Ron v. Sommeren

Do-it-yourself brushless e-motor drawings
From slowflight up to 2kW and helicopter motors.

Introduction
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.

Technical
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:
http://www.yahoogroups.com/group/lrk-torquemax
To join the list, click ‘Join This Group’ in upper-righthand corner, or send an empty message to [email protected].
If you can read a bit of German, check out the German lrk-torquemax forum:
http://www.rconline.net >> rc-forum >> lrk-motoren

Construction articles & tools & pictures
Construction article I:
http://www.aerodesign.de/peter/2001/...4-2000_eng.htm
Construction article II:
http://www.aerodesign.de/peter/2001/...1_2001_eng.htm
The bible, winding calculation tool, diagrams, measurements, some theory:
http://www.aerodesign.de/peter/2001/...index_eng.html
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:
http://groups.yahoo.com/group/lrk-to...ny%20turns.xls
Winding calculation tool by Roman Pollak:
http://www.geocities.com/roman65536/fly/mot.html

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 suppliers
http://www.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:
http://www.geocities.com/SouthBeach/...2/speedybl.htm
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:
http://www.megra-elektronik.de

chase044

My Feedback: (1)

any english sites

Ron v. Sommeren

Discussiongroup, moderated by yours truly:
http://www.yahoogroups.com/group/lrk-torquemax/

Construction article I:
http://www.aerodesign.de/peter/2001/...4-2000_eng.htm
Construction article II:
http://www.aerodesign.de/peter/2001/...1_2001_eng.htm
The bible, winding calculation tool, diagrams, measurements, some theory:
http://www.aerodesign.de/peter/2001/...index_eng.html

Kit manufacturers:
http://www.high-torque.com
http://www.torcman.de/
http://www.torcman.de/index_e.htm / http://www.maxrivers.com (UK)