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Date: Wed, 22 Jun 2005 15:39:58 -0400
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From: "Dan Schaefer" <dfs155@adelphia.net>
Subject: Re: Induction air filter
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Hang in there, John.

A "can of worms" is the worng definition - this is merely the usual spirited
debate often kicked off on this forum by what is a neat idea, but carries
the NIH (Not Invented Here) syndrome.

Of course anyone considering using your idea should give the operational
implications some careful thought - but that's true of of anythig we do to
our experimental airplanes.

I, for one, think your device is quite elegant and useable in a lot of
applications. I can't see all that much difference between the automatic
alternate air feature on your unit picking up air from inside the cowl and
those that use a spring-loaded door to do the same thing. If that's a severe
problem, then a number of certificated aircraft have it too.

For NA engines, I can't see how ingesting lower cowl free air can result in
higher IAT's than when one pulls the carb heat knob and pulls in air heated
by the exhaust pipes. However, having made my living from an engineering
background, I'm willing to admit that sometimes the old acronym "ASSUME"
(ASS Out of U and ME) always lurks and can jump up and bite one.

I still think your idea is an elegant solution to what has been bugging me
for a long time - mainly, how to get a filter for ground operations into the
very limited space on my early 235. I will use your idea (and the device if
available) when I do the long delayed rebuild of the lnlet scoop (for other
reasons) on my cowl. Also, to be sure I'm not ASSUMING anything, I will
measure the IAT's before and after.

Good ideas (or at least ones that seem to be) always generate lots of give
and take on the list, looks to me that this is one of those. Stick around.

Dan Schaefer