Hello all,
I succeeded in the improvement of my cooling problems! Yesterday (28C/82F, MTOM,
light wind around 5kt) I made two flights with climbs to 5500 ft with several
minutes at the holding point and after landing also several minutes to cool
down the turbo. I didnt try the limit of 118C CHT (it boils around 120C), but
at 103C temperatures only went up very slowly (2200 RPM, climb pitch, something
like 1C every minute). Mind you, my CHT climbs rapidly to 90C due to my water
thermostat. My estimate is, that I match or at least come very close to the
figures Bud Yerly quoted for ground operation.
In the climb I didnt even come close to oil- or CHT-limits. In a steep climb at
MCP/80KT/MTOM I only touched 110C oil (mind you with a 7-row oil cooler!) and
107C CHT. On the other hand the oiltemperature fell to 75C in the quick descent
---From 5500ft, which might be too much in winter, but its easier to address a
problem of running to cool.
On the second flight I closed up the gills on the upper cowling, which didnt
make
a big difference. But since they seem to mitigate heat buildup at low revs
and just before/after shut down (where I had the biggest problems) under the
cowling
a bit, Ill leave them open.
So how did I achieve the improvement? (Bud, I followed your advice and tried to
think like an air molecule ;-)
I let the gap between the top of the cooling tunnel and the cowling open, since
closing and sealing it added 5C to the CHT and also increased the
oiltemperatures
especially in the climb significantly. My theory: since the front openings
in the cowling are rather small, it seems like the gap - in sum - more
contributes
to cooling of the engine than its closing/sealing adds to the airflow through
the radiator. Also the gap is just in front of the oilpump and thus obviously
cools the oil several C. In this regard I didnt follow Buds advice for
the mentioned reason but maybe will reinstall the sealing in due time to test
with the new setup.
I opened up the gap at the air exit from the lower cowling just in front of the
firewall (which is completely in front of the nosegearframe in my aircraft) to
about 1 inch.
I cut away the edge at the air exit of the lower cowling completely.
I sealed a gap of 1mm between the top of the tunnel and the radiator. I made
also
sure, that the complete cooling tunnel is properly sealed.
(I already had) an aluminum sheet at the bottom of the lower cowling to force
all
air flowing through the tunnel through the radiator, leaving only a gap of
Inch below the radiator for the 7-row-oilcooler mounted behind the radiator,
4 rows overlapping with it.
I bended the lower ends of the cooling tunnel in such a way to the inside (I
know
that this is unconventional), that more air/heat from under the cowling could
exit only compromising the heat exit from the coolers a little (if any).
I sealed the joining between the upper and lower cowling, the fuselage in front
of the windscreen and the two access holes on the top thoroughly with a
Tesa-sealing
band (very simple and cheap).
Still on my to do list is the removal of the water thermostat to increase the
margin
to the CHT-limit significantly.
After all Ive learned from the countless individual solutions, that there is no
such thing as plug and play (a Woodcomp SR 3000 aside) to address the cooling
issue of the XS cowling. Im even afraid, that my actions might lead to another
result in another Europa (e. g. the Mono). Finally I have to agree with Bud
Yerly, that one can improve the given setup to a point, where you can live with
it 99,9% of the time. Still, Frans and Ilona did the most sophisticated solution
but with huge modifications, that are definitely beyond my own skills.
Im a lucky man now, thanks to all who contributed to this thread :-)
Regards
Roland
PH-ZTI
XS TG 914
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