What Cold Weather??

AlexPeterson · #1 02-04-2007, 07:21 AM

Not to let a little cool weather stop me, I went for a one hour flight yesterday. Temps on the ground were about -8F (-22C), and at 6500' were -15F (-26C). I have spent a fair amount of time weatherproofing my plane, and messing with heater arrangements also. Cockpit temps were probably in the 50F range, so really not too bad. I have one more heater modification planned, which should bring the temp in the cockpit up to summertime temps. I have one 2" scat, 9" long Robbins heater on the right tailpipe, fed with restriction from behind the #3 cylinder. The other heater is a 1.5" scat, 9" long Robbins on the forward crossover, fed with restriction from the left cooling inlet ramp. My last modification will be to put another 1.5" heater in series on the other crossover pipe.

For those who haven't done a max angle, sustained climb in these temps, it is breathtaking.

Something else I've noticed over the years in very cold flying is the flap motor sounds. It makes some real clunking/clattering sound. I mention this just so that if any of you experience this, it appears to be normal. I'm sure it is related to the grease viscosity.

azrv6 · #2 02-04-2007, 07:31 AM

Alex, in your installation, what is "fed with restriction"? Thanks, Dave

LettersFromFlyoverCountry · #3 02-04-2007, 08:25 AM

Alex. do you have the heater mods documented anywhere? I got a message this morning -- from another Minnesota resident -- who -- for some strange reason (g) -- suggested I write something about heating an RV cockpit.

-12 here this morning. Frankly, I think it feels pretty good. I imagine in this weather, your RV takes off like the space shuttle.

AlexPeterson · #4 02-04-2007, 09:56 AM

Quote:

Originally Posted by azrv6

Alex, in your installation, what is "fed with restriction"? Thanks, Dave

Restriction means that about 80% - 90% of the inlet area (feeding the heater) is blocked. Too much air = lots of cold air. That is why I am trying the 1.5" scat. I actually think 1" diameter would be enough.

Bob, regarding your question of documentation, not really. After I make the next mod described, I'll write something up.

AlexPeterson · #5 02-04-2007, 12:30 PM

I will be taking the cowl off this week, so I will take some pictures.

Kyle Boatright · #6 02-04-2007, 01:19 PM

There are lots of fixes which help with flying in cold weather.

On any of the aircraft, you can make aileron push tube boots which keep air from being sucked into the cabin through the holes for those tubes.

In addition, on the slider models, (and probably the tip-ups too), the most important thing (IMO) is to prevent air from flowing out along the side canopy skirts. If you eliminate this outflow of air, you'll have a lot less incoming (cold) air. On the slider, you can simply take some flexible pipe insulation - the foam rubber type, slit it into two "C" shaped sections lengthwise, and cut those "C" shaped pieces about as long as the slider tracks. Slip the pieces between the slider rails and the skirts after you've closed the canopy and they will give a great seal.

Beyond that, you can use RTV to better seal the cheap plastic vents Van's sells and you can also use weatherstrip foam to make a seal around the aft edges of the canopy and between the roll bar and canopy frame (slider only).

From a heater efficiency standpoint, people have success doing two things - first, slowing the airflow through the heat muff and second, increasing the surface area of the heat sinks inside the heat muff. The best ways seem to be to stuff the heat muff with stainless steel pot scrubbers or wrap small diameter (but long) springs around the exhaust pipe inside the heat muff. I found the pot scrubber thing to be easy to do, so that's what I did.

I've flown down to about 0F, and was comfortable (though on the cool end) for a 3 hour X/C which began at dawn. I was wearing thermal underwear, jeans, probably a sweatshirt, and a jacket. Later, it became bright and sunny outside, which added quite a bit of solar heat.

I would say that there are very few GA aircraft that are shirtsleeve comfortable below 20 or 30F. RV's are not much different.

Howie · #7 02-04-2007, 08:34 PM

Folks,
Don't forget to maintain your exhaust system, if you're going to seal up all the little leaks. Carbon Monoxide is nothing to mess with. With a sealed cabin a CO detector is a good idea.
If you're doing a lot of winter flying, look at those heat muffs before winter and sometime during the season. It's cheap insurance.
Howie