Electric Motors - attn. Lief

[RyanShort]

Leif,

Have you actually finished a model with a working motor yet?

Ryan

[Leif Ohlsson]

Yes, but not as many as I have dreamed about, planned for, and sometimes written about.

It started many years ago with a 1/25 scratchbuilt Tummelisa. The motor was a small one, originally to be used for much smaller plastic models. There was two surplus TV memory NiCads aboard. After a while of successful running the little motor burned out, no doubt due to excessive voltage and load (big prop, plus rotating replica rotary engine).

Then I built two models with larger toy 1,5V motors and lead-outs for external battery; the Schreiber Fokker Triplane (with rotating replica rotary engine), and the Westland Lysander (MM, rescaled to 1/25). Worked fine, but too much trouble to attach the battery all the time.

I learned the lesson and have included on-board rechargeable batteries in the two next models, including recharging socket and on-off switch. In 1/16 scale this is easy.

The Halinski Airacobra (rescaled to 1/16) used a single 1,5V NiCad. It still works fine, although the prop doesn't make more than a little bit more than idle. On the other hand, it doesn't need recharging more than once every Christmas or so (you don't turn it on that often). The twin-engined DH88 Comet (also rescaled to 1/16) has double sets of 1,5-3V motors and 3V NiMh accus for a little bit of better rpms (still just taxiing power I guess). Chargers are surplus 6-9V (the kind you just stick in the wall).

I have dabbled with the very small motors used for vibrating mobile phones, but they are too small and finicky for me. Others have done very well with them.

I think I have found my standard for future models - 1/16 scale makes everything (including building) easier; 1,5-3V motors are readily available and cheap; 3V small accu-packs likewise. Total cost is not more than for a purchased model, plus ink for printing the enlarged version.

Rotary engines provide a special and satisfying challenge, since you very much like to sort of let the motor be as far forward as possible, actually half inside the rotary replica engine, which then rotates around the electric motor. The model has to be assembled in a certain order - motor in fuselage, then rotary engine on to the motor axis, then cowling, then prop onto replica rotary engine.

Ordinary engines are easy - just mount the motor in the front former, and stick the prop/spinner onto it.

As for chargers, I think it's good to settle on one voltage, and one plug size, if you plan to build a motorized model (with potential follow-ups). Then you can easily install proper resistors in the model to regulate the charging current. If not, it's no big deal, since the accus will stand a certain amount of quick-charging. After all, they are not supposed to carry out some real work.

Leif

[Leif Ohlsson]

Your question triggered a trip down memory lane, Ryan, through the archives of my hard-disc. If it can serve to inspire someone else to go try motorization of their beautiful upcoming projects, I guess I'll settle for that as enough of an excuse.

1. Tummelisa 1/25 - replica rotary engine was really rotating with the prop, until the undersized motor burned out. Actually double NiCads on board, which was somewhat of a feat at that scale.

2. Westland Lysander 1/25 - you can just about spot the electric motor, painted black, and satisfyingly unobtrusive. I've kept to this size of motor ever since. No battery on board, however, which is a major drawback.

3-5. Bell Airacobra 1/16 - various stages of laying out the hardware on to formers, etc. Note successful trial run. Was very happy at that time, I remember.

6-7. Finished Airacobra filling up at the charging station, and then test-running. Note very unobtrusive on-off switch, just under the "21" on the right-hand side.

Are you contemplating something really challenging, Ryan? I'd be very happy to see one of you L-birds spinning its prop. Makes for a great exhibition piece, particularly at larger scales. Or could it even be a 1/16 Mitchell bomber? Impressive size, two props spinning, very convincing sound, LED lights from the cockpit and navigation lights glowing. What a sight it would be...

Kind wishes, Leif

[RyanShort]

Well, I've got several pager motors coming, as well as some battery packs, but frankly, I am not that great at electronics, so I'm going to have to do some work to get something done. I was thinking a nice L-5 with a spinning prop would be fun. Wouldn't mind motorizing a few other aircraft as well in the future, if I can get one figured out and finished first.
I wonder if a motorized L-5 in 1/48 with enough power would take off of a scale Brodie Device...

Ryan

[Don Boose]

Leif -- So many beautiful models and so much innovation! Bravo!

Ryan -- I want to see the LST model that you put under the Brodie Device with the motorized 1/48 L-5.

Don

[RyanShort]

Ah, but there was a ground-based version!

Ryan

[stone]

Leif,
Noticed from your fascinating model shots (You realy had me fooled at first with that DH 88 shot!) that you are also using a Mac. Have you ever managed to find one of those scaling progs. for Mac ? All the ones I could find only ran on Windows machines, very frustrating.
I should very much like to bring my L-19 up or down to a proper scale size.
Any suggestions?
Regards,
Serge

[dansls1]

Serge,
Here's an online scale calculator. I found it using a quick yahoo search, I know there is at least one more out there that is web based instead of a downloadable program if this one doesn't work for you.
Hope this helps

[stone]

Hello Dan,
thanks very much for the pointer in the right direction. Salvation at last !
The scales are tipped ! It sure helps.
Thanks again,
Serge

[dansls1]

Glad to help Serge