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8 motor power system, any suggestions?

Old 02-26-2013, 02:49 PM
  #26  
road king 97
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Originally Posted by hayofstacks View Post
I se nothing wrong with adding 6" or so of wire, like many parrellel and series conectors are wired up. This should be enough to get all of the esc's mounted in the wing.

Supposedly, adding length to the motor wires isn't really an issue.

Dc greatly increases load and loses efficency, requiring a lot of power loss the longer the leads get. They get around this by going with much larger wire when you increase length. The motor wires are esentually ac voltage pulsed to allow the motor to spin. The speed control converts it to a higher voltage pulse. The higher voltage the ac is, the less loss there is overdistance.

In the early days of electrical power, it was way more expensive to run dc electricity. It could also only be transported about 2 miles. This is why the first places with power were industrial areas and big citys. Now that we rely on ac, power is sent from my home town in utah, to california.
Our wings, mine and neons is over 80 inches so the most outside necelle is around 25 to 30 inches away from his lipo he is getting away with running the wires that far away without getting any spikes to the esc;s.
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Old 02-26-2013, 02:58 PM
  #27  
r_kopka
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The problem with brushed motors is that there are only big and expensive motors with low rpm/Vs. So you probably need a (8) gearbox(es). Especially if you want to go 4-bladed.

A cheap brushed motor weighs at least twice as much as a comparable brushless motor and has significantly less efficency. Add the weight of the gearbox and multiply it with 8 and you get a lot of weight added. And if you use the motors at their limits you have to change them often because of worn brushes.

E.g. Speed400 ~80-90g Gearbox 30g(?) brushless ~40g -> Diff 80g x 8 -> 640g

Instead of small lipos at the motors I would use electrolyte condensators which are less trouble to handle.

RK
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Old 02-26-2013, 03:53 PM
  #28  
HugoW
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That AC/DC comparisson does make sense, thank you. BTW, adding 6 inches won't nearly get the ESCs in the wing! This fuse will be about 1.900mm / 75" long!

I'm making a test set-up with the motor and prop I have chosen, let's see what that does. I was amazed by the small motor I think I need, then again there will be 8 on the plane producing a nice lot of power. And it's not a 3D machine. If this set-up works, I need only fairly thin wires, and making long wires between ESC and motor won't be a huge wait gain. I allways think about mega gauge wiring, but for a 10A motor that won't be required.

Cheers,

Hugo
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Old 02-26-2013, 04:33 PM
  #29  
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Originally Posted by HugoW View Post
That AC/DC comparisson does make sense, thank you. BTW, adding 6 inches won't nearly get the ESCs in the wing! This fuse will be about 1.900mm / 75" long!

I'm making a test set-up with the motor and prop I have chosen, let's see what that does. I was amazed by the small motor I think I need, then again there will be 8 on the plane producing a nice lot of power. And it's not a 3D machine. If this set-up works, I need only fairly thin wires, and making long wires between ESC and motor won't be a huge wait gain. I allways think about mega gauge wiring, but for a 10A motor that won't be required.

Cheers,

Hugo
You can look at post 127 here in neons build to see what he did to put escs in his necelles . joe http://www.rcgroups.com/forums/showt...1597636&page=9
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