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My first Spuddie

Post questions and info about combustion (flammable vapor) powered cannons here. This includes discussion about fuels, ratios, ignition systems, safety, and anything else relevant.
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My first Spuddie

Unread postAuthor: WitSkaapie » Thu Feb 22, 2007 9:26 am

Hi guys, firstly thanks for making a really cool forum all about spud guns.

OK, on to business.

our church is having a men's camp (just for all the dudes) and the pastor of the church built a spud gun. sooo, he made a wager that if anybody could beat his gun, he would pay them 300 bucks. obviously, i wanna win.

so, onto my spuddie...

i have been reading up abit about c:b ratios, fuels, and ignition systems and such, and i have a few questions...

1. c:b ratios -> the correct c:b ratio is about 0.6/0.8:1 but is there an ideal ratio between the width of the combustion chamber and the barrel? i've seen 3" -> 2" and others, but is there an ideal ratio???

2. fuels -> other than butane/propane, what is the best fuel??? hairspray/deodorant/wd40???

ok... now here is my plan for a spuddie: 4" x 15" c/chamber -> 2" x 25" barrel...

i have ideas for ignition systems, fans, etc. but i just wanted to get the essentials sorted first, before i start building my spuddie...

anyhoo guys, i a cant wait to get started...

thanks for the help in advance...

witskaapie ;)
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what's happenin' this year? takin' over the world baby... takin' over the world...
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Unread postAuthor: imjustpk » Thu Feb 22, 2007 12:29 pm

First off it is good to see such enthusiasm, Hope you win that 300 man! Also I am no expert but I will give advice based on my limited experience

1. Age old question, I use a 1.5:1 chamber to barrel ratio based on volume, I've heard that wider chambers do have a performance advantage although I haven't tested it myself

2. I use axe, has butane in it and does a pretty good job for me, though I'm trying to get switched over to metered propane because it is apparently just that great

IGNITION! I actually have my gun working on 2 different ignitors, a flint lantern striker, and a spark ignitor from a cheapo long lighter
I feel the flint is more reliable and great for a hip shot, i added on the spark ignitor as an experiment, but it lets me shoot off the shoulder which is pretty cool

anyway just rock on!
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Unread postAuthor: iknowmy3tables » Thu Feb 22, 2007 12:35 pm

1. that is the ideal ratio, its just safe to have the barrel alittle shorter, the whole point o C:B ratios are to maximize the preformence from the given chamber, so just go with a little larger chamber and that energy will be turned into sound
2. I think gas, hair spray, or static gaurd, just use what you have

make sure if you want to beat him you should have one or more of the following that a ameuter can make
chamber fan
multiple spark gaps in series
camera flash ignition
paint job
union breechloading
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Unread postAuthor: Hotwired » Thu Feb 22, 2007 12:57 pm

If you really want to beat him, make a pneumatic cannon :wink:
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Unread postAuthor: MrCrowley » Thu Feb 22, 2007 1:14 pm

You will kick his ass in to outer space if you use either a:

1.Pneumatic
2:Propane/MAPP metered combustion.
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Unread postAuthor: noname » Thu Feb 22, 2007 1:24 pm

Use anything possible, just make it kickass. My most expensive gun so far was my paintball rifle ($85), but most of the parts, including the valve, were lying around. Make the coolest gun possible, as long as you beat the pastor's, you still have an awesome gun and 150+ dollars.
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Unread postAuthor: A-98 » Thu Feb 22, 2007 2:01 pm

you officially have the coolest church i have ever heard of.

also,if i were you i would build a pneumatic cannon, however i have no idea on you skill level/ resources, so i cant give you suggestions on what valve.
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Unread postAuthor: iknowmy3tables » Thu Feb 22, 2007 5:36 pm

will a pnematic really kick his ass, even if its a little getto,
if it has a sprinkler valve, or piston defenatly
also in what way does the gun have to beat his? (range, velocity, size, chucking capacity)
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Unread postAuthor: WitSkaapie » Sat Feb 24, 2007 10:28 am

hey guys, thanks for all the help so far... i'm one step closer to putting together my first spuddie.

so far there's still 2 things which i need help on/i'm a little confused about.

1. c:b ratio -> sorry, i'm just not getting this. OK, so the c:b ratio is the ratio of the volumes. so should the chamber be 1.5 x bigger than the barrel or other way round???

2. chamber fan -> is it better to mount the fan near the front of the chamber or near the rear of the chamber??? and secondly, what is the best way of powering the fan??? i want to use a fan from a computer case, but thats 12 volts (i stand to be corrected)... it's kinda impractical to strap a whole bunch of batteries together...

anyways guys... i'm almost there...
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Unread postAuthor: SpudBlaster15 » Sat Feb 24, 2007 11:19 am

I am feeling generous today, so...

Chamber fan mounting/setup info

Chamber to barrel ratio info

Chamber to barrel ratio calculator

Use the forum search function and the Spudwiki database next time, I found all of these within 5 minutes of searching.
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Unread postAuthor: TwitchTheAussie » Sat Feb 24, 2007 9:20 pm

Stick with combustion. They are a lot eaier to make plus all guys love a loud bang to get the blood racing :wink: Just follow the above advice and you should be right.
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Unread postAuthor: frankrede » Sat Feb 24, 2007 10:36 pm

Propane metered over under with spark strip.
That would do it.
Spend 400 and you have a kick ass gun for only 100$
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Unread postAuthor: WitSkaapie » Mon Feb 26, 2007 2:17 am

Thanks everybody for your help... i'm sure with the information you have all given me, and a little bit of ingenuity i will kick butt in the competition.

i will keep you all posted on how the spuddie construction is going and how the competition turned out...

once again thanks...

p.s. spudblaster15, next time i will search first ;)
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