Effect of air temp on engine power - RC Groups
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Jun 29, 2007, 10:05 PM
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Effect of air temp on engine power

So I left San Diego earlier this week and went to Phoenix to visit a friend. I put hawk up in the air and it was super gutless. Now mind you it's never got much power (OS .32) but this was rediculous. The thing could barely get outta its own way.

The temp was up over 110 and I know that effects power since less oxygen is in each stroke and poor heat dissipation but I didn't think it would be THAT bad.

I know....I need to move up to a .37. That will happen quite soon.

Just curious what you guys think of power and heat.

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Jun 29, 2007, 10:11 PM
I don't want to "Switch Now"
pmackenzie's Avatar
Two problems - less power from the motor and less lift from the blades.
Also SD is more or less at Sea level , Phoenix about 1100 feet.

More nitro and/or a bigger motor

Pat MacKenzie
Jul 06, 2007, 08:14 PM
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The hotter air is, the more water vapor it contains, which lowers its density which gives your engine and blades less air to bite into, which equals less power.
Jul 06, 2007, 11:12 PM
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Not quite... water and temperature are separate problems (although there can be a lot more water in hotter air, I bet there wasn't in Phoenix).
Jul 07, 2007, 12:02 PM
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All I know is that the thing was running pretty dang hot until I richened it up. Then the power fell and it was difficult to maintain headspeed while doing much of anything.

My .37 arrived yesterday. About stinking time. I've been cheap and pushed that .32 to the limit. I'm tired of gimping around.

Thanks guys

Jul 08, 2007, 12:46 PM
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Hi Andrew, do you mean to get your density altitude?
Jul 08, 2007, 06:05 PM
Registered User
Density altitude first, and then correct for humidity (I forget the correct name for that).
Jul 08, 2007, 08:34 PM
Kamikaze Heli Pilot
This document may be of interest

Jul 10, 2007, 02:23 AM
Registered User
Been 3 years since CPL Met

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