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Final Construction has started

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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Unread postAuthor: frankrede » Wed Dec 20, 2006 12:15 am

I am almost done with my new combustion that features a 4" chamber,1.5" barrel, chamber fan, onboard propane, 100,000k stun gun dual spark ignition,
It is pretty much just like Boogies quadzilla with some differences.It is also made almost entirely out of SCH-80 with and exception of the barrel.
I have a few questions, I want a .8:1 chamber/barrel ratio, how do I find how long my chamber and barrel should be?
I have 7+ft of 1.5" SCH 40 and 6ft of 4" SCH 80.
Should my ignition be placed at the rear of the chamber?
And my cannon has a 2" SCH 80 union for burst disks so I plan on using it as a hybrid after I use it as a standard combustion for a while.
I know these are n00bish questions to be asking but I can't search for the answers right now because I am grounded from the computer(Got in another fight at school)


Btw-the fight got broken up before I could punch back
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Unread postAuthor: Insomniac » Wed Dec 20, 2006 12:31 am

Well I'm sure there's a way to calculate chamber volume using math, but I don't know the formula. You could just fill the chamber with water, measure how much it holds, then seal off one of the ends of the barrel and fill it and measuer.
I've herd that the best place for your igition is about 3/4 of the way back, but seeing as you have a stungun, why not use dual ignigion?
or triple ignition....or quadrouple? (If memory serves me right, Boogies quadzilla was named after it's quad ignition system)
Hope that helps
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Unread postAuthor: pyrogeek » Wed Dec 20, 2006 12:35 am

Pi *(R*R)*L
pi (3.1315927) X radius squared X length

that will give you the volume of a cylinder
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Unread postAuthor: sgehring » Wed Dec 20, 2006 12:54 am

Radius is half the inside diameter of he pipe....
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Unread postAuthor: frankrede » Wed Dec 20, 2006 1:47 am

Like I said I am doing dual I'm just not sure where to put them so one in the front, the other in the back?
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Unread postAuthor: Insomniac » Wed Dec 20, 2006 1:53 am

Yeah, put as many points of ignition in as possible, have one near the back, and spread the rest out evenly across the chamber. My opinion is that its better to have lots of smaller sparks (3mm) versus the big huge one of a stungun wired up to a single spark gap.
Seeing how your gun will have propane injection and a chamber fan, you should get a perfect mix every time. That means that even a tiny spark will ignite it. So, if you wire up a whole bunch of spark gaps, the fuel won't have to wait long until the flame front reaches it, as there will be several flame fronts at any one time. Another advantage to using smaller sparks is that you can disconnect a few of the spark gaps when it's used as a hybrid. It's harder for a spark to jump when more air has been added, and that means a large sparkgap that works for regular combustion may not be suitable for a hybrid as the spark won't have enough votage to jump that far. I think you should use 2 sparkstrips end to end down the length of the chamber, and you can disconnect the one at the front when used as a hybrid (unless your stungun can make it spark with both while being used as a hybrid.
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Unread postAuthor: noname » Wed Dec 20, 2006 5:50 pm

"Radius is half the inside diameter of he pipe.... "
The formula for the volume a cylinder was taught in 7th grade, if I remember correctly. And in 7th grade you turn 13, so technically shouldn't be on this forum. You know, the "I am 13 or over years of age" button you have to click when you register?
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Unread postAuthor: Insomniac » Wed Dec 20, 2006 5:53 pm

Well I asked my parents anyway, and I just finnished year 7, and I have been 13 for quite a while now, so technically I should be on this forum. I would have signed up to spudfiles sooner, dad just wouldn't let me. He changed his mind though. :D
Oh, and we arn't required to know much about circles in math in year seven. Must be different where your from.
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Unread postAuthor: jjk92 » Wed Dec 20, 2006 5:56 pm

noname wrote:"Radius is half the inside diameter of he pipe.... "
The formula for the volume a cylinder was taught in 7th grade, if I remember correctly. And in 7th grade you turn 13, so technically shouldn't be on this forum. You know, the "I am 13 or over years of age" button you have to click when you register?


no offense but i do believe that we learned that in 6th grade and i was 11 in 6th grade
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Unread postAuthor: Insomniac » Wed Dec 20, 2006 6:05 pm

I suppose it differs. We have 12 year olds in my class, although most of us are 13. And I know that the diameter is twice the radius, just not how to calculate the volume of a cylinder.
It's unlikely that we all learn the same math at the same time seeing as there are people from all over the world on this forum.
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Unread postAuthor: frankrede » Wed Dec 20, 2006 10:45 pm

Well I was going to ignore his stupid post but I might as well jump in.
I'm in 10th grade geometry, not the highest class out their but I'm sure that I know what a radius is.
I learned that in 5th grade, we were learning about how to find circumference by using a piece of string and a ruler.
Ms also told us about radius and diameter.
Now lets stop bickering over it, he was just offering help.
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Unread postAuthor: jjk92 » Thu Dec 21, 2006 1:50 pm

it is a pretty rediculous thing to argue about my apologies
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Unread postAuthor: MisterSteve124 » Thu Dec 21, 2006 2:56 pm

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Unread postAuthor: frankrede » Thu Dec 21, 2006 9:11 pm

mistersteve, your awesome, lol, I never seen this tool, it rocks!
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Unread postAuthor: Bluetooth » Thu Dec 21, 2006 9:16 pm

Theres one on Burnt Latke too. Its called Rat Calc. There is also a fuel calculation tool on Burnt Latke called Fuel Tool.
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