-----Original
Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf
Of Steve Brooks
Sent: Sunday, June 06, 2004 2:11 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] opinion
Ed,]I
wanted to get your opinion about increasing the size of my cooling
scoop.
The existing scoop is a NACA scoop upon which I extended the scoop
portion
a little e bit to try to capture more air. I took some measurements
today,
and the inside of the scoop measures 1-3/4" high by 15-3/4" wide.
Now
there is an additional area that same size which is recessed that is the
actual
NACA inlet. I'm not sure about how to calculate the inlet size, but
if
you exclude the NACA, it is about 27.5 SQ IN, and if you include the NACA
area,
about 55 SQ IN.
I
am looking at building a scoop on the landing gear cover which extends 9"
forward
of the current scoop. I am looking at making the width of the scoop
21-3/4
inches, which is 3" wider on each side, and 1-5/8" taller (or deeper
depending
on how you look at it). That would make the inlet size 73.4 SQ
IN.
There is also the actual NACA inlet along that area that tapers toward
the
front. I don't know what the SQ IN of the NACA is on the cover, but I
could
make some more measurements and calculate it if you think that it
would
be significant.
I
am interested in your feedback about the size, or from anyone else for
that
matter. Today when flying straight and level, when I increased
throttle,
and increased speed, I also increased in oil and coolant
temperature,
which tells me that I don't have enough air flow, or velocity,
or
pressure, or whatever the correct term is.
Thanks,
Steve
Brooks
-Steve;
I haven’t taken
the time to review the details of your plan; but remember rule one – the smallest
cross-sectional area of the scoop should be at the entrance. Some
rounding at the entrance edge is good, and an airfoil shape of the entrance
edge (bottom of the airfoil toward the inside of the scoop) is even better.
FWIW,
Al