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New Cannon... Maybe

Post questions and info about combustion (flammable vapor) powered cannons here. This includes discussion about fuels, ratios, ignition systems, safety, and anything else relevant.
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Unread postAuthor: rcman50166 » Thu Apr 10, 2008 4:29 pm

I do appreciate the video. And you're right not exactly the best performance. That conductor didn't know what the hell he was doing; flailing his arms and all. Not a very good technique... Anyway, now you see why there must be cannon. And better yet you know how fast of a reload time this cannon would need to have. In a good performance, the cannon overloads the audience's senses and they become immersed in Napoleon's invasion of Russia. The room thunders, the ground shakes, the air smells of gunpowder (not in my case) and at the end the audience roars to life, throwing babies in the air and what not. So you get the idea.

Now the question is how to make a 5 step loading process quick, easy and reliable. My idea is to try to put link arms between the valves connecting them to make one single action. When the chamber side valves close, they come in contact with the ignitor shooting it. A mechanical solution, but it's what I'm best at.
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Unread postAuthor: rcman50166 » Thu Apr 10, 2008 5:37 pm

Here, just finished a quick diagram to show what I'm proposing for the fueling system. Both mapp and oxygen are connected to this system which would be connected to each other so a rapid open and close are all that is needed to fuel the chamber.
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Unread postAuthor: starman » Thu Apr 10, 2008 6:51 pm

Should work if you're injecting oxygen as well, no need to evacuate the gases in between shots that way. Just be careful you get your mixes right.

You'll still want a chamber fan for a good healthy blast. How are you going to seal your chamber? Check valve? Burst disk?

Also, with these relatively fast shots, you might have a little bit of a heat build up that isn't desirable in PVC especially sched 40....One reason I was going with 4 seperate units.

What are you using for actuation of the fuel valves?
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Unread postAuthor: JDP12 » Thu Apr 10, 2008 7:07 pm

huh, well if you need something loud....use either a pneumatic or a combustion, with a burst disk... that will get it incredibly loud. For faster shots like you want, i would use a pneumatic though for the reason starman mentioned
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Unread postAuthor: starman » Thu Apr 10, 2008 7:26 pm

ilovetoblowthingsup wrote:huh, well if you need something loud....use either a pneumatic or a combustion, with a burst disk... that will get it incredibly loud. For faster shots like you want, i would use a pneumatic though for the reason starman mentioned


Check earlier in this thread...
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Unread postAuthor: Blitz » Fri Apr 11, 2008 12:02 am

As most public performances are, thunderlord. Heck, in Chicago during the 4th of July, there are so many fireworks going off downtown that you could not hear a gun being fired if you were next to one!
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Unread postAuthor: rcman50166 » Fri Apr 11, 2008 5:36 am

starman wrote:Should work if you're injecting oxygen as well, no need to evacuate the gases in between shots that way. Just be careful you get your mixes right.

You'll still want a chamber fan for a good healthy blast. How are you going to seal your chamber? Check valve? Burst disk?

Also, with these relatively fast shots, you might have a little bit of a heat build up that isn't desirable in PVC especially sched 40....One reason I was going with 4 seperate units.

What are you using for actuation of the fuel valves?


Hmm... well I thought the chamber side valve on the metering system could handle sealing the chamber. Can it not? Or are you talking about the open barrel? If so, then I haven't really thought about that. Perhaps some wadding, just to plug up the huge hole.

Yes I would need a chamber fan to mix the fuel fast enough.

And the PVC teperature isn't really a concern. I've fire the sarge while the PVC was hot. I doubt failure will occur from anything other than a DDT, which, now that I mention it, is a serious threat. Umm.. how do you guys suggest I protect the audience from one. I was thinking using a blast barrier made around the chamber. It uses fishing line wound around the PVC with duct tape around that. You think this could absorb the shock from a DDT. (not necessarily hold the chamber together, just absorb any kinetic energy prom PVC shrapnel)
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Unread postAuthor: igpay » Sat Apr 12, 2008 6:10 pm

I might be too late to help, but make magazine ran an article about an air cannon made only for making noise. it looks nothing like a cannon, recharges fairly fast and is supposedly rather loud. Google "boom stick".
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Unread postAuthor: igpay » Sat Apr 12, 2008 6:12 pm

actually, dont google it, goto makezine.com and then search for boomstick through the website
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Unread postAuthor: DYI » Sat Apr 12, 2008 6:17 pm

It uses fishing line wound around the PVC with duct tape around that. You think this could absorb the shock from a DDT. (not necessarily hold the chamber together, just absorb any kinetic energy prom PVC shrapnel)


Firstly : :laughing5:

Secondly: what is the big DDT risk? Because unless the chamber is more than 30 feet long, or of uselessly low diameter, the threat of DDT at atmospheric pressure with propane air and no deliberate detonation causing devices is... well... non-existent.
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Unread postAuthor: rcman50166 » Sun Apr 20, 2008 11:47 am

Well I don't honestly know all that much about DDT. All I know is that it is extremely powerful, only occurs at absolute optimium fuel mixtures, and is nearly unpredictable. It sounds like a force not to be messed with. Anywho, I found that the quick diagram I drew up won't actually work because the linkage arms will conflict with eachother. Can anyone think of a solution for this?

BTW: I think you underestimate the potential strength fishing line can add. If you add 30 lbs tess to a pipe and there are, say, 15 windings per inch well... a 4 inch pipe can be increased almost 35 PSI. (Unless I'm looking at it the wrong way) Also, epoxy resin coating adds strength. I won't add reinforcement without it. It also makes a nice finish. :)
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