Search found 194 matches

by Cthulhu
Wed May 24, 2017 7:16 am
Forum: Pneumatic Cannons
Topic: CO2 Stokes Mortar
Replies: 32
Views: 13542

Re: CO2 Stokes Mortar

Or possibly just add extra weight to the projectile and add a hole for the air to escape through.

But I've already done that, now my problem is is that the cartridge keeps missing the nail at the bottom.
by Cthulhu
Tue May 23, 2017 4:32 pm
Forum: Pneumatic Cannons
Topic: CO2 Stokes Mortar
Replies: 32
Views: 13542

Re: CO2 Stokes Mortar

I've realized the reason I may not be getting the CO2 to puncture is that the fit of the projectile in the barrel may be enough to cause resistance as the air beneath it searches for a way out. Sounds like plenty of projectile modification for me.
by Cthulhu
Sun May 21, 2017 10:15 pm
Forum: Pneumatic Cannons
Topic: CO2 Stokes Mortar
Replies: 32
Views: 13542

Re: CO2 Stokes Mortar

I simply folded some tin foil a couple times then cut it into a disk about the diameter of the bottle cap (which I had cut a hole into) then I placed the burst disk inside and tightened the cap on to form it. I will try again with a larger dismayed though. I tested the mortar today, couldn't get it ...
by Cthulhu
Sun May 21, 2017 3:29 pm
Forum: Pneumatic Cannons
Topic: CO2 Stokes Mortar
Replies: 32
Views: 13542

Re: CO2 Stokes Mortar

If you aren't hell bent on using CO2, I would install a Shrader valve into the rocket/mortar and pressurize the bottle with air. I'm willing to use whatever it takes to get it flying, where would you suggest installing the Schrader valve? On the cap or on the bottom of the bottle. I experimented wi...
by Cthulhu
Sun May 21, 2017 9:29 am
Forum: Pneumatic Cannons
Topic: CO2 Stokes Mortar
Replies: 32
Views: 13542

Re: CO2 Stokes Mortar

Those are pretty expensive valves for something that will probably fly away never to be returned to me hahaha.
Do you know of any cheaper alternatives? I might go old school and mix some vinegar and baking soda in the bottle and then quickly cap it with the end cap.
by Cthulhu
Sat May 20, 2017 8:25 pm
Forum: Pneumatic Cannons
Topic: CO2 Stokes Mortar
Replies: 32
Views: 13542

Re: CO2 Stokes Mortar

WizardNoodle wrote:
The burst disk could be in that small circular bead in the bottom of the bottle.
I'm not very familiar with burst disks, how would you attach it at the bottom?
by Cthulhu
Sat May 20, 2017 2:13 pm
Forum: Pneumatic Cannons
Topic: CO2 Stokes Mortar
Replies: 32
Views: 13542

Re: CO2 Stokes Mortar

Well, I threw on a couple layers of olive drab paint, it's a bit spotty and I left the Axel it hinges on unpainted (it would rub off there anyways), but for all things considered it looks pretty good.
by Cthulhu
Sat May 20, 2017 12:13 pm
Forum: Pneumatic Cannons
Topic: CO2 Stokes Mortar
Replies: 32
Views: 13542

Re: CO2 Stokes Mortar

That's actually a really good idea, wouldn't I have to drill another hole and fit in a fitting for the pump though?
by Cthulhu
Fri May 19, 2017 4:25 pm
Forum: Pneumatic Cannons
Topic: CO2 Stokes Mortar
Replies: 32
Views: 13542

Re: CO2 Stokes Mortar

I considered that, but couldn't come up with a cheap or easily manufactured design.

The closest I came to was a pressurized pipe with a very strong burst disk.
by Cthulhu
Wed May 17, 2017 9:26 pm
Forum: Pneumatic Cannons
Topic: CO2 Stokes Mortar
Replies: 32
Views: 13542

CO2 Stokes Mortar

A friend and I are making a mortar that fires foam projectiles powered by 12g CO2 cartridges. It isn't anything fancy, just a 3" PVC pipe with a nail at the bottom to puncture the cartridge and a bipod to hold it up. It's 4 feet long with a 3 inch bore, and can adjust it's trajectory​ between 45 Deg...
by Cthulhu
Tue May 16, 2017 8:07 pm
Forum: Pneumatic Cannons
Topic: Large bore (3 inch PVC) field gun
Replies: 8
Views: 3181

Large bore (3 inch PVC) field gun

I'm attempting to design a large bore field gun for paintball and I'm running into a few major design concerns. I think that the use of a paintball CO2 tank (or two) released into a pressurization chamber before being fired with a sprinkler/solenoid valve would be best, but we'll the small size of t...
by Cthulhu
Fri Apr 21, 2017 8:29 pm
Forum: Combustion Cannons
Topic: Help with large combustion cannon
Replies: 1
Views: 1931

Help with large combustion cannon

I'm making a combustion howitzer that has a 3 inch PVC barrel that is 6 feet long as the barrel, I know that I need a 1.5:1 ratio combustion chamber, but my main concern is heat. Will my Spud gun melt on the inside from this enormous combustion? I also need to know if there are any tips for building...
by Cthulhu
Thu Apr 13, 2017 9:16 am
Forum: Combustion Cannons
Topic: Combustion chamber below barrel for repeating cannon?
Replies: 3
Views: 2556

Re: Combustion chamber below barrel for repeating cannon?

Thanks so much on the info, the breech for the projectiles will be a PVC interrupted screw that has a de bange interruptor for an airtight seal, my only concern is the space between the breech and combustion chamber.
by Cthulhu
Wed Apr 12, 2017 7:13 pm
Forum: Combustion Cannons
Topic: Combustion chamber below barrel for repeating cannon?
Replies: 3
Views: 2556

Combustion chamber below barrel for repeating cannon?

Hi, I'm new to the forum, so if I make any mistakes please tell me. I have built a simple combustion cannon before, but after watching Grant Thompson's YouTube video with the "Sonic blast cannon" I became amazed at the ability to use a sponge fuel cell to get repeated shots. However, I disliked that...