Combustion Launcher Explosion

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Postby mcook » Tue Feb 27, 2007 2:14 am

<img src="TTP:www.spudfiles.com/triplechambercombustiongun.jpg">
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Postby joannaardway » Tue Feb 27, 2007 7:29 am

Your web-address needs correcting.

And I want concrete proof of this - otherwise, I'll agree with Gort. This smells like 100% pure, filtered, distilled and matured bullshit.

You've either not told us something critical, or you're lying.

It would not have turned into Ground zero under the facts you've listed.
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Postby aturner » Tue Feb 27, 2007 10:07 am

mcook,
PVC can become brittle in cold weather. What was the outdoor temperature when you were launching?

Also, it sounds like the chamber fans became projectiles. Where were the fans placed within the chamber, and how were they secured?

Finally, you say you used a 6" sch40 cleanout cap? How are you sure it was sch40? Was it a special order item (McMaster), or something you found at a local hardware store? Most 6" cleanouts have the overall appearance of sch40, and they will fit together with sch40 pipe/fittings. But they are almost always marked with "dwv".

Anyone know if McMaster even sells 6" plugs in sch40? My quick search found nothing.
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Postby mafia_mike » Tue Feb 27, 2007 12:18 pm

As far as the specifications are layed out for this thing, the cannon wouldnt blow up because the loose rag would be pushed out of the barrel first. Second, (im sorry correct me if im wrong) isn't the maximum combustion pressure of propane around 90 psi. ?. Third, aerodynamics proves that end caps, cleanout plugs or whatever are not aerodynamic, so how did it achieve a high enough velocity to go through ... A WALL?? Fourth, did the fans leave some kind of smudge? or a dent in the PVC?. In that case if the imprints were similar on both endcaps, then that would be some kind of miracle of circumstances for the pressure to occur exactly the same on both sides. All evidence here (and that other spudgunners have displayed) proves that this is ... well ... BS (ok to everybody i apologize if any of these assumptions and explanations of physics are wrong ... im still pretty new here and im not a physicist lol)
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Postby joannaardway » Tue Feb 27, 2007 3:49 pm

As well as what Mafia Mike said, I'd say that the endcaps were just too light to do that much damage, and they'd just disintegrate on contact.

Mafia Mike, your explanations seem fine - I agree, the loose rag would have at least moved first.

Anyway, in my opinion even if it is true, if it was set up in such a place that an accident would blow a hole in a neighbour's house, the idiot responsible deserves to have to foot the bill for it.
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Postby SpudMonster » Tue Feb 27, 2007 5:29 pm

<blockquote id="quote"><font size="1" face="tahoma,verdana,arial" id="quote">quote:<hr height="1" noshade id="quote">Originally posted by joannaardway
[br]As well as what Mafia Mike said, I'd say that the endcaps were just too light to do that much damage, and they'd just disintegrate on contact.
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">


If an endcap will disentegrate on contact with a wall, why is it that we can use a soft squishy potato to make a hole in 1/2" plywood?
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Postby mafia_mike » Tue Feb 27, 2007 7:07 pm

have you put a hole in a steel plate with a potato? ... same thing applies here, yet the sheet-rock is composed of crushed calcite (most likely) and thats softer than your fingernail
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Postby mcook » Wed Feb 28, 2007 1:20 am

I work for a general contractor so I have access to any pipe and fitting materials I need. I did not buy any of these materials from a local hardware store. I ordered these materials from a local pipe supplier. The 6" screw caps are schedule 40. The manufacturer is Spears which is a major manufacturer of PVC pipe and fittings. If you go to there website, you can review the specs of all their pipe and fittings. No drain pipe or fittings were used in this build. The weather is not an issue as I live in Las Vegas and the temp does not dip below 45 this time of year. I am currently paying for my neighbors drywall and window repairs.

Believe me, those caps are heavy and had enough velocity that they did travel accross the street through my neighbor's house windows and put a hole through the first layer of drywall.

The fans were located in the center of the pipe approximately 3" from the back of the chambers. They were set in a piece of 2" pipe secured with set screws.
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Postby sgort87 » Wed Feb 28, 2007 1:47 am

Sounds a bit too detailed to be made up. But still, these things don't blow up for no reason. There has GOT to be something wrong.

Spears is a VERY good PVC company. The best, in my opinion. It must not have been DWV parts.

I'm stumped dude. You sure you screwed that cap on all the way? :p
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Postby joannaardway » Wed Feb 28, 2007 5:29 am

I still don't like the sound of this.

Both (or is it three?) endcaps simultanously blowing off in almost exactly the same manner, rather than the damp rag moving instead?

The chamber(s) should have failed in one place, and one place only - having multiple <b>identical</b> weak points so that they go at exactly the same time (if one had blown off, the pressure should have dissappeared in an instant - all the caps would have had to have started moving at the same time) has a chance so long that I'd rather my chances at winning the lottery without a ticket.

If everything you've told us about the cannon and accident is entirely true and unembellished - then you must have made a serious mistake somewhere which you haven't told us about.

Please show us a picture of the damage to your neighbour's house - at least that way you can prove that the incident happened (although not necessarily exactly the way you described). Then we can stop doubting it's truth, and get on to working out "why/how?"
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