SpudFiles

I'm calling abuse of insider knowledge Will!

I should make my machinist sign an NDA next time


But entirely correct


I'll fill in the spaces:


- 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.


- 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.



- 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.






And that is the Copperhead Pocket Launcher



Well done to everyone who tried

woops...

I was wrong...

Maybe the CO2 thing isnt so bad either..



Lovely innovation!! And beautifully made

Gippeto wrote:Time to come clean...it's a pneumatic sewing machine isn't it??

He's not that camp ;p

Hehe so basically you've turned the piston into the projectile, good stuff

Damage pics?

cool now you just have to turn that projectile into a homing missile

Hotwired wrote:I'm calling abuse of insider knowledge Will!

Pfft I used my MEGA SKILLZ!11!!!11! to crack this puzzle. No, honestly I had no idea. It was only when I thought of the modified nut that I got the idea.

You need to put some spring loaded fins on that sucker
Any chance of a vid, I'd be really interested to see how well it works.

There is actually the clearance for fins but they'd be incompatible with the gas check I'm going to install in the launch tube.

Not anything very high tech, it's just tape used to tighten the bore of the launcher and provide sufficient resistance against gas trying to escape that more energy is put into pushing the projectile out.

Sprung fins would have a small collision problem with that.


I've done some low power tests to ensure everything works but the burst disks need working on before I can take it further.

Either that or I add a pilot gas booster to assist the burst disk in blowing out

Seems very cool yet extremely inefficient. I recon a projectile like that wont travel too far out.

Is that so

Explain the inefficiency compared to a conventional launcher

what psi are u gona us i did not see it in the thread

I think it should be ok to the maximum 240psi I can do, 2-300m range.


Although if I redid the Tee by soldering I'd try unregged CO2 and moar PPE. Rumour has it the rocket would land half a mile away... Not bad for a launcher 60cm long.

the compresion fitting i would think could hold 900 psi i think

That's a really cool idea Copperhead, I really like it. You don't see many new practical ideas come through anymore!

Mitchza89 wrote: You don't see many new practical ideas come through anymore!

This one certainly isn't one of them

The issue as I see it is that you have a burst disk sitting out super vulnerable, with the rocket up to pressure, the entire time. Then, when you press the trigger, it punctures it, but many things could go wrong. If, for example you were to make a weaker burst disk than normal, for what ever reason, it could fire while you were filling, or if the rocket were to slide down the tube and tap the burst disk. Be super careful about never pointing it in the general direction of anything important, even if you are nowhere near the trigger.