Secret Weapon (Spray & Pray)

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.
EphOph
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Sat Nov 01, 2008 7:53 pm

This is a spray & pray combustion I built in April 2008. It is called "Secret Weapon" because it is fueled with aerosol Secret (women's deodorant).

Specs:
• DWV ABS construction
• 3" x 8" chamber
• barrels:
- 1.25" x 36" breech loaded
- 1.5" x 25" breech loaded
- 2" x 18" muzzle loaded

Features:
• Centro electric BBQ igniter (trigger switch included in package)
• 1.5" PVC ball valve to facilitate easy fueling
• Modified $1 laser pointer with switch mounted on chamber
• Dual spark gaps

Being a spray & pray with a relatively small chamber, it is not overly powerful. However, when I was testing it in my garage, I missed what I was shooting at and blew a hole through my garage door with a potato (damage pic included). It can be quite loud, though, when I get a good mixture.

Note: I do not intend to upgrade this cannon, as I am currently working on an advanced PVC combustion.
Attachments
Front view of the cannon, with 1.5" barrel attached.
Front view of the cannon, with 1.5" barrel attached.
Back view of the cannon, with 1.5" barrel attached.
Back view of the cannon, with 1.5" barrel attached.
Closeup of the chamber.
Closeup of the chamber.
Inside of the chamber. The white stuff is deodorant.
Inside of the chamber. The white stuff is deodorant.
Full view of the cannon with barrels.
Full view of the cannon with barrels.
Hole in my garage door. Damage is from a potato shot from the 1.25" barrel.
Hole in my garage door. Damage is from a potato shot from the 1.25" barrel.
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VH_man
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Sat Nov 01, 2008 8:44 pm

wow. I dont know why i like this so much... but I do. When i saw it it caught my eye.....

All the funky potrusions are housings for Electronics i presume? Keep them, they look schweet, but still, what are they?.
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starman
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Sat Nov 01, 2008 9:22 pm

Very nicely done!! Top notch effort here even if it is a spray and pray. My only observation is that the electric BBQ button seems little out of the way for ergonomic firing.

This thing is screaming for a metered propane and fan update....you should consider it.
EphOph
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Sat Nov 01, 2008 11:57 pm

Thanks for the comments!

VH_man - the protrusions from the side of the chamber are indeed there to cover the screw heads and spark wires. I made them by cutting a section of 1.5" pipe lengthwise into thirds and then sanding the edges of two of pieces so they fit together at a narrower angle.

starman - the BBQ igniter is triggered by an external switch, which is mounted in the handle. It is actually quite ergonomic to use. I was very close to upgrading it with fan/propane this summer, at which point I scored a foot of 4" clear PVC so I have been working on a new cannon instead. The propane tank holder I made from 3" PVC is pretty much the same size as this gun's chamber.
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starman
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Sun Nov 02, 2008 2:09 am

EphOph wrote: starman - the BBQ igniter is triggered by an external switch, which is mounted in the handle. It is actually quite ergonomic to use.
I gotcha. I see the external switch now!!
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Demon
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Sun Nov 02, 2008 7:22 am

Wow...This thing is powerful! i Have the same barrel and chamber then yours but on a pneumatic and with a sprinkler valve(non-modded). And i never been able to shoot trough a door!

So combustion are more powerful?

I love the look of your cannon, its very 8)
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elad311
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Sun Nov 02, 2008 12:09 pm

Wow! I like it!! :)
and, very good idea, ball valve is a lot better than a threaded cap!
JohnBoi89
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Mon Nov 10, 2008 10:53 am

where did you get the ignighter? did the set up come with the two sparkers? how did you hook them up? and what kind of aresol did you use? iai am wanting to make a golf ball cannon :D
EphOph
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Mon Nov 10, 2008 10:36 pm

The igniter is for a Centro barbeque - I got it at Canadian Tire for $15. The two sparks are created by wiring them in series, there are many resources on this site and other sites to help you figure out how to do that.
The aerosol I use is an antiperspirant called 'Secret'. It packs a punch but leaves a nasty white paste on the inside of the chamber.
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FishBoy
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Tue Nov 11, 2008 5:05 pm

Sorry for getting to this kinda late, but very nice job. I really like the look of it and the damage is impressive. Now on to something even more powerful!!
"You polish a turd, it's still a turd"

Remember DYI!!!
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jonnyboy
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Tue Nov 11, 2008 5:25 pm

starman wrote: This thing is screaming for a metered propane and fan update....you should consider it.
Really my guns have never screamed at me. :lol:
This thing would really be rocking with the said mentioned suggestions. You get some nice damage there too.

Demon wrote:Wow...This thing is powerful! i Have the same barrel and chamber then yours but on a pneumatic and with a sprinkler valve(non-modded). And i never been able to shoot trough a door!

So combustion are more powerful?

I love the look of your cannon, its very Cool
Your door is probably sturdier than what he was shooting at. A spray and pray generates about 40 psi so I would imagine most pneumatics could do that as well.
mobile chernobyl wrote:I can shoot a Canuter Valve off my '82 Chevy Ram F150 AT LEAST 3/4 Mile with 'ma cannon made of soup cans duct taped together, then I just squirt some bacardi 151 in the chamber and hold up my cigarrete lighta and WHOOSH! That thing flies at least 3/4 mile
EphOph
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Tue Nov 11, 2008 10:54 pm

The door is only particle board (not plywood) and has quite a few years behind it, so I would assume that a pneumatic of the same size could easily accomplish the same thing (I won't be testing this - repairing the door once is more than enough).

I'm really looking forward to seeing what a 4" diameter advanced combustion can do, but I probably won't be posting it until spring as it is getting too cold here to work on and shoot it.
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mark.f
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Wed Nov 12, 2008 12:31 am

That looks pretty cool. Keep us up to date on the next combustion!
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