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Project: 10 gallon

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 » Sat Jul 26, 2008 6:37 am

mobile chernobyl wrote:As you can tell, I don't go to extremes to make my pneumatic launchers look like real guns. To each their own, but I prefer to have my real guns look like real guns, and my spud guns look like artistic creations of my own.

I don't deliberately try for it either, but as I borrow some ideas from firearms to make my launchers more ergonomic and practical (after all, there is no reason to disregard the lessons learnt from those long centuries), it sort of happens anyway...
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Unread postAuthor: mobile chernobyl » Sat Jul 26, 2008 7:27 am

Hotwired wrote:On another note the small cannon's looking good :)

How suitable is the 2" for using as a grip? I'm wondering about a grip design at the moment...


It's not ergonomic by any means, but it works. Think of the little gun as a regular size gun for someone 8-9' tall haha.
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Unread postAuthor: Fnord » Sat Jul 26, 2008 8:35 am

I know it was a joke, but after thinking about it, rifling for water balloons (or ANY non-viscous liquid-filled projectile) wouldn't do anything at all. If you don't understand why, try spinning the bowl around next time you eat cereal.

If it did work, the balloon would explode from centrifugal forces.

Oh, and that's one of the more interesting models I've seen lately. Are you planning on getting it done before the end of summer? Should produce interesting damage :)
I still remember your other guns by the way.
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Unread postAuthor: mobile chernobyl » Sat Jul 26, 2008 9:17 pm

The water ballon thing was a joke referring to a converstation debating the neccesity of rifling for improving a paintballs accuracy. That's all I will say, and that should not be debated in this thread, end of story. :wink:

I do plan on having it done by the end of summer. I kinda ran outta time this week, and the weekend hasn't been as good as I planned. Things I need to do to finish 10 gallon.

-Assemble it obviously
-Draft up the holding tray, and a recoil absorbtion device:
-I need to find the center to center distance of the air tanks. The CAD drawing was an accurate estimation, but we all know the guns don't always glue up perfectly. I need to get tolerance control on the tanks distance. I also need to find height above tanks centerline for the barrel for this.
-Paint it
-Test it

I want to finish the holding tray FIRST so I can assemble the gun IN IT. That way it will be held in place and have very little chance to warp during solvent curing.

I'm gonna try and draft up the tray tonight :D

I really wanna be able to test fire 10 gallon by next week.
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Unread postAuthor: Ragnarok » Sun Jul 27, 2008 4:01 am

mobile chernobyl wrote:The water ballon thing was a joke referring to a converstation debating the neccesity of rifling for improving a paintballs accuracy.

And I will repeat my earlier point that I made in that thread - paintballs can provably be affected by backspin, so they can obviously be spun up.
If it can be affected by backspin, there is absolutely no reason why (should you choose to) you couldn't rifle one, as both are a spin effect, just in different axes compared to the bore centreline.

The paintballs and water balloons have totally different characteristics in terms of fluid viscosity, shear forces and rotational radius, so you simply can't compare the two in terms of rifling.
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Unread postAuthor: mobile chernobyl » Sun Jul 27, 2008 12:16 pm

Ragnarok wrote:...And I will repeat my earlier point that I made in that thread...


mobile chernobyl wrote:... and that should not be debated in this thread, end of story. :wink:


Go ahead and do it if you want, I want to see results - I'm done debating. I've already regurgitated test results from this exact same experiment conducted a few years ago (and since the dawn of the true rifled barrels in PB, 10 years ago easily, or more) by myself and many others more experienced than I on PBNATION.com (one of, if not the biggest PB forums on the net) and Automags.org (big paintball "engineer" discussion board) and Tom Kaye, owner of Airgun Designs (creator of the Automag series) concluding the benefits were null compared to a properly bore matched barrel for the paint/humidity/temp of the day.

Backspin is a completely different form of spinning than rifling. Back/Front spin is an aerodynamic effect along the X-axis of the projectile (higher speeds over top of ball, lower over bottem induces lower and higher pressures, creates lift, see airplane wings). Rifling is Gyroscopically ballencing projectile along the Z-axis. I NEVER said you could not induce spin, it's too easy actually, yadda yadda yadda, the backspin argument is already flawed because of the different axis, and how much easier it ise to produce spin on either the X, or Y axis's than it is the Z-axis. Even that said, I'm not arguing you can't put spin on the Z-axis, just that its not beneficial TO A PAINTBALL.

..........................

Of course you are throwing a curveball into the equation by using patched balls, and a longer barrel. If the exit velocity of the ball is the same as in paintball, it will have a slower acceleration to induce a more gradual spin along the Z-axis, and right there it deserves a new test because being scientifically correct, you can't change a variable and expect the same results.

So please, Test your rifled barrel shooting a PRB, verses a paintball gun with a barrel kit such as the FREAK kit by smartparts, both shooting at 300fps, 5 feet after barrel exit. The paintball gun should have high quality paint (at least $80 a case, and FRESH, humidity controlled to prevent hygroscopic effects) and the bore kit should match the dia. of the paint within .002". Your PRB gun can be whatever setup you like it. Shoot 20 balls each at 25 yards, both guns chroni'ed at 300 fps at 5 feet after barrel. Next shoot 20 balls each at 40 (or 50 if you so choose) yards, same setup on speeds.

-Now each target should have a 5" dia solid orange circle, surrounded by a 10" dia orange ring. (colors are examples, use a different color than paint obviously) Obviously sight the guns in first, by taking a few shots and averaging - aiming for the solid 5" circle, and have them vice mounted to a solid table to eliminate the human aiming variable.

- Make sure air supply is as consistant as possible, and both guns use the same air. Co2 suffers air chamber expansion under heavy or prolonged firing, then stopping, then shooting again causing a spike in the next shots velocity. So I would suggest using a high pressure regulated air system like a SCUBA tank to avoid the liquid to gas expansion phase.

Record the shots from both guns placed on the 5", within the 10" and outside of both. Plot this data on a chart, produce chart to me, and - if your idea has proven to be 5-10% or greater in accuracy (to account for outside varibles like ambient air temp fluxuations, crosswinds) - I will HAPPILY shut my mouth and cook you dinner :)

Just an FYI, I use this testing method because it is a benchmark test used in paintball, and has been for many years. So if your going to make claims and want to support them, It's best to used a standardized, and readily excepted test in the industry.


Just don't debate it on this thread, make a topic in the Non-Spudgun Related Discussion forum, or Utilize the sister website of spudfiles.com - Theopia.com for conversations like this. I will happily post in that thread, but NO MORE debating in this one.

Thanks :D
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Unread postAuthor: Ragnarok » Sun Jul 27, 2008 2:17 pm

Just don't debate it on this thread

Well, riddle me this - if you didn't want anything about it in this thread, why did you put the comment about rifling in this thread in the first place? That's at the least counter intuitive.

Backspin is a completely different form of spinning than rifling.

Please don't take me for an idiot. I've studied ballistic effects inside out, back to front and next to it, only slightly higher with a two level effect with a little path running down the middle.

(Sorry, couldn't resist fitting in a Python reference)
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Unread postAuthor: THUNDERLORD » Sun Jul 27, 2008 4:31 pm

( :lol: ) Anyway,

I was thinking the PB will act differently from a water-Balloon due to it's hard shell. But if it has even the slightest air bubble inside, that would induce a wobble caused by rifling.

Are PB's totally full of fluid without the slightest bubble?
Still, If it did have the slightest bubble, seems like the backspin Ragnarok mentioned might still be useful along that axis(Backspin).

I'll check on Theopia I guess. :roll:
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Unread postAuthor: mobile chernobyl » Sun Jul 27, 2008 9:46 pm

Ragnarok wrote:Well, riddle me this - if you didn't want anything about it in this thread, why did you put the comment about rifling in this thread in the first place? That's at the least counter intuitive.


To see if people like you would bite, success on that one :wink:


Ragnarok wrote:Please don't take me for an idiot


You don't need to say please, I understand your an intelligent individual.


THUNDERLORD wrote:Are PB's totally full of fluid without the slightest bubble?


Yes. Research how they're made. R.P. Scherer produces a majority of the industrys paint and would be a good starting point.

THUNDERLORD wrote:I'll check on Theopia I guess. :roll:


Good. Try PBNation.com, automags.org and Google while your at it. This question has been asked (and answered) a million times and the answer after testing is 99.9% of the time what I said, unless you count the "kewls" comments as answers. 8)
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Unread postAuthor: mobile chernobyl » Tue Jul 29, 2008 12:09 pm

::UPDATE::

Well 1 gallon's valve works so well, I've decided to use it like it was originally planned.

1 Gallons valve was intended to be a QEV for 10 gallons 3" porting valve. One 1" sprinkler valve I didn't feel would be worthy of porting the might 10 gallon, so I wanted either 2 sprinklers (messy) or something with a 1.5" effective porting dia. 1 gallons valve is just that.

QEV's are commonly used in spudgunning, most are used to seeing the metal variety used on copper rifles. However a QEV is not constrained to just that type of valve however. In paintball QEV's are used now on valve manifolds, or spool housings that rely on moving a spool back and forth, and venting the gas used to held it in one direction very fastly while it is moving back in the other direction (So it doesnt have to vent back through the air inlet lines and through the spool's exhuast porting, which is higher resistance by far).

A smaller QEV used for paintball is essentially a barrel sealing piston valve without a barrel. where the barrel would be is just the exhaust.
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So I'll be using 1 gallons 2" T barrel sealing piston valve as a 1.5" porting QEV. It will be ported by at 1" sprinkler valve that is Pnuematically modified already to be ported by a safety poppet valve (a good amount more flow than your average blow gun). Attached to the safety poppet valve's ring will be a string of whatever length. My goal here is to be able to fire "remotely" like they do with howitzers sometimes (OK I dunno how often they do it, but i saw some guy pull a 100' string to fire a howitzer once haha).

Summary:

3" high flow porting "X" Valve
Ported by 1.5" High flow porting "T" QEV
Ported by 1" Normal Sprinkler valve
Ported by, err 3/16" spring balanced poppet valve.
Fired by pull string from any distance desired.

Too many valves? :shock:
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Last edited by mobile chernobyl on Tue Jul 29, 2008 12:23 pm, edited 1 time in total.
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Unread postAuthor: Carlman » Tue Jul 29, 2008 12:18 pm

A qev is a commercially made barrel sealing piston valve or diapragm valve, cant really call your piston valve one.

qevs are used for guns on this site aswell thr is heaps of them, i have 3 :D
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Unread postAuthor: mobile chernobyl » Tue Jul 29, 2008 12:30 pm

Thanks for repeating what my second "paragraph" :roll: :D
(That is the first responce I've actually thought a rolly eyes was deemed neccesary)

2" tee valve is serving as a quick exhaust valve. AKA It is playing the roll of, and meeting the definition of a quick exuast valve.

ALERT THE PRESSES ITS NOT ACTUALLY A COMMERCIALLY MADE ONE!!!!!!!! DISCLAIMER DISCLAIMER DISCLAIMER!!!
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Unread postAuthor: Ragnarok » Tue Jul 29, 2008 12:32 pm

mobile chernobyl wrote:Too many valves? :shock:

Probably. You could likely cut out the 1.5" piston valve from that stack and not notice any difference in performance.

Often, people either do total overkill on the pilot valve, or use something so small it won't pilot properly (or at all) - neither extreme is good.
I suggest a modicum of moderation...
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Unread postAuthor: mobile chernobyl » Tue Jul 29, 2008 12:36 pm

True Ragnorak.

It will come down to if I have a spare $20 sitting aside, as that is about how much it will cost to add the 2" Tee valve all things said and done.

My Pilot volume is not so small, I could make it smaller I guess. This was just a lazy way around it, and sort of a "Mines bigger" of porting valves thing haha.

::Edit:: Or I could just vent the 2" Tee valve via string actuated 1/2" ball valve, eliminating the sprinkler valve and poppet valve.
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Unread postAuthor: Ragnarok » Tue Jul 29, 2008 12:52 pm

mobile chernobyl wrote:My Pilot volume is not so small, I could make it smaller I guess. This was just a lazy way around it, and sort of a "Mines bigger" of porting valves thing haha..

Well, seldom are pilot volumes optimised to the perfect point.
I know mine are usually quite a bit bigger than they have to be, but I doubt that it hurts performance noticeably.
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