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Tx05xb12s
| | Posted on Wednesday, February 20, 2008 - 10:59 pm: | 
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so to load you make sure the fast action valve is closed, screw the pressure vessel in to the back,
and open the pressure vessel ball valve charging the pressure chamber.
then you load the projectile like a muzzle loader and pull the trigger.
Constructive Criticism:
Consider loading the projectile before you charge the pressure chamber to reduce the chance of being shot by your own gun due to valve failure or accidental discharge. Treat this thing just like any other weapon. Please be safe while you're having fun. |
Natexlh1000
| | Posted on Wednesday, February 20, 2008 - 11:03 pm: |
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How hard could you chuck a 12 gauge slug?
They are hollow in the back and expand with pressure.
Like this:
http://en.wikipedia.org/wiki/Mini%C3%A9_ball |
Slaughter
| | Posted on Wednesday, February 20, 2008 - 11:15 pm: |
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Hokay - don't know if it will make sense.
Top is the concept for the fast acting valve - inlet for high pressure, vent and dump into barrel.
Middle shows the pieces in battery - valve opened (trigger opens poppet) - pressure drops to 1 ATM behind plug, 5000 psi drives the trigger plug back, dumping air down the bore. Closing trigger poppet, allows spring to re-seat valve and pressures equalize, plugging the barrel again.
Dunno if this makes sense. Actual design is more complicated.
Fun thing is that this program was named (by me) the Pneumatic Function Advanced Rifle Technology (PFART). Navy wanted me to change the acronym to Pneumatic Function Firearm Technology (PFFT)
 |
Just_ziptab
| | Posted on Wednesday, February 20, 2008 - 11:47 pm: |
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Cool Slaughter! That thing works pretty much just like an automatic dump valve that I made for a pneumatic potato cannon. |
Mr_grumpy
| | Posted on Thursday, February 21, 2008 - 04:16 am: |
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I just love the idea that your missus doesn't want electromagnets in the basement, but accepts 5000 psi pressure vessels.  |
Corporatemonkey
| | Posted on Thursday, February 21, 2008 - 07:25 am: |
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5000psi...
Where is that darwin award entry form???
Seriously, why not use parts from a pressure washer? Better yet, why not use water? I imagine the power from a 5000psi pressure washer could launch a projectile quite far. |
Oldog
| | Posted on Thursday, February 21, 2008 - 08:33 am: |
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CM You would be supprised how poorly that water would work,
Air or gas will expand many thousands of volumes to reach ambient pressure from 5K psi, please be carefull with pressure at those levels, It might be a good idea to "proof test the parts with a pressure washer that developes 5k first.
IF any thing lets go at that pressure with gas the shrapnel will be horrible, as will the concussion. With water it should just go Pop-squirt
Where I work we build ASME Code pressure vessels the forces can be supprising, for instance We build autoclaves with quick acting doors on at least one end. at 150 PSI a 6' diameter door has close to
1 MILLION pounds of force acting on it.
5k psi at 20 sqin should equate to roughly 100,000 pounds of force
Please do be careful constructing that thing. |
Mikef5000
| | Posted on Thursday, February 21, 2008 - 11:02 am: |
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Pee Fart! |
Sub65chris
| | Posted on Thursday, February 21, 2008 - 12:19 pm: |
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the idea had been sidelined for the moment because the wife had discovered my plan. I will have to hire my friends to machine and test the parts in their pressure tester. They recently got their license? to manufature certain sizes of high pressure containers etc. I will post further as time goes on.
the idea of using a bullet is loosing my interest due to the lower velocities that can be obtained using the air, but a "dart" moving at high subsonic would be very interesting.
Slaughter - nice design and PFART? wow the navy was right to change the name. I hate when physics get in the way of ideas, but makes for interesting conversations.
Tx05xb12s- good call on loading first and charging second. my post was long an i lost track of where i was.
Please do be careful constructing that thing.- yeah like i said i will have a licenced shop build it, it was a licence or certification something like that.
Hexangler - i will look into the rail gun soon. sounds fun but me and electricity dont mix.
More food for thought
a diesel gun-
compresion piston that sets offa charge of diesel or similar product that will expand at a higher rate than air.
-safety I dont care just a thought, what do you think?
I will start next week on the "Dart gun from hell" !!!!! |
Mr_grumpy
| | Posted on Thursday, February 21, 2008 - 02:18 pm: |
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Diesel gun? you're looking at around 22-1 compression ratio & spot-on timing.
Have you thought about using the pressure vessels themselves as the projectile, with fins for guidance and a nozzle for the gas release, less explosive discharge but longer thrust duration.
Think bottle rocket! |
Sub65chris
| | Posted on Thursday, February 21, 2008 - 03:46 pm: |
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Mr_grumpy- i will think about it but how would you make them cheap and in expensive? I guess you could use a 12 gram co2 cylender but they dont last that long. Also how accurate are bottle rockets? I remember shooting them at my brother and not really hitting him all that much. i will consider though. thanks.
THIS PLACE IS GREAT!!!!! where else could one simple question spawn so many different ideas.
teh diesel gun. use air pressure to compress a piston that will inturn compress the diesel then when the right compression is reached bang! Now i am assuming the diesel expands at a higher rate than compressed air? And the diesel would need to be misted into the chamber to really work and i know that the idea is basically an explosion 6 inches from my face. but wouldent it be cool? also you would need a way to hold the bullet in place untill the diesel explodes. im thinking a trap door with a spring that flips up and out of the way when the explosin happen but would stay in place so teh correct compression could be reached. |
Mr_grumpy
| | Posted on Thursday, February 21, 2008 - 05:10 pm: |
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The problem you're going to have with the diesel gun is that to get such a high compression ratio, I reckon you'll incur serious friction losses from the sealing system.
The injection timing is reasonably simple, you use a common-rail type electronic injector & high pressure pump linked to a contact in the base of the barrel, when the slug hits bottom (max compression) it closes the circuit to the injector & bingo.
Like I say your problem will be to get the slug to compress the charge enough.
Personally I'd go for gas powered system,
reed valve to let in compressed air at 9bar, spring & ball detents to hold the slug against the pressure, with a hemispherical combustion chamber, spark plug, injector, switch, & away you go.
Sorry about the design quality, drawing was never my strong suit, but you get the general idea. |
Cowboy
| | Posted on Thursday, February 21, 2008 - 05:46 pm: |
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Mr. grumpy you are almost correct, just dont place the projectile so far back. then in ject some (small amount of acetylene) at atsphere presure and fire with a electronic egnighter. we use to make these in the welding shop on rainy days.when the gas fires it will have a hell of a push. we used to use 2 7/8 p 105 grade pipe. beleve me it is a real canon. |
Slaughter
| | Posted on Thursday, February 21, 2008 - 07:52 pm: |
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Remember, the propelling gas works best the less mass it has. Hydrogen is a better propellant than air for example. Water would be 3 orders of magnitude worse.
The same volume of HOT gas has less mass than it does at a lower temperature.
5000 psi at room temperature doesn't have as much potential to push a projectile forward as the same gas at 5000 psi at higher temperature - fewer gas molecules that have to be accelerated.
Cool problem though.
(Now my brain hurts) |
Slaughter
| | Posted on Thursday, February 21, 2008 - 08:02 pm: |
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Chris - your "compression ignition" concept isn't too far from what Lawrence Livermore National Labs did with their SHARP gun.
http://www.astronautix.com/lvs/sharp.htm
I worked with Harry Cartland and John Hunter at Lawrence on a scramject projectile concept that they were going to try launching before the program shut down.
Way cool concept - SHARP.
Barrel was about 140 feet long, 8 inch bore. Barrel had a plate over the muzzle and was vaccumed down to a nearly perfect vacuum. Propelling gas was hydrogen which was supercompressed by a piston driven by a primary charge of oxygen/methane. Way cool and a whole lotta BOOM. A 5 pound projectile would exit the muzzle at about 10,000 fps!
It was known as the "Jules Verne Gun." Had a long list of people who just wanted to be involved for the experience.
It was hoped that an adaptation could have been used to launch small satellites.
(Message edited by slaughter on February 21, 2008)
(Message edited by slaughter on February 22, 2008) |
Reepicheep
| | Posted on Thursday, February 21, 2008 - 08:49 pm: |
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Whoa. Thats a thought. Can you make a bullet that transforms into a ramjet in flight? Or would the G forces kill it? |
Slaughter
| | Posted on Thursday, February 21, 2008 - 09:00 pm: |
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Govt labs have already made scramjet bullets with a combustible metal propellant. They had to exit about mach 8 to function. |
Sub65chris
| | Posted on Thursday, February 21, 2008 - 10:00 pm: |
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well the wife got on teh computer and read my posts(crap!) now i cant seem to change her mind , i was going to ask for forgivenes but not any more. If i want to stay married i will stay away from the other than gunpowder gun for awhile untill she doesnt remember. Thankyou all for the ideas and help i would have spent many hours and alot of effort to get to where our conversation has led me . thanks. |
Reepicheep
| | Posted on Thursday, February 21, 2008 - 10:01 pm: |
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Must have been one heck of a barrel to hit mach 8. Very cool stuff! |
Just_ziptab
| | Posted on Thursday, February 21, 2008 - 10:51 pm: |
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oxygen and acetylene powered bb gun: http://ca.youtube.com/watch?v=mGRKYcsTImo |
Slaughter
| | Posted on Friday, February 22, 2008 - 12:35 am: |
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Here's a SHARP gun function drawing:
Used to be pics of the scramjet in flight at about M11 |
Mr_grumpy
| | Posted on Friday, February 22, 2008 - 04:57 pm: |
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Nice idea Slaughter, but I think Matthias might have a bit of trouble smuggling 3 100ton railroad cars into his basement, mind you he could always tell his wife he's given up on the gun & started to build a train set.  |
Slaughter
| | Posted on Friday, February 22, 2008 - 08:08 pm: |
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Geeez - that got me laughing out loud!
Those railcars were filled with concrete and used to react the recoil loads.
Too bad it all got un-funded. 'Twas an amazing thing... but would mean enlarging the basement. |
Sub65chris
| | Posted on Saturday, February 23, 2008 - 10:23 am: |
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train set!! hahahhaahahahahaha . that might not go over well. |
Slaughter
| | Posted on Saturday, February 23, 2008 - 05:03 pm: |
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Having worked with the Feds on licensing auto weapons and destructive devices - be VERY careful:
Compressed air and gas = "air rifle" regardless of bore size. No permit or registration.
Projectile bigger than 0.50 bore = destructive device... unless propelled by air/gas - NO by-products of combustion... meaning that yes, those clever potato guns are technically felonies if you really were to get reamed.
Use of ANY byproducts of combustion of ANY sort will require the beast to be registered as a "firearm."
In today's day and age, just watch your step. Penalties can be ugly.
In our gun concept, we bench tested with nitrogen - no permits required - even with the 20mm round. When we went to gas generator cartridges to charge the cylinder, it WAS A FIREARM. |
Sub65chris
| | Posted on Saturday, February 23, 2008 - 06:06 pm: |
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understood, i will be carefull. |
