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1" QEV?

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: Ragnarok » Mon Dec 10, 2007 2:33 pm

psycix wrote:Surface of flow: 2*pi*r*r

There's no factor of 2 in area of a circle.
It's 2*pi*r for circumference, pi*r<sup>2</sup> for area - you have a blend of both. However, the ratio is fine.

The problem with dual valves is that the extra pipe work adds a lot of dead space.

I still have plans I drew up a while ago for a 30 bar four piston valve cannon with a 2 metre barrel (appropriately called Leviathan). GGDT tells me it would get 262m/s or 860 fps (2434 J/1795 ft-lbs) with a potato.
I was suffering from visions of kickass because the A-Team theme had come up on my music player though - I find that cannons change depending on the music I was listening to when I came up with them.

I'm almost tempted to try it, simply to see what that much power is like.
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Unread postAuthor: ALIHISGREAT » Mon Dec 10, 2007 3:10 pm

The problem with dual valves is that the extra pipe work adds a lot of dead space.

I still have plans I drew up a while ago for a 30 bar four piston valve cannon with a 2 metre barrel (appropriately called Leviathan). GGDT tells me it would get 262m/s or 860 fps (2434 J/1795 ft-lbs) with a potato.
I was suffering from visions of kickass because the A-Team theme had come up on my music player though - I find that cannons change depending on the music I was listening to when I came up with them.

I'm almost tempted to try it, simply to see what that much power is like.


that sounds awesome although wouldn't it be hard finding a 4 into 1 socket? the pilot would also have a large(ish) volume and as you said the dead space is a limitation but it could be done, although i wouldn't like the job of making four identical piston valves :lol: i haven't even made one work yet :(
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Unread postAuthor: Ragnarok » Mon Dec 10, 2007 3:32 pm

ALIHISGREAT wrote:that sounds awesome although wouldn't it be hard finding a 4 into 1 socket? the pilot would also have a large(ish) volume and as you said the dead space is a limitation but it could be done, although i wouldn't like the job of making four identical piston valves :lol: i haven't even made one work yet :(

4 valves is easy work, it's just a repetition of a basic concept. Also, 4 into 1 isn't that hard either - Two valves feeding into the arms of a tee on each side, and those tees feeding into a third. Remaining tee arm goes to barrel.

Those would be minor issues. A high volume of 30 bar air dumping through 4 valves... would be loud.
I might make it in a smaller size, for somewhere between a thousand joules/thousand foot pounds.
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Unread postAuthor: ALIHISGREAT » Mon Dec 10, 2007 3:39 pm

Those would be minor issues. A high volume of 30 bar air dumping through 4 valves... would be loud.
I might make it in a smaller size, for somewhere between a thousand joules/thousand foot pounds.


maybe a marble cannon with a 2m barrel working at those pressures would have good power :twisted: although the barrel would be expensive or you could use four 1/4" qevs on a 6-10mm cannon...

on an unrelated note how were you planning to get to 30bar? i'm guessing an air rifle pump or a homemade pump?
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Unread postAuthor: Ragnarok » Mon Dec 10, 2007 4:13 pm

The modified compressor I'm planning to make should get to just over 30 bar.
I was thinking more like a 4 foot long 28mm or 35mm barrel.
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Unread postAuthor: ALIHISGREAT » Mon Dec 10, 2007 4:38 pm

Ragnarok wrote:The modified compressor I'm planning to make should get to just over 30 bar.
I was thinking more like a 4 foot long 28mm or 35mm barrel.


i think i may try and find a freezer pump and make a compressor out of that which should be a challenge (for me) at some point when i have decided whether i really want a paintball marker or not... damn my indecisiveness :roll:
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Unread postAuthor: Ragnarok » Mon Dec 10, 2007 5:58 pm

I don't know whether I want to build a gas booster or modify a fridge compressor, but I'm sure prices will make the decision for me.

And I have a similar thing going on. Right now, I'm telling myself I don't need things, and then want them, then realise there's a way round it, then...
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Unread postAuthor: psycix » Tue Dec 11, 2007 5:53 am

Ragnarok wrote:
psycix wrote:Surface of flow: 2*pi*r*r

There's no factor of 2 in area of a circle.
It's 2*pi*r for circumference, pi*r<sup>2</sup> for area - you have a blend of both. However, the ratio is fine.

The problem with dual valves is that the extra pipe work adds a lot of dead space.


OMG your right.....
I should look up formulas before posting them argh....
Feeling stupid lol...

But indeed the ratio stays the same. So its not a worse mistake... only stupid.
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Unread postAuthor: Carlman » Tue Dec 18, 2007 4:16 am

octane89 wrote:Ions...paintballs low point. I have seen a 1inch qev, and will see if I can find it in my history online.

I read about some here.
http://www.globalmanufacturing.com/prod ... ccessories


Could this be used as a ready made chamber and valve package on a marble gun say?

sorry for hijacking ill get back on topic now. if you were to have those four qevs would the added 10 turns make a difference to the power or will it be overshadowed by the sheer flow of those valves
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Unread postAuthor: Ragnarok » Tue Dec 18, 2007 4:39 am

Carlman wrote:sorry for hijacking ill get back on topic now. if you were to have those four qevs would the added 10 turns make a difference to the power or will it be overshadowed by the sheer flow of those valves

Well, I would probably make piston valves... but the flow from the valves would be a much larger deciding factor than the losses from the turns.

Per valve, I've built launchers with a similar number of turns which worked just fine.
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Unread postAuthor: Velocity » Tue Dec 18, 2007 8:32 pm

I found a 3/4" QEV for you on eBay that is $9.99 + shipping, ending at 10 pm (1.5 hours from the time of this post) Eastern Time (I think :oops: ). Not only is it a quality QEV, it can be filled from the chamber side, a quality which the McMaster ones do not have.

Send me a PM if you want it.

Edit: Found a big 1.5" for the same price :lol:
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Unread postAuthor: sjog » Tue Dec 18, 2007 8:56 pm

Are those QEV's gone ?
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Unread postAuthor: ShowNoMercy » Tue Dec 18, 2007 9:03 pm

You better not buy all of them! When I come home tommarow I expect to see at least two there! :wink:
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Unread postAuthor: ShowNoMercy » Wed Dec 19, 2007 12:53 pm

Ok I just bought a 3/2 inch QEV and I was wondering, it has two pilot intakes on the back of it. Whats the deal with that? Oh and btw there are now 29 left. :wink:
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Unread postAuthor: socoj2 » Wed Dec 19, 2007 2:33 pm

I have 2x 3/4 deltrols ill sell for $30 Shipped.
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