Frans
You may be interested to know that Europa did some testing of several duct
positions with a view to producing a mod along the lines of what you are
doing. The aim being to improve cooling, reduce drag and improve the looks.
Unfortunately it never got produced :-(
I spoke to Andy Draper today and he is going to send me a drawing of the
design that worked the best in terms of cooling. I will happily forward it
to you when I get it.
Regards
Paul Atkinson
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Frans Veldman
Sent: 02 March 2009 20:53
Subject: Europa-List: Cowling mods
Fred Klein wrote:
> Frans...this sounds really interesting...cheers for getting rid of the
> dog house...how bout some photos?
I guess more people are interested in seeing some preliminary work that has
been done.
Note that a lot of work still needs to be done. It is a sort of "concept"
that is ready now.
The idea is to reduce drag, and improve cooling at the same time.
Picture 1: the nasa-ducts in the top cowling. Inside is a deflector screen.
The air is aimed between the front and read cylinders, cooling both
efficiently and equally. The air is directed to the bottom, so the heated
air will hopefully not collect in the top cowling. The air outlets (inlets?)
on the side are closed off. If the engine is shut off, the remaining heat
will find its way out via the nasa ducts which are actually higher than the
side vents.
Note that the front openings will be used for taxi & landing lights, and not
as an air passage.
Picture 2: the cooling inlet and diffuser for the radiators. The idea is
here that the frontal area is reduced, the air inlet is in a better position
in the propellor wash (important for cooling on the ground!), and drag is
lowered because of the diffuser in front of the radiators.
The area where the original air duct was, has been filled with blue foam,
and then sanded until it had the shape the cowling should have. A few layers
of bid (inside and outside) to make it strong. Some (a lot?) of filler is
required to finalize it. The diffuser is also made from blue foam, shaped,
and with two layers of bid.
Picture 3: closeup of the diffuser. The area inside is funnel shaped with a
round curve, but that is hard to see. Every wall of the diffuser can be seen
as a wing. The air going inside is slowed down by expansion, to match with
the airflow the radiators can handle.
Picture 4: Underside/rearside of the radiator housing.
What you are seeing here are actually two air outlets: The opening for the
radiators is obvious. Directly behind it (towards the camera) is the opening
---From the engine bay. Both radiators are in line with each other:
the oil radiator will only get air that has gone through the water radiator.
I believe that this is a good thing. (The reason that this is sometimes done
differently in the Europa is because of the bad properties of the original
cooling duct).
On the bottom panel you can see a hinge. Here will be attached an adjustable
cowl flap. In the cruise position, it will be in a direct line with the
bottom panel of the radiator housing. It will extend considerably rearward,
where the belly slopes down. The outgoing air will be speed up, and
hopefully smootlly mix with the air passing the radiator housing because it
has the same speed and direction. If more cooling is required, the flap will
move down, making a greater opening, and causing some vacuum behind the flap
to help the air out. Obviously, in maximum cooling position it will create
some drag, although it wouldn't be worse than the factory cowling.
Note that the sides of the radiator housing will not be visible when the
cowling is finished, as it will overlap the sides of the radiator housing.
(Problem here of course is that the radiator housing is fixed to the
fuselage, while the bottom cowling needs to be removable. Am not sure yet
where exactly the seam will be made).
Picture 6: Here the shape is better to see. If the cowl flap is in place, it
will be in a direct line with the radiator housing, horizontal with the
flight direction. Because the belly of the cowling slopes down, the air
going to the exit will be compressed (read: "speed up") somewhat.
The complete air path is as follows: There is a small opening in front, and
behind the opening is a diffuser which has "wing-shaped" walls that increase
the area, thus slowing the air down. The slower moving air can pass the
radiators, and after that the air is speed up again, so when the air is
released, it has the same direction and speed as the surrounding air.
Of course, al this is theory. Because the cooling properties of the factory
cowling are so bad, I believe that it would actually be difficult to make it
worse. So chances are that my cooling at least gives some better cooling and
aerodynamics.
Note that before I started with the Europa I had no experience at all with
making shapes and working with epoxy. I'm sure that a lot of people can do a
better job than I did, and I'm not really sure how things will look after
applying filler and sanding. I hope it is going to be ok.
Comments are welcome of course!
--
Frans Veldman
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