SpudFiles

UPDATED AND COMPACTED

Hey people, I am planning to make my next spud gun! I have a $150 (USA) bugdget, and I am looking to make something revolutionary! LOL. Also, I might not get around to making it for a while, so don't be mad when I kick this thread back to life every couple of weeks.

My idea is to build a gun that can shoot pnuematicly, through combustion, or as a hybrid. And the best part is, this design can be retro-fitted on most piston pneumatics! No need for two chambers.

I plan to have an under-over setup, with two chambers, one right behind another. See the new pic. The first chamber could be used for combustion, pnuematic, or hybrid, and the second would be a refil/extension chamber, separated by a ball valve. This chamber would vent the combustion chamber and propel a second potato.

I also will be able to do either 2 pneumatic shots, or 1 combustion and 1 pnuematic, or 1 really big pnuematic, or one really big combustion. This would mean that a sprinkler valve would get in the way. So, I would need to use a piston that would be open by default. If it was closed, this would turn into a pipe bomb.

Also, I do not want the second shot to be less powerfull than the first. That would mean that I would either need to make the second chamber be able to (safely) contain 200 psi, or I would need to use the "pnuematic refill" idea (using a spring) to accomplish this.

To accomodate the "2 shot" consept, I have also made this gun use cartrages, or a magasine. This way, I would mearly need to flip a valve and slide in a new cartrage. Also, a 1.5 inch barrel could be slid into the 3'' barrel.

I am looking to get at least 200 yards woth this beast, so I'll up the budget to $200 if need be.

Thanks for reading, that was a long post! ANY help, ideas, critisims, refinements, or anything is apreciated!!

Use double chambers with a ball valve on each chamber to select between chambers and have the ball valves linked by a Tee and 2 elbows. Have the Tee connected to the pneumatic valve of your choice. That will give you two shots. With this design you can also combine the two chambers by opening both ball valves to allow both chambers to be fired at once giving you a more powerful shot.

EDIt: i didnt read all of your post, so i just realized you already mentioned this

what you could do is have two chambers, connect them with a tee and put ball valves between them. the sprinkler valve would be attached to the ball valve.

that way you can fire a combustion shot, close the combustion chamber and fire apneumatic shot (open ball valve, then open sprinkler valve).

thats my idea.

if this is totally off topic its because i only read about half your post.

you could also just make a combustion with a union, that way it could be a burst disk pneumatic.

edit- orgin unknown beat be by 5 minutes, how did that happen?

Oh. I kinda sorta thought of that. The difference is that I wanted It to be in one line, so it could be held easier. Also, the tee design doesn't vent the first chamber, but that is easily fixed with a fan.

Also, how would the combustion work? Would the sprincler valve be okay in front of the combusion chamber? Also, could I use a solonoid instead of sprinkler? How much is one of them? I want a triger grip, so should I use that or an airgun?

How much does the under-over design hurt performance (if at all)?

Edit- I thought of the burst disk thing already, but I like the idea of being in contol of when the gun shoots.

Why not build a pneumatic powered by a 5lb co2?
Portability of a combustion with the ease of a pneumatic

For portability, you might try this. It'll be hard to do, but it might work. Make the combustion and pneumatic chambers parallel to each other. Then make some device that rotates the barrel around an axis that is between the chambers, and have the barrel be able to slide back so you can lock it in with a cam lever coupling, or whatever that's called. That way, you hold the gun by the chamber(s), and the barrel rotates. You could even do multiple barrels for a minigun look!

The only issue with the concept is the method of actuation for the pneumatic chamber. You could have an unmodified solenoid for the pneumatic part, so that you can mount a switch near the stungun. If you want to go with a piston, you could still have the solenoid for simplicity of firing, but have it be the pilot instead. Sorry if I seem vague...

I do know someone on the UKSGC forums made a 'hybird' pneumatic and combustion in one gun, I don't mean a pressurizing fuel hybird, I mean hybrid as in two things made into one. Go check their forums out.

Hey, I saw what you mean, MrCrowley. That is sorta what I mean, except mine would be pvc.

I want to keep the orriginal form factor, so maybe I will just attach them at a tee (using a long pipe) instead of one behind another.

My design seems to create lots of bends though, how would this affect preformance?

You could use a wye. It'd be slightly less bends...

u know i just akd the question some were else if this was possible good luck building it.

Hey people, I updated the post, Be sure to look at the new pic!!

I like the magazine idea that fits between the two couplings like a cartrige. I might have to use that on my cannon with the same cartrige style reloading.

Lol, it was a revelation! glad you like it.

Do you think that Sch 40 PVC could hold 200 psi safly? I think I saw them rated up to 250-300 psi, but I could be wrong. Could I do hybrid shots? 1.5 mix, maybe?

Don't use 3" for the 200psi chamber. 3" PVC is usually cell core and it may explode. I would go with 2" sch40 for that chamber. Make sure your endcap is welded on tightly too. I would never trust it for a hybid shot of any type mix.
EDIT: you could use a large fire extinguisher for the 200psi tank

^I didn't think 3" pvc-pw was that rare. I have yet to see dwv around here. At least sch80 is needed for a hybrid though.
Unfortunately, I can only see half of the new diagram because spudfiles keeps timing out on me (or something). Maybe if you make a gif that loads faster it would solve the problem.
You know, the hybrid I made fires as a combustion and pneumatic also. It isn't very powerful as a normal combustion, but as a pnuematic works fairly well at ~100+psi.
If you still want ideas and suggestions, maybe you can rip some ideas from it and apply them to your launcher.