Sent: Saturday, June 12, 2004 7:39
AM
Subject: [FlyRotary] New Truncated
Streamline Ducts
Here are a few photos of my new radiator ducts
modeled along the Streamline Duct profile. The Right radiator duct
inlet has been reduced from 24 sq inch to 14 sq inch and the left one from
24 to 10 sq inches. Both use a "truncated" version of the Streamline
Duct profile described in K&W Section 12.
SNIP
The flared entrances are not part of the
streamline duct. They are simply to smooth the airflow from the cowl
duct opening to the actual duct inlet. This could in effect result in
more air moving into the inlet than my previous ducts which had an approx
1/2 -3/4" blunt lip around the entrance. Also, it may provide more inlet
velocity (Bernoulli effect) which in turn may provide more energy conversion
to pressure increase inside the duct - just speculation. But, at a
minimum, the smoothed transition should produce less drag than
the previous blunt duct entrance. On the other hand, the
flares could act like an external diffuser and slow the air before the
entrance. Just too many factors to analytically account for them and
their interactions.
I have kept the old ducts and will put
them back on when I get some instrumentation hooked up so we can do a side
by side comparison.
Best Regards
Ed
Ed Anderson
RV-6A N494BW Rotary
Powered
Matthews, NC
Geeze, Ed..... those look too good to hide
underneath a cowling.....Very nice work. Paul Conner
Thanks, Paul,
But, you should have seen
the first pair I made. I tried using 3 lb cloth as I thought it would hug
the compound curves best. A big mistake, the cloth was unmanagable
once wet. When dry it just wasn't strong enough. But, then
I tried using 4 mil plastic to do the sandwich job and found that it was too
heavy, should have used the 1-2 mil as advised.
. About the only thing I did right was to
buy one of those disk (Pizza type) cutters. Boy, did they make the job
easier, I had been using shears and once my gloves got resin on them trying
to cut cloth was - lets say not my idea of fun. I ended up using 8 lb
cloth and it layed up well. Still have problems on corners
{:>).
Ed Anderson