At what temp should you stop flying nitro airplane? I was wondering if the fuel gel like disel.

As long as it's above -130F, you should be OK. Don't think you will get anywhere near that in KY.
Tuning and ease of starting will suffer a little but you can't use fuel freezing as an excuse not to fly.
Batteries and appendages will stop you way before the fuel freezing will.

Oh, and methanol is a commonly used as anti-freeze for windshield washing fluid and marine anti-freeze.

In my experience, the biggest problem is the receiver battery. I have flown at temps below -20C/-4F (once), and the fuel was fine. My fingers were not. The receiver battery (nicad) didn't like the temperature at all. After one short flight, the VoltSpy's red lights flashed when I moved the sticks. I admit it, it was stupid to fly, but I couldn't resist. I put the fuselage in the car with the heater on full before flying, and that made it easier to start the engine (ASP FS30AR). It ran fine in the air.

Non toxic RV antifreeze, which is all you should use in potable (drinking) water systems is not methanol, it is propylene glycol. Automotive antifreeze is ethylene glycol, and is very poisonous. Or, is it the other way around? Better not drink either.

Sincerely, Richard

You are correct.. Rv antifreeze is Propylene

I think the problem is when the temperatures get below a certain point, the carb starts to ice up. I notice on my four cycle engines that the intake manifold develops a lot of condensation on it when i fly in the morning when it is chilly. if it was near freezing temperatures, the condensation would turn to ice on the intake manifold.
Plus below a certain temperature the nitro/methanol/oil mixture begins to separate.   I think I remember reading about a guy in Northern Canada and when the temps went below -30 degrees F, was when his fuel would get funky on him.

I and several others have had ice form on the intake manifold on a 4 stroke when the ambient temperature was in the 60 degrees F range. The first time it happened I was very surprised as the intake manifold had a layer of ice on the outside of it when I landed a 1.20 4 stroke.

Both types taste bad, but cold fuel is the worst!!!

We fly when it's cold and fuel isn't the issue, but it can be an effort to get the engines started; a few drops of cigarette lighter fluid helps a lot. What usually gets too cold to operate correctly are our thumbs. A portable heater solves that problem. [sm=regular_smile.gif]