my new super project

Post questions and info about combustion (flammable vapor) powered launchers here. This includes discussion about fuels, ratios, ignition systems and anything else relevant to launchers powered by igniting things like hairspray or propane.

Postby jetpilot » Mon Jan 01, 2007 11:31 pm

<a href="http://img388.imageshack.us/my.php?image=pcj3viewportsxx8.png" target="_blank"><img src="http://img388.imageshack.us/img388/8111/pcj3viewportsxx8.th.png" border="0" alt="Free Image Hosting at http://www.ImageShack.us" /></a>
***CLICK TO ENLARGE***

these are some of the photos i screenshot from my CAD program.
heres my idea, the barrel is pretty much the length of the cannon, the chamber is surrounding it with an endcap on the end the barrel extends out(as seen on bottom right pic of viewport). these gasses will have no other choice but to expand in the opposite direction of the potato's trajectory and then expand into the barrel direction(as seen on top right pic of view port).
this is probably very confusing, but i hope the pic helps.
i got this idea from how a space shuttle boosters work.
<a href="http://img403.imageshack.us/my.php?image=rocketengineww9.png" target="_blank"><img src="http://img403.imageshack.us/img403/4053/rocketengineww9.th.png" border="0" alt="Free Image Hosting at http://www.ImageShack.us" /></a>
thats how i got the idea.
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Postby SpudMonster » Mon Jan 01, 2007 11:35 pm

You have just reinvented the coaxial combustion cannon.

http://www.spudtech.com/images/products/Coaxial-2.jpg
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Postby An Apple Pie » Tue Jan 02, 2007 12:08 am

Already been done, although I am impressed at you coming up with this by your self.

SpudMonster- I have never really understood how that cannon works. I mean when you screw the cleanout cap on it looks like it would be hitting the end of the barrel.
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Postby c0mpl3x » Tue Jan 02, 2007 12:31 am

<blockquote id="quote"><font size="1" face="tahoma,verdana,arial" id="quote">quote:<hr height="1" noshade id="quote">Originally posted by An Apple Pie
[br]Already been done, although I am impressed at you coming up with this by your self.

SpudMonster- I have never really understood how that cannon works. I mean when you screw the cleanout cap on it looks like it would be hitting the end of the barrel.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

rofl i totally agree
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Postby benstern » Tue Jan 02, 2007 12:53 am

Na, remember the clean out cap has that square hollow space?
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Postby An Apple Pie » Tue Jan 02, 2007 1:40 am

Oh, I never realized that. Doesn't that decrease flow A LOT? I mean all the air has to squeez through a very small opening, doesn't it?
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Postby jetpilot » Tue Jan 02, 2007 4:51 pm

well yea i didn't quite think about that untill i went to bed, it would probably be smart to possition the barrel a good foot away from the cap, as to not turn your potato cannon into the worlds largest firecracker.
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Postby aturner » Tue Jan 02, 2007 5:41 pm

It does not affect flow, performance, or safety. It's fine.

The only thing I don't like about the standard coaxial combustion design is the clearance between the chamber and barrel. The clearance is a bit tight, and I tended to scrape up my knuckles on the threads on the chamber cleanout when reloading. Therefore, I extended the barrel breechward and built a chamber extension for the blackhawk...
http://loose-cannon.home.mindspring.com/blackhawk/
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Postby An Apple Pie » Tue Jan 02, 2007 7:33 pm

It is also almost imposible to use arosol fuel. It is hard to get it spread out through out the entire chamber.
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Postby nicholai » Tue Jan 02, 2007 8:00 pm

I like that propane setup you have aturner. Thats pretty cool to use a grill tank solely for your spud gun!
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