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Registered Member #311
Joined: Sun Mar 12 2006, 08:28PM
Location:
Posts: 253
Thinking a about potential semi-commercial (entertainment) application for an air or gas cannon - just wondering if anyone has any thoughts /knowledge/experience....
It would need to launch a payload into the air of around 30-50 grammes, maybe 25-40mm dia for a parachute descent of duration 30-60 secs, maybe more if possible. Some random rough calculations from my very basic physics knowledge suggest an apogee altitude of 500m with a 1m barrel, launch energy 250J, muzzle velocity 100m/S, parachute dia about 200-300mm.
I think this is in a similar sort of zone for larger firework rockets in terms of altitude and weight
Just initially thinking about possible legal limitations (US and UK in particular) : a) Below what altitude would something like this be considered effectively unregulated (provided not near an airport!) b) At what point would an air cannon be classed as a firearm - it would not be portable, not be fireable when not nearly vertical, and probably have a barrell length at least 1M.
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
I don't know, but I used to own a pair of experimental air cannons that were used for launching nets to catch birds for wildlife study kind of things. They were made of ABS pipe with quick release valves triggered by solenoid, could be charged to 100psi, and were scary powerful.
I looked into the legal implications of owning them, and apparently anything over 16 joules of muzzle energy in the UK needs a firearm certificate:
These seemed to be a good deal more than 16J, since they would shoot a C size battery clean through a plank. They were probably getting into the 250J ballpark you were looking for. So to cut a long story short I got rid of them.
Registered Member #311
Joined: Sun Mar 12 2006, 08:28PM
Location:
Posts: 253
I appreciate the muzzle velocity issue, but I'm wondering what distinguishes a portable (carryable) weapon and a relatively fixed piece of machinery ( if there is one...).
Registered Member #75
Joined: Thu Feb 09 2006, 09:30AM
Location: Montana, USA
Posts: 711
Awesome to see this thread here, since I recently developed an interest in these contraptions too, and recently ordered a bunch of high pressure PVC plumbing waiting to be used now.
I don't know about the UK, but in Germany (where I luckily don't live anymore) everything that can "propel a projectile with gas pressure" is considered a firearm, and even though air rifles up to a certain power are sold over the counter, making these devices yourself, regardless of power and portability or lack thereof, is illegal. Kid's have been busted for playing with hair-spray powered spud guns, which are certainly on the lower powered end of the spectrum.
If you are interested in state of the art pneumatic cannons I suggest a visit to which seems to be a rather good forum. The most efficient designs seem to be co-axial piston valve designs at least that's what I have been looking into. Also check out for hard to find parts like QEV's (quick exhaust valves), and since the owner of the shop is in the UK, maybe some more legal information.
Registered Member #1062
Joined: Tue Oct 16 2007, 02:01AM
Location:
Posts: 1529
in the U.S: its legal to build any sort of weapon, but it is illeagal to sell or transport it. But along with that, theres other laws, like its illegal to pack gunpowder in a enclosed space (pipe bomb)
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Air cannons
