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Cannon as senior project. Info, Ideas, Suggestions?

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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Unread postAuthor: MountainousDew » Mon Jun 08, 2009 7:41 pm

Sorry for the bump...

I hope this helps!

Pull the plunger back, release, it will hit the pin and start the valve to open, the air in the chamber will keep pushing the piston, the ammo will shoot, and Hooray!
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Unread postAuthor: dirker88 » Mon Jun 08, 2009 9:18 pm

That helps alot thank you i thought of the same thing heres another idea for a valve/chamber <a href="http://s581.photobucket.com/albums/ss258/dirker88/?action=view&current=Untitled.jpg" target="_blank"><img src="http://i581.photobucket.com/albums/ss258/dirker88/Untitled.jpg" border="0" alt="xcvxc"></a>

This way you can have co2 constantly flowing. i know it looks bad dont laugh :oops: EDIT: to add click on the image to get full size it looks much better.
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Unread postAuthor: MountainousDew » Mon Jun 08, 2009 10:31 pm

I don't understand, because for it to release the CO2 the piston has to move forward, and if it moves too far forward it will block the outlet... Maybe if you could explain further, it might make more sense.

Also, instead of using CO2, look into HPA; HPA stands for High Pressure Air.
They come in tanks the same size as CO2 does, but the pressure is more consistent. If you don't know, CO2 maxes out at a peak pressure of ~900 psi, and that is at 90 degrees Fahrenheit. So if the temperature is lower than that, the pressure will go down, while HPA will always be at the same pressure no matter the temp. And HPA tanks are charged at 3000 and 4500 psi, a big difference.

Oh yeah, a 13 year old just took you to school!!!

P.S. I attached a link to a video that explains how QDV (Quick Dump Valves) work. The design I gave you is an example of a QDV...
I told you so!
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Unread postAuthor: dirker88 » Mon Jun 08, 2009 10:41 pm

What i have shown is the open valve and when it is open no more air can enter the chamber so i dont lose any extra air. When it is closed the chamber can fill with air the piston that blocks the co2 is skeletonised if you didint guess that already. plus i can get a 20 lb co2 tank with a regulator for less money than a good HPA tank.
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Unread postAuthor: MountainousDew » Mon Jun 08, 2009 10:49 pm

Okay, I get it now...
But it is still flawed, if the pressure in the chamber is at say, 100 psi it is going to take at least 100 pounds to open it.
And I'm guessing you were planning to take it to a higher pressure than that too.
And I understand how you open it either.
I think you should go with a design more like mine, or just a plan old piston valve...
Yeah, go with a piston valve, there's plenty of examples already on this site and almost all of the people on these forums can further explain them.
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Unread postAuthor: jook13 » Mon Jun 08, 2009 10:51 pm

Have you thought about using large diameter copper? Like 2 inch. For your budget, something special could be made with that.
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Unread postAuthor: dirker88 » Mon Jun 08, 2009 10:56 pm

MountainousDew wrote:Okay, I get it now...
But it is still flawed, if the pressure in the chamber is at say, 100 psi it is going to take at least 100 pounds to open it.
And I'm guessing you were planning to take it to a higher pressure than that too.
And I understand how you open it either.
I think you should go with a design more like mine, or just a plan old piston valve...
Yeah, go with a piston valve, there's plenty of examples already on this site and almost all of the people on these forums can further explain them.


i though of that but a simple lever will solve the opening problem think of one of those fancy wine bottle openers. Now im going to sleep wrestling practice was a killer today good night.
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Unread postAuthor: MountainousDew » Mon Jun 08, 2009 10:58 pm

jook13 wrote:Have you thought about using large diameter copper? Like 2 inch. For your budget, something special could be made with that.

With $1000 USD I think he should go with a High Pressure gun like Gipetto's.
He could something awesome like that!
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Unread postAuthor: Technician1002 » Mon Jun 08, 2009 11:06 pm

MountainousDew wrote:Okay, I get it now...
But it is still flawed, if the pressure in the chamber is at say, 100 psi it is going to take at least 100 pounds to open it.
And I'm guessing you were planning to take it to a higher pressure than that too.
And I understand how you open it either.
I think you should go with a design more like mine, or just a plan old piston valve...
Yeah, go with a piston valve, there's plenty of examples already on this site and almost all of the people on these forums can further explain them.


In his first design, there is no pressure behind the piston. A 2 inch QDV with 100 PSI is relatively easy to hand pull even though the pressure on the area of a 2 inch circle exceeds 300 lbs or on a 1 inch version 78 lbs. My grandson, a preschooler, can hand pull my 1 inch at 100 PSI with no problem. I have a video online of him doing it.
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Unread postAuthor: MountainousDew » Mon Jun 08, 2009 11:26 pm

Technician1002 wrote:
MountainousDew wrote:Okay, I get it now...
But it is still flawed, if the pressure in the chamber is at say, 100 psi it is going to take at least 100 pounds to open it.
And I'm guessing you were planning to take it to a higher pressure than that too.
And I understand how you open it either.
I think you should go with a design more like mine, or just a plan old piston valve...
Yeah, go with a piston valve, there's plenty of examples already on this site and almost all of the people on these forums can further explain them.


In his first design, there is no pressure behind the piston. A 2 inch QDV with 100 PSI is relatively easy to hand pull even though the pressure on the area of a 2 inch circle exceeds 300 lbs or on a 1 inch version 78 lbs. My grandson, a preschooler, can hand pull my 1 inch at 100 PSI with no problem. I have a video online of him doing it.

Yeah, I misunderstood his design...
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Unread postAuthor: dirker88 » Tue Jun 09, 2009 8:01 pm

Heres another little drawing.

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