Brownie points to the one who can explain this cannon video

Boom! The classic potato gun harnesses the combustion of flammable vapor. Show us your combustion spud gun and discuss fuels, ratios, safety, ignition systems, tools, and more.
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Moonbogg
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Sun Jun 16, 2019 9:07 pm



What is going on here? The video has strange music and there is something artistic about the whole thing that I love, but I am wondering what is going on inside this cannon? What kind of "valving" do you think they might have in there that would have broken with an oxy/fuel shot?
This whole cannon looks freakish and crazy. How do you think this thing used to work?
Also, they use bolts in shear to hold the end caps on. I know this is a thing and people do it, but I don't like it for some reason. I imagine the holes loosening over time and I don't like the complete lack of pre-tension with a shear configuration. What are your thoughts on using bolts like that? Is it fine? No big deal? It bugs the hell out of me.
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D_Hall
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Mon Jun 17, 2019 1:05 am

First impressions....

They've mad machinist skills and access to equipment but don't know a damned thing about gun designs. This is evidenced by obviously having to zero in on the fuel/air mixture via experimentation. Anyone who's put that much work into a gun should never experience a misfire. **NEVER**.

About the bolts in shear... I think this is just further evidence of them not knowing proper design or perhaps demonstrates a gap in their equipment. Putting bolts in shear like that can allow for easy O-ring seals and the like at the price of non-optimal structures. This doesn't have to be a problem provided you design for it. When you design for it, however, you typically end up using a fair number of fasteners. They appear to use six. SIX?? Yeah, I'm betting they put zero thought into it.

Valving? Just a guess, but I'm going with this being a very early valved hybrid attempt using diaphragm valve in a coaxial configuration. Zero knowledge, but that's what the overall look of the gun screams to me.
Simulation geek (GGDT / HGDT) and designer of Vera.
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jackssmirkingrevenge
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Mon Jun 17, 2019 5:16 am

D_Hall wrote:They've mad machinist skills and access to equipment but don't know a damned thing about gun designs. This is evidenced by obviously having to zero in on the fuel/air mixture via experimentation. Anyone who's put that much work into a gun should never experience a misfire. **NEVER**.
Agreed, and playing with oxygen in that situation is really not a good idea.
hectmarr wrote:You have to make many weapons, because this field is long and short life
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jrrdw
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Mon Jun 17, 2019 5:17 am

This video was posted to YouTube 4 years ago and the web address in the end of the video didn't work for me.

http://www.troynietschmann.com

[youtube][/youtube]
Look if you must.
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jackssmirkingrevenge
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Mon Jun 17, 2019 5:22 am

jrrdw wrote:This video was posted to YouTube 4 years ago
Just over 7 years:
Published on Feb 15, 2012
url is down for me too, hopefully our intrepid inventor didn't blow himself up.
hectmarr wrote:You have to make many weapons, because this field is long and short life
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Moonbogg
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Mon Jun 17, 2019 12:57 pm

Nice analyses and comments. I can't get over that freakish music, and the website doesn't work for me either. That was the first thing I tried. I'd love a closer look at this cannon and how it works, but we may be out of luck for anything more than this video.
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jrrdw
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Tue Jun 18, 2019 5:39 am

The chamber wasn't built very well...
Look if you must.
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mark.f
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Mon Jul 01, 2019 9:38 am

archived
Looks like he had been working on it long before 2012 it seems, although of course since it's a smaller site the actual page on the gun isn't archived. Looks like your typical "buy an oxy-propane/butane torch from Lowes and plumb it into a cannon" cannon with more money to burn but not enough know-how. :D
(by the way, what's up Moonbogg?)
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