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| elitesniper |
 Posted: 12/29/2007 18:03 PM Post subject: |
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Brigadier General
Joined: 13 Oct 2007
Posts: 1002
922.09 Spud Bux
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DYI you do like burst disk alot dont you? 
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| SpudBlaster15 |
| Posted: 12/30/2007 0:26 AM Post subject: |
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Human blast shield
Joined: 18 Oct 2006
Posts: 1554
52.84 Spud Bux
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| DYI wrote: | | Updated original post with new damage video (SB15, this is for you). |
YES!!!!!!!!!!!! That was awesome! Much more impressive than I expected, I had no idea that the door would completely shatter into dozens of fragments. But I guess when you deliver nearly 6000ft/lbs of energy to almost anything made of wood, it is going to suffer some pretty immense damage.
Also, this cannon has inspired me to build a monstrous (2" bore, 13,000+ft/lbs) hybrid launcher over the next few months.
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| Carlman |
| Posted: 12/30/2007 3:33 AM Post subject: |
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The Aussie
Joined: 24 Nov 2007
Posts: 1170
375.30 Spud Bux
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hmm local cops might want that to bust into some house one day...
well at least you can get in if you get locked out lol
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| Billy Bob |
| Posted: 12/30/2007 12:28 PM Post subject: |
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Corporal
Joined: 28 Oct 2006
Posts: 70
170.57 Spud Bux
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What are your neighbours say about the. "Huge Weapontestings "
The gun is excellent !!! simple and usefull AND POWERFULL dont forget.
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| DYI |
| Posted: 12/30/2007 13:13 PM Post subject: |
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Rear Brigadier
Joined: 07 Jul 2007
Posts: 2308
1164.60 Spud Bux
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Well, the neighbours are either indifferent, or actually like it. Kind of strange, but it isn't that loud because of its high efficiency.
SB15, I'm assuming that this must either be using 10x+ mixes, or be impractically long, because that's almost half the muzzle energy of FEAR.
But I'm building a 20x, 2" bore hybrid in the summer, so that should be pretty impressive too.
But my next main project is the massive backstop I'm building for the SCTBDC so I can safely fire it in my backyard. Probably 1/2" plate steel of something, with 4x4s for supports. That, and the recoil absorbing stand for the launcher, to avoid another mishap like yesterday's.
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| SpudBlaster15 |
| Posted: 12/30/2007 13:38 PM Post subject: |
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Human blast shield
Joined: 18 Oct 2006
Posts: 1554
52.84 Spud Bux
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| The launcher will likely use a 3" x 36" Sch 40 steel chamber, a 2" x 144" ABS barrel, and 8x mixes. GGDT estimates a muzzle energy output of ~13,600ft/lbs. My backyard is ~5 acres, so I should have lots of room for such a huge cannon.
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| DYI |
| Posted: 12/30/2007 13:52 PM Post subject: |
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Rear Brigadier
Joined: 07 Jul 2007
Posts: 2308
1164.60 Spud Bux
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Where do you live Spudblaster?
My plan is a 3" x 24" steel chamber, and a 2" copper barrel, with 10x - 20x mixes. EVBEC forecasts a hell of a lot of muzzle energy, about half what FEAR generates.
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| markfh11q |
| Posted: 12/30/2007 14:15 PM Post subject: |
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Magic Dust Man
Joined: 06 May 2006
Posts: 1584
60.70 Spud Bux
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DYI, have you considered bungees and a sliding platform for a stand? I'm not talking just one or two cords, either. Depending on your max projectile weight, several bungee cords and a platform allowed to slide "freely", (minus the friction from wood on wood), backwards, but not side to side, should allow enough flex to avoid future failures of your stand due to "quick" loads. Your stand will still have to be pretty beefy, however, if you plan to fire heavy rounds. Perhaps you could try reinforcement with 1/2" or 3/4" threaded rod? Or maybe rebar if you've got the tools to work with it...
SpudBlaster, do you think a larger (3") chamber would survive many 8x mixes? I know you and others have lit off these kinds of mixes in smaller chambers, like 1-1/2" or 1-1/4" SCH-40 steel, but with the larger pipe, I think your "safe" pressure would be reduced. I definitely forsee some sort of remote ignition in your future.  Probably the RC servo again, no? I've just been using a pull-string tied off to the toggle switch on my new ignition box, playing around with my old hybrid.
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| DYI |
| Posted: 12/30/2007 14:32 PM Post subject: |
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Rear Brigadier
Joined: 07 Jul 2007
Posts: 2308
1164.60 Spud Bux
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I'd be using SCH 160 steel in my design. The purpose of wider chambers is to reduce the chance of DDT at higher mixes (or at least that's the purpose of the wider chamber on my design).
My plan was to make a stand out of 4x4s, and instead of a single support in the middle of the carriage, I would use one on either side. Then I would make a rectangular-prism shaped base, with 4 wheels, so that the whole thing would slide backwards, and use chains and various clamps to secure the cannon to the stand.
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| SpudBlaster15 |
| Posted: 12/30/2007 15:04 PM Post subject: |
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Human blast shield
Joined: 18 Oct 2006
Posts: 1554
52.84 Spud Bux
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DYI: I live in Mackenzie, BC, Canada.
Mark: Remote ignition will be a must. No way will I be standing anywhere near a 3" diameter steel chamber filled with a mixture that can potentially generate internal pressures on the order of 800psi. The servo setup will likely be used.
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| markfh11q |
| Posted: 01/01/2008 11:41 AM Post subject: |
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Magic Dust Man
Joined: 06 May 2006
Posts: 1584
60.70 Spud Bux
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| DYI wrote: |
If you can show me how to post GGDT files, I'll show you the GGDT output for it. I don't actually have any close up pictures of the valve area.
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You don't have the option to export GGDT files in a format convenient for this forum, but most people just take screen-shots. This is from the steel ice-slug shot...
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81.08 KB |
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56 Time(s) |
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| WOW!! |
| Posted: 01/01/2008 11:50 AM Post subject: |
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Brigadier General
Joined: 16 Mar 2006
Posts: 892
490.29 Spud Bux
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| For ammo you could take 2 1 1/4" end caps and make a little section of pipe with them at the ends and then fill it with concrete, Pykrete, or something to that extent and shoot that. Since the 1 1/4" end caps give a good seal in 2" pipe.
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| DYI |
| Posted: 01/01/2008 21:35 PM Post subject: |
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Rear Brigadier
Joined: 07 Jul 2007
Posts: 2308
1164.60 Spud Bux
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Mark, that GGDT is close, but not quite;
The pressure used was 470, not 450, the dead space is more like 10+ cubic inches, and the flow coefficient of a burst disk valve is at least 50, possibly 55.
The most significant problems however, are the bore and the valve:
I used a 3" barrel for this shot, and you entered a 2" barrel. The use of a 3" barrel significantly increased muzzle energy for this shot.
Also, you entered 2" porting, while the porting on my valve system is only 1.61". This slightly reduces performance. (the union is ~1.9" ID, but the rest of the valve is only 1.61, and the flow is determined by the place with the least flow)
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