🚀 go-pugleaf

In article <1htc3aINNek1@shelley.u.washington.edu>, whit@carson.u.washington.edu (John W writes...
>In article <30DEC199200153934@pierre.mit.edu> chuck@pierre.mit.edu (Chuck Parsons) writes:
> 
>>strength of the chemical bonds forming the material. 
>>Consider a thin hoop flywheel. Any flywheel can be thought of as being made
>>up of many such hoops. Let the hoop have a fixed cross-sectional area A
>>and the average mass of each atom in the material be M.
>>
>>  The energy stored in each atom of the hoop is E=.5 M*V**2.


 Rest of argument that any pratical flywheel can only store a fraction of
its heat of vaporazation deleted

>	Not a reasonable expectation, though, that in a FAULT
>the failure will always deliver exactly equal strain energy
>to all molecules in the whole danged flywheel.  A sensible 
>scenario is NOT going to be so obliging: a crack will
>develop, a fragment will whizz off (and through the 
>containment), then the remainder of the rotor will shake
>itself apart.  Not in molecule-sized pieces, but in large
>ballistic chunks.  Maybe large enough to have a THOUSAND
>molecules in a single fragment.
> 
>	That means that the energy absorption in bond 
>breaking will be roughly in the ratio of volume/area of 
>the one-atom and thousand-atom fragments.  This makes
>90% of the energy of the rotor available to do damage.
> 
>	If you want to get back the energy in the rotor,
>you'll have to argue why no chunks come off it, only
>individual molecules.  And, if the chunks that come off
>are LARGE, like bits of visible fluff, it's gonna
>be multibillion atom fragments that one must figure on.
>With a billion atoms in the chunk, the bond energy can
>only take 0.1% of the energy you need to absorb.
> 
>	John Whitmore

  I agree with every thing said above, I would only clarify that I
did not imply (or at least didn't mean to) that the flywheel will 
break up into atom size pieces when it fails. In fact my argument was
quite the reverse, there isn't enough energy to do that. I assume
that the small pieces of flywheel left will get quite hot due
to friction and impacts and that is where the majority of the heat will
go.  There will not be enough energy to vaporize more than a small
fraction (<5%) of the carbon composit rotor. Also implied in the
argument was that the total rotor(s) mass(es) will have to be substantial
 (>100Kg) _if_ the proposed vehicle is similar to a modern automoble
in size, weight, acceleration, and areodynamic and rolling drag. 
I see no reason it couldn't be 1 200kg rotor or 40 5 kg rotors

 Regards, Chuck@pierre.mit.edu