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Old Apr 13, 2016, 03:06 PM
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20mm EDF

Hope to test this over the weekend.

Using a 8mm BL tail rotor motor for the MCPX heli.

... tiny little sucker ...
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Old Apr 13, 2016, 04:23 PM
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That looks very neat.
Tiny yes but how much thrust and weight?
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Old Apr 14, 2016, 08:53 AM
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I'm going to try and get some numbers for this, as is, and then cut off the tail cone and try it again. I would like to get 30g of thrust on 2S.

I'm going to attempt to balance the fan. Working with something this small is going to be a challenge, that's for sure !
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Old Apr 15, 2016, 05:11 AM
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30 grams would be good. Something like this would be good for a small scale model, where the weight really matters and the payoff could make a difference. From what I remember, I probably didn't get any more than 30 grams of thrust from my EDF30 Vampire, using a much heavier Feigao motor, BA 2.5gm servos, and GWS Pico receiver years ago. Still flew well, but done again with modern gear and built lighter, I could see the potential for an ultra light BL fan, in a scale app which weighs a bit more than a profile and requires BL power. FWIW something like this could even be practical in models like the foamie UMs out now. Not as fast, but would be easier to fly and land at the lighter weight. Shaving off 10 grams of battery and motor weight makes a lot of difference on these small models. Could make them better indoor candidates.
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Old Apr 15, 2016, 09:46 AM
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I'm really not sure what I would put this in. I'm at a loss with what electronics to use, would I use a brick or separate components or should I use actuators (of which I have no knowledge) ?
Another thing is that it might require some complicated build techniques such as a molded foam fuse.

Of course this all depends on the thrust I can get out of it ...

But it's all fun !

Thanks.
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Old Apr 15, 2016, 08:49 PM
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30 grams on 2s shouldn't be a problem. Here's a couple 1s 20's I did a few years age. Thrust was about 20 grams.
http://www.rcgroups.com/forums/showthread.php?t=1159390

Nice to see some experimenting going on!
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Old Apr 16, 2016, 01:42 PM
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All things considered I'm happy with the balancing ... I didn't even think I'd get this close.

I think I got lucky !


20160416 141949 (0 min 24 sec)
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Old Apr 16, 2016, 03:12 PM
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Jumo004,
Very slick micro balancer!
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Old Apr 16, 2016, 09:49 PM
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It is a nice little part there. Seems far better than a single rod setup. The problem with those arrangements is that they have to be beyond Swiss Watch precision, to get good results with parts this small. With this setup, even if it's not 100% perfectly straight or level, you start to see a pattern when observing the rotor roll across the bars, which will show you which side is heavy/light.
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Old Apr 17, 2016, 08:42 AM
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Quote:
Originally Posted by pdawg View Post
Jumo004,
Very slick micro balancer!
Thanks !

Quote:
Originally Posted by AntiArf View Post
It is a nice little part there. Seems far better than a single rod setup. The problem with those arrangements is that they have to be beyond Swiss Watch precision, to get good results with parts this small. With this setup, even if it's not 100% perfectly straight or level, you start to see a pattern when observing the rotor roll across the bars, which will show you which side is heavy/light.


Yea, after a few tries you get the hang of it ...
One problem I had with this setup was that the rods were slightly magnetized and that effected the cross bar roll. I'm still not sure how that happens, maybe I bought them that way or maybe it happened when I polished them but with this tiny (.032 dia) cross rod it doesn't seem to be a problem.

In my 'never ending quest' to balance these small fans I made this setup.
It works okay .... but I like the other one a little better.
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Old Apr 17, 2016, 11:56 AM
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.... disappointing ....

What I should do is make a more aggressive fan (higher pitch). That would help for sure also I think the bushings have to be replaced with bearings and I'm wondering if a higher KV would help.

I ordered a GP Ammo 10-15-11500kv motor. It's 2mm bigger in diameter then this motor so I'm thinking of trying a 22mm fan size. It also has bearings ... OR ... I'll just keep playing with 30mm fans, they're frustrating enough ....


20160417 120211 (0 min 49 sec)
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Old Apr 17, 2016, 12:18 PM
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Still not bad, considering how little power used. You could use a really light lipo for 1A. I'm hoping the light weight GP motor pays off in the Comet, when I get around to flying it. Waiting for a bit more grass growth. There's more powerful motors, but not much lighter in the 10mm size.
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Old Apr 17, 2016, 12:21 PM
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Perhaps you might consider grinding concentric points on either end of your balance axle.
Stick a dime sized Neo magnet to each Vise Jaw..then open the vise to acomodate the axle length.. only one end needs touch a magnet.. for an even more accurate and dead simple to use Balancer?
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Old Apr 17, 2016, 12:56 PM
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The unknown factor is the efflux. Try mounting the EDF in a simple profile test bird. You may be surprised.
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Old Apr 17, 2016, 01:49 PM
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Quote:
Originally Posted by Bare View Post
Perhaps you might consider grinding concentric points on either end of your balance axle.
Stick a dime sized Neo magnet to each Vise Jaw..then open the vise to acomodate the axle length.. only one end needs touch a magnet.. for an even more accurate and dead simple to use Balancer?

I've all but given up on the magnetic balancer. I know the boat guys use them for their props and seem to get good results but everyone I tried left me pulling my hair out.
The problem I was having was grinding a PERFECT conical shape on the balancing rod. Anything less then PERFECT (at least in my case) didn't work. Another thing was that the balancing rod would get magnetized and would fight the field in the disc magnet. They would eventually align but always in the same spot which was never in the balance position. I admitted defeat and moved on ...

This was an early magnetic balancer that I made ...
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