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Re: Rotary SG Safety

Original poster: Terry Fritz <teslalist-at-twfpowerelectronics-dot-com>


Lexan also burns up very gasoline like...  I don't use it for robots due to 
the fire dangers...    I am really liking "G-11" fiberglass!!!  Not too 
pricey and noticeably better than G-10 for strength!!  All I use now...



At 03:33 PM 6/17/2004, you wrote:
>In a message dated 6/17/04 11:49:17 AM Eastern Daylight Time,
>tesla-at-pupman-dot-com writes:
> > More interesting is that the Lexan broke a couple inches
> >  away from where the bullet hit - we conjecture due to the shock wave
> >  travelling in the plastic.
> >
> >  Maybe at high spped, the rotary parts created a shock wave when they hit
> >  the shield?
>     High explosives will shatter Lexan into little tiny pieces as if it were
>tempered glass. Chalk that up to shock (brisance).
>     FWIW, it's easier to use Lexan to stop a .38 slug than a .22 of the same
>construction and velocity. Although the .38 has more mass, therefore more
>energy and momentum, this is negated by its larger cross-section. Sectional
>density is about the same, but the impact area makes a difference.
>     From this, I'd postulate that brass acorn nuts, which are much less
>deformable than lead and have six or so mild corners, might impact in such 
>a way to
>concentrate that force into a small area.
>     OTOH:
>     I don't have any brass acorn nuts to weigh, but I'm estimating one would
>have near the mass of a .22 LR bullet. If it's a 6" rotor at about 8000 rpm,
>that gives the brass nut a linear velocity of over 200 feet per second. Which
>works out to a measly 3-4 ft-lbs (4-5 Joules ;) ) of energy - more like a BB
>gun than a .22.
>     Has anyone noticed bad effects from UV to the plastics used in coiling?
>Granted that the total exposure times are small, but at a RSG I bet the
>intensity makes up for it. With all the UV, vibration, electrical 
>stresses, and
>ozone, are the plastics weakening? Especially with 
>non-UV-stabilized/coated types?
>-Phil LaBudde