Rotary Engine wrote:

Help me out here Paul. This is a point that could assist newcomers.  Perhaps
a rough explanation proof of this 'equivalent displacement' would be a
statement akin to:

  " and so if at similar comparative VE the Wankel rotary engine will have
to run at about twice the rpm compared to an RPE to pump (displace) the same
amount of air."

Doug,
I wasn't going to say anything anymore.
However, regarding your concern for the new people, above is also not
correct.

Both engine run at the same rpm. It is the number one aspect to have
equal speed.
Second we have to count two chamber not two rotations of the Rotary to
be equal to the RPE.
I know multiplying it out results in the same, but this would be
incorrect as the rpm number would be double. It is the displacement of
one rotation that needs to be doubled to make things equals with the
RPE. That is the same as counting two chamber per rotor.

There is difference between saying we we have to run the rotary at twice
the speed and saying we have to calculate its displacement at two shaft
rotations.

Your sentence could read:
" and so if at similar comparative VE the Wankel rotary engine will have
to run at the same rpm compared to an RPE and we have to count two
chambers per rotor to pump (displace) the same
amount of air."

Rolf


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