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| noname |
 Posted: 08/17/2007 13:10 PM Post subject: Does 6x + a 20 foot barrel = Supersonic? |
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Mr Vortex
Joined: 10 Apr 2006
Posts: 2524
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Just trying to get confirmation on this, because I'm pretty sure the gun is shooting supersonic but have no way of telling for sure. GGDT predicts that using an 8 gram ball bearing as a projectile, the gun shoots at 1700-2000 fps, depending on generous or crappy values.
Chamber diameter: 2"
Chamber length: 11"
Pressure: at least 575 psi
Temperature: It's like 2000-3000*, right?
Valve Type: Burst Disc
# of Valves: 1
Flow Coef: a good piston valve is like 40% or something, right? So a burst disc would be 50-60%?
Seat diameter: .7"
Dead Volume: .3 in^3
Barrel Bore: .63"
Length: 240"
Projectile Friction: Almost none, 1 psi or less
Projectile mass: 8 grams (measured on a triple beam balance)
Diameter: .62"
Initial Position: .5"
Does it all sound right?
I know it shoots a hell of a lot harder than with the 6 foot barrel; I can put a ball bearing through 5+ inches of wood. If I shoot without a projectile, I hear a sound like air being released, kind of like a quieter piston valve. With a projectile, I get a massive rifle-like CRACK! sound.
Edit: Almost forgot the best part: Pictures!
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| Suffering from extreme BBS (Bendy Barrel Syndrome) |
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| A triple layer of soda can burst discs holds 550+ psi in a 1/2" union. |
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| paaiyan |
| Posted: 08/17/2007 13:21 PM Post subject: |
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Ascendant Defenestrator
Joined: 27 Dec 2006
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Wow, I like it. I don't know about supersonic, hybrids aren't one of my specialties. I do, however, know that if you're putting a ball bearing through 5 inches of wood, I WANT ONE!
That barrel is crazy long and bendy, could you shoot around a corner with it? That would be sweet.
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| noname |
| Posted: 08/17/2007 13:25 PM Post subject: |
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Mr Vortex
Joined: 10 Apr 2006
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It's no ttoo hard to make one; just use steel and you won't kill yourself. I think I could shoot around a corner if I had a thicker barrel, but then it wouldn't bend, would it?  The force from a ball bearing going around the curve would probably crack/shatter the barrel.
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| mopherman |
| Posted: 08/17/2007 13:26 PM Post subject: |
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Brigadier General
Joined: 03 Feb 2007
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| paaiyan wrote: |
That barrel is crazy long and bendy, could you shoot around a corner with it? That would be sweet. |
lol, I'm pretty sure it would just blow a hole in the side of the barrel.
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| paaiyan |
| Posted: 08/17/2007 13:27 PM Post subject: |
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Ascendant Defenestrator
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| mopherman wrote: | | paaiyan wrote: |
That barrel is crazy long and bendy, could you shoot around a corner with it? That would be sweet. |
lol, I'm pretty sure it would just blow a hole in the side of the barrel. |
Poop, I wanted to shoot around corners. I figured that would be what happened.
So about how long is the delay between firing and the projectile exiting the barrel?
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| noname |
| Posted: 08/17/2007 13:33 PM Post subject: |
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Mr Vortex
Joined: 10 Apr 2006
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| A hole just appears in the target when you click the igniter. I don't know how fast that is, but it's pretty damn quick.
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| paaiyan |
| Posted: 08/17/2007 13:36 PM Post subject: |
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Ascendant Defenestrator
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| It just appears, nice. If you were to fire a pointed steel projectile, how deep do you think it could penetrate, say, a tree?
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| noname |
| Posted: 08/17/2007 13:39 PM Post subject: |
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Mr Vortex
Joined: 10 Apr 2006
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I was thinking about making some darts out of the remaining 10 inches of 1/2" aluminum rod that I have...
I think it would go frickin' deep, there's no telling just how deep though. At least 8"?
Edit: There's a few damage pictures in the gun's thread:
Thar we go!
Last edited by noname on 08/17/2007 13:40 PM; edited 1 time in total |
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| paaiyan |
| Posted: 08/17/2007 13:40 PM Post subject: |
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Ascendant Defenestrator
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| Sweet, now what about accuracy? I would think with that much barrel, there might be a bit of jump. Or do you have the muzzle strapped down somehow?
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| noname |
| Posted: 08/17/2007 13:43 PM Post subject: |
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Mr Vortex
Joined: 10 Apr 2006
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I could always duct tape it to the ground, I guess. There isn't too much recoil, surprisingly. If you want any accuracy, it has to have the 6 foot barrel on it; with the 20 footer, you just put stuff in front and watch it get blasted to oblivion.
Click the link in the above edit.
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| joannaardway |
| Posted: 08/17/2007 13:50 PM Post subject: Re: Does 6x + a 20 foot barrel = Supersonic? |
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Brigadier General
Joined: 09 Oct 2006
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Handing the numbers over to Ragnarok... the offical verdict is:
| Ragnarok wrote: | | Well, I can't say for absolute certain that it's shooting above 340 m/s... but judging by the 13% required efficency between the minimum kinetic energy for that and maximum potential kinetic energy, I'd say that - with reasonable confidence - it's probably firing at at least that. But nearly Mach 2 seems optimistic. |
So to cut through his jargon, yes, you're probably going supersonic.
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| mopherman |
| Posted: 08/17/2007 14:03 PM Post subject: Re: Does 6x + a 20 foot barrel = Supersonic? |
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Brigadier General
Joined: 03 Feb 2007
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| joannaardway wrote: | Handing the numbers over to Ragnarok... the offical verdict is:
| Ragnarok wrote: | | Well, I can't say for absolute certain that it's shooting above 340 m/s... but judging by the 13% required efficency between the minimum kinetic energy for that and maximum potential kinetic energy, I'd say that - with reasonable confidence - it's probably firing at at least that. But nearly Mach 2 seems optimistic. |
So to cut through his jargon, yes, you're probably going supersonic. |
does he talk like that all the time? 
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| noname |
| Posted: 08/17/2007 14:28 PM Post subject: |
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Mr Vortex
Joined: 10 Apr 2006
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| I wasn't expecting Mach 2 or anything like it, I just built the gun to shoot supersonic, so if it does, I'm satisfied.
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| jimmy101 |
| Posted: 08/17/2007 18:40 PM Post subject: |
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Major General
Joined: 28 Mar 2007
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| noname wrote: | | I wasn't expecting Mach 2 or anything like it, I just built the gun to shoot supersonic, so if it does, I'm satisfied. |
So you really don't know if it does or not. Ragnarok's calculation is very crude and assumes that you get the same efficiency out of a gun shooting supersonic that you do with a gun that shoots at 300 FPS.
Build a chrono and measure the muzzle velocity.
Extraordinary claims require extraordinary proof.
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| noname |
| Posted: 08/17/2007 18:51 PM Post subject: |
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Mr Vortex
Joined: 10 Apr 2006
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I'm telling you, there's no way I'd ever be able to put anything electrical together that has more than 3 parts.
Plus, don't you have to have it hooked up to a computer or something? I'm sure as hell not going to shoot inside.
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