Tennis ball mortar

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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Sat Jul 21, 2012 6:49 am

Does anybody know whether or not I can use deodorant sprays in lieu of lighter fluid for this: http://www.instructables.com/id/Tennis-Ball-Mortar/, and still maintain reasonable power?[/url]
jsefcik
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Sat Jul 21, 2012 7:09 am

maybe starting fluid?

just trial and error my friend
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jackssmirkingrevenge
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Sat Jul 21, 2012 7:50 am

jsefcik wrote:just trial and error my friend
No no no!

SCIENCE!


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hectmarr wrote:You have to make many weapons, because this field is long and short life
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mattyzip77
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Sat Jul 21, 2012 3:08 pm

try aqua net hairspray that always work the best for me
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jsefcik
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Sat Jul 21, 2012 5:12 pm

jackssmirkingrevenge wrote:
jsefcik wrote:just trial and error my friend
No no no!

SCIENCE!


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so science doesnt involve trial and error?????

starting fluid works great in a spray and pray
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jimmy101
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Sat Jul 21, 2012 6:18 pm

jsefcik wrote:so science doesnt involve trial and error?????
Not when it comes to fueling a spudgun it doesn't.
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jsefcik
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Sat Jul 21, 2012 7:27 pm

jimmy101 wrote:
jsefcik wrote:so science doesnt involve trial and error?????
Not when it comes to fueling a spudgun it doesn't.


yes it does, some fuels work some dont, and sometimes you have to figure that out, again by trial and error,
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mattyzip77
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Sat Jul 21, 2012 8:02 pm

Im getting a mod!!! :lol:

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Daltonultra
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Sat Jul 21, 2012 8:43 pm

I would NOT want to mess with any type of proellant more powerful than gasoline in that thing. It's just a couple can taped together; there's no structural integrity to it whatsoever.

Find yourself some sch40 2.5" nsf-PW PVC and experiment with gases to your heart's content, with no worries about catching a chunk of flying can.
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jackssmirkingrevenge
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Sun Jul 22, 2012 4:57 am

jsefcik wrote:so science doesnt involve trial and error?????
Of course it does :) but in this case, we have established what works and what doesn't, so saying "spray and pray" instead of metering is a bit like suggested homeopathy as opposed to proven medicine.
hectmarr wrote:You have to make many weapons, because this field is long and short life
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jimmy101
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Sun Jul 22, 2012 1:05 pm

jsefcik wrote:
jimmy101 wrote:
jsefcik wrote:so science doesnt involve trial and error?????
Not when it comes to fueling a spudgun it doesn't.
yes it does, some fuels work some dont, and sometimes you have to figure that out, again by trial and error,
If it doesn't work it isn't a "fuel".

Science is perfectly capable of telling you which fuels will work (and how much to use) and which things won't (regardless of how much you use). No need for trial and error.
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Zeus
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Sun Jul 22, 2012 9:30 pm

I understand Jesse's point, it's quite hard to quantify the amount of fluid expelled from an aerosol can, and you determine the amount of time you spray experimentally. Even if you know it takes X mLs of petroleum ether to get the requisite mix, but the nozzle is an unknown variable.

When you're using volumetric or manometric metering, you know exactly how much fuel you need, and that doesn't require any experimental determination.

Tl;dr, Jesse, you're right to an extent, everyone else is right as well.
/sarcasm, /hyperbole
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jimmy101
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Mon Jul 23, 2012 5:23 pm

jsefcik wrote: yes it does, some fuels work some dont, and sometimes you have to figure that out, again by trial and error,
Uh, no. A fuel works or it doesn't and that is 100% predictable without doing any trial and error.

The only time trial and error comes in is when a person is too lazy, and too poorly informed, to realize that a combustion spud gun will perform much better with properly metered fuel. The actual choice of the fuel has almost zero effect on the performance of the gun (as long as the fuel is sufficiently volatile, and that too is 100% predictable).
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