newbie here

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.
Mafia_Mike1321
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Sun Aug 20, 2006 1:55 am

well so im trying to make my first combustion cannon.... im was messing around with some extra PVC i had lying around and i bought a grill starter....i have a 4 ft long 1.5 inch wide pipe and a cap on one end that u can screw on and off and i installed the grill started about 2 inches away from the screw cap...i loaded in a wad of cloth leaving about a foot left for a "combustion chamber" .. spritzed in 2 sprays of model nitro fuel (screwed the cap on) and when i fire it, it kinda goes FLOOMP and it onyl travels halfway down the barrel....so what am i doing wrong? i mean u guys are hurking these things a hundred yards lol dont flame me im new to this stuff
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VEGEMITEMODDER
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Sun Aug 20, 2006 2:00 am

Have you tryed somthing like hairsprary of engine starter (eather)?

welcome to the forums
Mafia_Mike1321
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Sun Aug 20, 2006 2:17 am

nitro fuel is MUCH more powerful than hairspray, its 15% model nitro from my hobby shop.......i was wondering, does it just need a better seal from the ammo to build up more pressure?
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VEGEMITEMODDER
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Sun Aug 20, 2006 2:27 am

yes a tighter fit would help but not to tight
maybe you can just try hairspray or somthing like it just to see how it goes? or a chamber fan maybe
Mafia_Mike1321
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Sun Aug 20, 2006 2:40 am

i actually did try hairspray and axe and the nitro lights better out of the three, and what is this about a chamber fan? ive heard about it but i'd liek to know more
jeracoo
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Sun Aug 20, 2006 4:48 am

If you can't get it started on 15% nitro just build a simple pnemutatic all you need is a tubeless tire valve a .5 inch to 2 inch pipe one end cap a ball valve either plastic or metal and you can launch things preety far, its really easy.

I just use mortein to fire my combustion it works great mines 2 inch

Good luck with your current and furture projects
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killagorrila99
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Sun Aug 20, 2006 4:55 am

why dont u use oxy-aceteline? lol 8) anyway if u use potatoes it will work much better!
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rna_duelers
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Sun Aug 20, 2006 5:37 am

Well if u have it from about 1' from the bottom the camber to barrel ratio is at 1:3,try having the rojectile about half way down because any combuston cannon with a 1:3 C:B ratio isnt going to shoot very well at all.
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mark.f
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Sun Aug 20, 2006 6:56 am

Leave more of a "combustion chamber", and find a tight fitting projectile.

And when it does work, don't expect too much distance because you'll only be shooting out of a ~2' barrel.
Mafia_Mike1321
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Sun Aug 20, 2006 8:37 pm

well ok one thing i discovered while i was tinkering with it was the fact that i just need to make a combustion chamber lol .... i cut the barrel down so that it was about 2.5 ft long and i just put in some wadding in the tip really tight....when it fired it actually threw the wadding about 15 ft or so and there was a loud crack from the air escaping...my next hardware store trip will be to get a reducer down to 1 inch so that my 1.5 inche chamber will work with it...hope it will work ive just been messing with it a bunch to try and make it work.....when i get some money saved up im going to make a proper cannon with a 3" x 2' chamber with a 2" x 4' barrel....... another question i have: is there another alternative to getting one of those caps you can screw on? cus on the cannon i tried making, i can hear lots of air wooshing out from there and i cant tighten it anymore by hand....oh yea and with my very first config. i found a propane bottle in the barn and i tried it and i got the same result, floomp and about halfway down the barrel....that or i hear air rushing out from where the cap is
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chosen_way
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Mon Aug 21, 2006 4:04 am

go pneumatic, tons more accurate and alot more fun to shoot and you wont have any flames coming out that could burn you.
how do i put a picture here? woo i brought a signature and have nothing fun in it :(
jeracoo
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Sun Aug 27, 2006 4:30 am

hey i already suggested that air is the way to go if your a newb
Benny
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Sun Aug 27, 2006 4:37 am

hey i already suggested that air is the way to go if your a newb
Hey, he was just backing up your comment.
And mark, try less fuel.
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Shrimphead
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Mon Aug 28, 2006 4:40 pm

Ya, you may be putting too much fuel in, which creates a less powerful explosion.
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noname
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Mon Aug 28, 2006 4:45 pm

You can put a ball valve on the back, always seals, easy to refuel.
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