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Conrod force/acceleration

In message <34CE0C59.8DD8917F@novagate.com> Sargent Schutt writes:

> I believe that for two trillionths of a nanosecond you might have zero
> velocity as the crank swings by to pull the piston back down, owing to
> IMPERFECT properties of the sytem upon which you are practicing perfect
> theoretical trig.

Well, this is different.  You have to start looking at what the piston is 
actually _doing_.   During compression and the subsequent firing stroke, the 
whole subsystem is under compression and the path it follows is probably not 
far from the theoretical.  During the induction stroke, especially on a n/a 
motor, the subsystem switches from compression to tension as the piston is used 
to suck in the mixture.  At this point, the slack in the big end and gudgeon 
pin bearings will be taken up, plus the various pieces also change shape a 
little.  There will certainly be a discontinuity in the motion diagram, but I 
would expect it to be a tiny period of zero acceleration.  Not trillionths of a 
second - probably of the order of microseconds.  The same occurs, of course, 
when the subsystem switches to compression again for the next stroke.

 Phil Payne
 Committee Member, UK Audi [ur-]quattro Owners Club