Sender: <marv@lancaironline.net> (Marvin Kaye)
To: flyrotary
Date: Sun, 15 Dec 2002 12:01:15 -0500
Message-ID: <redirect-1911954@logan.com>
From: "Marc Wiese" <cardmarc@midsouth.rr.com>
Subject: discussion on rotary engines.....
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All,
I have been having an on-going discussion with this fellow, who has
decided to put a V8 into his Lancair (if he can get it insured). He has
also consider a DIRECT DRIVE 20B but disregarded that (I don't blame
him). He had mentioned a fellow who makes his own alum side housings for
race engines, here is our latest repartee, in which he identifies him.
Has anyone seen his engines or his alum side housings?
----------------
Marc,
The "rotary expert" is Eric Barrett, who owns Alternative Power in
Atlanta. I really don't know if he knows anything or not, but he has
built quite a few for race car applications, including some that have
run in the Petite LeMans, apparently without failing.  He uses my Engine
Management System. His number is 770-271-7122.  2121 Peachtree
Industrial Road, Beauford, GA 30518.

Your point about low-speed operation of the rotary is a good one.  So
far, the volumetric efficiency at low rpm is so poor that one would have
to run a very high boost level to get enough power at 3,000 or below to
make it worthwhile.  The new engines with side exhaust ports might
change that as the port overlap can be reduced to whatever value you
want.  The weakness remaining is the seal leakage, which can be
significant at the lower rpms. So for now it looks like rotary engines
and PSRU's will go together.  One idea I thought was pretty good was a
re-drive that someone suggested that used an internal driven gear.  I
think if you enlarged the gears so that the driven gear was basically
the diameter of the engine the side loads on the drive gear would be low
enough that it could be direct-mounted to the E-shaft with no other
bearings.  The torsional stiffness of the gear package would probably be
such that no flywheel or torsional absorber would be required.  Even
with the large gears the "I-X" configuration produces very low pitch
velocities, making for a very durable package.  The only thing left
would be to seal off what used to be the clutch housing as it would have
oil in it.

And, yes, one advantage of the rotary is that some charge stratification
is possible (maybe unavoidable) that allows operation quite lean.  Even
with that considered, I still think that the best rotary BSFC is
probably 5% worse than the average Piston engine.  The side exhaust
ports will give a higher expansion ratio and that will get back some of
it.  Rotaries have an inherent limitation on compression ratio, but for
a turbocharged engine that doesn't mean too much as the compression
ratio has to be down around 9 or less anyway.  Then what's left is the
high surface-to-volume ratio of the combustion chamber and higher seal
leakage.

regards,

Gary
-----------------------
Marc Wiese