----- Original Message -----
Sent: Thursday, March 01, 2007 9:53
AM
Subject: [FlyRotary] Re: diffusers
John, I would go with the 22 1/4 sq inches. For
these reasons:
1. Your engine may produce more power than the one
I run with - requiring more heat rejection.
2. It is easier to neck down the opening (than
widen it) if it turns out you have more than what is necessary - or do
nothing
3. My cowl exit area is probably a bit larger than
most which may produce less back pressure enabling smaller opening to flow
more air.
Ball up your fist and see if you can stick it through
the narrowest opening - it should just almost go (that is if you have the same
size hands I do {:>)) How's that for a standard of
measure?
Ed
----- Original Message -----
Sent: Thursday, March 01, 2007 9:39
AM
Subject: [FlyRotary] diffusers
Ed, If I add the extension, indicated
with cardboard w/lines, I have the original 22 1/4 sq. in's. If I
block off the cowl openings to match the diffuser, I will have 18 7/8 sq.
inches. The neck at the smallest point is approximately 15 sq. inches
as close as I can determine by my barn door math. Which is the better
way to go, opening wise, the larger or the smaller opening. If these
numbers are in the ball park, I'll lay up the glass. Thankyou
JohnD
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