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Copperhead Pocket Launcher

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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Copperhead Pocket Launcher

Unread postAuthor: Hotwired » Mon Sep 21, 2009 11:31 am

Several designs of mine were morphed into one for the Innovations contest but it wasn't completed in time and it didn't enter.

Thought you'd like to see some pictures anyway :)

Couple of handfuls of polymorph...
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...plus some magic powder...
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...and after 10 minutes in the microwave on full, plus extremely painful kneading of hot plastic...
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This shall be the entire control system of the cannon, everything is standard except the Tee that Will machined for me:
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Slapped on a bit of the old molten plastic to give it a bit of body...
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Did I mention it's painful to work this stuff? It's workable above 60 degrees, preferably higher, bare hands are the best way but ouch.
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Only took four hours.
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More pictures will be forthcoming later :D

A sneak preview was shown so if you did see and understand please don't spoil the workings, thankyou :)


Compiled from the rest of the thread below:


Here's a picture of the pipe on the launcher and the machined Tee before I clamp it down with the compression fitting and the JFC:
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The olive was secured first using JFC.

The pipe is 28mm copper with ~26mm ID x 600mm long
The pressure limit I'm setting is up to 300psi

And the projectile looks a little something like this:
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Projectile is 25mm 16 BAR PVC x 570mm long before the nose. Clocks in at ~150g.

More closely at the pointy end:
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The moulded polymorph nose has replaceable tips. The polymorph was blended with wax to allow self-lubricating of the screw threads. Also a steel nut in there to assist.

This is the entire launcher:

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- The projectile is inserted into the launch (this is why it's not a cannon) tube, the replaceable tip is now a pointed spade bit which screws in.
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- The compression fitting is then used to clamp a burst disk in place after the projectile, sealing it in. Unlike unions this clamp deforms the disk to hold it.
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- Air is pumped in through the fill/pilot of the QEV, fills the space between the projectile tip and burst disk and just as importantly, seeps around the projectile to fill the hollow tail with compressed gas.

- On firing the QEV vents the space between the projectile tip and the burst disk.

- The projectile is slammed forward by the trapped compressed gas in its hollow tail and with the assistance of the puncturing bit, smashes through the burst disk and ejects from the launch tube.
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And that is the Copperhead Pocket Launcher :D

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Last edited by Hotwired on Thu Sep 24, 2009 5:22 pm, edited 2 times in total.
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Unread postAuthor: psycix » Mon Sep 21, 2009 12:53 pm

Nice handle. That's some awesome stuff that plastic. Do hardware stores carry that? Its looking good!

Btw, are you chambersealing that QEV?
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Unread postAuthor: Ragnarok » Mon Sep 21, 2009 1:07 pm

psycix wrote:That's some awesome stuff that plastic. Do hardware stores carry that?

I've never seen it in them. I've had to order all of the stuff I've bought off the internet.
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Does that thing kinda look like a big cat to you?
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Unread postAuthor: Hotwired » Mon Sep 21, 2009 1:24 pm

Maplin (UK electronics place) has it and since they stock other stuff from MUTR (UK online supplier of stuff) right beside it I suspect they're buying from MUTR and jacking the price a bit.

But no, that's not a modified QEV, bog standard. Operates exactly like it's expected to.
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Unread postAuthor: Brian the brain » Mon Sep 21, 2009 1:26 pm

Nice work..but if , like you said, everything is standard...I don't get it..

This doesn't happen very often..

So if this isn't a chambersealer I'm looking at....the question is: why the cut up fitting on the chamberside...

:?:

The grip looks very 1950's sci-fi...
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Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: JDP12 » Mon Sep 21, 2009 1:27 pm

That's awesome Hotwired! I love it
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Unread postAuthor: Hotwired » Mon Sep 21, 2009 1:30 pm

You're not supposed to get it, when I do innovation I do innovation :P

The correct answer to how it works will be acknowledged but it won't be from me, I expect it to be worked out :)


It's missing one straight length of pipe, needs to be polished up and attached...
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Unread postAuthor: Brian the brain » Mon Sep 21, 2009 1:47 pm

Does the Tee block off the QEV?

In that case it would just be a smallchambered coax...and you would be missing the barrel...


T serves as a sight?

This is killing me,... :?
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Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: JDP12 » Mon Sep 21, 2009 2:20 pm

hmmm... does the pipe on the bottom somehow serve as pilot and chamber simultaneously???
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Unread postAuthor: MrCrowley » Mon Sep 21, 2009 2:30 pm

Better hope those fittings under the polymorph don't leak :P
Looking good though, you really go the polymoprh to work well.
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Unread postAuthor: jackssmirkingrevenge » Mon Sep 21, 2009 2:43 pm

Where'd you load the pockets then?

*ahem*

Did I mention it's painful to work this stuff? It's workable above 60 degrees, preferably higher, bare hands are the best way but ouch.


You masochist you, epoxy casting FTW!

But seriously, great stuff, can't wait to see it finished :)
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Unread postAuthor: Hotwired » Mon Sep 21, 2009 2:47 pm

jackssmirkingrevenge wrote:Where'd you load the pockets then?

*ahem*


Not quite that kind :P

Pocket in the same sense as Pocket Battleship :twisted:


I am worried about the fitting leaking but I took some measures to make sure the polymorph stuck (as opposed to wrap around but not stick) so I'm hoping all will stay quiet in there.

Normally the polymorph will just slide off metal if you whack a soft blob of it on... but if you heat up the metal (cleaned first) with boiling water the soft plastic won't cool and harden slightly on contact thus failing totally to hold by itself but will "wet" slightly with the hot metal and stick.
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Last edited by Hotwired on Mon Sep 21, 2009 2:55 pm, edited 1 time in total.
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Unread postAuthor: JDP12 » Mon Sep 21, 2009 2:55 pm

Am I close hotwired?
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Unread postAuthor: Hotwired » Mon Sep 21, 2009 2:56 pm

Nope :wink:

I'll see if I can find my camera for s'more pictures.
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Unread postAuthor: JDP12 » Mon Sep 21, 2009 3:06 pm

Damn. Ummm give me a few minutes to think...
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