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My first cannon

Built a pneumatic cannon? Then post it here! This section is for completed, finished cannons that you have built. Please include pictures and information.
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Unread postAuthor: goathunter » Wed Jan 30, 2008 8:21 pm

There is a game in SC that I want to take it to in July,


Which one?The only one I know of is on June 14th. at Adventure beach.I'm the alternative weapons guy for the field sponsored team.If you come to that game you'll likely have to check it in with me, so no problem there.Just PM me around that time and I'll get you set up.

That sucks about the grenades. You should remind them that any baseball pitcher from highschool on is subject to getting hit with a solid 5 oz object traveling at as much as 130 mph (~ 190 fps), and they're only allowed to stand 60 ft away.


You would think it would make a difference, but everything is about insurance these days.At least small grenades are more fun to shoot :D The recoil of off 8-10 oz. grenades is horrible.



and it looks as if you actually give a hoot about safety, too, which is sadly lacking these days


Commendation on that as well.
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Unread postAuthor: Corrupted355 » Wed Jan 30, 2008 8:40 pm

sthorne wrote:i know you said you use it for paintballing but have you tried any other means of ammunition besides paintballs.. like maybe marbles, or gumballs??

I've got a giant red superball that's just slightly smaller than the 2" inside diameter. That thing really goes a long way. When fired straight up, the superball gets a full 15 second hang time before it hits again. If it weren't red, it'd disappear completely. I've got a spare upper manifold for the sprinkler valve that's pneumatic'd with an blowgun. With that on there, that ball flies like a bat outta hell. It goes even better if you wrap it in a tissue, cuz there's less friction against the PVC.

I was thinking about making a smaller barrel adapter so I could shoot something smaller, like marbles or cat toys.

goathunter wrote:Which one?The only one I know of is on June 14th. at Adventure beach.I'm the alternative weapons guy for the field sponsored team.If you come to that game you'll likely have to check it in with me, so no problem there.Just PM me around that time and I'll get you set up.

That might actually be the one. I'll give you a ring around that time.
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Last edited by Corrupted355 on Wed Jan 30, 2008 8:44 pm, edited 1 time in total.
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Unread postAuthor: judgment_arms » Wed Jan 30, 2008 8:42 pm

Nice cannon, Corrupted355, appreciate you posting the results of your research.
You confirmed my theory that a longer barrel and slower acceleration, improves accuracy, thanks you saved me that money. :)

Hey Goathunter, thanks for the heads up on the grenades, there goes my 3inch, one pounder, shoulder cannon, and yes I’m serous, thought it would be cool to lob a pound of paint thirty yards, think of the area effect.

Oh well on to plan B, a 2inch double.

Still not joking.
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Unread postAuthor: dippydodo03 » Wed Jan 30, 2008 9:05 pm

Oh Spuddy. My old friend. Remember the good times we've had.
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Unread postAuthor: goathunter » Wed Jan 30, 2008 9:15 pm

It goes even better if you wrap it in a tissue, cuz there's less friction against the PVC.


Works great on nerfs too. I've been using watting in my 1 1/2" cannons for about 3 yrs. now.I'll never go back to 2" for long range guns.I've found a 1 1/8" wide strip of computer paper and an operating pressure of 80 psi is just about optimal.Funny thing was that all the tankers saw my guns and scoffed at how naive I was for using a 1 1/2" barrel.That was until I started picking them off out of marker range :wink:

Another tid bit to keep in mind.


You confirmed my theory that a longer barrel and slower acceleration, improves accuracy, thanks you saved me that money. Smile


Why didn't you ask?I could've told you that...
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Unread postAuthor: Corrupted355 » Wed Jan 30, 2008 9:17 pm

judgment_arms wrote:Nice cannon, Corrupted355, appreciate you posting the results of your research.
You confirmed my theory that a longer barrel and slower acceleration, improves accuracy, thanks you saved me that money.

While that is true for projectiles where trajectory is important, I don't know that it is for something like a ball. The reason slower acceleration is better for the JCS rockets is twofold. First, the foam rocket is subject to deformation, so the less force you can put on it, the better. Secondly, linear rotation is crucial to the flight of the rocket. So if you're using too much air to shoot the rocket, the blast as it exits the barrel could throw the rotation off, causing a wobble. Any kind of wobble will cause distance and accuracy degradation.

As long as you're shooting something solid (like a ball or potato) where flight dynamics are not important, you should be able to make any kind of valve/barrel you want. It's only with objects that need to fly a certain way in order to be effective
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Last edited by Corrupted355 on Wed Jan 30, 2008 9:27 pm, edited 2 times in total.
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Unread postAuthor: judgment_arms » Wed Jan 30, 2008 9:20 pm


...
You confirmed my theory that a longer barrel and slower acceleration, improves accuracy, thanks you saved me that money. Smile


Why didn't you ask?I could've told you that...


Figured I was right and never really thought about asking, was kind of common knowledge to me, derived from logic used in smoothbore muskets. Only thing I wasn’t sure of is if it mattered with a fin-stabilized round. I was joking about building a test rig.
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Unread postAuthor: goathunter » Wed Jan 30, 2008 9:25 pm

First, the foam rocket is subject to deformation,


Which brings up another good point.Proper carrying and loading of nerfs.Accuracy of a paintball LAW is only as good as the condition of the nerf.
What is you fix for nerf carrying and loading, Corrupted?

Secondly, linear rotation is crucial to the flight of the rocket. So if you're using too much air to shoot the rocket, the blast as it exits the barrel could throw the rotation off, causing a wobble.


I've heard of one guy fixing the problem by gluing straws in a honeycomb shape down the barrel in an effort to "straighten" the turbulent air.That is something I'll have to play around with to see if it has any validity.
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Unread postAuthor: daberno123 » Wed Jan 30, 2008 9:28 pm

WOW

I love the breech loading system, its one of the simplest i have seen. I have just two questions about it. How well does it seal and how did you glue on the end cap? Did you just sand it out until it fit the barrel then prime and cement it on? Did you have to hose clamp it on in order for the solvent welding to work?

Overall its a great gun, much better than my first, which was a simple ball valve gun that used drain parts in it like yours did. Luckily you caught yours pretty early. Its one of the first lessons i learned. I'm lucky it never blew up on me. :)
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Unread postAuthor: Corrupted355 » Wed Jan 30, 2008 9:31 pm

goathunter wrote:Which brings up another good point.Proper carrying and loading of nerfs.Accuracy of a paintball LAW is only as good as the condition of the nerf. What is you fix for nerf carrying and loading, Corrupted?

The breech loading makes it a lot easier. Also, the JCS rockets have a hole that goes from the back of the rocket, through the tailfin shaft, and into the head. I have a dowel that fits perfectly in that hole with a long screw on it. as long as that dowel is parallel to the barrel, it's loaded right.
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Unread postAuthor: Corrupted355 » Wed Jan 30, 2008 9:35 pm

daberno123 wrote:I love the breech loading system, its one of the simplest i have seen. I have just two questions about it. How well does it seal and how did you glue on the end cap? Did you just sand it out until it fit the barrel then prime and cement it on? Did you have to hose clamp it on in order for the solvent welding to work?

If you're talking about the barrel to valve seal, it's great. My head is right next to that spot when it's fired, and I never hear anything out of place.

Yeah, that endcap was just sanded to fit, then primered and cemented to the side of the barrel. I just held it there for about 30 seconds, then let it be for an hour or so before I put any real tension on it. To be honest, finding the perfect place where it lined up was the most annoying part.
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Unread postAuthor: judgment_arms » Wed Jan 30, 2008 9:36 pm

Corrupted355 wrote:...Secondly, linear rotation is crucial to the flight of the rocket. So if you're using too much air to shoot the rocket, the blast as it exits the barrel could throw the rotation off, causing a wobble. Any kind of wobble will cause distance and accuracy degradation...

I wrote:...Only thing I wasn’t sure of is if it mattered with a fin-stabilized round...


Well, guess it does matter, what you say make sense to me, never thought of it that way.
All the more reason to properly crown the muzzle.

I wonder what effect chocking the muzzle would have…
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Unread postAuthor: Corrupted355 » Wed Jan 30, 2008 9:58 pm

judgment_arms wrote:Well, guess it does matter, what you say make sense to me, never thought of it that way.
All the more reason to properly crown the muzzle.

I wonder what effect chocking the muzzle would have…


Well, I ported and chamfered the end of the barrel to see if I could get any noise reduction (which didn't work a lick), but it would also theoretically help reduce that exit turbulence. I haven't noticed a difference, but then I only got maybe one rocket in twenty to wobble anyway.

goathunter, this is what I use:
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Unread postAuthor: goathunter » Wed Jan 30, 2008 10:21 pm

I use a pusher rod I made.

Image


Image

Image





Well, I ported and chamfered the end of the barrel to see if I could get any noise reduction (which didn't work a lick), but it would also theoretically help reduce that exit turbulence


I put a fake muzzle brake on the MCS.As an added benefit, I did notice that accuracy did increase slightly.I assumed it had to do with the brake helping to shed off the paper wadding.But the escape of excess gas may have something to do with it.

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Unread postAuthor: Corrupted355 » Wed Jan 30, 2008 10:34 pm

Nice pusher. You probably need it using that 1 1/2" barrel. I find that I don't actually need my push stick unless I get a rocket back that landed in mud or got roughed up by impact. You don't have a problem with the Nerf tails ripping off? I can only get maybe a dozen shots out of one before I've got to re-glue the Nerfs back together.

EDIT:
Oh, wait....
I see you've done some modification to those tail fins.
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