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Jim, by diffusers do you mean the pic showing the little alum. angle's that
are [ look like anyway] bonded to the fuse ~12" ahead of the inlet? They
look like vortex generators? I was curious as to what the side 'rails' are
that are located on each side of the inlet ramp to the duct. If nothing
else they sure look cool. I think one of the major problems w/ the Naca
ducts used in this application is that they should still be placed in an
area of high pressure. I my humble opinion, right behind the thickest part
of the fuse isn't really a high pressure location. However having said
that.. I'm not sure where else he could have put them unless he had wanted
to do alot of ducting. I think that's why he put those little VG's where
they are. It would appear that he was having problems w/ airflow velocity
[boundary layer thickness] and by adding the vg's he re-energized or speed
up/thinned down the boundary layer and improved the airflow into his ducts.
I've seen several pictures of Long-Ez's w/ very large Naca ducts on the
bottom of the fuse, which in my mind would be a higher area of pressure that
on top at least, unless I'm missing something.
My two bits
Jarrett
----- Original Message ----- From: "james coffman" <jimcoffmanus@yahoo.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Thursday, November 20, 2003 12:08 AM
Subject: [FlyRotary] Re: Core vs Radistor was Re: [FlyRotary] radiator
Watch out for naca ducting for cooling. they have a
reputation for not working. Having said that, look at
an article in this months Sport Aviation. I forgot the
plane type, but using the naca duct on an IO-540. It
completely failed in several positions until he added
difusers (sp) in front. Now works fine. There are
pictures. Interesting! Jim Coffman
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