Tennis Ball Cannon

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.
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singularity
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Wed May 28, 2008 6:07 pm

im back!!! and ive brought a few slight innovations with me (along with some major ones i will be releasing shortly) i took a vacation form spudfiles for most of the school year but now that its just about summer i should have a few new projects to share with you all very soon.

...BACKGROUND...

this is my newest creation and my first true metered propane combustion. this will actually be the first cannon i will be making money off of since it will be sold to a man who messed up his back and can no longer play fetch with his dog. as with every other "toy" i have made its a slightly different/improved/modified version of the other cannons on this site. the one particularly unusual part is the one touch propane meter, but ill go into more detail on that later. other than the modified meter its your standard propane cannon.


...SPECS....

chamber volume----150ci
barrel volume-------120ci
barrel length---------2ft
barrel diameter------2.5"
C:B ratio-------------1.25:1
fuel-------------------metered propane
ignition---------------standard grill igniter
chamber fan---------no (well its external cause of a BS safety concern)
range-----------------150ft +
ammo----------------Tennis balls


<img src="http://i78.photobucket.com/albums/j85/i ... CN3284.jpg">

<img src="http://i78.photobucket.com/albums/j85/i ... CN3289.jpg">

<img src="http://i78.photobucket.com/albums/j85/i ... CN3285.jpg">

<img src="http://i78.photobucket.com/albums/j85/i ... CN3287.jpg">

<img src="http://i78.photobucket.com/albums/j85/i ... CN3288.jpg">

the propane meter is of a new design which was jointly built by myself and another member of this site known as "meatballs". it only has one valve so it can be used with more ease than a standard meter. the secret is in the propane torch head hidden within a coupler. this head limits the flow so that the propane doesn't over saturate the chamber if the blowgun valve is held open for too long. it takes about 10 seconds for the meter to completely re-pressurize. which is about the same about of time it takes a normal person to reload and shoulder the cannon.
be sure to check out my <a href="http://www.spudfiles.com/forums/ak-styl ... 9.html">AK Styled Vortex Gun</a> and my <a href="http://www.spudfiles.com/forums/at-4-t9627.html">AT-4 Rocket</a>

upcoming projects... finalized clip fed BBMG and ball point pen sniper
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bigbob12345
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Wed May 28, 2008 6:18 pm

Great cannon you got there
Its very clean
And I really like the idea of a blowgun insted of two ball valves, Ill have to try it sometime
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starman
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Wed May 28, 2008 6:20 pm

Beautiful work, beautiful gun!

Only a couple of comments...the PVC lettering could have been painted over with plastic white paint...the bar code thingy needs to be peeled off the propane tank holder...I would do a shorter propane hose, maybe with right angle brass connectors.

All piddly stuff though. Really really nice. Could you go into a tad more detail about your propane meter system. I didn't quite follow the why's and the wherefore's of your concept.
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singularity
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Wed May 28, 2008 6:47 pm

well basically i built a ghetto flow restrictor into the coupling just after the regulator. which makes it so the blowgun valve can be held open for several seconds without severely offsetting the propane mix. this flow restrictor also means the propane meter takes several seconds to reach the proper pressure. however this time delay is not a problem beacuse of the slow fire rate of a standard combustion cannon. i hope that clears things up...

and yea i know i should clean it up...
be sure to check out my <a href="http://www.spudfiles.com/forums/ak-styl ... 9.html">AK Styled Vortex Gun</a> and my <a href="http://www.spudfiles.com/forums/at-4-t9627.html">AT-4 Rocket</a>

upcoming projects... finalized clip fed BBMG and ball point pen sniper
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starman
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Wed May 28, 2008 7:01 pm

singularity wrote:well basically i built a ghetto flow restrictor into the coupling just after the regulator. which makes it so the blowgun valve can be held open for several seconds without severely offsetting the propane mix. this flow restrictor also means the propane meter takes several seconds to reach the proper pressure. however this time delay is not a problem beacuse of the slow fire rate of a standard combustion cannon. i hope that clears things up...
Ok I follow...definitely a different approach, but sounds like it will be effective. The blowgun is definitely more ergo than flipping the ball valve...
subsonic_karet
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Wed May 28, 2008 7:31 pm

That is one very nice "toy".

singularity wrote:well basically i built a ghetto flow restrictor into the coupling just after the regulator. which makes it so the blowgun valve can be held open for several seconds without severely offsetting the propane mix. this flow restrictor also means the propane meter takes several seconds to reach the proper pressure. however this time delay is not a problem beacuse of the slow fire rate of a standard combustion cannon. i hope that clears things up...

and yea i know i should clean it up...
Some cheap propane torch heads actually have this built into them. I've never been a fan of them. More gas has been my motto.
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elitesniper
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Wed May 28, 2008 7:40 pm

More gas has been my motto.
but more gas would mean it wouldn't fire :lol:
wow very cool, but how come only 150 feet? I would say it could easily do 100 yards eh? Mabey you should just try a chamber fan, I treid my combustion with out and with, it makes a pretty big velocity difference, I give you a 9.5/10 teeheee, just need that fan and ball valve vent :)
And I see you use the warninglabelgenorator too haha.
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CS
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Thu May 29, 2008 3:27 am

Awesome! I love the compact fun guns. Just a gun to shoot off the back porch here and then.

I would have recommended a 3-way to have cleaned up the look of it all, but to ensure some easy accuracy. Manual propane metered guns I've found to be a bit of a hassle. What ends up happening is everyone of your buds that wants to shoot it has to learn the magic touch on the metering valve. And the accompanying explanation that more propane is not better.

Again thanks for posting, it's a awesome cannon.
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kostaki
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Thu May 29, 2008 9:31 pm

Very cool design small compact and probly alot of fun good job I like it
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mark.f
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Fri May 30, 2008 8:50 am

Nice gun! But, no fan?

What is this external BS safety concern you speak of? In very large launchers, a chamber fan increases performance a lot.
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SpudFarm
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Fri May 30, 2008 8:53 am

EXTREMELY nice gun you have made!

looks so clean!
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singularity
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Fri May 30, 2008 8:55 pm

elitesniper - it can go more than 150ft i just don't know how much more beacuse my "firing range" (some may call it a backyard) is only 150ft long

pimpmann22 - i wanted to use a three way valve but couldn't find one locally and the ones off the internet never end up being what i want (i like to see the valve before i buy it)

markfh11q - yes yes i know it should have a real chamber fan but for some reason people like to have irrational fears. and this one in particular is just way out there in fact when they first told me why i shouldn't put the fan in i laughed thinking they were joking... sadly they were not :( you see for some reason they believed the (nonexistent) sparks created by the fan as it turned on would ignite the propane prematurely. i don't know why but people treat propane as if it were more sensitive and explosive than nitroglycerin... and that would be why they made me remove the fan

everyone else - thanks for the compliments!!!
be sure to check out my <a href="http://www.spudfiles.com/forums/ak-styl ... 9.html">AK Styled Vortex Gun</a> and my <a href="http://www.spudfiles.com/forums/at-4-t9627.html">AT-4 Rocket</a>

upcoming projects... finalized clip fed BBMG and ball point pen sniper
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Maniac
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Fri May 30, 2008 9:38 pm

markfh11q - yes yes i know it should have a real chamber fan but for some reason people like to have irrational fears. and this one in particular is just way out there in fact when they first told me why i shouldn't put the fan in i laughed thinking they were joking... sadly they were not you see for some reason they believed the (nonexistent) sparks created by the fan as it turned on would ignite the propane prematurely. i don't know why but people treat propane as if it were more sensitive and explosive than nitroglycerin... and that would be why they made me remove the fan
Well as long as you dont use a brush fan there will never be a spark. Hey do these people actually know about cannons because they made you remove the fan, and not many people would know a brush fan can make sparks.
Coodude26 wrote:
People who laugh really hard at stuff that pisses you off/you getting hurt, who then say "I'm sorry, I can't stop" but you know they easily could.

Mr.C: That's not as easy as you think. It's like me kicking you in the balls and telling you to stop crying.
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starman
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Fri May 30, 2008 10:43 pm

All computer case fans are brushless and perfectly safe to use in a combustion chamber.

It's still not too late to back-fit one in there.
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King_TaTer
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Sat May 31, 2008 3:09 pm

Yeah prettty sweet looking cannon you got there.

Right now based on your volume calculations you C:B ratio is 1.25:1 yes you know this already but... If you were to have a 3 ft barrel you would increase the C:B ratio to approximately .85:1 you would get a good power and range increase from this. but seeing as you built this for a guy who messed up his back it shouldnt be a problem. hah and also it can't be too powerful or the dog wouldn't fetch it :lol:
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