Umm, I have been flying on mogas for 6 years/330hrs with the ULS from a grass
strip
often damp/wet all year round in UK weather without so much as a hint of
carb icing; similarly with a C42 for 350 hours again with a ULS.
Even if skydrive had the carb heat kits in stock, I am a bit loath to put 10
more
connections and three more pipes and two more items in the water system with
an increased risk of issues and loss of coolant with no problem to solve.
On the C150s I trained on and Rallye's, the carb was gulping in air (and it
needed
a lot) hanging down under the engine and in the prop wash but the 912 ULS
in the Rotax/Europa configuration the carbs sit behind and in line with the
engine
under the warm cowl and over the rear cyclinder exhaust pipes. Rear vents
at the side of the top of the Europa cowl mean there will be an airflow over
the engine and up from the exhaust box past the carbs and out. A pretty good
design
really. Cold air comes into the carbs via the plenum and NACA inlet so its
well behaved.
There is no conductive heating from engine to carb due to the rubber mount but
also the inlet and plenum are GRP/rubber so there is no condensation there
(unlike
the Cessna with its metal ducting) so it depends whether the carbs are cooled
more by the air into the engine than the warm air in the cowl from the oil
and water systems, detonation and exhaust. The surface area of the carb exposed
to convected heat is also much more that exposed to cold air. It's rare that
the air is less than -5 C when I fly and it has to be +80 under the cowl,
even with the venturi effect of the carb inlet i'd wager the odds are stacked
significantly against ice formation. Most wetness in the air will be stopped by
the filter an plenum.
I shall stick some thermocouples on them and in the cowl and see what kind of
temperatures
we get.
--------
Graeme Bird
G-UMPY - Mono Classic/XS FFW 912S, Woodcomp 3000/3W CS, trutrak Gemini 2 axis
AP, PAW, PFLARM core, ads-b out, 8.33khz, mode S, FP-5, Aera500, SD on Nexus,
SmartA3
325 hours & 6 years on the Mono, 930 total
g@gdbmk.co.uk
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