I've come across a little bit of pipe.

[Blitz]

Someone I know offered me some 6" and 8" diameter schedule 80 pipe, as long as I get it off his lot.

I pick it up Monday. Any suggestions? By the way, it's about 14 feet of the 6" and 8 feet of the 8".

[tigerblues28]

BOWLING BALL CANNON.

BILLARDS BALLS SHOTGUN.

Nick

[hawktalk]

crazy mutable barrel cannon that uses loads of 1/2" tubing and cram anything down there and put it on a artillery type rolling stand thingy i would use 6" for barrel and 8 inch for chamber

[Technician1002]

Suggestion, get to know MasterCard and Visa well. The fittings for that size will come with sticker shock.

[Blitz]

Yep, about 30-50 bucks for a 8" to 6" bushing. Considering Mc Master Carr wants $138 for a 10ft section of 6" schedule 80, and $200 for 10ft of 8" schedule 80 (plus tax!), I'm still saving a fair amount of money by only having to buy fittings. Besides, it's been a while since I've seen anyone else do a larger cannon!

But I'm not too concerned with fittings cost. It's cheaper (and easier to find) than ammo or reloading components for my other hobby.

If this pipe were metal, I'd consider a bowling ball cannon, but it wouldn't be something for this site. You know what I mean. I'm fairly certain this calls for a combustion cannon and the 8" will be for a chamber, but I'm not sure if I want to do a 6" diameter barrel or 4". Or both I guess! Can just use threaded adapters. And of course, I'm not going to be using it ALL for the chamber. Too big to manage. Pipe pics coming tomorrow.

[Technician1002]

Unless you got a piece of pipe with a bell on it, you will need an 8 inch coupler in addition to the bushing. Kachin$$$$

This is why I learned how to make the bells on my Dragon cannon, so I didn't have to buy two couplers.

The bells on the pipe are home made. One sched 40 and one sched 80. It was really hard to do.

[Blitz]

You're not being very supportive. Why are you concerned with the money I spend on this project?

[Blitz]

Oh, I see what you were saying. That picture didn't show up when I loaded up your reply.

That'd save me about 60 bucks doing that on both ends, actually. But if you had trouble doing that with scheudle 40 pipe, I'd have a HELL of a time doing that well with schedule 80. I am probably better off just ponying up for a coupler or two, depending on what design I want to go with.

[Technician1002]

Sorry, If you have the budget, go for it. With the 8 inch by itself, it would make a fantastic basketball cannon.

Are you planning on a combustion cannon? As the chamber increases in diameter, the power increase is better than linear as more of the combustion gases are further away from external cool surfaces and the flow in the pipe has lower losses. An 8 inch chamber and 6 inch barrel would make a great melon or cabbage cannon.

[youtube][/youtube]

[Blitz]

That's kinda funny actually. I'd feel uneasy using a hammer to load anything. I briefly thought about a basketball launcher, remembering that kickball cannon Spuddin made some years back.

Oh yeah totally, I've certainly decided that a combustion is the way to go for a larger cannon, for the very reason you mention. And secondarily, I don't think I'd have what it takes to make a pneumatic valve capable of handling such a large cannon without using some BS butterfly valve setup, ala punkin' chuckin' setup. That'd be just too much money. Although, the size would probably make it easier to come up with a piston housing. But definitely somewhat more expensive.

I think it's time for me to fire up HGDT and play around with some numbers.

[Blitz]

It appears that with a 48-inch chamber with the 8" pipe and 120-inch barrel with the 6" pipe... I'd be looking at around 9500 ft-lbs of muzzle energy with a 5lb projectile. Ballpark of course, assuming 3-gap spark strip, etc. I'll further tweak with these numbers to see what I can accomplish.

If these are the dimensions I go with, unfortunately for my wallet, I think the sheer size warrants an over-under design. Otherwise storage is going to be a serious challenge. And I'd like to place this on a chassis. It's going to weigh over 100lbs(!) and I really think breech loading is going to be a must. I'd have to seriously support the barrel on the chamber so the recoil doesn't wreak havoc on any fittings; probably will also consider a recoil dampening system. These, and other factors, are considerations I'll have to contemplate tomorrow when I get home with my pipe. If time (and wife) allows, I'd like to have this operational by Saturday, but I KNOW that's not going to happen. End of the month seems more reasonable.

So tomorrow, I'll take a picture of my newly acquired pipe and start a build log in the combustion cannon section once I hash out some details.

[Gun Freak]

To make it a combustion all you really need is a female adapter and plug

[Blitz]

Oh ok, don't need any ignition. Gotcha!

[jackssmirkingrevenge]

I've come across a little bit of pipe

Better wipe it down then before anyone sees it I know what you mean though, I find pipes really exciting too!

Suggestion, get to know MasterCard and Visa well. The fittings for that size will come with sticker shock.

Or... epoxy casting!

[Blitz]

I was thinking of using epoxy on projectiles that are a bit too small to have a good air fit.