31 replies to this topic

[AssassinNF]

First off, I want to make something clear: Yes, this is a concept thread. I do not have the time, resources, or experience to make this, but many of the members here do, and I felt like this idea was too interesting to ignore.

This is a concept for an extremely compact Air-powered homemade. What makes it so compact is that the barrel and tank are in the pump. The entire gun would basically be a small tube with a blast button.

Here's a sketch I quickly whipped up in Microsoft Word. It's not very exact at all, but it gets the basic idea across:



To prime it, you would pump it by the barrel/tank assembly, which is also the pump. Then you would extend the pump/barrel (so you could get to the blast button), and fire it.

This would obviously involve alot of work and air gun experience, but if this design was improved upon and created, it would probably be capable of AT2K ranges, would only take a couple pumps, and it would be perfect for integrations. You could stick one anywhere.

I posted this concept so the idea would be out there, and so it can be critiqued. I have very little knowledge of how blast chambers work, so I'm curious to hear what the more knowledgable members here have to say about this design.

So, what do you think?

[CaptainSlug]

That won't work. Your blast button isn't actuating a QEV poppet and will just dump out all of the pressure.

[AssassinNF]

That won't work. Your blast button isn't actuating a QEV poppet and will just dump out all of the pressure.

Like I said, I have no clue how blast chambers work. Sorry about that.

But the concept of having the barrel/tank in the pump is still valid. I'm sure someone who knows what they're doing could revise the design and come up with something that would work.

I'm going to do some research on how this type of tank works, and try to come up with something more feasible.

[PointBlank]

I think I understand What you are getting at, it would be very difficult to create, you would need to cut the pvc in have to put together the internals, then glue together. It would be very cool however if someone could do it.

Edited by PointBlank, 11 April 2009 - 10:19 PM.

[AssassinNF]

Okay, here's V2. I looked at QEV's/Back pressure systems and how they work, and now that I have a better idea of what I'm talking about, I came up with this:



This one's a little more complicated. It's the same basic idea as V1, but the blast button is inside the whole assembly, and the gun is fired by pushing the pump/barrel all the way back and engaging the blast button.

For that purpose, I added in that "Pump-Stroke Limiter," which is basically just a piece of plastic that hits the outer tube before the blast button can be enchanged. The outer tube of the assembly would be cut like the picture below, with one side shorter than the other. While pumping, the barrel is rotated so that the P-S Limiter contacts the longer side, and the blast button isn't engaged. To fire, you would rotate it so the P-S Limiter lines up with the shorter side, and push the barrel all the way back to engage the blast button and fire.



Well there's V2. Any major problems with this one?

[Darth Freyr]

It looks like your blast button would release air into the sealed end of the pump, which would probably be at the same pressure as the blast chamber, and do nothing.

Edited by Darth Freyr, 12 April 2009 - 12:25 AM.

[TantumBull]

It looks like your blast button would release air into the sealed end of the pump, which would probably be at the same pressure as the blast chamber, and do nothing.

That's a good point.

AssassinNF, you could fix this by putting another blast button at the end of the tube. Then when firing, you could hold down that button and pull the barrel back. Ooh, just got an idea, expect a modified pic of your diagram in a bit.

Here it is, does away with the pump limit thingy:

Edited by TantumBull, 12 April 2009 - 02:23 AM.

[wingd man]

here's my design: . Any problems?

EDIT: yeah, I'll work on the size of that...

EDIT 2:

Okay, one more time...


You know what?
Fuck this, here's a link:
Good fucking picture

(I tried 5 different sizes)

Edited by wing'd man, 12 April 2009 - 09:34 AM.

[Zorns Lemma]

here's my design: . Any problems?

Your qev is facing the wrong direction.

[wingd man]

here's my design: . Any problems?

Your qev is facing the wrong direction.

Forgive me, what is a QEV?

[Zorns Lemma]

Quick Exhaust Valve. Used primarily for paintballing (and probably industrial) purposes. I didn't think of the plug and retainer in backpressure tanks as a qev until CS mentioned it.

[rork]

And, short of inhuman fabrication chops and/or a major breakthrough, they are quite difficult to make.

[AssassinNF]

It looks like your blast button would release air into the sealed end of the pump, which would probably be at the same pressure as the blast chamber, and do nothing.

That's a good point.

AssassinNF, you could fix this by putting another blast button at the end of the tube. Then when firing, you could hold down that button and pull the barrel back. Ooh, just got an idea, expect a modified pic of your diagram in a bit.

Here it is, does away with the pump limit thingy:

I like that idea.

but I'm not convinced Darth Freyr's suggestion would be a problem. I figured the tank would have alot more pressure than the pump (otherwise, what's the point of the check valve?). I think the blast button would still vent enough pressure to fire it. But if not, Tantumbull came up with a great fix for it.

And after thinking about this design a little more, it wouldn't be very hard to make a slightly larger version of this out of PVC and hornet parts. I'll have another diagram up in a bit.

[AssassinNF]

Okay, here we go:


This is a larger version of the design, made out of hornet parts. This diagram, once again, is by no means exact, and the proportions are probably terrible, but it gets the point across. I didn't put in the pump-stroke limiter stuff out of laziness. I added an extended button to the hornet blast button, because you'd kinda need it. Also, it doesn't show it in the diagram, but the blast button would have to be glued to the tank.

All you'd need is a hornet tank, a hornet blast button, a check valve chopped off a hornet, a t-connector, and some assorted PVC/o-rings. You could probably even substitute electrical tape for the o-rings if you had to.

I don't know how practical this gun would be, but I might try it if I ever get another Hornet.

[minsc]

The larger the diameter of your pump, the harder it is to pressurize. With the hornet chamber and everything in there, you're looking at at least an inch in diameter if not more. I don't think you could get high enough pressures to make it useful.

[Darth Freyr]

My argument still holds. Tank pressure + cracking pressure = pressure in the pump. Can you see the pump, when fully compressed, has a greater pressure than the tank. The blast button has nowhere to release. Air would most likely flow in the opposite direction. Tantum's idea would work, but I don't believe it needs the gizmo on the bottom.

Edited by Darth Freyr, 13 April 2009 - 09:13 AM.

[TantumBull]

Darth Freyr is right. The pressure in the pump actually has to be higher than the pressure in the tank in order for it to force air into the the tank. Pressure wants to equalize, so more air won't go into the tank if the pressure in the tank is higher than that of the pressure trying to push the air in. That's why it gets harder to pump as the tank gets to higher and higher pressures. That on top op the cracking pressure of the check valve.

[Galaxy613]

Isn't a blast button itself a check valve? It just has really heavy duty spring.

[Darth Freyr]

It could be thought of as a check valve with a manual release.

[Galaxy613]

That is correct but I was impiling that instead of having both a checkvalve AND a blast trigger, you could just have one.

[Darth Freyr]

I think it would work and I never said or "impiled" anything to the contrary.

[Zorns Lemma]

Construct the barrel+gun/pump similar to a 2 step backpressure trigger, except the second chamber slides.



Of course, this is all rather moot, as it is contingent on being able to build a homemade back-pressure tank. Everything else is just icing.

[wingd man]

I know there should be a button at the end of the pump, but this solves Darth Freyr's problem.

http://img27.imagesh...mpacthomade.gif

[Zorns Lemma]

Is that blast button permanently connecting the pump/tank body to the outside of the pump tube? That would defeat the purpose of this concept: a moveable tank that doubles as a pump.

[wingd man]

Is that blast button permanently connecting the pump/tank body to the outside of the pump tube? That would defeat the purpose of this concept: a moveable tank that doubles as a pump.

No, it's not, the picture is just cramped.