BTW H. Heisler in his book Advanced Engine Tech also disagrees
with you. He states it is equivalent to a two cylinder four cycle
engine of twice the displacement. Just like a two cycle is
equivalent to
a four cycle of twice the displacement. You are out of sync with the
world
on this point alone Vance :)
Paul Lamar
We will have to add R.F. Ansdale to the list of world famous authors
writing
on the rotary engine that disagree with you. Here is one of his
illustrations.
Ansdale also mentions the two stroke displacement equivalency to twice
the
four stroke displacement. You do agree that a two stroke is equivalent
to
a four stroke of twice the displacement do you not?
VJ - The two stroke, four stroke equivalency has been argued back and fourth
for ages with various results - indeed the two stroke should process twice
the
wt flow as the same displacement 4 stroke but is usually limited by
breathing
and filling issues and "lost" displacement with port opening. In racing
venues
it has usually resulted in handicap to the two stroke to even out
competition
but it is never as much as 2 to one. The displacement number is seldom
contested - Theoretical charge volume processed per each completion of
the thermodynamic cycle.The rpm of any physical mechanical implementation
does not enter into the equation - The fact that the two stroke does it in
one
rev and the four stroke in two - does not make either one a larger or
smaller
displacement engine . The Wankel is a four stroke engine !!- any comparison
with a two stroke is erroneous- VJ
Next I will examine Jan Norbye's book on the subject of displacement.
Paul Lamar
If that mid row example is supposed to represent the Wankel as by Mazda,
he
is exhibiting
a total lack of understanding of the Wankel system - When has a single
rotor
had a
John Deere firing order - -ie put put-------put put------- put put? The
minimum volume
(tdc at power stroke start) is not when the point of the rotor protrudes
into the top (in this
sketch), it is when the flank of the rotor lays against the necked
section
where the spark plugs
are, BDC maximum expansion is when the flank faces one of the enlarged
ends
of the housing,
and travel from TDC to BDC requires 270 degrees of E shaft rotation ( as
differing from
180 degrees of a conventional crank. Actually this is also 180 gegrees
of
the eccentric
rotation relative to the rotor. This guy is really clueless.
I think my illustration is much more correct (which compares it to a 3
cylinder radial
true to my displacement exhortations. Both engines are shown with
clockwise
rotations
(altho on second look my flank numbering is anti-clockwise - in the
order
they approach
the spark plug) cylinder numbering is clockwise.
Vance Jaqua
Your diagram is totally bogus. You are comparing a 3 cylinder engine
that fires one and a half times per 360 degrees with a one rotor
engine that fires once in 360 degrees. You are fixated on the rotor
rotation when it has nothing directly to do with the amount of fuel and
air processed in unit time. The reference for the unit time is the RPM
of the output shaft and NOT the rotation of the rotor. Again HP
is the amount of air/fuel processed in unit time.
VJ - I challenge you to tell me anything that is physically untrue in these
diagrams!!!
Yes I am fixated on the rotor! The rotor is the engine, all work on and
from
the engine is provided by the face of the rotor, and how it's surface passes
to and from
the housing wall. The bulged ends of the housing are NOT the chamber - the
volumes
facing the rotor flanks are the "chamber". The proper reference time is
NEITHER the
eccentric nor the rotor rotation, but the processing time of the cycle. The
eccentric
does not have a one to one relationship to any portion of the cycle, it is
just the
most convenient way to extract the mechanical power. The mechanical
relationships
are that the eccentric has to turn 270 degrees for a "stroke" or 3 full
turns to complete
the four stroke cycle, and the rotor completes the 4 stroke cycle for al 3
of the
rotor faces. VJ
Here is the Ansdale proper comparison with a 3 cylinder engine.
Note there is an engine that looks like the Mazda but the housing
rotates with a different gear ratio to the rotor. There are many
variations
on this type of rotary engine. Many of which are covered in the
Ansdale book.
VJ - None of the figures from the Ansdale book that you have displayed
describe any Wankel in current production, and particularly not the
13B 0r the RX8 - VJ
Here too is the info from the Norbye book on the displacement
comparison.
Get some of the books I mentioned and read up on the wankel engine.
I don't think you understand how the Mazda wankel really works.
VJ - I used to think that you understood how the Wankel worked, but you are
shaking my faith
Paul Lamar
You are right. I sent you the wrong 2 cylinder compare diagram.
There are a bunch in the book and I picked the wrong one by mistake.
Here is the right one. Sorry.
If you don't get it after looking at this YOU will have to assume
that you are right and the rest of the world is wrong.
Of course that does not mean >>> I <<<< have to assume you are right
and the rest of the world is wrong :)
Paul Lamar
The AirCraft Rotary Engine NewsLetter. Powered by Linux.
ACRE NL web site. http://home.earthlink.net/~rotaryeng/
Copyright 1998-2003 All world wide rights reserved.