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New vacume pump cannon model

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New vacume pump cannon model

Unread postAuthor: zeigs spud » Tue Sep 19, 2006 5:46 pm

I'm not sure if one like this has been made but i saa a pic of a very simple one and decided to make this one.
plz click link to view plans.

http://img157.imageshack.us/img157/3889/vacumedg9.png

Questions/comments? no flamers plz.
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Unread postAuthor: Atlantis » Wed Sep 20, 2006 5:17 pm

This is the second time this has been posted today. You don't need the turn at the end, that actually hurts performance.
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Unread postAuthor: kris » Thu Oct 05, 2006 6:43 pm

its a good idea :D :D
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Unread postAuthor: -T0OL- » Sun Oct 08, 2006 11:56 pm

I'm no expert. It looks like a good idea, but i dont think it would be all that powerfull, cause the projectile would have go through the cellophane or whatever hold in the negative pressure but as far as i know the pressure pushing the projectile is the same pressure that the collophane is holding in (out?) so unless the projecile is really pointy it wont make it througheven then it would slow down alot wouldnt it?

please correct me if im wrong.
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Unread postAuthor: brumby » Mon Oct 09, 2006 12:16 am

Tool...... you are a TOOL!!!
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Unread postAuthor: -T0OL- » Mon Oct 09, 2006 12:26 am

you have no idea how many times ppl have told me that... but that doesnt have anything to do with the topic does it?
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Unread postAuthor: Atlantis » Mon Oct 09, 2006 1:47 pm

The only things holding the cellophane on is the suction cup effect, once air comes in it won't be holding on anymore, the cellophane will probably just fall off.
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Unread postAuthor: boilingleadbath » Mon Oct 09, 2006 2:24 pm

More important, from a muzzle-energy stantpoint, is the fact that the launcher is operating at <b>13 PSI</b>.
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Unread postAuthor: zeigs spud » Mon Oct 09, 2006 8:00 pm

boilingleadbath wrote:More important, from a muzzle-energy stantpoint, is the fact that the launcher is operating at <b>13 PSI</b>.


don't you mean -13psi tho? eventualy it would impload from the pressure (if you used a very strong pump and the celefane didn't suck in lol.. mabey a sheet of rubber would create enough of a seal..) anywho that lil thing had nothing to do with the 13/-13 psi question.

EDIT IN>>>
Atlantis wrote:The only things holding the cellophane on is the suction cup effect, once air comes in it won't be holding on anymore, the cellophane will probably just fall off.

if there were no progectile yes it would fall off. but the progectile acualy does launch out fast enough that it will hit the cellophane before it falls off.
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Unread postAuthor: CS » Tue Oct 10, 2006 12:04 am

Atomspheric pressure is 14.7 PSIA and 0 PSIG. After you reach 0 PSIA there is nothing to 'suck' [Thats a incorrect term, but for the sake of trying to keep it low-tech. Also considering im not very tech savy... Anyways].

"Absolute negative pressures occur in some theories in physics. See dark energy, equation of state (cosmology) and negative mass." ~WikiPedia [Article - Negative pressure]

So by BLB giving you a slight margin of ~1.7PSI off a perfect vacuum is to account your backyard sceince and rough means of acheiving it. While getting the quote I also read up my curoisty to see if getting negative pressure is possible... It is, but I dont care to explain it seeing as im not sure I even understand it fully. :-p

I think in all, BLB is trying to exploit the power of such a cannon. Why would you go all threw this trouble to make your 'uber-cool vac gun' when a aersol combustion will whip its @ss as far as power goes. Wouldnt call that 'flaming', but go ahead and waste your time in ignorace.
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Unread postAuthor: zeigs spud » Tue Oct 10, 2006 1:59 pm

i don't see it as flmaing lol. when i first saa a vacume pump cannon and it's damage, there was a pretty intense amount of shrapnel from what was shot. Granted i dought i'll be able to find the site again all i modded for the disighen was that instead of having the plastic wrap on the back end as well just have a modded sprinklervalve.

The amount of power it has depends on the volume of air taken out of the cannon so u can't just assume that a combustion is better.

Anywho i just relized that my disighen acualy WOULDN'T work lol. This is becuase as the air is taken out (and we will use -psi just for an example) the what i call a "diaphram" of the sprinkler valve will quickle quealize to "-2" forsay PSI. when the Blow gun is opened air would acualy enter the sprinkler valve on the top side and therfor the pressure on the top is greater that the pressure below the "diaphram" keeping the valve closed.

EDIT>>>
I just relized tho i havn't reseached much, wouldn't the negative psi acualy exist but the amount of pressure you would use would increase the more air that is taken out. This is becuase after 0 PSI then the pressure is no longer forcing within the pipe to go outwords rather inwards to collapse in on it'self and the less air within the greater the normal 1ATM (atmospheric pressure -1atm is just outside your house if you are at sea level-) wouldn't increase to the amount of pressure pushing inwards on the cannon. Another example of this is on an airplane that is forsay 2-3 thousand feet in the air just the exact opisite, or a space shuttle in outerspace.
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