The Origin of the "Shuriken Gun" ?

[BP]

You guys are real cut-ups! :lol:

 

[DFW]

Have I missed something or will this weapon fire in an upward curved path before beginning to drop at some range (as the spin slows down). That will make aiming interesting.

No, it wouldn't as there is no force acting on it to do so.

This is what the formula is for how it works:

 

[far-trader]

Have I missed something or will this weapon fire in an upward curved path before beginning to drop at some range (as the spin slows down). That will make aiming interesting.

No, it wouldn't as there is no force acting on it to do so.

This is what the formula is for how it works:

Which means what exactly.

 

[DFW]

Which means what exactly.

It is the Magnus effect equation. This is why/how a curve ball does what it does.

 

[far-trader]

You know, I thought all the physics issues were addressed in this thread, must have been somewhere else. So while DFW mulls over expanding on his thought...

...the simple answer is of course as noted above: "Ignore physics, it's KEWL!"

But if you don't want to ignore physics then there are several major issues that make it less than... I was going to say "less than ideal" but it's even worse than that... um, less than useful, yeah:

One good point first, it is (as I understood) already stabilized by being gyroscopic, no need to add a gyro to it as was suggested above. But it may not be a good point in fact since it introduces spin.

A spinning disc is a wing. It produces lift. Your trajectory is going to be ballistic even if you aim down. This will produce interesting scenarios but make aiming even more complicated than a simple slug.

Further because of the spin it will also turn. More or less depending on the spin and other factors. It's terminal range will have greater turning forces meaning long range shots are even more likely than other weapons to miss. Unless you do include a built in self powered gyro to maintain the stability.

Aiming will be further complicated (no doubt a feature to some) by inducing curving flight depending on the release angle. Twist your gun left or right when firing to make your disc curve in flight.

What have I missed? It's been a while, and feels like I'm missing something about disc flight...

So in short it's KEWL, but silly. And yes there have been silly weapons throughout history, but nobody denies they are silly or would suggest we really missed out on a great piece of war tech because it was sooo KEWL!

IF it were to be in my game it would be as a footnote of historic interest "there was this brief period where this useless weapon was made and used, before being abandoned" and the PCs might come across an old stash or something and get to experience the faults first hand IF they thought it was KEWL and wanted to use it :twisted:

 

[DFW]

You know, I thought all the physics issues were addressed in this thread, must have been somewhere else. So while DFW mulls over expanding on his thought...

??
Why would I expand on it? Are you expecting a course in fluid dynamics?

 

[Ishmael]

Because its not quite correct.

The equation DFW gave is for lift when using a known lift coefficient for a specific profile, aka an aircraft wing or propeller blade element.
When using a known drag coefficient, it gives the amount of profile drag, not induced nor parasitic drag.

The proper Magnus effect equation

[/i]
where S is dependent on the average of the air resistance coefficient across the surface of the object. The 'X' denotes the vector cross product.
It can be found at can be found at http://en.wikipedia.org/wiki/Magnus_effect

Actually, I wonder if Trav would have weapons that used a sphere projectile with lots of backspin to increase range...

 

[far-trader]

You know, I thought all the physics issues were addressed in this thread, must have been somewhere else. So while DFW mulls over expanding on his thought...

??
Why would I expand on it? Are you expecting a course in fluid dynamics?

No, silly me, I'm expecting you to actually participate in the discussion, not just fling random formulae that don't apply or simply pontificate about how nobody is as brilliant as you are :roll:

<grumble mutter mumble> Never mind...

 

[DFW]

No, silly me, I'm expecting you to actually participate in the discussion, not just fling random formulae that don't apply or simply pontificate about how nobody is as brilliant as you are :roll: .

:lol:

"random formulae that don't apply"

That's funny.

 

[alex_greene]

How about if the weapon fires balanced rings, rather than disks, where the mass is distributed as far from the centre of rotation of the disc as possible, along its rim?

 

[DFW]

How about if the weapon fires balanced rings, rather than disks, where the mass is distributed as far from the centre of rotation of the disc as possible, along its rim?

That would lessen the effect vis-a-vis fluid dynamics as the total surface area
would be smaller in relation to its mass. However, to make a sharp edge you'd need a nit more surface area.

 

[far-trader]

How about if the weapon fires balanced rings, rather than disks, where the mass is distributed as far from the centre of rotation of the disc as possible, along its rim?

It'll change the lift properties and everything associated with it, not eliminating it but reducing it. Enough to make it work? Depends on how well you need it to work.

It (the whole concept) will always be well behind simpler, cheaper, easier ballistic weapons in effectiveness. It's difficult to imagine a situation where a disc weapon would be chosen over others. The only one I've seen yet that made any sense to me was for religious/traditional reasons.

 

[kristof65]

The issue of lift is only going to apply in an atmosphere, isn't it? Doesn't it also assume that the disc is being fired in a horizontal position, rather than a vertical one? I'm guessing that a vertical profile would cause it to veer left or right more. What about firing it in a vacuum?

Even though a simple ball or dart does seem a lot more likely, it's a big universe out there - surely there would be situations where a flying disc would be the most effective solution - so let's try and dream some up.

What about as a shredding weapon, say to take down large spider webs?

What about any richochet effect? It seems to me a spinning disc might be likely to ricochet off in the directiion of it's spin upon hitting certain types of surfaces. Perhaps something like this could be used to good effect to get inside a small opening in an otherwised armoured suit/exoskeleton and shred the soft tissues inside?

 

[DFW]

The issue of lift is only going to apply in an atmosphere, isn't it? Doesn't it also assume that the disc is being fired in a horizontal position, rather than a vertical one?

It also depends on whether or not is is an airfoil.

I like the idea of it bouncing around in a confined space.

 

[Ishmael]

the real origins of this weapon

http://en.wikipedia.org/wiki/Tracer_gun

who didn't have one as a kid?
http://www.samstoybox.com/toys/TracerGun.html

 

[far-trader]

The issue of lift is only going to apply in an atmosphere, isn't it?

True. But that doesn't really apply does it? How is it superior for operation in a vacuum? The only thing the design has going for it (if any) are the aerodynamic properties. Take those away and it might as well be a rock, or a bullet. Simpler for the same effect.

Doesn't it also assume that the disc is being fired in a horizontal position, rather than a vertical one? I'm guessing that a vertical profile would cause it to veer left or right more.

Yep, touched on above. If fired off horizontal you induce more curve in the path of the disc.

Even though a simple ball or dart does seem a lot more likely, it's a big universe out there - surely there would be situations where a flying disc would be the most effective solution - so let's try and dream some up.

By all means, but I've not seen or thought of any yet where a bullet or something else wouldn't be superior, and simpler. It really is simply a KEWL weapon. But I'm willing to consider ideas to change my mind.

 

[kristof65]

I like the idea of it bouncing around in a confined space.

Yeah, I kind of wondered if would be an effective weapon against my settings K'klk - they're a race of exoskeleton aliens that sort of look like a centaur made out of half an ant, and a crab. Right at the join between the upper torso and the lower body, they have a soft fleshy spot where the reproductive and waste organs are. That's the most effective spot to hit when you're trying to kill them. Something that could enter that zone and bounce around inside the exoskeleton would be utterly devestating to them.

 

[far-trader]

...I kind of wondered if would be an effective weapon against my settings K'kree - they're a race of exoskeleton aliens that sort of look like a centaur made out of half an ant, and a crab. Right at the join between the upper torso and the lower body, they have a soft fleshy spot where the reproductive and waste organs are. That's the most effective spot to hit when you're trying to kill them. Something that could enter that zone and bounce around inside the exoskeleton would be utterly devestating to them.

Or something like a hollow point bullet? With which you might actually have a decent shot at actually hitting and penetrating said small unarmoured spot And if you miss still have a chance at penetrating and doing decent damage, unlike the disc which is likely to bounce off.

You know, I do think there is one application for a disc weapon I might get behind. As a less-than-lethal round. It's more likely to deliver a non-penetrating hit and the larger size could be made to deliver a shock, a chemical, or a gas by making use of the volume for a capacitor or delivery capsule. Again though, conventional rubber bullets, canister rounds and such seem likely to be superior in every way... nope, still not sold on the idea.

 

[kristof65]

The issue of lift is only going to apply in an atmosphere, isn't it?

True. But that doesn't really apply does it? How is it superior for operation in a vacuum? The only thing the design has going for it (if any) are the aerodynamic properties. Take those away and it might as well be a rock, or a bullet. Simpler for the same effect.

If you're going for the same effect. I only mentioned the issue of lift and vacuum because it might change the parameters under which such a weapon becomes more effective than a simple rock or bullet.

There's been a discussion of lethality of these versus "standard" bullets. But what if lethality isn't one of the parameters? What about as a weapon that shreds up skin and clothes, but usually isn't lethal? For something like sadistic riot suppression? Sure, rubber bullets and water cannons can be used effectively for the same thing, but sometimes image is more important than effect - I imagine a scene of protesters bleeding from multiple slash wounds would be far more effective propoganda wise than a bunch of bruised and wet ones.

Yes, there are many things that a simple bullet or dart can do better - the thing is to look at what characteristics a spinning disc has that a bullet can't do better, and extrapolate possible uses from there - even if they aren't the most efficient from a physics standpoint, they may be more effective in other ways.

 

[kristof65]

Or something like a hollow point bullet?

Don't hollow points often rely on hitting the bone, though? If a hollow point bullet had a high enough velocity to pierce the exo-skeleton, how effective would they be inside? I truly don't know, never really studied it.

[qquote]You know, I do think there is one application for a disc weapon I might get behind. As a less-than-lethal round. [/quote]
I see we cross-posted there.