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Electric Stunt => Gettin all AMP'ed up! => Topic started by: Igor Burger on August 20, 2012, 07:23:02 AM
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forecast for Bulgaria says hot hot hot hot VD~ ... so I decided to make cooling for my AXI ... after first flights success :- )))) ... I hope my AXI will survive those conditions :- ))
all done from piece of alu "L" profile and mounted between firewall and motor stator ... "quick" solution but I like it anyway
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Very cool! #^
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You are a genius Igor. y1
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well ... I am from country where we often had in past as we say "knit the string out of the @#$%" ... so I did one :- )))))))))
but thanx anyway :- )))))))))
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Good idea for conductive cooling from the stator. I wouldn't use it instead of air through the motor, though -- only as a supplement.
If you have some white silicone heat sink goo, be sure to use it.
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Very nice, every little bit helps. Do you have any tests showing the cooling effect?
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Yesterday we had very hot day here, 35 degrees C and motor had aproximately same temperature than days before at 27 degrees without cooler, so for me sucessful fix :- ))
I use 6s battery and charge back ~2000mAh after 5 min. flight so motor has feeding 24A x 22.2V = 530W ... that is more than healthy for such small AXI :-)))
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Igor,
Thats nice, but it reminds me to go get a haircut x: LL~ LL~. But seriously good luck to U and all the folks flying
electric. I hope U all can get together and have a impromptu seminar and tell us all about it. ( Hint Hint!)
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Igor,
Maybe you can anodize the heat sink black to make it even more efficient!! ;D
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Yesterday we had very hot day here, 35 degrees C and motor had aproximately same temperature than days before at 27 degrees without cooler, so for me sucessful fix :- ))
I use 6s battery and charge back ~2000mAh after 5 min. flight so motor has feeding 24A x 22.2V = 530W ... that is more than healthy for such small AXI :-)))
Any PHDs in the crowd. My question is: does the motor have to dissipate 530Ws of heat? I thought the efficiency number determined the heating. A 90% efficient motor would dissipate 53W of heat at 530W input. Is this true or not? Of course 53W is still a bunch.
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Any PHDs in the crowd. My question is: does the motor have to dissipate 530Ws of heat? I thought the efficiency number determined the heating. A 90% efficient motor would dissipate 53W of heat at 530W input. Is this true or not?
True. You don't need a PhD for that -- you just need to know that energy in equals energy out plus energy stored, and that for the purposes of this discussion a motor doesn't store any energy.
Of course 53W is still a bunch.
Yup.
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Yes yes ... Today it survived without troubles in 38 degrees repeated flights without complete cooling, so It looks OK
BTW do not beleive that such motor in PWM mode can run at 90% efficiency, I think also 80 is to optimistic. Especially with active regulation.
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BTW do not believe that such motor in PWM mode can run at 90% efficiency, I think also 80 is to optimistic. Especially with active regulation.
I'm not sure that an outrunner can achieve 90% efficiency at all, much less at useful power levels with a PWM drive. But I'd be happy to be wrong.
I lamented on this forum at one point that none of the magazines that I take currently publish motor efficiency test results -- someone came back and named a magazine that does. The name totally escapes me, but you could look.
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I have a slightly different question, how does the efficiency of an electric motor of the type we use in control line compare to the efficiency of an IC engine of comparable performance. In short are we more efficient or less efficient?
Andy
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IMO much less efficient.
A thermal engine (converting heat to work) is bound by Carnotīs thermodynamics law. It is in the order of 40% at the most. Diesels are more efficient on account of higher compression ratio.
Electric motors are converting work to work, i.e. in a sense the stored energy in the battery is "condensed" work.
Luiz
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Good idea for a heat sink!
In a future project, what do you think about installing a micro fan? (various sizes)
Would it draw too much current?, Would ducted ram air be more efficient?
http://www.ebay.com/itm/Micro-Cooling-Fan-5V-25mm-25X25X6mm-2-Wire-Plug-/150711337363?pt=US_CPU_Fans_Heatsinks&hash=item2317188193
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I think that since you're moving through the air anyway, that properly ducted ram air would be better than fans.