8" SCH 40 steel pipe - ideas?

[THUNDERLORD]

Wonder if a bowling ball would fit that pipe

BTW, there's a video on youtube of some guys shooting one out of a welding tank up into the air like a mortar, Insane But gets boring

[DYI]

The pressure required to get a bowling ball up to useful velocities from such a short barrel would be more than the pipe could handle. If I could get the 10' long section of 8" they have, that's what I'd be doing, but someone owns it as well.

A recoilless hybrid is a rather interesting idea. It could be done cheaply, and would be great fun to fire off in the field by my house.

Here's a rough idea of what I'm thinking, in the form of an epic MSpaint diagram, which you're going to have to enlarge to see properly:

[DYI]

Well, it seems as though this thread has died, and I like the above idea anyway, so I'll probably go with it.

[jrrdw]

I thought that hybrids had to be inline because of the pressures genarated????

[DYI]

I thought that hybrids had to be inline because of the pressures generated????

Why does that mean they would have to be inline? This'll be less efficient than an inline due to flow restriction and heat loss, but it should still pack quite a punch. And it won't be generating a whole lot of pressure either, an absolute maximum of 500 psi or so due to the use of ABS barrels.

[SpudFarm]

think if you do this wrong and end up with a "forward" recoil

you want to do something nice? a two stage cannon should be cool.

[biggsauce]

How bout something like DR's basketball cannon? If i remember correctly, his was about 3' tall. Don't soccer balls fit in 8" sch 40? Just a simple vertical pipe with some pojectile stops, and the ball will separate the chamber and barrel. It would be cheap, simple and lots of fun!

[DYI]

Hmm... an oxy-MAPP basketball cannon is tempting, and it might not be as, well... terrifying as a recoilless gun. I'd already thought of the possible forward recoil, and it'd be pretty freaky if it happened. On the other hand, I'd need to find an 8" flange or some way to seal the pipe, and something tells me that wouldn't be cheap at all.

[THUNDERLORD]

Hello DYI, I was trying to see the enlarged diagram, but my home computer won't enlarge it, then I had an arguement w/ my roomate and my computer priveledges were suspended, (hopefully temporarily)

So I finally walked to the library, to get updated. Atleast I can enlarge here though.

Looks like it would be a working recoiless from the design, I have been hoping to build a small scale version to test possibilities of using a heavier counterwieght, which could be a plastic bottle(for the wad) and a bag of water inside. (Mathematics research is in order also)

With a heavier counter shot the rear barrel could be shortened perhaps 1/4 length of the barrel. for length/weight considerations.

I was imagining if the pipes could all be metal, with threaded pipes.
For weight consideration it could have a one legged stand (like a primitive firearm had) maybe a wheel could be attached to that for transport.

I will be going by a hardware store to check standard pipe sizes in metal.

I am a noob when it comes to hybrids, but I was thinking of a simple blow open piston in T below the barrel. and if it could be all metal you could maybe use some exotic gas like nitrous oxide or mapp or something w/ oxygen.

Also if the end caps for the 8" pipe were welded from flat steel that would really cut down on weight then you'd only need like two T fittings one on 8" or an (elbow), and one connecting the chamber and barrels.

It's cool if you decide for something more traditional but I'd love to see a giant shoulder fired recoiless. well my one hour session is up here at library--Later 8)

[SpudFarm]

Hmm... an oxy-MAPP basketball cannon is tempting, and it might not be as, well... terrifying as a recoilless gun. I'd already thought of the possible forward recoil, and it'd be pretty freaky if it happened. On the other hand, I'd need to find an 8" flange or some way to seal the pipe, and something tells me that wouldn't be cheap at all.

steel plate and a welding guy

[iknowmy3tables]

carbide canon?
calcium carbide or what ever they call it, plus water that produces acetlyane ignite that and its really loud, and you can shoot stuff

[SpudFarm]

ikm3t: it has a really short runup dictance

[cdheller]

but building a serviceable steel piston valve from welded parts doesn't sound like a very pleasant endeavour.

victalulic web page
http://www.victaulic.com

victaulic would let you take the rig apart but acess to a groove machine,parts,and cost would be your downsides.
taking it apart to change parts or even the whole design are a major plus.

for what its worth

[DYI]

carbide canon?
calcium carbide or what ever they call it, plus water that produces acetlyane ignite that and its really loud, and you can shoot stuff

Yeah, and I can have fun getting hit by chunks of shrapnel screaming through the air at Mach 1 when it fails from repeated shock loads after a hundred uses

I had thought of grooved fittings, but having it threaded would likely end up being cheaper (although it would still be far too expensive). I'm still thinking the recoilless gun would be pretty cool.

[cdheller]

[/quote]
I had thought of grooved fittings, but having it threaded would likely end up being cheaper (although it would still be far too expensive). I'm still thinking the recoilless gun would be pretty cool.[/quote]

I guess you could find a machine shop to thread it ,but then you'd be in for a long search for expensive 8" treaded fittings'.
I'm not saying they don't exist ,Ive never seen or heard of them though,or a pipe threading machine for 8"

I was thinking the low buck approach of finding a construction site with fire sprinkler guys and offering a beer/food bribe at lunch or quiting time to groove the pipe.
maybe bring a couple of guns,and a plan for the 8" project.

the most they can say is no.
thats your answer anyway until you ask them.

I have a couple of 8' couplings that are yours for the shipping from austin tx.

edited to add
looked in my shed for 8" fittings ,didn't find any , just a 6x5 and some 4"s,
same offer