using a relatively simple lathe. One has to be capable of making a press-fit ball-bearing seating though. The lrk-torquemax principle features a high torque at lower rpm than a conventional high-revving brushless layout. There's no need for a gearbox, which means less weight, less losses, lower costs and no gear whining. The motor can swing a bigger prop which results in an even higher efficiency. It can be tailored to the planes needs by choosing the stator diameter, magnet length and number of windings you want. It's possible to rewind the motor (or even swap the complete stator) for a different type of application.
You can use an old brushed motor or gut your CD-ROM player, harddisk, wife's or your own blowdryer, powerdrill or fanmotor for stator material. Check the bin of a motor re-wind(???) or transformer re-coil(???) company for material. Or you can buy the parts.
The LRK-torquemax is an inside-out motor, the coils are stationary, housing and magnets rotate. This has the additional benefit of good magnet cooling and the coils are not stressed by centrifugal forces. The motors built to date, range from slow-flight to 2kW and helicopter applications. LRK-torquemax motors operate with normal brushless controllers although some are better suited than others.
Discussion & help
The lrk-torquemax e-mail list for help and discussion on construction and design (English), monitored by yours truly:
To join the list, click ‘Join This Group’ in upper-righthand corner, or send an empty message to firstname.lastname@example.org.
If you can read a bit of German, check out the German lrk-torquemax forum, very good:
http://www.rconline.net >> rc-forum >> lrk-motoren
Construction articles & tools & pictures
Construction article I:
Construction article II:
The 'bible', winding calculation tool, diagrams, measurements, some theory:
All in English and German.
http://www.torquemax.de/Motor.htm picturs, tables, drawings, lrk in helicopters, Detlev Koch
http://www.torquemax.de/Andere.htm pictures, tables, other builders
http://members.aol.com/schwaabbel pictures, tables, drawings, lrk in helicopters, Frank Schwaab
English version of winding calculation tool by Jussi Sirkia:
Winding calculation tool by Roman Pollak:
More LRK-torquemax builders’ homepages
http://home.t-online.de/home/GHagerBI/homep1.htm stator glueing and insulation, Günther Hager
http://www.yahoogroups.com/group/lrk-torquemax English help & discussion mailing list
http://users.cybercity.dk/~ccc16084/ta400a3.html FW Ta400, 4.35m wingspan, 6 LRK's, Søren Kjaer Nielssen
http://photos.groups.yahoo.com/group/lrk-torquemax/lst mailing list’s pictures and drawings archive
http://home.t-online.de/home/e-huber/BL/BLEigen.html slow-flight, drawings, tips, Kai Huber
http://martin.muennich.bei.t-online.de mini-lrk drawings, tests, Martin Münnich
http://www.geocities.com/roman65536/fly/lrk.html winding/wire diameter/prop calculation tool, canard delta, Roman Pollak
http://www.cenara.com/users/ce00359/Default.htm pics & diagrams, Christian Johansson
http://www.cenara.com/users/ce00359/LRK220.htm, LRK ‘inrunner’ by Christian Johansson
http://www.online-club.de/~rp10337 lrk & piccolo helicopter
http://members.aol.com/renderwahn/Bild/Start.html pole & magnet combinations
Material & kit suppliers
http://ww.batt-mann.de/#torque Stator material, magnets
http://www.torcman.de Soon in English too. Stator material, magnets, turned parts, shafts, ball-bearings, wire, kits & complete motors and a very good downloadable construction/assembly manual.
http://www.flyware.de Soon in English too. Stator material, magnets, turned parts, shafts, ball-bearings, wire, kits, assembly tools, complete motors.
Diy brushless controller
While on the subject of diy: Jo Aichinger from Austria has three versions of his diy brushless Speedy-BL: SBL-classic, SBL-mini and SBL-sprint. These controllers work fine with lrk-torquemax motors, but other makes are also suited, albeit some better than others. The SBL-sprint has separate powerboards. Jo can supply the printed circuit board and programmed microprocessors:
The information is German only for now (classic also in English), but the tables speak for themselves. If you don’t want to hunt for components, buy it as a kit or ready-made:
Last edited by Ron van Sommeren; Feb 05, 2002 at 07:27 PM.
|Sep 12, 2002, 11:52 AM|
Model Motors ?
I know that it is not an outrunner, but it is relatively new, and brushless - and I have two !
Who else has tried the MiniAC1215/16 motor ?
They spin a Gunther VERY fast on 7-cell 500AR packs, with good duration . . .
|Sep 12, 2002, 12:23 PM|
Who else? Me.. . I am really liking the AC1215/16 motor. It has been a 'super' good replacement for the 370 motor that was in my SB. Not going to buy a 370 brushed again . Flying with it geared.
Keven, So you like it direct drive with the gunther prop? What were you flying this on? The Boomerrang?
|Sep 12, 2002, 12:31 PM|
As mentioned above, I have two MiniAC1215/16 motors, and would love to do a twin with these !
Any idea as to whether or not one of the controllers in the above link will work both motors at once ?
|Sep 12, 2002, 12:37 PM|
Yes - after a fashion !
I'm going to put one into an MFA Olympus this weekend with an 8" x 4" Slim Prop . . .
|Sep 12, 2002, 01:05 PM|
It's being done as we speak, Fourleaf is working on a neo magneted twelve pole, six winding true LRK micro for parkflyers.
I know the demand is present, I mean who as an E-modeler, wouldn't love a motor that is a lightweight replacement for a brush motor/geardrive? I'm suprized that one of the European manufacturers of brushless motors hasn't tooled up for this already. Maybe its time we Americans carried the ball for yooze guys. I know Pletti has one already, but the price.....
|Sep 12, 2002, 01:26 PM|
United States, VA, Arlington
Joined Dec 1996
This is fascinating stuff, and I'll be in the linequeue for fourleaf's outrunner - more so if it will replace that cheapo brushed motor in my SB or Duskstik.
To anyone who's worrying about the cost - you only have to fly one to quit that habit. I've been working my way backwards from my first brushless (20 cells!) and am now down to a mere ten . The only thing that can touch them for no-fuss reliability is my dear old Astro cobalt collection, but they are no match when it comes to weight. My AXI 2820/10 with ESC weighs a half ounce less than my AF035G on its ownsome.
Assuming that kind of benefit translates downward to parkflier sizes, we could be seeing Duskstiks becoming Nightstiks, and Switchbacks doing amazing things for ages.
|Sep 12, 2002, 02:41 PM|
Joined May 2002
I've been watching the can-vs-brushless motor race for some time and have a couple of observations. The reason can motors have been so successful is their low cost. A motor/gearbox AND an ESC can easily be had for $50.00 or less. Given reasonable usage -ie- refraining from cooking the motors trying to get more power than they can deliver, they provide good value and performance for the bulk of the people involved in modeling.
The reason brushless has been slow to come on is, first, cost. The small brushless motors can be purchased for $50.00 or $60.00 dollars, but the ESC costs about the same, so motor and controller runs at least $100.00 or more. Not everyone in the hobby is looking for prop hanging vertical to speck out performance. The power-to-the-edge-of-possible group is the minority in the hobby. The manufacturers see this in their sales.
Although prices will come down and there will be more motors to choose from, brushless will always be more expensive and aimed at a small segment of the people involved in the hobby.
Having said that, I'm in the market for a 180 sized brushless WITH controller in the $75.00 range.
|Sep 12, 2002, 03:17 PM|
....besides I've already got the controller I use with my CD-ROM motors. I will say this in defense of ferrites, I've had a bit of a renaissance, (or maybe it's renascence) about sp 280 motors, they seem to have a nice efficiencey for a cheapy motor.
|Sep 12, 2002, 03:18 PM|
Des Moines Municipal, Iowa, United States
Joined May 2002
I continue to make progress - getting closer and closer.
Depends - one thing to keep in mind is "value" and long term costs. Outside of potential performance increase, a good brushless motor will last a long, long time compared to a brushed can. Sure, initial costs are lower for a can, but when you consider longevity and the price of replacing can motors that wear out over time - they can actually be MORE expensive than a brushless setup. If you buy quality, you buy once, rather than over and over again.
|Sep 12, 2002, 03:24 PM|
Another thing too...
Some of the CD-ROM motors already have some decent magnet rings in them. Mr. Bungle from the Antipodes posted in Micro and Indoor, about the grey compounded ring magnets in the latest CD drive spindle motors.
I think that the strength of the magnet rings were half ways between good ferrite and cobalt magnets
Pretty cool huh?
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