Thread: Build Log 100% scale, Electric Lazair
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Old Jun 21, 2011, 02:44 AM
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Dale,

Re. thermally conductive resin: this provides 2 functions - discouraging hot spots and conducting heat to the stator (& thence away via a heatsink and/or stator ribs in airflow). We found in our burnt-out windings that some parts were still fine; the problem is that a hot spot increases resistance and then gets hotter still - so good uniformity reduces thermal runaway. The thing is that, to be effective, you need a vaccum rig to impegnate the resin into the windings. Once applied though, the air gaps between adjacent pole windings are pretty much unchanged - its mainly the air gaps between the windings and to the stator steel which are filled.

I think the Joby motors look a really good match for the Lazair. Guesstimating from the motor dimensions, you should be able to get ~50% more torque (& power) from these than from the Turnigys. I can't quite tell from their photo, but it looks like the windings are varnished anyway - so that should help the heat transfer. Personally, I would still think about a radial fan to draw air though the insides - it looks like the outside cooling fins will get some prop wash anyway. Very best of luck with it - I look forward to hearing how they perform.

Paul
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