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From: "Al Gietzen" <ALVentures@cox.net>
To: "'Rotary motors in aircraft'" <flyrotary@lancaironline.net>
Subject:  Oil temp
Date: Mon, 23 Jul 2007 08:59:46 -0800
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replying to an old post from 8-6-07, because it had relevant pics

Hi Al,

Here are a few thoughts, from only from the things I've read & seen on=20
fast planes.

In OCinlet1, you mentioned that the bottom 'lip' of the inlet is to the=20
rear of the inlet top. I can't cite any references, but I think I've=20
read that air will have a harder time being 'captured' by the inlet if=20
it's configured that way
---------------
Charlie,
I agree.  The original inlet was that way, but I have since extended the
scoop so that is no longer the case.
------------
In the exit pic, it looks like the top edge leads the bottom edge. Any=20
chance that this allows the higher energy air high on the sides to curl=20
around the into the outlet, since the edges slope forward? Also, how=20
sharp-edged is the exit duct end? If the exit lip is rounded at all, it=20
will encourage the air to curl back into the inlet. How sharp edged is=20
the wing trailing edge behind the exit? (Same issue: air curling up &=20
forward on the wing.)
You mentioned possible flow separation on the top of the exit. What if=20
it's just pressure recovery on that part of the wing? From the pics, it=20
looks like both the inlet & outlet are placed far back toward the=20
trailing edge. All the stuff I've read implies that the boundary layer=20
gets very thick as you get closer to the rear of a structure, and also=20
that pressure near the trailing edge of an airfoil is actually positive=20
instead of negative.=20
------------------
The trailing edge of the exit fairing is relatively sharp, maybe 1/16 -
3/32" radius.  Yes, it might be better if it squared off.  The wing =
trailing
edge is quite sharp.

It is likely that the BL is quite thick at the exit position.  I have =
tried
VGs on that surface with no gain.  My measured pressure on the top of =
the
fairing, and at the midpoint of the opening behind the fairing, is about
-0.75" H2O, so it is slightly negative.

Al =20