AirTalk.org

Bruce Tibenham · Guest

I fly a Rans S4 taildragger powered by a Rotax 447, in Aberdeenshire,
Scotland. The weather here is particularly conducive to carb iceing. I need
to get some heat onto the carb. Has any one got experience of installing a
mod to achieve this on the 447 ? As the engine is inverted, i could bolt a
folded piece of aluminium onto the cylinder cover to deflect some warmth up
to the carb, this seems to be the simplest thing i can think of (great to
keep things simple if possible) but i'm not sure how effective this could
be. Other possible methods that come to mind.......electric heat trace round
the carb, ducted hot air from the exhaust (or muffler as our american
friends would say). So, anyone got any experience of this they could pass on
to me.

Thanks,

Bruce Tibenham

Dean A. Scott · Guest

Bruce,

Contact Mickey Patterson at mikeaero (AT) netscape (DOT) com

He made around 20 very professional looking clamp-on carb heater devices and sold it to
several members of my Weedhopper yahoo group last year for $65US. I have not heard
reports to its effectiveness. It's an electrically powered unit using an industrial
heating cartridge similar to how a soldering iron pen works. The element runs off any
rotax lighting coil and is mounted in a 5/8" thick square block of aluminum with a hole
machined into it so it slips onto the neck of a Bing 54 carb, btwn the carb body and air
cleaner.

OR

I found this posted on my group...

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I can't remember my whole thought process, but it evolved from a fellow listee who used a
15w tail light bulb taped to his carb to successfully defeat carb ice. Trying to improve
from there, I had figured that 20w would provide approximately a maximum of 100 F heat to
the carb body which would be warm enough without being too hot.

I used NiCrA-30DGL at 30 awg, which is a glass-insulated wire. I had calculated that 18
ft of wire would yield 9.8 ohm > 20w > 1.42amps (per carb). I initially wanted to wrap
the wire around the carb intake, but after concern for the rubber air filter mount and
discovering that the aluminum carb conducts the heat so fast, that it did not matter where
it was wrapped. I then wrapped it around the easiest place, on the Bing's case, around the
slide housing. I used high temperature silicon around the housing, and simply wrapped the
wire into it.

I chose to connect it to DC thru a switch. It can also be wired AC directly. I use it as
an "ANTI-ice" system, turning it on at engine start whenever conditions are conducive for
icing. It does not create enough heat to wait until ice is present before using it. This
is my personal untried opinion. It does not degrade engine performance, as the air going
in is just as cold, but the water cannot turn to ice because the carb body temp stays
above freezing.

If I were to do it again, I would wire it directly to AC and have it always on (I keep
mine on all of the time anyway). Having not been plaque by carb ice, I did not do anymore
testing. Though I fly in conditions that the carb ice chart will show as being prone, I do
not fly in mist, fog, etc.

This conversation does prompt me to further investigate the effectiveness of the heater,
but in 2yrs, I haven't had a problem. I would like to see what my carb body temp is with
the heater on while actually flying in cold damp air. More heat requires more wattage/amps
and less wire.

I bought the wire from www.wiretronics.com (209-296-8460).

They have a downloadable calculator that is real good to check (in my case to teach)
things out. They had a 20 ft min order; you only need 18 ft per carb. Perhaps someone
wants to ˜group order." I gave my excess to guys around here who didn't have any heat
system. You can also use it to make warm gloves, sock, etc. I think it was about $40.00
total with shipping.

author unknown

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Dean Scott

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