8x pvc failure

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jackssmirkingrevenge
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Fri Aug 14, 2009 12:30 am

theBOOM wrote:How much damage did the shrapnel cause?
Maybe the test could be repeated under different conditions?
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Moonbogg
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Fri Aug 14, 2009 12:40 am

jackssmirkingrevenge wrote:
theBOOM wrote:How much damage did the shrapnel cause?
Maybe the test could be repeated under different conditions?
Yes...perhaps with an aluminum chamber.
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frankrede
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Fri Aug 14, 2009 4:09 am

Come on guys, we have long established that DDT is not a factor that should even be considered on most hybrids.
Its probably failure of the PVC from imperfections in the plastic or near microscopic cracks cause by previous firings.
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Brian the brain
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Fri Aug 14, 2009 6:17 am

I've seen a bulge like that ( in the first hybrid) in copper before..

On my stirrup pump- after the checkvalve failed at 80 bar...and the handle broke my pretty face..
So I guess it's just a sudden rise in pressure that causes it...not neccesarily DDT.

It bulged at the point of the blockage ( in my case the pump piston).
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pat123
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Fri Aug 14, 2009 9:04 am

I am guessing that one of the other 8x shots cracked the inside pipe but the outside pipe still held, then the last shot was mostly acting only on the 2" pipe.

There was a lot of shrapnel but it all went straight forward into the trees. The barrier did its job. The only other damage was to my electric bbq ignitor which flew about twenty feet and hit the metal pole on my basketball goal.
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Mr.Sandman
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Fri Aug 14, 2009 11:40 am

This has pretty much shattered (how ironic) my project plans in the contest. But thanks for the post. Might i asked how you made the blast chamber?
Yeah, it's that important.
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pat123
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Fri Aug 14, 2009 11:46 am

the blast chamber is made out of cinder blocks. it covered the back and both sides of the gun so that all of the shrapnel would shoot forwards into the trees.

We probably should have made it a little bigger but none of the shrapnel flew backwards so it was good enough.
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Mr.Sandman
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Fri Aug 14, 2009 11:47 am

pat123 wrote:the blast chamber is made out of cinder blocks. it covered the back and both sides of the gun so that all of the shrapnel would shoot forwards into the trees.

We probably should have made it a little bigger but none of the shrapnel flew backwards so it was good enough.
oops my bad. i didnt see the picture long enough now i understand
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c11man
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Fri Aug 14, 2009 3:11 pm

so did you have to chage your pants after this?

anyway, what size barrel did you have on this? and what was you estemated fps before "the incedent"?
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pat123
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Sat Aug 15, 2009 12:09 am

The barrel was 1" diameter 5' long.
estimated 2000ft/Lbs and 400fps with a 19oz 10" long steel nail.
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Sat Aug 15, 2009 12:29 am

pat123 wrote:The barrel was 1" diameter 5' long.
estimated 2000ft/Lbs and 400fps with a 19oz 10" long steel nail.
Impressive ballistics for pvc!

The cinder-blocks seemed to help contain it and from photos didn't seem to break(?)...

But I was remembering this lecture a cop gave me as a juvenile about some kid who had put a pipe b*mb inside one, electrically ignited it,
got hit in the head with a cinderblock chunk and was drooling and wears a helmet all the time...(course I was thinking, "dumb cop...")
I know they shatter pretty completely from rifle hits though. :roll: 8)
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c11man
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Sat Aug 15, 2009 9:20 am

pat123 wrote:The barrel was 1" diameter 5' long.
estimated 2000ft/Lbs and 400fps with a 19oz 10" long steel nail.
i see some problems with your calculations, at only 10inches long and a hefty 19oz that would mean that the average diameter of 0.73055869
inches. so i think you have a slight math problem. if you give me the correct diameter i would be happy to recalculate
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inonickname
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Sat Aug 15, 2009 9:27 am

THUNDERLORD wrote: some kid who had put a pipe b*mb inside one
I hope you realize the difference between a failure in a (comparatively) low power spudgun to a sealed metal tube filled with a low explosive..
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Sat Aug 15, 2009 9:30 am

c11man wrote:So I think you have a slight math problem.
I could say the same of the number you churned out.

You shouldn't give an answer to more significant figures than the inputs. One s.f. more is acceptable in some cases, but still questionable.

... you gave an answer of 6 s.f. more than the inputs.
Does that thing kinda look like a big cat to you?
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Mr.Sandman
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Sat Aug 15, 2009 10:48 am

Ragnarok wrote:
c11man wrote:So I think you have a slight math problem.
I could say the same of the number you churned out.

You shouldn't give an answer to more significant figures than the inputs. One s.f. more is acceptable in some cases, but still questionable.

... you gave an answer of 6 s.f. more than the inputs.
Lets keep the smart level down shall we? Btw @pat, where did you get a 19oz nail?!?
Yeah, it's that important.
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