Let me introduce myself...

[Cojaro]

First off, I'm not really a novie at this stuff. I've looked into and researched pneumatic spudguns at length. Something about launching things hundreds of feet into the air seems really cool to me.

My first gun (no pics, sry) has a 5' long, 1.5" diameter barrel (SCH 80, I think) and a 18" long, 3" air chamber with a ball valve (yeah, I know, not the most efficient). The barrel-to-chamber ratio is about 1:1.5, or at least as close as I could make it. It launches pretty well. I used those small potatoes (kinda pinkish and round) and my best shot with that was 450ft @ 110psi with no wind. Depending on wind strength and direction and my reaction time of opening the ball valve, the majority of the time it will launch potatoes about 250-400ft, which I think suffices for my first potato gun.

That's about it, but I got plans to make another gun, but with a somewhat complex valve operation (piston valve variation) so that all of the pressurized air is released almost instantly.

I'll try to explain what I want to do.

The barrel is inside of the air chamber and almost go to the other end (but leaves room). That end of the chamber will go down to about 1.5" and then back up to a much smaller 2.5" chamber. Let's call the 1.5" length the "bridge".

Here's how the operation should work (i'll post a pixel art explanation here later this weekend):
There is a rod that extends from the large chamber to the small chamber, and it has rubber discs of some sort (think sink drain stopper) at either end. I would first pressurize the small chamber so that the rubber stopper is pressed against the "bridge" and creates a seal (hopefully).
So now only the small chamber is pressurized (@ ~110-120psi). As the rod is pushed towards the end of the small chamber, it is also pushed against the barrel end to create another seal. So now the large chamber is completely sealed up and ready to be pressurized. (this is when I put the potato in the barrel) I would then fill it to no more than 10psi less than the small chamber (so @ ~100-110psi), otherwise equilibrium may set the gun off prematurely.
To fire the gun, I would release (probably via ball valve) the air in the small chamber. The pressure would drop inside the small chamber and the pressure inside the large chamber would force the small chamber rubber seal to open (by being forced back by the large chamber's pressure). As that happens, the other end of the rod moves away from the barrel opening and is forced against the end of the "bridge" and creates another seal. At this point, the only exit for the large chamber air is the entire opening to the barrel.

The only drawback is that setting it up takes some time, but then again, cannons weren't quick to prep either.

It's fast, and dumps all the air almost at once. That's me, and those are my plans.

[BC Pneumatics]

Please allow me to introduce myself, I'm a man of wealth and taste.

Welcome to the forums, hope to hear of some success with this new valve.

[Brian the brain]

Pleased to meet you....Hope you guessed my name...

[UKSGC]

Ive been around now many a long year.

[StealthSpud]

Welcome! From what I could muster up from that explaination, that sounds like a sweet design! But I guess I'll have to wait for the pics!

[Brian the brain]

I can wait..
Time .....is on my side

[BC Pneumatics]

Sorry... I seem to have started something.

[MrCrowley]

Way to go BC

Anyway back on TOPIC hurry up and get that diagram done so I can understand what your saying



Oh and im MrCrowley.....I like to post

I am BC Pneumatics.....I like to edit MrCrowley's posts :bom:

[drac]

Yes, I want to see that diagram, it sounds like quite the interesting design.

And I'm Drac, the moderator with a voracious love of Heavy Metal and topic locking.

[MrCrowley]

Way to go BC

Anyway back on TOPIC hurry up and get that diagram done so I can understand what your saying



Oh and im MrCrowley.....I like to post

I am BC Pneumatics.....I like to edit MrCrowley's posts :bom:

Edit:Thats a first, hope your not making a habit out of this BC
Drac, alot of members here listen to heavy metal....funny that

Edit 2;WTF I clicked edit not quote

[medievalman]

This has gotten alittle off topic...

welcome to the forum, cant wait to see pics!

[BC Pneumatics]

Gort, doesn't that shop belong to your boss or something? (I thought you said something about windows... but I may just be going insane.)

[Cojaro]

Way to go BC

Anyway back on TOPIC hurry up and get that diagram done so I can understand what your saying



Oh and im MrCrowley.....I like to post

I am BC Pneumatics.....I like to edit MrCrowley's posts :bom:

Edit:Thats a first, hope your not making a habit out of this BC
Drac, alot of members here listen to heavy metal....funny that

Edit 2;WTF I clicked edit not quote

Makes sense to me. Heavy metal and weapons of any sort always seem to go hand in hand.

[BC Pneumatics]

I agree. Nothing like jamming out to Dragon Force while practicing with a long bow.

[Cojaro]

I agree. Nothing like jamming out to Dragon Force while practicing with a long bow.

Eh, I'm not much of a Dragonforce fan. 80's hair metal rock ballads aren't my interest, although I will give many kudos to the guitarists, as they have fingers of flying fury!