Future Reference ?

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.
Rob748
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Tue Feb 24, 2009 9:41 pm

ok whatever guys
jmeyer1022
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Tue Feb 24, 2009 9:57 pm

Rob no offense we have reason to believe this just from "future reference". Forget the past, don't worry about the future cause it has yet to come, live in the present because its here now. We have no problem helping as long as your doing the research, people just expect things out of you because you came on here talking about building a hybrid with no ideas of metered propane or what burst disk is. I'm glad to see your getting into spud guns but do research, tell us what you know and we'll correct you. Good luck on the propane meter.
Rob748
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Tue Feb 24, 2009 10:09 pm

well it works well for them apparently :?
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rp181
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Tue Feb 24, 2009 10:31 pm

I must ask, where did a hybrid and burst disk come into this? Look at his first post, it asks about a Advanced Combustion, which dosnt even need a valve.
When starting spudgunning, im sure most people aimed really high, no one says "ooh, i wanna build a small safe gun". Even if someone does try something out of their league, they are going to fail, and eventually (hopefully) learn from it.
jeepkahn
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Tue Feb 24, 2009 10:35 pm

Rob748 wrote: well it works well for them apparently :?
I really hope you don't think that's a powerful cannon... My modular gun with a short 2' tennis ball barrel will set you on your heels, with a 4oz potato you better lean into it... and it's only a pneumatic...

My GB cannon when firing 12 oz missiles has 280lbs of recoil(measured with a digital scale), and that's with just 125psi...
Rob748
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Tue Feb 24, 2009 10:36 pm

Thanks Rp181, But Im not immature they are right ( not saying you are at all lol ) , about a few things, but sometimes they go a bit overboard with a simple question. No offence. Alot of you have helped me out alot. Some of you not so much but in good intention.

Yes its mostly my fault

I just dont have money right now for awhile. I have the combustion chamber and thats about it. So im just asking stuff to learn stuff :)

And I never said that was a powerful cannon. If it was metered and built like a advanced then Id bet my left nut it would be lol
tape fist
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Tue Feb 24, 2009 10:40 pm

well it works well for them apparently
They never said it wouldn't work they just said that you shouldn't use it because the gas can instantaneously explode under pressure or ideal temperature but if your going to take the chance then do it and stop arguing on here.
if you are going to critize me for god sake dont make up stuff that I supposively said and use it against me.
Rob748
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Tue Feb 24, 2009 10:42 pm

I am not arguing. Im just wondering. If you guys have to, just quit answering this post. You are taking it way to seriously. Comeon Im 15 years old. I bet some of you are in ur 30s+ you dont see me arguing about anything Im just asking......... Look Im sorry for the trouble
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trigun
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Wed Feb 25, 2009 12:16 am

Rob being young is not an excuse I'm 16 so nice try. We say these things because nobody and I do mean nobody wants to see you get hurt and/or killed.

As for the actylene if you didnt notice in the video they had a few misfires. That means in most cases they are putting in way to much gas which results in very poor perfomance. If properly metered they would have an extremely high chance of blowing that chamber to bits and pieces inside of themselves.
Note epoxy cure time very important barrels are hard to remove from the wall
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D_Hall
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Wed Feb 25, 2009 1:02 am

rp181 wrote:Hydrogen isnt sold in stores (as far as i know) but can be found online.
You're just not shopping at the right stores. It CAN be purchased in stores... But we aren't talking Ace Hardware. We're talking Praxair and the like.
Hydrogen also corrodes some meta, caussing it to be more brittle than normal.
True and not true.

If I remember my metallurgy correctly, hydrogen embrittlement has nothing to do with corrosion but rather hydrogen's ability to actually infiltrate the crystaline structure of the metal and collect in crystaline defect sites (that become slip-plane failures if the metal fails). The really cool part is that hydrogen embrittlement CAN be reversed given time... Just let the hydrogen "dissolve" out the same way it "dissolved" in.


Aside related to this thread: And helium could very well improve the performance of a gun by lowering the overall molecular weight of the working fluid. In other words, a gun that uses an 80/20 mixture of nitrogen/oxygen (in other words, air) is not going to perform as well as a gun that uses an 80/20 mixture of helium/oxygen.
Simulation geek (GGDT / HGDT) and designer of Vera.
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starman
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Wed Feb 25, 2009 1:22 am

Rob748 wrote:I just dont have money right now for awhile. I have the combustion chamber and thats about it. So im just asking stuff to learn stuff :)
Rob, you are doing better. I definitely understand, not having access to money and materials can be very frustrating. Have you included your parents (and their associated pocketbook) in you spudding adventure?

If you haven't, I suggest you try to do that for a couple of reasons. Number 1, so they know and understand and support what you're doing and so they don't think they have some rogue pyro sneaking around out in the garage. Number 2, Dad's can very often be persuaded to help pay for some things you need if he gets interested enough.
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Lentamentalisk
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Wed Feb 25, 2009 1:42 am

D_Hall: Yes you are remembering your metallurgy correctly
As for the whole helium rather than nitrogen deal, that could be an interesting addition to HGDT, allowing for the inert portion of the gas to be imputed, to what ever ratio of what ever you want (assuming no catalysts or reactants of course)
Do not look back, and grieve over the past, for it is gone;
Do not be troubled about the future, for it has not yet come;
Live life in the present, and make it so beautiful that it will be worth remembering.
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trigun
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Wed Feb 25, 2009 1:48 am

starman wrote:
Rob748 wrote:I just dont have money right now for awhile. I have the combustion chamber and thats about it. So im just asking stuff to learn stuff :)
Rob, you are doing better. I definitely understand, not having access to money and materials can be very frustrating. Have you included your parents (and their associated pocketbook) in you spudding adventure?

If you haven't, I suggest you try to do that for a couple of reasons. Number 1, so they know and understand and support what you're doing and so they don't think they have some rogue pyro sneaking around out in the garage. Number 2, Dad's can very often be persuaded to help pay for some things you need if he gets interested enough.
Wish I had my dad help pay for building guns. ( kicks dirt)
Note epoxy cure time very important barrels are hard to remove from the wall
jmeyer1022
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Wed Feb 25, 2009 11:01 am

rp181 wrote:I must ask, where did a hybrid and burst disk come into this? Look at his first post, it asks about a Advanced Combustion, which dosnt even need a valve.
When starting spudgunning, im sure most people aimed really high, no one says "ooh, i wanna build a small safe gun". Even if someone does try something out of their league, they are going to fail, and eventually (hopefully) learn from it.
His first post on the site was asking about making a SCH 40 hybrid launcher. The point I was trying to make was simply that he's been lacking in his research. I'm glad hes aiming big, but knowing your limits especially with something like a hybrid is a helpful.

http://www.spudfiles.com/forums/hi-wond ... 17424.html
Rob748
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Wed Feb 25, 2009 4:53 pm

well parents are out of the option figuring im on my own witha friend.....
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