Paul,
    Here is the latest on the snorkel scoop.  I made the front

portion part of

the "hell hole" door so I have access to brake lines and main
gear.  Getting ready to glass the entire lower cowl.

Joe Berki
Limo EZ

Looking real good Joe. Ought to cool on the hottest days.

Paul Lamar

=) Paul, gonna keep this picture a secret or going to share with the

rest of us?

alventures wrote:

One thing would concern me about the scoop.  From the photo it looks
like the x-sectional area gets smaller some way into the scoop.  That
can (not saying it will in this particular case) seriously degrade its
performance, causing air to spill out around the edges of the scoop.
The smallest x-section should be at the entrance with a rounded edge, or
better yet, an airfoil shaped edge with the outside edge looking like
the top of the airfoil. With expansion inside the scoop beginning just
aft of the entrance you present a low pressure hole for the air to go
into, and it will gladly go there.

Al

I agree if the reduced area of the duct happens before the rad.
On the other end you have a rad restriction at the end of the duct.
You need to shape the duct in that area to distribute the air
evenly over the face of the rad. That can be mostly achieved
by a Kays & London wedge shape diffuser fed by a constant area duct.

There is not enough length in these things to use the classic
diffuser shape to which you refer. Modified by K&M incidentally.
That general requires 2.5 times the max dimension of the rad. It
also is based on a perpendicular mounting of the rad. It could
be done of course if the scoop opening was carried further forward
under the pusher fuselage. You would still have the problem of not enough
room in there for a perpendicularly mounted rad. Therefore we are forced
to use an "oblique cooling block" in KIM speak AKA a wedged shaped
diffuser fed by a constant area duct and a more or less horizontal radiator
mounting.

Paul Lamar

Joseph M Berki wrote:

I am concerned with the change in area do to the addition of the snorkel
section.  The change occurs on the sides and bottom.  When I glass the
inside I am thinking about placing foam wedges at those locations to
provide an even taper to the restriction. The restriction is the original
opening.  The snorkel was added to get some clean air away from the
fuselage bottom and any interaction from the main gear. These ramps will
make the inside of the scoop like a funnel with no bumps or curves to the
wedge area just in front of the rad and oil cooler. Thanks

Joe Berki
Limo EZ

I am not following you here Joe. Got a sketch? There should be no restriction
or change in internal duct cross sectional area  until you get to the wedged shaped diffuser 
above or below the rad in your case.


Paul Lamar
 
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