Chad Kurszewski WE9V wrote:
> >That got me thinking that my assumtions might be out in left field.
> >For 2"O.D./1.5"I.D. -> pi((2*4)-(1.5*4))/32(2) = 0.537 in*3
> >For 2"O.D./1.75"I.D. -> pi((2*4)-(1.75*4))/32(2) = 0.325 in*3
> > 1.75"O.D./1.5"I.D. -> pi((1.75*4)-(1.5*4))/32(1.75) = 0.242 in*3
> > Sum of modulii = 0.325 + 0.242 = 0.567
> >0.567/0.537 -> 5.6% improvement from taking it in two layers???
> >Weird, eh? What am I doing wrong here??
> I don't think that you can add the modulii like that.
> The correct way (from QHS book) is the total OD and the total ID.
> I'm not sure of the reason.
> Chad Kurszewski, WE9V e-mail: Chad_Kurszewski@csg.mot.com
> The Official "Sultans of Shwing" Web Site: http://www.QTH.com/sos
Hi Chad, thanks for the reply. I looked thru Dave's book as closely
as I could muster and didn't see the reference; and I was looking there
I asked an M.E. (I'm an E.E.) at work who used to build hi-performance
bicycle frames, and he thought one just added them. When I showed him
my example, he thought that it was approximately correct and the
differences were probably due to the formula being a short-cut from the
integrals that tell the real story and that 5% was maybe due to some
dropped polynomial terms that didn't show up in the formula for sake of
What page is your reference?
Thanks again for taking the time.
Mike - W8MM - EM79sd
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