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spudgun physics project

A place to ask general spud cannon related questions.
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Unread postAuthor: Redcoat » Fri May 25, 2007 3:52 pm

wow you get too make a spud gun for a school project? thats awesome! :toothy10:


Anyway i reckon you should make a combustion first and shoot that for fun.
Then make a fancy to make it look good. If you have a year.
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Unread postAuthor: jimmy101 » Fri May 25, 2007 5:03 pm

Paaiyan: thanks for posting the link for Evbec. I was too lazy to look it up.

A brief summary (see also the spud wiki on <a href="http://www.spudfiles.com/spud_wiki/index.php?title=Computer_Applications">Computer_Applications</a>)
GGDT: Gas gun Design Tool predicts the performance of a compressed air gun based on the chamber volume, pressure, characteristics of the valve, barrel and ammo characteristics. GGDT calculates the performance of the gun from basic (and advanced) physics principles. If you have reasonable values for the various input parameters it will give a very good prediction of the muzzle velocity. GGDT is available from D. Hall's <a href="http://www.thehalls-in-bfe.com/GGDT/">site</a>.

Evbec: Energy & Volume Based Estimator for Combustions. As with GGDT it is primarily concerned with predicting the muzzle velocity of the gun. (Though both GGDT and Evbec will predict other things.) With Evbec you describe the chamber and barrel geometry, the fuel and the ammo. Unlike GGDT, Evbec does not model the gun entirely from basic physics principles. Instead, Evbec compares the parameters of your gun with a small set of guns for which it has muzzle velocity data. A little physics is used to correctly interpolate your gun into the data set Evbec has to make the prediction of performance. If your gun is similar to the guns that Evbec is based on, then the predictions are pretty good. If you gun is radically different then the accuracy probably drops off pretty quickly. The spud wiki for Evbec is <a href="http://www.spudfiles.com/spud_wiki/index.php?title=EVBEC">here</a>. <a href="http://www.spudfiles.com/forums/viewtopic.php?t=5966&">Here</a> is the most recent description of Evbec from here on Spudfiles.
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Unread postAuthor: jimmy101 » Fri May 25, 2007 5:09 pm

Imperialist1 gave me an idea that would be cool. No predictions necessary (but they could be done if required)...

Build a gun that can be operated as both a compressed air gun and a combustion. Ask the question "Which is better in terms of muzzle velocity (or kinetic energy)?"

One way to do it would be with a ball valve gun. Easy enough to open the valve up when using it in the combustion mode. Only problem is that ball valve guns aren't all that great. You certainly wouldn't be able to convincingly answer the age old spudding question of "which is better, combustion or pneumatic?"

I would think that there is probably a way to setup a barrel sealing valve so that it can be locked into the open position when you want to use the gun in the combustion mode.

Edit: fixed bad engrish and speeling.
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Unread postAuthor: gotbass7 » Fri May 25, 2007 6:51 pm

hey im doing spudguns for school to
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Unread postAuthor: sandman » Fri May 25, 2007 7:11 pm

i as well am doing one for school too

but i bet you are not doing it for Language Arts :P
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Unread postAuthor: Modderxtrordanare » Sun May 27, 2007 12:36 am

sandman wrote:i as well am doing one for school too

but i bet you are not doing it for Language Arts :P


You my friend would lose that bet. :wink:
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Unread postAuthor: sandman » Sun May 27, 2007 10:47 am

crap, well i bet it not a how-to paper :P
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Unread postAuthor: Modderxtrordanare » Tue May 29, 2007 1:31 am

sandman wrote:crap, well i bet it not a how-to paper :P


That was part of it. Big ol' research paper collage thing.
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