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You could just try duct taping a bent tab at the
leading edge of the hole to act as a deflector and create low pressure at the
hole. Then go fly it again. Quick and dirty.
Wait a minute! Who am I to give advice
to the master of all things rotary?
Mike Wills
RV-4 N144MW
----- Original Message -----
Sent: Friday, September 18, 2009 5:00
PM
Subject: [FlyRotary] Re: Re RV-8 cooling
test
Because it looked easy to modify the bottom cowl outlet on the
RV-8 to a cowl flap configuration I decided to try that before installing some
louvers in the same area. Attached is a picture of the cowl after I cut
out the area that would form the bottom of cowl flap.
Couldn't
resist the urge to test fly the plane with that big gaping hole in the bottom.
I was thinking that it would show if it was the small size of the stock
opening that was causing the problem or if aerodynamic factors
dominated.
The 'big hole' outlet ran about 10 degrees cooler than stock
which was not nearly the improvement I'm looking for so I can't believe that
the louvers would work in this location. Back to working on the cowl
flap in the hopes that the low pressure area behind it will extract a lot more
air. I don't have a warm fuzzy about it though. After this (if
it doesn't work) I'll try a bluff body extractor vent as described by some
CAFE Foundation reports.
Just as a point of reference, I have about 35
sq in of inlet area and 52 inches of outlet area with the stock cooling
outlet. Now I know that the inlet area is more than large enough (from
the cowl off flight test) and the 52 sq In outlet should be enough but I think
the pressure is too high under the fuselage where the outlet
is.
Tracy
On Thu, Sep 17, 2009 at 6:13 PM, <SHIPCHIEF@aol.com> wrote:
Thanks for that.
I'm
making my radiator chin scoop right now.
I made a 'buck' out of 2 part
pour foam, then cut & sanded to shape. After laying up the part, and
removing it, I began to remove the edges. Good thing I made it too deep. Now
you guys have revisited the Exit/Inlet relationship issue.
A little time
with a ruler, some quick math, and some trimming is leading me right to the
reccomended 30% bigger exit area than inlet area for the radiator. I was
going to use Van's original exit, but now I'm adding about 1/2" more
depth.
My oil cooler exit area is really over sized. It is kept separate.
The right cowl inlet is ducted to the oil cooler, then exhausted straight
out the right side thru louvers.
The left cowl inlet has not been made
yet. It will feed air to the turbocharger and provide surface cooling air
for the exhaust system and fuel injectors. If that chokes the air exit at
the bottom, I'll have to make a left side hot air exit as well.
Tracy,
your comment about overheated coils and alternator has me thinking about
blast tubes?
Scott
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