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Unread postAuthor: Labtecpower » Sat Apr 02, 2011 2:17 am

MrCrowley wrote:Labtecpower watch what you say otherwise I will have to lock the topic. No mention of powders (or their composition) please.


I'm sorry.



I am not a fan of the bolt used to seal the chamber. If something would fail, that would be the first thing I think.

Just machining it out of a solid steel bar is a better option, but makes inserting the advanced combustion cartridge harder.
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Unread postAuthor: DYI » Sat Apr 02, 2011 9:34 am

Assuming the use of normalized 4340 or similar for the chamber, pushing out that bolt quickly would require the application of about 150 kpsi to its entire face, or just over 1 Mpsi to the 9/16" area. The initial "decompression" pressure of the *air* will exceed that, but the "steady state" pressure (*decompression wave* has passed, but heat transfer has not played a significant role yet) won't even come close. For comparison, the initial "decompression" pressure in my attempt exceeded the ultimate tensile failure point of the chamber by about a factor of five. These things survive seemingly by inertia alone...

After running that rough calculation, I'd suggest either a decrease in bore diameter, an increase in bolt diameter, an increase in thread engagement, or some combination thereof.
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Unread postAuthor: Labtecpower » Sat Apr 02, 2011 1:31 pm

I made a very simple stand for the cannon today. I wanted to be able to load the cannon vertically, and aim it by tilting up and down.

Thrown together in 5 minutes

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