ideas for a noise maker cannon

[swires]

My two boys are playing high school football in the Texas panhandle and our mascot is a pirate. I have been looking to build or purchase a cannon to use when the team scores. I am looking for something that is loud but safe to use in a high school setting. I am not looking to shoot any projectiles. I am just looking for noise and possibly a little smoke. I have looked into purchasing a propane bird scare cannon but they are somewhat expensive. I figure I can build one cheaper. Any suggestions??

[D_Hall]

Look for a carbide cannon.

Or make your own. Granted, propane can be done, but if all you want is loud noise, it's difficult to beat acetylene (which is what carbide cannons burn).

[swires]

Thanks. Are there plans somewhere to make a large scale carbide cannon? All I have seen of those is the little "Big Bang" cannons on ebay. How big do you have to build the thing to get a bang that would be similar to a real cannon?

[MrCrowley]

Something like this will also do the job. It's a propane metered combustion cannon that uses a few layers of tape as a low-pressure burst disk. You could get a shot off every 30 seconds if you had a quick way of replacing the burst disks.

[swires]

Also. I am looking for something that I could fire instantaneously.

[Mr.Tallahassee]

Thanks. Are there plans somewhere to make a large scale carbide cannon? All I have seen of those is the little "Big Bang" cannons on ebay. How big do you have to build the thing to get a bang that would be similar to a real cannon?

I'm not sure you want that kind of volume going off in a high school field. I would start with experimenting with smaller sized cannons. PVC pipe is pretty cheap to play with.

[MrCrowley]

Also. I am looking for something that I could fire instantaneously.

If the burst disk on the above combustion cannon was 100% sealed, I don't see why you couldn't fuel the cannon and wait until a goal is scored.

[swires]

MR. Tallahassee,

What volume are you talking about and for which suggestion? Please forgive my ignorance. I have done little research on how to build one. Some of these things that I have seen look pretty complicated to build. I would be good with using something small to make the noise but I was wanting something that would be life size. I am sure I could hide the actual cannon inside a larger piece of pvc.

[jackssmirkingrevenge]

All you need is a tube closed at one end and a couple of sparky wires

Pretty much what I did here: http://www.spudfiles.com/forums/clear-c ... 22067.html

Nothing to it. Heck, you can even prepare "cartridges" made from cardboard tubes capped with duct tape to give you a repeated rate of fire.

The best thing to understand is fuel mix and ignition.

For the first, I recommend syringe fuelling - just as cheap as spray-and-pray but much more accurate: http://www.spudfiles.com/forums/how-to- ... 22301.html

As to ignition, a clicky piezo cigarette lighter is all you need: http://rimstar.org/materials/piezo/how_ ... ighter.htm

[Gippeto]

...I was wanting something that would be life size.

[youtube][/youtube]

[Fnord]

For an authentic gun, some 3 or 4" thinwalled steel conduit will work for a carbide cannon. If you have a scrap yard around, look for a three or four foot section- it won't cost you much. If you already have an oxy/acetylene torch, everything else can be easily found or improvised.

Acetylene is easy to use it you just want a bang- no fuel meter is needed. If you want to build a meter for fast reloads, look up fuel meters for normal propane cannons, but build them knowing you'll be limited to 15 psi of meter pressure (acetylene has stability issues above that).

If you don't have any way to weld things, go with a propane cannon and use normal pvc pipe. There are tons of loud combustion cannons on this site; have a look around and ask again when you find something you like the looks of.

[D_Hall]

What Fnord said. Although depending on your budget I might upgrade the steel conduit to sch 40 pipe. Not that there's anything wrong with the conduit, just because the pipe would withstand abuse better (By "abuse" I mean people dropping it when offloading the cannon from a truck, or similar "oops" moments).

Also, pipe can be threaded which means that you can make all the connections to the gun in a pipe cap that just screws on to the breech of the canon.

I see you can buy a 36" long piece of 4" sch 40 pipe threaded at one end for about $120 at McMaster-Carr. And McMaster, while a great "one stop shop" is *always* overpriced so you can probably do better at a pipe supply store if there's one in your area.


Oh, and I think you should definitely build a meter for such a canon. It would make it easier to fire the gun *consistently* which I'd wager will be a requirement to get school officials to approve of the design. They'll need a way to *know* that the gun will only do [whatever] when fired.

You'll probably also want a second metering pipe to push a charge of compressed air into the back of the canon to purge after each shot. There are other ways to purge, but based on what you've said so far I think hitting it with a bit of compressed air is likely the best for your application.

edit...

Thinking more, I see a procedure that looks something like....


1) Remove firing line. Call that 5 seconds.

2) Release air (from air metering pipe) into breech of gun. Should maybe take 2 seconds.

3) Release acetylene (from C2H2 metering pipe) into breech of gun. That's maybe 3-4 seconds.

4) Take a piece of saran wrap and place it over the muzzle of the gun, securing with a rubber band. Meh... I'll call that 10 seconds.

5) Hook up firing line (you do NOT want to be around that muzzle while the gun could conceivably be fired). That's another 5 seconds.

5.1) Wait until touchdown is scored.

6) *BANG*

7) Return to step 1.

So you've got about a 25 second reload time with each shot costing you a bit of air, a bit of acetylene, and a small piece of saran wrap. Is that acceptable?