tiny propane injection

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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A-98
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Mon Mar 19, 2007 10:12 pm

ok, well, its been forever since i've done a combustion, but my pneumatic cannon might be ruled out for the contest, so i have another idea.

i was wondering if there was some way to get a metered propane into a 1" by 3-4" chamber. i cant have any holes drilled in it, so i need to inject it barrel side.

i've been thinking about a detachable coupling on the front that would have a meter hooked up to it, but im not sure.

and the barrel is 1/2" by ~1"

speaking of barrels, what would be the proper length for the barrel of a chamber that size? the barrel needs to be 1/2". i can get a C:B ratio from the two measurements, but i dont know how to get the barrel out of the C:B ratio. curse you ratios!
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A-98
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Mon Mar 19, 2007 10:49 pm

and im almost done with the "chamber"(actual name is classified)
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hi
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Mon Mar 19, 2007 11:09 pm

If you had a 1'' chamber that was 4'' long and a 1/2'' barrel, the appropriate barrel length would be about 10-11 inches.

As for the meter- have a nipple and a ball valve on the end cap. Use a pressure guage that goes up by 1 psi at a time.attach the it to a tee and the tee to the nipple/ballvalve. have about 6 inches of 3/8 inch hose and attach it to a tourch head. attach the hose to the tee. This would be a fairly good meter, but your best bet is to just simply open the cap and spray it in. this cannon is only going to shoot maybe 150-200 feet. It will be fun though
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A-98
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Mon Mar 19, 2007 11:13 pm

see, thats my problem, i cant have anything coming out of it. hell, the barrel isnt even coming out of it. just a stub. im having to make my own plus out of epoxy

i need something that can acurately do it from the barrel-stub, and has to be removable.
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hi
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Mon Mar 19, 2007 11:17 pm

Wait, how can the barrel not come out of the chamber? Is it a coaxial combustion? Just take a wine cork, drill a hole in it, and attach the tourch head.... Maybe? That way you could have a decently tight seal and it would come off. Id like some pictures, im sill stumbed about the barrel that dosnt come out of the chamber.
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A-98
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Mon Mar 19, 2007 11:20 pm

well, i would draw you a image, or give you a pic, but i cant because its classified. the barrel will attache to a stub coming out of the barrel.

and i cant just spray in propane cause its too in-exact, i could as a last resort. i think ill go and consult DR or someone.
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hi
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Mon Mar 19, 2007 11:28 pm

http://www.advancedspuds.com/propane.htm

Just build this and put a ball valve on it instead of a shrader valve.
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A-98
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Mon Mar 19, 2007 11:46 pm

see, i cant put a ball valve on it, but i could put one onto a coupler, which would intern connect to the barrel stub.
Last edited by A-98 on Tue Mar 20, 2007 4:10 pm, edited 1 time in total.
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crazyfreak0075
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Tue Mar 20, 2007 1:39 pm

Are you entering this in the contest or something.
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A-98
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Tue Mar 20, 2007 4:09 pm

yes. no plans, no details.

does anyone know if i could use a syringe as a meter, i only need 2.1 ml of propane.

and does anyone know whether you can adjust fuel tool to use butane? i would like to use a lighter/lighter re-fill setup.
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deusXmachina
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Tue Mar 20, 2007 8:56 pm

A syringe would probably work. What I was thinking was drill a 1/16" or smaller hole, then cut the end off of one of those basketball fill tips, and use a 1/8 to 1/4 adapter to hook that to whatever your fuel source is. Epoxy/JB the gap obviously.
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jackssmirkingrevenge
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Tue Mar 20, 2007 11:02 pm

A-98 wrote:see, thats my problem, i cant have anything coming out of it. hell, the barrel isnt even coming out of it. just a stub. im having to make my own plus out of epoxy
That would be a cartridge then :wink:

I used a syringe to meter butane into my carts quite successfully, from a lighter refill can:

Image
hectmarr wrote:You have to make many weapons, because this field is long and short life
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A-98
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Tue Mar 20, 2007 11:07 pm

SHHHHH! you giving away secrets!!!
he knows too much *snaps jacks neck*

ya, i was inspired by your cartridges and im making my own with my own mechanism.

thats all im going to say, not that any of you will remember this post...*puts on sunglasses, pulls out flashy thing* :glasses5:
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jackssmirkingrevenge
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Tue Mar 20, 2007 11:10 pm

Good luck with that :wink:
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hectmarr wrote:You have to make many weapons, because this field is long and short life
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Bubba05
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Thu Mar 22, 2007 6:19 am

i had an idear that worked for a bit then blew out during firing lasted bout 12 shots on one of my cannons. how many shots do u get in the comp? drill small hole and implant a gas lighter refill valve into it make sure its able to be screwed in and reinforced from the outside!! with fiberglass mesh. and resen it heaps. the fiber glass idear just came to me??? why didnt i try than? shit now u know? ahhhh just an idear? then u can just take the cap off what eva propelent ur using jam it into the hile and whala!!! Shit go bag and i hope progectile leaves muzzel at high speed?? and u not have an anoying hissing sound leaving the chamber :(

Bubba
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