perhaps the increased displacement of the 912s has a higher vacuum and thus
greater temp drop through the carb for any given throttle opening
below 100%, just a theory
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com]On Behalf Of NEEL Jean
Philippe
Sent: Sunday, December 12, 2010 6:35 AM
To: rotaxengines-list@matronics.com; europa-list@matronics.com
Subject: Europa-List: Icing: 912S versus 912
Hi all,
I flown my europa with a 912 80hp during 1200h/11years.It's a mark one but
with XS engine mounting and cowlings.Majority of flights took place here in
the French Alps as well in summer as in winter. I never had icing issue
although I had no carb preheater .The only caution I had ,when descending
,was to keep 4500/4800 rpm . Never in idle position.
In the beggining of that year I change my 912 for a new 912S 100hp. That
new engine has now about 125h. Yesterday I had for the first time a rough
running during few seconds.Outer Air Temp was negative at every level and
the issue occurs at the end of a descent 4500/4800rpm from 8000ft to 1500ft.
There was about 8C of difference at ground level betwen OAT and dew
point.
Several time I read on Rotax and Europa web site discussions about icing
issues and I kept in mind that 912S should be more sensitive to icing than
912.
As I know:
a.. Carbs are the same ,except needle diam (2.72 versus 2.70 on S) and
,may be, main fuel jet and diffuser (in accordance with needle) .Does those
difference could explain more sensitivity to icing?
b.. Compression ratio and bore are increased on S but stroke is the
same . In my opinion these difference have not thing to do with icing issue.
So here is my question : Could some body explain why a 912S should be
more exposed to icing than a 912?
Jean-Philippe Neel
F-PSLH Kit N273
Grenoble France
|