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| Larda |
 Posted: 03/07/2008 14:14 PM Post subject: |
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Donating Member
Joined: 18 Jul 2007
Posts: 108
274.88 Spud Bux
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Thanks.
Next time i will take the scale with me and measure more exact how much aluminium i use.
I take the powder and wrap it in foil to keep it in place.
Normally i clean the chamber and barrel every time, but i think that you can get away with doing a few shots before cleaning.
Yes you could put all the caps it in parallel for lower ESR, and it will make it possible to get a higher current pulse.
But if you are discharging them into a load with a little higher resistance, then you can get higher current with the caps in serie/parallel and a higher voltage.
I can rearrange the capacitors in my bank to 0,36F 400V if i want, maybe i try that some day and see what gives the best results.
The current limiting resistor is used to limit the charge current so i'm not risking damaging the rectifiers.
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| benstern |
| Posted: 03/07/2008 17:10 PM Post subject: |
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Joined: 21 Sep 2005
Posts: 920
176.97 Spud Bux
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I am extremely impressed with this. Great job!
I too would like a new section of the the forum devoted to electronic based cannons.
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| SpudMonster |
| Posted: 03/07/2008 18:02 PM Post subject: |
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1st Lieutenant
Joined: 08 Aug 2005
Posts: 253
195.26 Spud Bux
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I can state unequivocally that this is one of the most impressive cannons I have ever seen. The workmanship, innovativeness, and the overall "Holy crap" factor are really incredible. Great work! 
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| clide |
| Posted: 03/07/2008 19:15 PM Post subject: |
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Joined: 06 Mar 2005
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2301.84 Spud Bux
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Haha, that is amazing  . That video has got me grinning ear to ear, it is a great combination of noise, impressive muzzle blast, and great destruction.
What are the overall dimensions and weight of the capacitor bank?
Great job.
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| fatcat |
| Posted: 03/07/2008 20:06 PM Post subject: |
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Specialist
Joined: 16 Mar 2007
Posts: 51
78.88 Spud Bux
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That is an amazing idea(and gun). I hope we will see more of these around.
I looked around the internet but didin't find much info on Electothermal weaponry. where did you come up with an idea like this?
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| Larda |
| Posted: 03/07/2008 20:09 PM Post subject: |
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Donating Member
Joined: 18 Jul 2007
Posts: 108
274.88 Spud Bux
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| clide wrote: | What are the overall dimensions and weight of the capacitor bank?
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The bank weight about 73Kg.
Tomorrow i will do some more shooting and try to determine the muzzlevelocity..
What do you think is the best way to do that on a ETG?
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| cenzo188 |
| Posted: 03/07/2008 20:47 PM Post subject: |
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Private
Joined: 15 Sep 2007
Posts: 18
43.88 Spud Bux
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| that is amazing. If I had the shop, time, and money i would totally build one of those. It would be nice to know the FPS of the projectile, if you happen to have a chronometer (I probably spelled that wrong).
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| Larda |
| Posted: 03/07/2008 20:53 PM Post subject: |
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Donating Member
Joined: 18 Jul 2007
Posts: 108
274.88 Spud Bux
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| cenzo188 wrote: | | It would be nice to know the FPS of the projectile, if you happen to have a chronometer (I probably spelled that wrong). |
Unfortunately not, i was planing to try a ballistic pendulum, or try to use a microphone to record the sound of the projectile.
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| chartreusesnot |
| Posted: 03/07/2008 21:48 PM Post subject: |
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Staff Sergeant
Joined: 05 Jun 2007
Posts: 111
25.21 Spud Bux
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to determine the speed, you can shoot it into a hanging block of wood, or something that it will stick in, and measure the mass of the projectile and hte wood, and measure how far up it swings. This is called a ballistic pendulum, and it is very inaccurate. Look it up on wikipedia for calculations. Or you could get a Chrony.
^^^^^^
Edit... Heh didn't read ^^that^^
^^^^^^
Last edited by chartreusesnot on 03/09/2008 23:41 PM; edited 1 time in total |
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| Larda |
| Posted: 03/07/2008 21:55 PM Post subject: |
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Donating Member
Joined: 18 Jul 2007
Posts: 108
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| The problem with a normal Chrony is that will have a problem with the big muzzle-flash from the ETG.
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| bigbob12345 |
| Posted: 03/07/2008 22:00 PM Post subject: |
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Experienced n00b
Joined: 01 Dec 2007
Posts: 1515
370.57 Spud Bux
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well to fix that you could simpley move it back from the chrony 10 or 20ft but then you risk hitting the chrony which would be bad.
I say just make a ballistics pendulum as mentioned above which isnt very accurate but will give us a rough idea of how fast it is going.
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| MrCrowley |
| Posted: 03/07/2008 22:09 PM Post subject: |
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Kaleun
Joined: 23 Jun 2006
Posts: 7619
4936.83 Spud Bux
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Very very very nice!
Those videos were great too 
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| ghostman01 |
| Posted: 03/07/2008 22:25 PM Post subject: |
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Major
Joined: 23 Nov 2007
Posts: 370
420.34 Spud Bux
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| wow this thing really packs a punch sort of like the electricity is the firing pin and aluminum is the black power
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| starman |
| Posted: 03/07/2008 23:23 PM Post subject: |
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Big Daddio
Joined: 11 Dec 2007
Posts: 3057
7463.73 Spud Bux
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| ajdevi92 wrote: | | wow this thing really packs a punch sort of like the electricity is the firing pin and aluminum is the black power |
Some modern consumer fireworks use aluminum powder as the primary fuel with an oxidizer agent blended in. Aluminum has an amazing amount of potential energy just waiting to be released...just needs a fairly high level of energy to release it. This gun certainly applied the right levels...VERY VERY nice shootin'....
I can't see this as the next "spud gun" type. Too expensive, too dangerous.
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| Hailfire753 |
| Posted: 03/07/2008 23:44 PM Post subject: |
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Captain
Joined: 28 Jun 2007
Posts: 343
44.15 Spud Bux
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| Wow, I never thought this much carnage was possible with a homemade electrothermal gun! Absolutely Amazing.
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