Hi Bob
I've just picked up on this thread as I've been away. I have flown for the
last year with the gills taped over. No problem. Can't say as I've noticed
much difference as flight profile, temp, altitude etc etc make such a
difference.
I'm building an RV7 with a full plenum and am told that any pressure release
is bad.
I control my water / oil temperatures by adding or removing lengths of pipe
insulation from the water radiator inlet. Seems to work.
All the best
Rick
Rick Morris G-RIKS
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From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of R.C.Harrison
Sent: 15 November 2006 11:43
Subject: RE: Europa-List: Oil cooler thermostat
Hi! Nigel/all
My two pennyworth .....I also tried a cowl exit flap but not to close off.
My Jabiru cooling system of course was ALL air cooled and the theory
ventured by the Jab dealer and Factory was to extend it into the air stream
and create a low pressure area aft of the cooling exit to suck out the hot
air..... needless to say it made no improvement whatever. However what I did
find was that it was important to maintain top cowl pressure high to promote
the mass down flow of air past the engine, I even collected my cabin heating
air(when not being used for purpose) and dumped it in the cowl top which
also assisted. Since all the high pressure oil cooling air was directed
under the sump cooling fins(Rotax oil and water cooling likewise) to leave
it "floating" in the lower cowl restrained the downward flow of engine
cooling air.
You may ask why am I "rabbitting on" about damn Jabiru's ?.... so to my
question:-
What purpose do the Europa "Gills" serve?
Has anyone flown with them blocked off to check the effects?
As it happens, against most advice, I have decided to fit an intercooler on
my 914 Turbo which of course has a huge discharge of warm air mostly into
the top cowling and I'm not sure it's the right philosophy to let it exit
out the "gills", with my Jabiru experiences I'm suggesting that to increase
the down flow of air, even with water and oil cooling on the engine, it
would be best maintaining the top cowl pressure.
I never had any top cowl exits on my Jabiru set up ...all air was discharged
out the lower cowl exit plus the lower cowl was "jacked" off the fuselage by
approx 1" increasing the discharge annulus considerably.
Any help with these questions would be gratefully received.
I also would have liked to have the Rotax oil flow to its cooler selectable
and/or meterable which I achieved on the Jabiru by a hand control valve
operated from the P1 Position allowing most flying to be accomplished
without the cooler being in circuit. The resultant warm air (even with no
oil circulating though the cooler) was a primary source of cabin heat and
with the oil cooler in full flow I could fry the passenger, I get the
feeling that a number of Europa Rotax owners would dearly like such a
facility !
Regards
Bob Harrison G-PTAG (Still prepared to learn!)
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of nigel charles
Sent: 15 November 2006 09:38
Subject: RE: Europa-List: Oil cooler thermostat
>It is best to place a flap at the exit of the cowl/radiator duct.
Placing an obstruction in the front destroys dynamic pressure. An we
need to recover as much pressure as we can to persuade the air to flow
across the rad core.<
For what its worth I tried a cooler flap at the rear of the radiators.
With it fully closed it cut off nearly all the airflow and it made
little difference to the CHT and oil temperatures.
When I was at Vichy this year I met one of our French owners (sorry I
forgot his name). He has a very clever inlet cowl flap. It is part of
the lower cowl in front of the radiators and has a hinge at the rear of
it. In very hot weather it is lowered below the normal cowl allowing
more cooling air in. In cold weather it is raised impeding airflow to
the radiators. This is all controlled from the cockpit so that inflight
adjustments can be made. From what he told me it works very well.
I appreciate that normally control of cooling air is best done at the
outlet but in this case it seems it is better to use the inlet.
Nigel Charles
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