Indoor Scene - CD ROM Motors

After a very satisfying long weekend at the Champs, it is time to start thinking forward for the new competition year ahead. Indoor 1 to be held a Digby on the 13/14^th November will be primarily for duration class models, i.e. EZB, Hand Launch Glider, Co2 Duration, and Helicopter. For anyone interested in wanting to have a go at these models, I have a starter pack of plans and information for all these classes, just send me your postal address and I’ll send you a copy, a couple of postage stamps next time you see me will cover the hassle.

I was going to do an article on building an EZB model for this edition, showing my way of constructing and covering these models. Unfortunately, my friendly furry helpers had other ideas and decided that the wiggly bits of balsa would be their next toy, so I shall carry this over to the next edition while I cut some more pieces in secret.

Instead, I have a new long-term project that I have been toying with that might be of interest to anyone who like me likes to dabble, especially to the R/C power boy’s, this is Indoor R/C.

This type of flying is catching on in a big way throughout the UK, and advances in technology (motors and batteries) are racing forward. There are a lot of Slow fly and Park fly kits on the market made from moulded foam at a reasonable price complete with motors and sometimes other items to get them flying quickly. These are fine, but I for one have never been satisfied just doing circuits and figure eights with the occasional landing. Something manoeuvrable and aerobatic is the way to get the palms of your hands sweaty. A model like the TINY (above) whilst not particularly fast will certainly get the pulse racing and raise your blood pressure avoiding the six sides of the hanger, (ask Mike Goldby, who commented after flying it, ‘I’ve never concentrated so hard in such a short time, got a towel’).

Power is the key, combined with a low all up flying weight. The TINY tipped the scales at 135g ready to fly, (most civvy venues have a max flying weight of 150g) this using a GWS IPS 180 size carbon brush motor turning a 9x7 prop through a gearbox and power supplied by 2 Li Poly cells. Whilst this is adequate, more power would be nice. However, like all things, more power usually means more weight, unless we go brushless, which means lots of money; or does it. This brings me to the project. George Bennett dropped the idea at the Champs after watching Gary Chiles flying his DEPRON Extra 3D model at the campsite on Honington’s sports field, he said, ‘all you need is an old CD Rom motor, change the magnets and windings, and you have a brushless motor’. Could this almost be something for nothing?

As I said above, this is a new project, and I do not yet have a working motor. That is because it requires a brushless speed controller, which at present I do not have. A normal brushed one will not work these motors and suitable ones cost from £30 to £40, I am still deliberating on which one I will get, (Something for a latter column) but I have been re-working old CD Rom motors. Once completed, these motors weigh c24g, are much more powerful than brushed motors, and as a bonus, are more economical on battery consumption.

For anyone wishing to have a go at trying these re-worked CD Rom motors, my research has come up with a few web sites that have been more than useful and have cleared up many grey areas. (After all, I was only a MT Tech) In effect, these brushless motors are 3 phase motors, with the coils wound in either star or delta configurations, the illustrations show windings in star.

More work will be needed to fabricate a bearing tube to mount the stator on and support the prop shaft, and also a prop driver/saver. To save re-writing all the gen, I refer you to the following web addresses:

Both these sites give good guidance and explanations on how to convert the drive motors, ideally, later high-speed drive motors are the ones to go for (48x to 52x). I am trying this root, mainly to see if the motor works and whether it will be cost effective.

Of course, if you fancy a go at trying these motors and do not feel you have the resources to fabricate the necessary items, or you are a bit flush and don’t mind throwing a few pounds at the project, you could purchase a kit of parts as an ARTF. If available, a kit from:

http://www.electricflight.co.uk

will cost £16.95 (CD Rom motor set). Click on Products > Motors & G/boxes > CD Rom Type Motors. This site also has good informative pages on their Instructions/Info link which covers instructions for assembling the CD Rom motor set, Li-Poly cells, Chargers and lots of other good stuff.

Another hit is:

http://www.brushlessmotors.co.uk

This is a lovely site with a motor kit @ £29.95 incorporating a CNC rotor and other parts including the bearing mount tube. You will have to wind the coils on the stator and fix in the magnets (although these can be purchased ready fitted). All parts are available individually and are reasonably priced.

Has this wet your appetite to try Indoor R/C yet. Well if it has, then this is a cheap way of getting a model plan. Again, a few web sites have some free downloads for suitable models. These are usually in PDF format and print out full size on multiple A4 sheets that just need trimming to size and taping together. Some will download in DFX files if you have the means to open and print these off.

For the plans of TINY, a fun fly aerobat, showing a conventional or ‘V’ tail, visit:

http://www.rcmicroflight.com

This is a subscription magazine, but if you click on Downloadable Plans then continue onto page 2, TINY will be found at the bottom of the page and is a free plan. The model is constructed from conventional balsa with a carbon tube (arrow shaft) fuselage.

http://www.flyelectric.ukgateway.net

On here will be a number of free plans for Depron type models and others again on A4 PDF files. These include Extra 300, Ultimate Bipe and Mumbo Minor 3D types. More hits on Li Poly cells and charging circuits for the home builder (useful), plus more on CD Rom motor conversion, nice.

Lastly, this site. An up and coming hit with the promise of more to come:

http://www.jetworksmodels.com

Click on 3D Airplanes and you should be able to download a couple of plans for:

3DX a 3D aerobatic flyer

Ultimate Bipe 3D aerobatic flyer

More free plans are due shortly and also building guides to help construction.

I hope that this article might convert some of you hardened R/C flyers to come on in out of the cold and join in the addictive fun of indoor flying and perhaps have a go at fiddling with things that may promote additional interests. All it took for this spread was someone mentioning a CD Rom motor.

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Phil Morgan

rafmaa-indoor@rafmaa.co.uk