Larda's Coaxial Piston Valve (injector!) pneumatic.

[ondskehem]

This is a Coaxial Piston Valve pneumatic made by my friend Larda.

It is a Injector made for his upcomming railgun projcet (!) but that doesn't stop him from taking the gun out for a spin.
it uses the method explained at http://www.spudfiles.com/forums/piston- ... t8157.html
well, I let the pictures speak for them self.

[jackssmirkingrevenge]

beautifully built and impressive penetration, what's the thickness of that plate?

The railgun idea makes supersonic velocities well within reach if he's got enough power to spare, looking forward to see the final product

edit: what pressures is he using? for that barrel length it looks like the chamber is a little small if using conventional compressor pressures (100-150 psi)

[spanerman]

Buitiful....looks powerful aswell

[spudthug]

that coax is awesome! could u give us some specs? and what that piston is?

[jackssmirkingrevenge]

looks like your friend has his work cut out - I'm surprised at the short barrel length of the aforementioned project, as the builder states ideally the "injection" velocity should be as fast as possible, and with 500 psi of nitrogen on tap, a QEV and much longer barrel would potentially offer near-supersonic velocities to begin with.

[spud yeti]

Looks good to me. What is he using as a pilot valve (I cant see in the photos, sorry!)

[dauphinoise potato]

That is a really nice cannon do you know what diameter barrel that is?

[iPaintball]

Wow. Did you machine all of the parts? They look so perfect. Your barrel looks a bit long though.

[ondskehem]

Nice with such great response. I'll have to ask Larda for answers to all questions. stand by!

[Spedy]

Wow, It looks great. Where did you/friend get those parts? the railgun project sounds neat too, I made one with alum. foil, a couple of NdFeB discs, a piece of coat hanger wire and a 9v. It threw little red sparks lol.

[ondskehem]

He didn't got them, He made them!

[Larda]

beautifully built and impressive penetration, what's the thickness of that plate?

The rail-gun idea makes supersonic velocities well within reach if he's got enough power to spare, looking forward to see the final product

edit: what pressures is he using? for that barrel length it looks like the chamber is a little small if using conventional compressor pressures (100-150 psi)

The wood is 1inch thick and i think the steel is 2mm (0.079 Inch).
Right now i using 7bar (100psi) but its good for much more.
The barrel gives a nice fit with 20mm ballberings, the reason the barrel is so long is that this only was a quick test and i didn't want to destroy the pipe.
The chamber is 90mmID and the length is about 250mm (i don't have the exact numbers i my head) and is made of Hydraulic Cylinder Tubing , the piston is machined of Acetal POM plastic.

With the rail-gun i aiming for supersonic and i think i have enough power.
The capacitor bank will consist of 24, 15000uF 400V capacitors with a total energy of 28,8Kj.

Her is a some videos of a few test shoot and a picture of the almost finished Capacitor Bank.
http://www.hv4all.com/aircanon/skott1.wmv 2.2Mb
http://www.hv4all.com/aircanon/skott2.wmv 2.1Mb
http://www.hv4all.com/aircanon/skott3.wmv 1.8Mb
http://www.hv4all.com/aircanon/skott4.wmv 6.1Mb
http://www.hv4all.com/aircanon/skott5.wmv 5.7Mb

[iknowmy3tables]

wow thats very beautiful piece of art

[Fnord]

Can you post a picture of the railgun too? I'd like to see it.(I'm a dialup loser and can't watch the videos)

Do round projectiles really work? I would think the contact area would be to small for the current to be dumped effectively.

Oh, and nice coax/injector:)

[Larda]

Thanks,
In the railgun i wont be using round projectiles, as you said you want maximum contact area between the projectile and the rails.
The railgun isn't finished yet so i don't have any picture.
Before i continue with the construction of the railgun itself i must finish my cnc mill.

Here is some more Damage Pict's if you want.