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----- Original Message -----
From: <kenpowell@comcast.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Sunday, September 21, 2003 3:43 PM
Subject: [FlyRotary] Re: DIE Power Calculations
Ed,
Please bring copies (electronic is OK) to Tracy's. I am interested in
understanding the math and would like to work thru the theory. Even
though I'm
planning on a peripheral port engine this is really interesting stuff.
Besides, if I were to come up with a RX-8 motor then I might need this
info.
Also, you guys need to come to Tracy's and Laura's Fly-in. More fun than
Oshkosh! I'm driving 13 hours to get there and consider it time well
spent.
You won't be sorry.
Ken Powell
Hi Ken,
Will be good to see you again. Believe it or not, when you see how
simple the equations develop (not kidding), you'll hit yourself in the
forehead with "Of course". Well, at least that is what the one local rotary
enthusiasts did when I gave him the briefing. In fact once, I got him on
track, he was jumping ahead with the next logical step - was playing havoc
with my presentation timing {:>). Once you see DIE=>Ta=Tr (if not before)
all will start to fall into place. In other words, the equations are no
challenge to understand. I guess I could try to map them into a polar
coordinate system to make it a bit more exciting. {:>) The interpretation
can be a bit more of a bite, but not much more.
I took a quick look at the RX-8 intake system (well, as much as I could
tell from a couple of photographs and schematics (since I haven't seen one
yet). At least from the initial cut, it appears that they have decided on a
different intake concept. For example, the strong pulse created when a 13B
intake port opens is due to the exhaust gas residue held over from the
exhaust stroke overlap. Welllll, the Renesis does not have that
exhaust/intake overlap anymore, because they now have the exhaust port in
the side housing (in fact their literature makes a point of this). So that
implies to me that the powerful exhaust residue created pulse is no longer
there. There is some benefit to be gained from the "inertia pulse" created
when the port is closed (that effect is still there), but it would seem that
without the "exhaust Pulse" created wave the DIE effect would be
considerably diminished.
But, remember what I said --- the DIE is an adjunct to a fundamentally
sound induction configuration. It appears that they decided to capture that
power with longer retention of the combustion cycle gases (later exhaust
port opening) at the lower RPMs and by increased RPM (lighter rotors) at the
higher RPM. I ,of course, could be wrong - not even having seen the engine,
but that's my first cut. No saying NO DIE, but if there- I believe its
considerably reduced.
See you in October
Ed Anderson
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