How much Proppellant

Devilsmed98 · Wed Sep 07, 2005 5:49 pm

Ok I have a 6.5 foot potato gun. I should first off try telling you that I tried firing a blank. Basically I just put 5 seconds of axe in and tried to make it blast a shot of fire. I don't know if this will work. My first shot wouldn't work so I took out the potato thinking I messed up the design. Then my sister comes outside and presses the igniter. There is a 10 foot flame and a little shockwave and its very loud. If I am doing everything right... how much propellant should I put in. Please get back to me I am very eager to make a first successful shot. And should i let it dry out? And what should i use to clean it?

boilingleadbath · Wed Sep 07, 2005 6:38 pm

...where'd that debugging guide go?
<a href="https://netfiles.uiuc.edu/hanson2/www/C ... htm">Ah</a>, here it is.

I almost garantee that you'r putting too much fuel in it.
I don't think it'll be neccicary to let it 'dry out' - but I don't have much experience with combustions.
Water? Denatured alchohol? Soap & water?

Devilsmed98 · Wed Sep 07, 2005 7:01 pm

ok i just tried putting less fuel. I sprayed about 2 seconds of axe. i am wondering if the fuel is hitting the spark area wich is making it too wet? or should i just clean it first? its got alot of wd 40 in it, (from past attempts)

spudshot · Wed Sep 07, 2005 7:42 pm

i would clean it, my chamber gets a residue after about 100 shots or so, there is also the possibility of that residue catching fire, its happened to me before. WD 40 no longer has propane in it, so its useless for fuel, do you have a lantern ignitor (flint one)? if you do you CANNOT get it wet, thats what i hate about those damned things, but they do throw good sparks

Devilsmed98 · Wed Sep 07, 2005 7:44 pm

spudshot wrote:i would clean it, my chamber gets a residue after about 100 shots or so, there is also the possibility of that residue catching fire, its happened to me before. WD 40 no longer has propane in it, so its useless for fuel, do you have a lantern ignitor (flint one)? if you do you CANNOT get it wet, thats what i hate about those damned things, but they do throw good sparks

i have a bbq started the cheap 10$ kind i got it at home depot, and wd 40 doesn't work?

spudshot · Wed Sep 07, 2005 7:52 pm

ok, the bbq ones are fine, as long as you use screws for electrodes and dont just put the ignitor in a big hole in the cannon, and now WD 40 doesnt work anymore, i have an old can of the stuff and its a good fuel

Devilsmed98 · Wed Sep 07, 2005 8:02 pm

umm the igniter is on the top of the chamber and it has wires going to the mid back of it that has a screw in the top that leads to this spark mechanism. i press the putton and it sends something through the wires and makes a spark appear between 2 bare metal wires about 1/16th of an inch appart. would that be a problem?

spudshot · Wed Sep 07, 2005 8:34 pm

i dont understand, is the ignitor IN the gun, or is it mounted on top of the gun and you have wires running to the electrodes where your spark gap is?

Devilsmed98 · Thu Sep 08, 2005 5:37 am

i have a little button on the top wich i press. then it sends some stuff thorugh wires wich are in the gun back to the end of the chamber where i have a metal bar thing wich has a metal wire next to it. when i hit the igniter it makes a spark between the metal wire and the metal bar.

Devilsmed98 · Fri Sep 09, 2005 5:47 am

i love how so many people got back to me answering my question. Well i came home from school and i thought hmmm mabye i should use gas to proppell it. so i took some gasoline, put it in a spray bottle. Then i ducted taped my barrell and all remaining chamber spots. I then loaded the gun with a potato, put in 5 shots of the gasoline, aim, BOOM! Thats all i remembered. Then i woke up in the ambulence. Where i was taken to the hospital. Luckly when i shot the gun, my dad was a swat officer, i had on bullet proof gas mask, swat helm,swat shield, and body vest. so the only part of my body that was effected was my hands. I now have 2 hand casts and i can't take them off till next year. Wich means i can't write. So i am having my sister writing this. o yea when i do get these off i will have formed a thick layer of skin over the pvc pipe. the reason they can't take it out now is because there is something in the gasoline that may cause my blood to break down, wich causing death. so i am now scared for life with pieces of plastic in me. And the duct tape really didn't help. I guess i should of wrapped it a 3rd time. So i don't think i will be going on this site anymore or going anywhere near a potato gun again. But, i will still go on to help people with problems and not let them make a mistake i did. I will also be donating all my spudbux to spudshot for helping me the most. Thank you for your help

b-nice · Fri Sep 09, 2005 7:59 am

that is not good to hear. personally i think propane it the safest mast efficent way to launch spuds. i use to experiment with different flamable sprays in my youth of building spudguns and one detonated on my friend when we were 9 and it was 5 years before i built another one and that one and the rest have always had propane on them and to this day ive had no miss fires or duds.

Devilsmed98 · Wed Sep 14, 2005 6:15 pm

i got gloves! so now i can type and i am currently working on a cannon the size of my first one hopefully i learned from my mistakes. and i will post when it is finished

guitarfreak · Wed Sep 21, 2005 5:32 pm

u were lucky,u should never use petrol in a thing like that

i am using butane or butane-propelled aresol,btw.

zaphar · Thu Sep 22, 2005 12:40 am

Can you link me to one of these "bullet proof gas mask"? The reason I ask is that I've never heard of such a thing?

Devilsmed98 · Thu Sep 22, 2005 5:27 am

zaphar wrote:Can you link me to one of these "bullet proof gas mask"? The reason I ask is that I've never heard of such a thing?

it is a full faced gas mask with bullet proof material in the forehead, cheeks, and chin