M224 Mortar

[Mishkan]

This is sort of the starter topic for this project I hope to be working on. I haven't worked too much with pneumatics, alot more with different projectile launching mechanisms. I'm an avid airsoft player and there's a lack of a reasonable semi-reasonable

As I'm new to the whole spud gun thing any help would be greatly appreciated. I've been reading through this forum on and off for the past day to get a better idea of what I'm doing.

Original Goals

• Fire a projectile at decent maximum ranges 500 foot+
  Have a projectile that shatters (non lethal) and spreads BBs
  A projectile that can strike a person without creating damage
  Use a coaxial barrel design
  Be able to drop rounds into the barrel, and have them fire either automatically or manually (manual at first stages of development)
  Electronic trigger to fire
  After firing sequence is complete, re-pressurize chamber to be ready for next round
  2" projectile

Initial Design
Projectile

• Hollow, thin walled styrofoam projectile. Weighted to about 100 grams.

Mortar
So basically this is what I've come up with. Solidworks model to come soon.

• Coaxial design
  SCH-40 Pipe using 2" inner with 3" outer
  Inner barrel 40" length (approximately equal to real thing)
  Aluminum barrel spacers (or whatever else I can find in the shop)
  Completely closed piston design
  Piston actuated through solenoid (a linear solenoid not the solenoid valve)
  CO2 tank (20 oz?) attached to 100 psi regulator attached to somewhere on the outer tank. (Hidden in box)
  When trigger is pulled solenoid pulls back piston allowing air to flow and fire projectile
  Solenoid returns to initial "closed valve" position and tank will re-pressurize
  For a "drop" trigger, use IR interrupt circuit

Might explain better once I draw some pictures...
I'll also come up with the parts I'll probably use....

If someone can recommend a good 100 psi regulator for CO2 that would be great. (Fixed or adjustable)

[BC Pneumatics]

This was actually designed for this specific application:
http://www.bcvids.com/store/product_inf ... ucts_id=57

[Mishkan]

Thanks . Question: What makes it "remote"?
And what about any fixed ones?

[TwitchTheAussie]

There is an electronically fired mine. Have a look in the pneumatic section

[Mishkan]

Well I just really only need the regulator, the hose, and a connection to my tank then.... really no point in all the other stuff. Since I'll likely just leave it on during the entire firing process, and then its only necessary at the most to turn it on or off when I'm done firing or need to do a final discharge. Then I can just use a quick release for that.

Edit: Just in case it wasn't clear in my original post, I edited it to include that I mean a linear solenoid.

[NoXi]

just use an expansion chamber, there cheaper.

http://www.actionvillage.com/is-bin/INT ... D3gualA_2s

http://www.actionvillage.com/is-bin/INT ... ms-remotes

those are remotes that you can modify to attach to the reg.

[singularity]

i got a 5lb co2 tank and a reg for $100 got it off beveragefactory.com that might be too big for what your doing but it works awesome on my bbmg

[Mishkan]

Here is a quick example I put together of the valve design. The obvious advantages are less wasted air and easier build. Plus much faster trigger reaction time, (albeit I know the difference between the usual coaxial design is smaller). More efficient air usage overall.

(Yes I know the example has the ball in there all the time)

Blue is pressure

Slowed down obviously. Regulator allows tank to fill to 100 psi, the solenoid actuates pulling the piston back allowing air to flow into the barrel.

And so there's basically no reason for any fancy stuff.

[Mishkan]

Sorry to double post, not sure rules on it.
Would a regulator like:
https://weldingsupply.securesites.com/Western-RP.pdf
Work?
(second one down)

And how could I get it to fit a 20oz tank.

Edit: Third time's a charm

[iPaintball]

IF you use a 3" outer pipe with a 2" barrel, your chamber will be way to small. Either up the chamber pipe to 4", or make your barrel 1.5"

[Mishkan]

Chamber size on this would be around 129 cubic inches
Barrel would be about 125
GGDT seemed to be fine with CO2 at 100 PSI

And I'm not getting any major increases in power when I increase it to 4" pipe. I think the short length of my barrel has a lot to do with this.