snips.....

Of course I jest. But the PSRU still does not care about all this.
All it cares about is the torque pulse. One per e-shaft rotation
for a one rotor just like a two cycle one cylinder piston engine.
Paul Lamar

Yup, that a single rotor would be a bit of a bruiser on torque pulsation. Sorta
Lycoming like. ;(

The "roughness" of the output, and severity of the pulsation on redrives
etc,
is not just the number of pulses per revolution, but the duration, and peak
levels of the pulse (as you have shown in the famous picture of overlap
and no reversal with the two rotor).

Well yes and no...

In a single cylinder 2 stroke, the

theoretical duration of the expansion power pulse is 180 degrees out
of 360 degrees of cycle rotation - actually a bit less because the exhaust
port opens and scavanging starts before bottom dead center.

Ok I can give you that.

With a 4 stroke

 single, the pulse is closer to the 180 degrees, and thus is 180 degrees
out of 720 degrees for the cycle.

Yes but you are now comparing 1 full rev to 2 full revs and this is not the same!

The single rotor Wankel shaft (getting

it's power from the expanding gases on the face of the rotor, where this
expansion theoretically extends over 1/4 turn of the rotor)

It would be less than that, probably around 1/5 of a rotor rev.

turns 3/4 turn

(3 to one) during this power stroke or 270 degrees out of 360.

No, I'd say that that the power stroke would be about 180 degrees or a bit less.

Thus the

the pulse extends over 75 percent of the time ( no overlap and some
reversal). An even firing 3 cylinder 4 stroke has 3 180 degree pulses
(540 degrees) out of 720 (two turns) for 75 percent (son of a gun!).
The 2 cylinder 2 stroke has almost 360 out of 360 = almost overlap.

HUH? Your logic is breaking down here. Go get "Rotary Diagram.MOV" a quicktime movie
and it is one of the best moving models of a single rotor in operation.

Overlap is a matter of engine design. Like my Triumph Tiger is a 3 Cylinder, and a
Harley is a two cylinder. So what is the HD's overlap during its cycle? One pulse per
crank rev?
Nope!

By the way - if you took power directly off the rotor, it would not
be any bigger - just 3 times the torque for 1/3 the rpm - same
horsepower - I am sure that Herr Wankel would have liked to do that,
but the complexity outweighs the advantage. - Vance J.

SNIP!!!

This was

not proposed as a workshop project, but an effort
to get you to step outside the "box" we all live
in, for a fresh look at displacement defination.

Looks like one or two good exhaust pulses would set up a bit of a resonance in the
prop / U joint combo and blow the connection off the rotor.

The five sided Wankel is in the same vein - if
it is sized such that one flank has the same
displacement as the Mazda with the out put shaft
travelling at the required 5X speed -

A 5 sided shape has poor swept volume when compared to a 3 sided.

I'll let all this speak for itself :-)>
Paul Lamar

Interesting idea, but not workable for many reasons...
Blake

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