SpudFiles

OK, Joerg has inspired me with his apocalyptic slingshot of ridiculous power. Lets have a cannon ft-lbs / jules power contest shootout! Of course I assume that Larda hasn't already ruined this for everyone, and in fact maybe he hasn't. I suggest an unofficial hand held cannon ft-lbs/jules contest. I will shoot the heaviest thing my little body can handle without throwing me back 50ft or cleanly removing my arm from my...my self and I will do so when I get a chrony built. Any takers? I will likely slowly work myself up to something like a Ø1.75 lead ball. I talked about doing something like this earlier but got side tracked. Not this time I tell you!

Are GGDT/HGDT gun files acceptable, or is chronograph data acceptable.

I shouldn't just be ft/lbs, it should be something like ft/lbs x velocity/100 or something... i dunno. Because if you keep using a heavier projectile you will end up with an uncanny amount of energy at near no velocity.

Yeah and the stronger the gun the faster it will shoot that heavy thing. I duno maybe its pointless. I guess you could state your cannon specs and be done with it but thats borring.

If the test was done on just muzzle energy alone then a PVC and sprinkler valve cannon could outdo Gippeto's 3000 psi co-ax, any of BTB's guns..whatever, just because of the larger bore size.

I'm sure Ragnarok could contribute something to this. He did have a solution which divided some figure by the bore for a fair comparison.

I guess i could drive my car through a large tunnel and claim it to be my cannon. That would win.

inonickname wrote:If the test was done on just muzzle energy alone then a PVC and sprinkler valve cannon could outdo Gippeto's 3000 psi co-ax, any of BTB's guns..whatever, just because of the larger bore size.

In theory this could beat a sprinkler valve PVC cannon. In reality a high mass projectile recoil could easily bowl over a large man. In theory 240 PSI (tank working pressure) on the 4 inch pipe (if it holds) against a massive projectile could exceed 1.5 tons of recoil force. Needless to say, the cannon handheld would insist on making it's own path.

At 100 PSI the force could exceed 1/2 ton. The ABS barrel material has been tested to 100 PSI. I launch lightweight projectiles with this barrel.

inonickname wrote:I'm sure Ragnarok could contribute something to this. He did have a solution which divided some figure by the bore for a fair comparison.

It was simply dividing muzzle energy by barrel volume, which gives an "average pressure" in the barrel. Possibly useful, but equally, it's just a result of valve efficiency, C:B ratio and initial pressure.

On the note of your "heavy projectiles = more energy" conundrum, it is a law of diminishing returns, but if you really want to be rid of it, then...

Based on analysis of Apocalypse's outputs, an equation that proves to have an output largely independent of projectile mass for most cannons is:
Mass^0.7 * Velocity²

Basically, if you just calculate KE with a power of 0.7 on the mass (obviously, the equation above is not that, but is proportional to it), the end result is pretty constant across the various masses, so using a heavy projectile in order to gain raw energy will do the user no favours.
In fact, the equation tends to have a slight peak at about 60% of the SOS of the gas in the cannon.

The outcome will only depend on the physique of the shooter.

My large cannon can put out much more footpound than my body can handle recoil wise.

It can take 30 bar and after that is its just a matter of " at what projectile mass will my wrists snap" .

I'm sure I can't fire a 2" lead cilinder at 30 bar without permanent damage to myself.

It would give me enormous muzzle energy...

Brian the brain wrote:The outcome will only depend on the physique of the shooter.

My large cannon can put out much more footpound than my body can handle recoil wise.

It can take 30 bar and after that is its just a matter of " at what projectile mass will my wrists snap" .

I'm sure I can't fire a 2" lead cilinder at 30 bar without permanent damage to myself.

It would give me enormous muzzle energy...

There are other build variables that can permit high velocities while limiting the peak acceleration and thus the peak recoil forces. A long barrel with a counterweight can be used to achieve very high velocities if a system to provide constant acceleration within hand held limits is maintained.

I thought we were discussing existing cannons.If we were to build especially for this, I'm out.
Not something I'm interested in.


I want to get the most acceleration so I can keep my barrels short.
Sorry.

8)

Gee... Why does it have to be hand held?

Who said you'd have to be able to lift it while shooting.

Just hug it while it fires.
I'd love to see that..

i think you should all shoot the same object
a golf ball or tennis ball
or even a sock
that way every body that shooting ( enter this contest ) will have same weight and there no cheating kind of thing

Remember that at some point, the ammo weighs more then the gun, causing the gun to be more of a projectile then the ammo itself; or, actually becomes some sort of rocket, emitting one big particle with a few gases.

I think a velocity contest is more challenging, who's going beyond the big barrier we call mach one...
It puts size of the cannon out of the equation and depends mostly on the flow-wise quality of the valve (assumed that you are using a light projectile with a high pressure).

i think you should all shoot the same object
a golf ball or tennis ball
or even a sock

That would be no fun, we want to see people flying backwards through the air after firing rediculously heavy projectiles