need a little help, with a mortar

[Sgt. Irvine]

ok i am have been building a airsoft mortar, that shots styrofoam cups cut in 1/2 to fit in a 2" barrel, it uses 12 gram Co2, to shot heres a pic from autocad, it seems to have a some bugs in it, it will not shoot more then about 50', would love some help making it work

[13Fido13]

How fast does the valve turn? The speed might be a problem because of a slow release of the gas.

Why does there need to be a 7" piece of tubing just after the co2 cartridge? Maybe try cutting that down and making it smaller.

If that still isn't enough power, try using a larger co2 cartridge.

I'll keep thinking about this, and let you know...

[tony123]

12 gram is too small and expensive.. Buy a paintball tank and build an adaptor for it. also the piece of 1" tube that is 7" long has to go, the problem is that the 12 gram co2 cartrage had too much room to expand thus cutting down the psi.

[mcguyver]

Are you using a manual valve? If so, this is your problem.

Now comes the censure. If you did not know that you should not be using a manual valve, you have no business building this. Seriously. And, you should not be using PVC pipe with those kinds of pressures. PVC can be unpredictable, expecially during temperature changes and can shrink or expand quite significantly. I know, I use it all the time at work.

You should be using steel. The pressures generated here can be hazardous if you have a failure, especially in your smaller pipe sections.

[Crunchmeister]

Just a thought here, but you could perhaps take an idea from the already quite perfected idea of the Potato Cannon (check youtube - LOTS of examples). I think that would probably suit your needs a lot better than this overcomplicated contraption. You can build it for about $25 worth of parts, all available from Cdn Tire, Rona, Home Depot, etc.

[Tankdude]

You don't have enough air volume in the reserve.

Potential energy is the game here. Pressure times volume. It is not safe to increase the pressure, but you can increase the volume. You will be amazed at the range you can get with a low pressure set up.

Big volume + low pressure + big valve = safe and fun.

[Jayne Finch]

Originally Posted by Crunchmeister

Just a thought here, but you could perhaps take an idea from the already quite perfected idea of the Potato Cannon (check youtube - LOTS of examples). I think that would probably suit your needs a lot better than this overcomplicated contraption. You can build it for about $25 worth of parts, all available from Cdn Tire, Rona, Home Depot, etc.

ok. i dont like to play the asshole here but it has to be said. YOUR A DUMBASS. potato cannons work on COMBUSTION. yeah. theres a plan. lets point something with and explosive gas in it at our friends! woohoo! let the good times roll. whatever. you do whatever you want.

anyway. i see a few problems.
1. bigger tank. 14 ounce paintball tank or bigger. (bigger is always better)
2. lose the PVC. its just a bad idea.
3. lose the 7" chamber. (the cylinder is already compressed you dont need it)
4.you need an electric (or similar) valve. something you can set for speed would be best.
5. try shortening the barrel

so basically. build it with steel with the tank the valve and the short barrel. should work beautifully. ive been thinking about doing something similar for a while but haven't gotten around to it yet.

good luck.

[Daes]

Originally Posted by Jayne Finch

ok. i dont like to play the asshole here but it has to be said. YOUR A DUMBASS. potato cannons work on COMBUSTION.

Actually, there are a ton of different types of potato cannons, don't be rude, do some reading first, google is your friend. There are pneumatic, combustions, and Hybrid (compressed air combustion, super PSI). Many people who are looking to build a first time cannon go with Pneumatic due to ease of setup and safety. You can make some pretty frightening air-cannons.





For Airsoft Potato Cannons, Pneumatic is by far the
safest (standard, compressed gas cannon).

Here are some crap photos from back in the day when experimenting with fast reload cannons:




Quick CAD of what I had in mind:



-Daes

[Kimbo]

woot, nice CAD

[ThunderCactus]

Been there done that, having a diaphragm sprinkler valve, especially the lesser quality model you have in that pic, is just too inefficient. I changed my valve and now I'm getting the same range on 50PSI that I was getting on 120PSI with the sprinkler valve. Keep looking for a better valve design

[Crunchmeister]

Originally Posted by Jayne Finch

ok. i dont like to play the asshole here but it has to be said. YOUR A DUMBASS. potato cannons work on COMBUSTION. yeah. theres a plan. lets point something with and explosive gas in it at our friends! woohoo! let the good times roll. whatever. you do whatever you want.

I'd throw back that you're a dumbass for not doing your research. There are plenty of pneumatic potato cannon designs out there powered by a plain old paintball pneumatic tank that would work just fine. The real issue with the threadstarter's design is the size of the chamber and the valve. And what I was referring to was the DESIGN of these things and how easily they could be adapted to airsoft. Why reinvent the wheel and try to design something from scratch when there are tons of already working designs out there that can do the same thing?

[Amos]

You don't have enough room for enough gas to expand and work properly I'll tell ya' that much.

[Sgt. Irvine]

the 7" chamber is there becuase the 1" to 5" blow up evey time i tested it, and explosive gas will start a fire to the shells i am shoting so NO I AM NOT A DUMBASS, and thanks daes and all of u who tryed to help,and the Co2 when it comes out of the 12 gram shell it comes out slowley so i need the air chamber

[Jayne Finch]

yes Irvine i realize you are not a dumbass. the comment was not directed at you. and to all of you. YES, i do realize that there are several types of potato cannons as i have made several over the years. however i may have been hasty in my assumption that Crunchmeister meant a standard combustion style potato cannon. because Irvine was building what basically amounts to a pneumatic style potato cannon i assumed Crunchmeister was going in the other direction. now. i never said to build anything from scratch or to reinvent the wheel or any of that. in fact i believe i mentioned using a paintball tank already. but if you feel better repeating my own words to me go nuts.

(btw i expect to be burned on this. so at least try and surprise me)

[Crunchmeister]

Originally Posted by Jayne Finch

...I assumed Crunchmeister was going in the other direction. now. i never said to build anything from scratch or to reinvent the wheel or any of that. in fact i believe i mentioned using a paintball tank already. but if you feel better repeating my own words to me go nuts.

I wasn't trying to repeat your words. The point I was making is that Sgt. Irvine is trying to design his own mortar system by trial and error (at least to a point) when it comes to measurements for the expansions chamber, barrel, valve, propulsion, etc. By simply looking up pneumatic (and I should have specified that in my original post) potato cannons powered by paintball tanks, he can find that all these hurdles have already been overcome. This is what I meant by not 'reinventing the wheel'. I was merely suggesting that he could save himself a lot of design and testing time by using these designs rather than trying to figure all this stuff out by trial and error. Proven designs are already available for anyone to copy.

Hope that clears things up somewhat. I don't want this discussion to turn into a shit-slinging match when all I was doing was trying to provide some advice.