Sorry Dale.
Much too understandable.
As the rotor orbits the crank, it generates a centrifugal bearing
load based on the crank RPM and the rotors weight. Relative to the crank this is
orbital motion. (Rotary motion of the rotor which is also spinning)
Relative to the crank throw this is purely rotary motion. Bearing loadings
are more complex, as the cylinder combustion pressure lifts (or cancels) some of
the centrifugal bearing loading. It also does it in the same place in the circle
every time, and in proportion to the throttle setting.
The centrifugal load passes zero around 6,000 to 6,500 RPM. As seen on
Paul's site. In racing engines, where rotors are lightened to the extent
possible, this point might be much higher than for the stock rotors.
The rotors are lightened to reduce bearing loads so that much higher RPM
may be used. This reduces the amount of mass that must be accelerated after each
shift. Same as the flex plate instead of the massive flywheel.
The normally nice balance is upset by the rotors becoming lighter on one
side of the circle. This also loads the main bearings higher one side than
the other. You may have noticed that at lower RPM, the reduction box develops a
racket from the gear lash being used up in one direction then 180 degrees later
being clashed in the opposite direction.
In the race car, with little mass in the rotating assembly, the
transmission will suffer this problem and the noise is enough to make you think
a big gear has broken and is being ground up. Thus the idle speed in the race
car is 2,200 RPM. No problem up there.
So there is a value in the heavy rotors. They add flywheel effect the same
as a heavier flywheel.They also damp the hard accelerations from each power
stroke and smooth the engine nicely.
The single rotor people are short over 9 pounds of flywheel effect before
they get started. If you don't mind complexity, A much
smaller flywheel could be turned at a higher speed than the crank through a
gearing arrangement and be effective at a much reduced weight. Just some ideas
to throw around.
I do love this engine.
Lynn E. Hanover
In a message dated 2/10/2008 10:25:17 A.M. Eastern Standard Time,
dale.r@cox.net writes:
Not
reciprocating. There is acceleration and deceleration; and the
vectors are complex - the e-shaft makes a complete rotation every time a
new face of the rotor is presented to the spark plugs. Think of it
like
being in slow-and-go traffic on the freeway - you keep going forward,
but sometimes not by much. In fact, the path of the valve stem on
your
wheel as you roll down the freeway is a "classic" trochoid.
Take a look at: http://mathworld.wolfram.com/Trochoid.html
Dale
R.
COZY MkIV #0497
Ch. 13