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Hi Ed,
I sorta KNEW this would create contovesy. As I alluded to last
time, this whole capacity question is a can of worms, and it tends
to just keep going around and aound and back and forth }:>) .
I can appreciate the point you make that all three rotor faces each
going though a Wankel Cycle, and needing 3 revs of the eccentric
shaft to do so..
Experimentally, we can measure that a 13B's swept volume (Max -
min) is 654 x 2 = 1308 PER REV, 2616 cc per TWO revs, or
3924 cc per THREE revs.
We should always compare apples with apples, (and in Oz, the
standard is the nice green juicy but somewhat "tart" "Granny
Smith" variety, fresh picked off the tree). So I'm with Dale Rogers
who hit the nail on the head.
For ANY I.C. motor then, to be consistent, we should ALWAYS
compare the volumetric displacement (pumping capacity) on a
PER REV BASIS. (Otherwise we are comparing apples to
bananas or watermelons or pumpkins).
Which brings us back to a 13B being the approx. equivalent of a
1300 cc TWO stroke (one revver) or a 2600 cc FOUR stroke (two
revver), or a 3900 cc SIX stroke (three revver - should such a thing
exist) {:>).
Cheers,
Leon
On 7 Oct 2003, at 17:22, Ed Anderson wrote:
> Hi Leon
>
> Good to have you jump in. First, there is no disagreement over
> the
> equivalency of the 13B twin rotor engine with two stroke or four
> stroke engines. I agree that if you (for example) take a 160 (2616
> cc) CID displacement 4 stroke engine through one cycle (i.e. 720 deg
> of crankshaft rotation) you will end up with the same air displacement
> (say at 6000 rpm) as you will with the twin rotor. Similar for the 80
> CID two stroke. That is approx 278 CFM. However, that was not the
> point I was attempting to make.
>
> My point is that 720 deg rotation of the e shaft which would make
> rotory equivalent to the 4 cylinder 4 stroke only accounts for 4 of
> the 6 firing faces of a rotary engine having fired. There are two
> faces that have not yet fired at the end of 720 Degs. These two faces
> fire over the next 360 deg of e shaft rotation given the full 1080
> degs for a complete twin rotor engine cycle. The definition of an
> engine's displacement that I have always understood included all the
> power producing volumes (cylinders, chambers, etc) of the engine not
> just 2/3s of them.
>
> My point is if the above is correct then regardless of the chamber
> size (I do believe I did screw that up by a division of 2) , the
> complete cycle of the twin rotary engine (all six faces having fired)
> is not completed at 720 Deg. I realize that the e shaft doesn't
> know/doesn't care which two chambers fire during one of its
> revolutions so perhaps it doesn't matter in any case so long as four
> have fired within 720 Deg.
>
> But perhaps I have a conceptual misfocus and am focusing on the six
> faces of the rotor when it should be the two volumes?
>
> However, in any case, I certainly don't think additional discussion
> will add anything of further value and so will bow to you, Tracy, that
> Ayn Rand Lady and 99.99% of everyone else and terminate this
> thread{:>). It is officially 1308 CC and that's that!
>
> Ed Anderson
> RV-6A N494BW Rotary Powered
> Matthews, NC
> eanderson@carolina.rr.com
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