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Building
high-torque/no-gearbox
brushless e-motors From slowflight up to high performance 3kW and helicopter versions Ron van Sommeren
Introduction LRK-torquemax certainly is not a company or a product. Therefore, this is not spam; I rest my case!
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. The German builders/modellers who started this are too modest about their group achievement, I think. I myself am Dutch.
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 and magnet length and the number of windings you want. It's possible to rewind the motor (or even swap the complete stator) for a different type of application.
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. ESC manufacturers have already updated or are in the process of updating their controller software to make the controllers suited for this type of motor. You can use an old brushed motor or gut your CD-ROM player, hard-disk, wife's blowdryer, or your own, powertool or fanmotor for stator material. Check the bin of a motor/transformer rewind shop for material. You can do a little dumpster jumping at metal stampers, scrap yards, the local dump. Use shafts from VCR’s or broken drills. Or you can buy the parts. This document contains a suppliers list. Discussion & help
Construction articles & tools & pictures
All in English and German.
Material suppliers
More LRK-torquemax builders’ homepages
Diy brushless controller While on the subject of diy: Jo Aichinger from Austria has three versions of his do-it-yourself brushless Speedy-BL controller: 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/Port/1592/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:
About me Not very
relevant, only to show that there’s a person behind this and not
a company. As a trained electronics/software engineer and as a modeller,
I'm very enthusiastic about lrk-torquemax homebuilt motors. I think it's
a brilliant concept, no need for gearbox, big prop, etc. etc. One could
almost say that, after the initial publication in Elektro Modell
magazine, it became a joint German internet development. A bit like the
Linux operating system? The analogy sounds good to me. http://home.hetnet.nl/~ronvans/
tel: ++ 31 487 519483 [Please note that I have not tested every one of the links provided by Ron, but I feel confident I have copied them correctly.] |
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GPS - the way ahead? Gordon Cook makes a light-hearted response to airspace #55 I appreciated the article on Pete Well's Cub fitted with the GPS and particularly the track across and around our field. Pete is a great tinkerer and I know enjoys 'experimenting'. I was involved with him on the same task a couple of years back when we used an earlier GPS strapped to an aerobatic plane and flew a single large rectangle, which surprised us just how far away we travel. This new trial led me to two thoughts. Firstly, I read that that pioneer of extreme flight, Maynard Hill, is planning to fly a model non-stop across the Atlantic this year [see clubscene #53]. I remember this has apparently already been done but it did not seem to get the exposure it deserved. Maynard has been one of those names I have tracked ever since starting this caper in 1963. He did then, and perhaps still does, hold the world Altitude and Duration records. Something like 37,000 feet at the time. Must have had good eyesight! I know it wasn't done visually but do you know how? The point is, I wonder if he is using GPS. I bet he is. Could Pete send the Cub back to the States to land on Maynard's home field? Secondly, you will
be aware today that the UK Government is floating the idea of using GPS
to track cars, and in turn you and me, to extract (higher) road tolls.
Singapore is cited as a working example. I went there recently and I can
tell you it is not popular with the locals for those very two reasons. I am pleased to say though that this aviation scheme is doomed. After all, how many models do you see flying in Singapore?
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Want some extra planes for the FMS model flight simulator? Phil Hayward has passed on a source - http://www.interq.or.jp/sun/cyber/fms_aircraft_e.html Thanks, Phil |
Click the e-mail icon in the left frame to e-mail me now!
This
document contains more than twenty links to sites dedicated or related
to the do-it-yourself (diy) building of brushless outrunner electric motors
for (aero)modelling. 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! The LRK acronym stands for Lucas,
Retzbach and Kühfuss who adapted the concept for our modelling
purposes.