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| Larda |
 Posted: 03/06/2008 23:59 PM Post subject: 28,8Kj ElectroThermal Gun! (Soon handheld) |
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Corporal
Joined: 18 Jul 2007
Posts: 72
194.96 Spud Bux
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To start with i must say that aim not sure if this is the right place to post this, it doesn't fit in any of the categories.
So please feel free to move this if its in the wrong place.
Some time ago i started building a fairly large capacitor bank that aim planing to use for my rail-gun project.
Its consist of 24, 15000uF 400v capacitors for a total energy of 28800 Joules.
The capacitors are arranged in 3 parallel banks that are wired in series for 1200v and 40000uF.
To test the capacitor bank i decided to build a ElectroThermal Gun.
The ETG (ElectroThermal Gun) works by discharging the capacitor bank threw fine aluminium powder and foil inside a chamber.
The electric current then heats the aluminium enough to make it evaporate and turn into plasma.
When the aluminium turns into superheated plasma it expands and the pressure in the chamber increases, the plasma also heats the air so it expands.
The expanding gases then force the projectile down the barrel like a conventional (spud)gun.
The ETH have a 12mm smooth-bore barrel that is screwed into a steel chamber with a electrode that goes threw a insulator in the end, the power is then feed into that electrode and threw the aluminium-powder.
Some videos.
Test shot 1:
http://www.vimeo.com/751433
Test shot 1, Second view:
http://www.vimeo.com/751469
Test shot 2:
http://www.vimeo.com/751476
I hope you like it, 
If i made any typos please don't kill me, my English is not so good and its 6AM so i really need to get some sleep. 
Edit:Typos
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| The muzzle-flash caught on film |
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| The ETG compared to a calliper and a small ETG i also made of stainless steel. |
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| The projectile first went right threw a total of 60mm of wood, the continued threw the bricks and ricochet on a dumpster. |
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| The 28,8Kj CapacitorBank. |
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| 12mm ID smooth-bore barrel. |
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The chamber of the ETG.
You can also see the two 35mm2 cables connected to the chamber. |
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Last edited by Larda on 05/03/2008 21:42 PM; edited 2 times in total |
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| Killjoy |
| Posted: 03/07/2008 0:07 AM Post subject: |
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Brigadier General
Joined: 12 Nov 2006
Posts: 992
676.80 Spud Bux
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Good god thats incredible. I've heard of these discussed but never actually seen a finished working one.
Thats incredible, nice work.
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| Davidvaini |
| Posted: 03/07/2008 0:10 AM Post subject: |
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Airsoft and BBMG Expert
Joined: 29 May 2007
Posts: 575
76.33 Spud Bux
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I only see 1 bank in that lower picture... where are the other caps?
Also what gauge wire is that leading to the gun?
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| jackssmirkingrevenge |
| Posted: 03/07/2008 0:17 AM Post subject: |
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space monkey
Joined: 15 Mar 2007
Posts: 6418
9737.60 Spud Bux
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Fork in hell, that's brilliant
| Quote: | | Some time ago i started building a fairly large capacitor bank that aim planing to use for my rail-gun project. |
Is that the same railgun you have built this pneumatic for?
| Quote: | | If i made any typos please don't kill me, my English is not so good and its 6AM so i really need to get some sleep. |
I'm just going to pick on one if I may, 'cause it's hilarious:
"The expanding gases then force the projectile down the barrel like a conversational (spud)gun."
When you're spending enough time in your workshop for your projects to start talking to you, definitely time for some fresh air  the word is "conventional". But it's just a silly typo, with launchers like that you can make all the typos you want, can't wait to see that railgun
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| Killjoy |
| Posted: 03/07/2008 0:17 AM Post subject: |
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Brigadier General
Joined: 12 Nov 2006
Posts: 992
676.80 Spud Bux
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| Quote: | | Also what gauge wire is that leading to the gun? |
Looks like 4 gauge but I could be wrong. I forgot to ask, whats your
projectile?[/quote]
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| Larda |
| Posted: 03/07/2008 0:18 AM Post subject: |
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Corporal
Joined: 18 Jul 2007
Posts: 72
194.96 Spud Bux
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| Davidvaini wrote: | I only see 1 bank in that lower picture... where are the other caps?
Also what gauge wire is that leading to the gun? |
Ohh, i meant 3 rows that are wired in series, only one bank so fare.
But i have enough capt to built at least to more identical banks.
I use 35mm2 cables, that's about AWG 2, but aim planning to upgrade to at least two in parallel.
Last edited by Larda on 03/07/2008 0:22 AM; edited 1 time in total |
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| Davidvaini |
| Posted: 03/07/2008 0:21 AM Post subject: |
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Airsoft and BBMG Expert
Joined: 29 May 2007
Posts: 575
76.33 Spud Bux
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Id say get 2 banks and up the power... Your base seems to be able to support it and 2 banks would create 4X more power
but over all its very decent and looks like a good little project you have going on.
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| Larda |
| Posted: 03/07/2008 0:32 AM Post subject: |
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Corporal
Joined: 18 Jul 2007
Posts: 72
194.96 Spud Bux
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| Killjoy wrote: | | Quote: | | Also what gauge wire is that leading to the gun? |
Looks like 4 gauge but I could be wrong. I forgot to ask, whats your
projectile? |
I used two projectiles, first was a broken Center drill, the second a broken solid carbide drill, really hard and really heavy.
jackssmirkingrevenge:
Thanks for the correction. Sometimes the spellcheck choose the wrong word. 
Last edited by Larda on 03/07/2008 0:36 AM; edited 1 time in total |
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| POLAND_SPUD |
| Posted: 03/07/2008 0:33 AM Post subject: |
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Brigadier General
Joined: 13 Oct 2007
Posts: 800
1956.87 Spud Bux
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wow... 
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| Lentamentalisk |
| Posted: 03/07/2008 1:03 AM Post subject: |
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Resident Tinkerer
Joined: 07 Aug 2007
Posts: 627
251.05 Spud Bux
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Really nicely done! My friend and I are working on building a Cap bank and dis/charging circuit, mainly for our microwave gun, but we will also be testing it on on an ETG.
Why is it that everyone all of a sudden is making ETGs?
Yet again, very nicely done!
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| jackssmirkingrevenge |
| Posted: 03/07/2008 1:05 AM Post subject: |
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space monkey
Joined: 15 Mar 2007
Posts: 6418
9737.60 Spud Bux
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Ragnarok's going to cream his pants when he sees this
could we have some more detailed damage pics?
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| Novacastrian |
| Posted: 03/07/2008 1:45 AM Post subject: |
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Bloody Aussie
Joined: 11 Aug 2007
Posts: 1622
116.11 Spud Bux
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Effin wow, thankyou very much for making me aware of your project I will not for one second pretend that i know the faintest about what you have built but <GOD> that is some nice (stuff that words can't describe).
I agree with JSR, come on Rag where are you homeboy-Check this sh!t out!
Edit: Alright so i know how it works, but but but but i gotta get me one of those  It looks so sick.
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| Gunner |
| Posted: 03/07/2008 4:52 AM Post subject: |
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Sergeant
Joined: 21 Oct 2007
Posts: 93
145.36 Spud Bux
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| Larda, Thats amazing gun, but I`d like to know that can you shoot trough the 10cm wood and I would like to see more damage pics. Thanks.
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| Ragnarok |
| Posted: 03/07/2008 6:25 AM Post subject: |
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Lord of Karma
Joined: 19 Dec 2006
Posts: 2021
5110.27 Spud Bux
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| Novacastrian wrote: | | I agree with JSR, come on Rag where are you homeboy |
*Little fruit machine noise as head pops into view*
Answer: At that time, asleep, and I don't have JSR's superhuman powers to be on the forum as he sleeps (if he even does...)
There's not really much I can say to that wonderful piece of work - No real suggestions for improvement (at least, not practical ones.)
What I can say is that, I don't quite get Davidvaini's "2x cap bank = 4x power" theory - electrical power, possibly, if they were wired in series (but not quite - inductance and heating would slightly blunt the electrical power, but it would increase in that sort of region).
However, assuming we're talking about kinetic energy, no - that would require a doubling of efficiency, and by that logic, you could break 100% efficiency by just adding enough banks.
Well, I'm certainly impressed, and I'm looking forward to seeing either your next project - or any more info on this one.  - Not quite the right emoticon, but they don't do a suggestive "smile, thumbs-up and nod" one, that'll have to do.
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| Larda |
| Posted: 03/07/2008 7:09 AM Post subject: |
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Corporal
Joined: 18 Jul 2007
Posts: 72
194.96 Spud Bux
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Thanks for your comments, everyone!
Lentamentalisk:
What voltage and capacitance are you using?
Any link?
Here is a few more damage pics, really not that detailed but i can take some more this weekend when i do some more shots.
| Description: |
Second projectile made out of a broken solid-carbide drill. Weight 72.6g
Its 12.00mm and the ID of the barrel is 12.04mm. |
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