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28,8Kj ElectroThermal Gun! (Soon handheld)

Built a pneumatic cannon? Then post it here! This section is for completed, finished cannons that you have built. Please include pictures and information.
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Unread postAuthor: CpTn_lAw » Sun Mar 09, 2008 2:22 pm

That is quite a super lot of power here...but in a way, it's a great pain in the a** to build a cap. bank this big, even to get such killer results.
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"J'mets mes pieds où j'veux, et c'est souvent dans la gueule."
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Unread postAuthor: DYI » Sun Mar 09, 2008 2:32 pm

I'm very thankful that someone made one of these, because mine will never be this powerful, and at the rate I'm going, it'll literally be years before I complete it. Supersonic wouldn't surprise me at all with a design like this.
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Unread postAuthor: Larda » Mon Mar 10, 2008 12:01 am

I made another more successful attempt to measure the velocity today.
I added several layers of sheet metal to the pendulum to make it "bullet proof".
The projectile penetrated two pieces of 20mm wood, two pieces 3mm aluminium, and finally 5mm of steel before it disintegrated.
In this test i charged the capacitors to their surge rating 1350v, for a total energy of 36,5Kj.

High Speed video of the test, its captured at 100FPS but the resolution is lower.
http://www.vimeo.com/769985


The failed test earlier.
http://www.vimeo.com/770135
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Attachments
bullet_trap.jpg
Bullet Trap
damage3.jpg
Damage by a 90g 12mm Solid Carbide projectile.
small_pieces.jpg
The projectile turned into shrapnel after impact.
pendulum.jpg
The pendulum.
damage4.jpg
Damage by a 90g 12mm Solid Carbide projectile.
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Unread postAuthor: MrCrowley » Mon Mar 10, 2008 12:21 am

:shock: HOLY MOTHER OF GOD!
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Unread postAuthor: Killjoy » Mon Mar 10, 2008 12:36 am

Good god, thats beautiful.
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Unread postAuthor: chartreusesnot » Mon Mar 10, 2008 12:50 am

anybody else noticing the completely massive recoil? It appears to be launching bricks and those square metal bars backwards...
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_Fnord wrote:OMG you have broked teh universe!!!11exclamationpoint!1!

http://www.youtube.com/watch?v=UnKN7LXqizw
http://www.youtube.com/watch?v=oVm_3eEPEgM
http://www.youtube.com/watch?v=wLNjMSGxp00
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Unread postAuthor: Larda » Mon Mar 10, 2008 12:59 am

chartreusesnot wrote:anybody else noticing the completely massive recoil? It appears to be launching bricks and those square metal bars backwards...
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Unread postAuthor: chartreusesnot » Mon Mar 10, 2008 1:07 am

Dude... whats happening in that picture? did the recoil split that brick...?
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_Fnord wrote:OMG you have broked teh universe!!!11exclamationpoint!1!

http://www.youtube.com/watch?v=UnKN7LXqizw
http://www.youtube.com/watch?v=oVm_3eEPEgM
http://www.youtube.com/watch?v=wLNjMSGxp00
^^^^CLICK^^^^
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Unread postAuthor: Rokmonkey » Mon Mar 10, 2008 1:16 am

Holy Mary mother of God...
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Unread postAuthor: Novacastrian » Mon Mar 10, 2008 1:31 am

I herewith change my sig, sorry DYI but this truly takes the cake :P :) :D
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Unread postAuthor: Copperboy » Mon Mar 10, 2008 2:21 am

Satan i Gatan!!

How did you machine your "chamber"? Nice work! :)
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Unread postAuthor: jackssmirkingrevenge » Mon Mar 10, 2008 5:26 am

That's just spectacular, congratulations!

I love the way the chequer plate pattern is imprinted on the wood in this photo - amazing stuff, keep it up :D
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Unread postAuthor: Ragnarok » Mon Mar 10, 2008 9:08 am

Well, that sort of puts things into perspective. DYI has been well and truly beaten on the penetration front.

From that video, and guessing from the markings on your back board, it looks like you're doing about 260-270 m/s (860-880 fps), which is around 3200 Joules (2400 ft-lbs) of kinetic energy. That's a phenomenal amount from a 12mm barrel of that length, and it would seem you're achieving an average pressure of around 10000 psi - possibly more, I'm not sure how long your barrel is, so I guessed around 40 cm from the picture in the opening post - which is a full order of magnitude above anything anyone else has yet achieved (at least, that I can think of).

So, it's not actually supersonic, only about 80% of the way there, but no doubt if you used a projectile of somewhere under 50 grams, you could manage to break the sound barrier.

It's also a respectable 11% efficiency. Ooh, I can see more of these being made.
You sir, have what is no doubt one of the most kick-ass spudguns ever.
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Does that thing kinda look like a big cat to you?
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Unread postAuthor: starman » Mon Mar 10, 2008 9:40 am

I would be interested in the possibililty of adding some water in with the aluminum powder, possibly somewhat little less powder to make room in your chamber. If you added a minimalist (or more even) burst disk, you could experiment with different slurry mixtures and see what works best.

This is based on the aluminum powder flashing to plasma and thus flashing the water to steam. The military has been prototyping the plasma/steam combo for several years and it supposedly has multimach potential if configured correctly. It may require more power to work properly than you have here, but, maybe not.

Again, very impressive work!
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Unread postAuthor: DYI » Mon Mar 10, 2008 9:55 am

I tip my hat to you sir, you've achieved what most of us will only ever dream of :salute:

I have to get my ass in gear on the [redacted] project now...
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