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Engine basics => Engine set up tips => Topic started by: Chuck_Smith on April 18, 2019, 06:14:39 AM
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Have a motor that has run great for two seasons. Over the winter I replaced the aluminum spinner with CF. This is a full cowl install.
First flight overheated. Second flight after richening, still overheated but deeper into the run.
Scratching my head over was wrong the only variable that had changed was the spinner. I reached down and the metal backplate was still really warm after sitting for while. Hmmm.
Back home, replaced the CF spinner with the original metal. Next flight motor ran great. After the run the spinner was cool to the touch as was the backplate.
Very interesting data there. Tried the switch on a different plane. Similar results, not as dramatic.
The indication here is that the conductive path through the backplate to the spinner which sits in pretty much undisturbed airflow makes for efficient forced convection cooling.
I've often designed/recommended aluminum "heat flingers" that sit outside the bearing frames for rotating equipment but never made this obvious connection. Duh.
Moral of the story, if you have one that's running warm, you may want to ditch that sexy CF spinner.
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Interesting tidbit. Thanks.
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I had long ago noticed that when one of my models landed and you grabbed the aluminum spinner, it was cool, and over the following few minutes, got quite warm from heat creeping up from the crank case. The aluminum in the engine and spinner does this job very well! Have you flown the first model with out any spinner? Or checked the back plate of the carbon spinner for flexing when tightening the nose cone? The fuel/air mixture flowing at high velocity through the venturi and bottom end have a great chilling effect but can be overcome by friction of a back plate rubbing on a nose ring.
Type at you later,
Dan McEntee
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is it glow or electric , my theory is that u don't have enough cooling and it is transferring the heat through the back plate to the aluminum spinner.
the carbon spinner will not transfer the heat so it is over heating
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is it glow or electric , my theory is that u don't have enough cooling and it is transferring the heat through the back plate to the aluminum spinner.
the carbon spinner will not transfer the heat so it is over heating
Electric? Eewwwwh! I need to go take a shower.