What Do You Think?

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.
truemanator
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Tue Aug 21, 2012 6:02 pm

hi, just a quick (quick for a pro, VERY long time for me.) mockup of my new, simple cannon, looks pretty cool though, switch on the front is for fan, rear is piezoelectric ignitor, i personally like simple designs., should be done reasonably soon if i can find all the parts.
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PotatoEnemy17
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Tue Aug 21, 2012 6:08 pm

Nice, good job on the CAD. But if you are looking for simple and lots of power, then BUILD A PNEUMATIC CANNON! :D

EDIT: Apparently you already did, oops :oops:
Last edited by PotatoEnemy17 on Tue Aug 21, 2012 6:11 pm, edited 1 time in total.
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sharpshooter11000
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Tue Aug 21, 2012 6:10 pm

What program did you use? Looks pretty good! I'd say upgrade your pneumatic cannon first and then build this.
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PaperNinja
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Tue Aug 21, 2012 6:10 pm

Power yes, but combustion cannons are much more common and easy to build.
truemanator
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Tue Aug 21, 2012 6:21 pm

To be honest, i do much prefer combustion, mainly because it takes much less effort as everything does not need to be perfectly sealed, and because i just cannot understand Piston valve (or cant be bothered to understand them)

EDIT: I used google sketchup to do this
PotatoEnemy17
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Tue Aug 21, 2012 6:29 pm

If you want to do a pneumatic cannon, then the recipe is simple: Air chamber (same as combustion chamber) ball valve, barrel. No seals required. And very powerful. In fact you can simply Google ball valve air cannon, and people have made diagrams and stuff for these guns. Also don't worry about piston valves.
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sharpshooter11000
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Tue Aug 21, 2012 6:31 pm

I much prefer pneumatics, much more predictable! The spud wiki is extremely helpful with piston valves, here's the page on QEVs (ready made piston valves)
Last edited by sharpshooter11000 on Tue Aug 21, 2012 6:35 pm, edited 2 times in total.
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truemanator
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Tue Aug 21, 2012 6:33 pm

Potatoe ememy, i recently did one of these cannons, but to get any power out of it,i think i need a faster valve.
truemanator
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Tue Aug 21, 2012 6:36 pm

Actually, that is a very good point about the reliability, i sometines have to blow out all the feul and refeul it. It does gat annoying
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sharpshooter11000
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Tue Aug 21, 2012 6:37 pm

You could get more power by
- using a longer barrel
- using a faster valve (eg. QEV)
- using higher pressure
And a few more but those are the simple ones.

Just a note on your original combustion design- if you want to set the cannon barrel-up then you'll be setting it on the piezo which could accidentally fire it.
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MrCrowley
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Tue Aug 21, 2012 9:44 pm

PotatoEnemy17 wrote:If you want to do a pneumatic cannon, then the recipe is simple: Air chamber (same as combustion chamber) ball valve, barrel. No seals required. And very powerful. In fact you can simply Google ball valve air cannon, and people have made diagrams and stuff for these guns. Also don't worry about piston valves.
Well a typical advanced combustion will usually out-perform a ball valve pneumatic by quite a large margin. If we're talking about ~100PSI pneumatics here, go with a fuel metered combustion. You have to remember that combustions have no flow restrictions and a 'valve' that opens instantaneously (in other words, there is no valve). Even if you're only getting ~80PSI from the combustion, the gases are still far less dense than air and will more often result in better performance.
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wyz2285
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Wed Aug 22, 2012 3:21 am

MrCrowley wrote:
PotatoEnemy17 wrote:If you want to do a pneumatic cannon, then the recipe is simple: Air chamber (same as combustion chamber) ball valve, barrel. No seals required. And very powerful. In fact you can simply Google ball valve air cannon, and people have made diagrams and stuff for these guns. Also don't worry about piston valves.
Well a typical advanced combustion will usually out-perform a ball valve pneumatic by quite a large margin. If we're talking about ~100PSI pneumatics here, go with a fuel metered combustion. You have to remember that combustions have no flow restrictions and a 'valve' that opens instantaneously (in other words, there is no valve). Even if you're only getting ~80PSI from the combustion, the gases are still far less dense than air and will more often result in better performance.
I agree, but if he gets a fridge compressor :wink:
Personally I only built ONE combustion and fired it ONCE :lol: because they are only powerful by their size, a mini combustion can not be compared to a mini pneumatic. (Also because I have hybrids and 230bar air source :D )
CpTn_lAw wrote: :D "yay, me wanna make big multishot pnoob with 1000 psi foot pump compressor using diamond as main material. Do you think wet bread make good sealant? " :D
PotatoEnemy17
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Wed Aug 22, 2012 10:04 am

MrCrowley wrote:
PotatoEnemy17 wrote:If you want to do a pneumatic cannon, then the recipe is simple: Air chamber (same as combustion chamber) ball valve, barrel. No seals required. And very powerful. In fact you can simply Google ball valve air cannon, and people have made diagrams and stuff for these guns. Also don't worry about piston valves.
Well a typical advanced combustion will usually out-perform a ball valve pneumatic by quite a large margin. If we're talking about ~100PSI pneumatics here, go with a fuel metered combustion. You have to remember that combustions have no flow restrictions and a 'valve' that opens instantaneously (in other words, there is no valve). Even if you're only getting ~80PSI from the combustion, the gases are still far less dense than air and will more often result in better performance.
:roll:

Maybe an advanced combustion might out perform a simple ball valve cannon, but once you do a ball valve cannon, a QEV cannon is only a step away. Plus a ball valve cannon can be spring loaded. :D

Another option is using a burst disk pneumatic cannon. It takes extra time to load it, but it will likely out perform any combustion. And remember, loading a burst disk isn't much more work than loading a combustion cannon. :wink:

EDIT: Also the cannon truemanotor originally suggested is clearly not an advanced combustion cannon. truemanator even referred to it as his new "simple" cannon.
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sharpshooter11000
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Wed Aug 22, 2012 10:12 am

I don't think Mr C was referring to his original design, just stating that an advanced combustion would outperform a ball valve pneumatic.

Also, with a well built combustion, a hybrid is only a step away ;)
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PotatoEnemy17
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Wed Aug 22, 2012 10:30 am

truemanator said he likes simple cannons. Here's the problem to get a powerful combustion you need to build an advanced combustion or hybrid, both of which are inherently not simple (hence the name advanced combustion) :lol: But if you want power AND simplicity, a pneumatic cannon is just the thing. :D After all, everyone likes simplicity in a cannon and MOAR POWER!
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