Fitting a cannon in to a tank

[Tango71]

Hey guys, somewhat new guy here. I'd like to start out by saying that I have been lurking for years and it's actually my other hobby that finally brought me here. I like to build Scaled tanks (ones you can sit in and drive) My current build is a 40% scale M4 Sherman and I'm at the stage where I need to do some serious thinking about what I'll use as my primary cannon. Originally I thought pneumatic and I'd like decent power but I'm very limited on space inside the turret so a very long air chamber is out of the question. However a short but fat chamber would work. This will also force me to run an air compressor of some sort and take up precious space.

Another thought was a combustion cannon but I don't know if I like the idea of having a combustion chamber that close to my face, on the other hand, if built right I know it can be safe. Another thing worth mentioning is that it has to be breech loaded as well as I plan to use golf balls as the projectile but I'm open to suggestions. It has to be fairly cheap to shoot.

Any help is appreciated.

[jrrdw]

Dealers choice! With elbows and pressure rated flex hose your chamber can be placed anywhere. Use a cam lock on a sprinkler valve and there's a breach loader, not a fast way of loading but hay...

[Tango71]

Thought about the camlock but that would only work on a pneumatic cannon, I thought about making a mechanism on a slide with a camlock built in and an arm over top. One would lift the arm and the camlock would unlock and slide back ebough to fit a golf ball in to the breech. I definitely wouldn't want to use that on a combustion cannon. As for pressure rated flex hose, I think this stuff would be expensive in my neck of the woods...if I even find it.

If I decide to go with a combustion cannon then I'd probably use a sliding collar over barrel type setup for the breech. It would have to have a good seal on it though.

[matti]

How about a pneumatic coaxial cannon made so that the barrel is the same lenght as the chamber, this design would look very real and be compact size ? coaxial can be made pneumatic or combustion.

If you dont know what coaxial cannon is, it means that the gun barrel is inside the chamber pipe. Try to search from the pneumatic cannon database.

EDIT: here is some examples and ideas for you:
http://www.spudfiles.com/pneumatic-cann ... 24787.html
http://www.spudfiles.com/pneumatic-cann ... 24783.html
http://www.spudfiles.com/pneumatic-cann ... 24557.html
http://www.spudfiles.com/pneumatic-cann ... 23972.html

[Tango71]

How about a pneumatic coaxial cannon made so that the barrel is the same lenght as the chamber, this design would look very real and be compact size ?

If you dont know what coaxial cannon is, it means that the gun barrel is inside the chamber pipe. Try to search from the pneumatic cannon showcase.

A coaxial would work and I have thought about it but then the only problem is that it can only be a 2.5" outside diameter chamber to maintain a scaled look, meaning that the projectile cannot be a golf ball and must be something much smaller.

As stated above I am open to any suggestions on ammo and cannon designs which is why I posted this here. I thought about custom resin projectiles if I ended up having to use a small barrel. They're easy enough to make and can be made to any size. I could use polyester resin and an aggregate of some sort to cast any type of projectile I want and these would work very well with a barrel made of schedule 40 seamless which I have a lot of in stock. This doesn't have to fire over a mile or go supersonic, I'd like to achieve at least 300 meters/yards. A breech loaded hybrid coaxial would be nice too and I have a few ideas floating around in my head on how to build one.

[jrrdw]

Another disadvantage with using a coaxial is you would have to remove the piston to load through the breach.

[Labtecpower]

http://www.spudfiles.com/spud_wiki/inde ... Dump_Valve

I can highly recommend this design!
Short opening times, and works best with a fat chamber.

[Tango71]

http://www.spudfiles.com/spud_wiki/inde ... Dump_Valve

I can highly recommend this design!
Short opening times, and works best with a fat chamber.

Could take something like that and replace the second chamber with a spring and make a combustion hybrid. Combustion pressure would overcome spring pressure and push the piston back. I really don't think I'll have the room for an air compressor inside the turret and I'd like to have it be able to spin 360 degrees without any air hoses twisting between the turret and hull.

[jackssmirkingrevenge]

Have you thought of cartridges?

I have a rather long topic about preloaded pneumatic cartridges here: http://www.spudfiles.com/pneumatic-cann ... c8702.html

Preloaded combustion cartridges would be even easier to make, and certainly very safe if built correctly, I've had a play with those too: http://www.spudfiles.com/combustion-can ... 20150.html