Holland: do-it-yourself 'cheap' brushless e-motor links
Ron van Sommeren
First of all, the name for these homebuilt do-it-yourself brushless
outrunner e-motors, LRK-torquemax, is *not* a company or a product. It's
the electro-mechanical principle used in these motors. I'm trying to get
it out of Germany and into the world. The original construction articles
on these motors were published in the German quarterly Elektro Modell
magazine, issues 2000/4 and 2001/1-2-3, http://www.neckar-verlag.de
publishers.
LRK-Torquemax brushless outrunners can be made using a relatively simple
lathe. One has to be capable of making a ball-bearing seating though. The
lrk-torquemax principle features a high torque at lower rpm, compared to a
conventional high-revving brushless layout. There's no need for a gearbox,
which means LESS WEIGHT, LESS LOSSES, LOWER COSTS and NO GEAR NOISE. 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 and
magnet length you want. It's possible to rewind the motor (or even change
the complete stator) for a different type of plane. Use an old brushed
motor or gut your CD-ROM player, harddisk, wife's blowdryer, or your own
;-) , powerdrill or fanmotor for stator material.
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 by e-modellers, range from slow-flight to 2kW and even
direct drive versions for helicopters. It works with normal brushless
controllers although some are better suited than others.
construction article I:
www.aerodesign.de/peter/2001/LRK350/EM-4-2000/LRK-EM-4-2000_eng.htm
construction article 2:
www.aerodesign.de/peter/2001/LRK350/EM-1-2001/LRK_EM_1_2001_eng.htm
More construction articles, design formulas, diagrams, drawings,
measurements, controller theory, a test stand drawings/design.
www.aerodesign.de/peter/2001/LRK350/index_eng.html
All in English and German.
Lots of pictures, some brilliant ideas (e.g. the tail of a glider
*through* a motor in pusher configuration):
http://members.aol.com/TorquemaxLRK
http://members.aol.com/schwaabbel
English E-mail discussion list (still young, started last August):
www.yahoogroups.com/group/lrk-torquemax
If you read a bit of German, check out the German lrk-torquemax forum,
very, very impressive technical discussions:
http://www.rconline.net/ >>> rc-forum >>> lrk-motoren
Suppliers:
http://www.batt-mann.de stator sheets, magnets
http://www.flyware.de Online lrk-torquemax shopping: turned parts, shafts,
ball-bearings, wire, stator sheets, magnets, kits. English version by the
end of the year. Deliveries *worldwide*.
While we're on the subject of do-it-yourself: Jo Aichinger from Austria
has developed two new versions of his do-it-yourself homebuild brushless
SBL-controllers: SBL-classic, SBL-mini
and SBL-sprint. The latter has separate powerboards.
www.geocities.com/SouthBeach/Port/1592/speedybl.htm
The information is German only for now (classic also in English), but the
tables speak for themselves.
As a trained electronics/software engineer and as a modeller, I'm very
enthusiastic about lrk-torquemax homebuilt motors and do-it-yourself
brushless controllers. I think it's a brilliant concept, no need for
gearbox, big prop, ... etc. etc. One could almost say, after the initial
publication in Elektro Modell magazine, it became a joint internet
development (like the Linux operating system???, the analogy sounds good
to me).
About me, I'm the lrk-torquemax English language mailing list monitor. I'm
40 years young. I'll be organising my club's 2nd lrk-torquemax meeting &
11th E-fly-in, June 23rd see http://home.hetnet.nl/~ronvans/ Drop by when
you are in the neighbourhood that day ;-) Picture on my site is of my
big and little girl :-)
Met vriendelijke groet ;-) Ron van Sommeren, the Netherlands