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Date: Sun, 22 Jan 2006 02:15:30 -0500
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From: "Alan K. Adamson" <aadamson@highrf.com>
Subject: Ram air ideas
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I wasn't really looking for this, but I read and interesting thread recently
about a presentation that Cris Ferguson (of Evansville, AR) made.  He either
built or was instrumental in building one of the fastest, if not the fastest
qualifying biplane at this years race at reno.  

One interesting thing that they did as this was a NA 4 cylinder engine.
They created a specifically designed chin scoop to create ram air.  I've
included the quote that I read about it below..

"Another interesting thing I got to see was the air intake which he said was
an NACA design, not the classic half hour glass profile but a small chin
scoop picking up the high pressure air just below the 15" spinner similar to
that seen on a P-51D. He said they were able to pick up 2 inches of manifold
pressure with this configuration."

I did some further web research and found a few pictures, but not much more
information.  The first link is some basic information and a few pictures,
you'll see, but not very well the chin scoop... It just a very thin slit
below the spinner

http://www.aafo.com/racing/2005/lo_racer/

This is a picture of Don Barnes cowling being fit, which caused a light to
go off.... Looks like you could add the scoop pretty easy to the Legacy, but
you have the problem of how to get the ram air to the top of the engine,
when the lycomings are all bottom feed :(.... Maybe two smaller "eyebrow"
scoops could be created on the top?  Clearance with the prop extension, etc
may be the challenge here?

http://www.lancairlegacy.com/06_04_images/0604_cowl_15.jpg

This is Jeff Lo's, the owner the biplane, web site.  There is a link at the
end of the first paragraph with much better pictures, altho, none really
show the "design" of the scoop very well

http://flyin-lo.com/Racer/ 

The design is discussed as a "NACA" design, so doing a little more research,
I found the nose bowl NACA design documentation.  Most of this is on cowling
design, but there is a section on "chin" scoops... Warning, it's highly
technical.

http://naca.larc.nasa.gov/reports/1948/naca-report-920/

Lastly, this all may be for not.  While an additional 2" of manifold
pressure would be great, I'm not sure what the simply design of the Lancair
ram air system provides, perhaps it's similar with less cosmetic work
required.  I've heard that to get the max from the lancair system, you need
to stop the ram air from going back out the filter.  Also, once you start
playing with this stuff, on the continental engine, if  the injectors see
more air pressure than ambient, they will leak.  You really need to augment
their design with a "turbo" style injector housing, which takes the ram air
pressure and uses it so the injectors don't leak.  Cold fuel on hot
cylinders *is not* a good thing :)

So I didn't loose all this info, I figured, I'd post it, so at least I could
find it next time, in the archives :)

Alan