Monoblades

[Icosahedron]

Maybe the physicists and engineers out there can evaluate this?

Monowire is a staple Sci Fi device. Maybe single-atom strands would be uselessly weak, but the basic premise is that the stuff has no structural defects (Crystaliron) and strands of 10, 100, or 1000 atoms diameter could be constructed and would still be invisibly thin, yet have a useful strength.

The main disadvantage of monowire is that it is (presumably) not self supporting and needs to be fixed at both ends in order to cut anything.

However, suppose that instead of a solid wire, hundreds of atoms in diameter, you made it hollow, more like a cluster of nanotubes. And then you fill those tubes with liquid under high pressure. Perhaps it could extend from a hilt under fluid pressure, like a 'party tickler' (or whatever they're called), creating a monowire blade that was actually self-supporting and could be retracted when not in use. It could even have an optional optic fibre or two so you could see it if you needed to.

Any ideas if this could work? I heard somewhere that tubes are more structurally rigid than solid rod, and I figured that a tube kept under tension by fluid pressure might be even more rigid. Just guessing - over to the experts, if we have any.

 

[veltyen]

I dunno if you are going to find any cutting edge materials engineers here, but I could be wrong.

The problem I see is that the concept of "pressure" starts breaking down at the nano level, that and anything strong enough to hold any at that size would be somewhat brittle.

How about instead a memory metal sword with an inertial reel in the hilt. When uncharged the memory metal folds into a solid mass in the handle, when charged it moves into a hollow form of a sword extending the monowire as the leading edge of the blade.

... or you could just skip the monowire and have a memory metal sword.

 

[hunter]

Originally posted by Icosahedron:
The main disadvantage of monowire is that it is (presumably) not self supporting and needs to be fixed at both ends in order to cut anything.

I've always figured having a small gravitic generator or something at the 'tip' of the wire that keeps the blade extended and rigid.

Add some lasers in the grip focused on the tip and viola you have a light saber!

Ok you can shoot me now...

Hunter

 

[Theo D Lite]

I think Larry Niven had a mono fillament (sp?) sword in one of the Ringworld books. This was from memory something that extended the fillament in some sort of "field" to maintain rigidity. I do recall that it used to have a small "marker ball" at its extreme end so the user knew where it all was.

As an alternative William Gibson had a mono fillament (sp?) in the short story Johnny Mneomic part of the Burning Chrome collection. In this a corporate assassin had an artifical thumb which contained a monofillament reel and used the tip of the thumb as a counter weight. Basically it was weilded something like a whip using the weighted "thumb tip" to give it impetus. I don't see why such a concept couldn't be reproduced in a non cybertech way the weapon could well be disguised as a smallish torch.

I can well imagine that the training sessions could get a little bloody as I strongly suspect that it would be almost as easy to slice your own limbs off as it would be to slice your opponent. But doing it this way gets over the whole rigidity problem (if you'll pardon the innuendo).

 

[redwalker]

I'm not a materials scientist but I know a couple so I'll stick my neck out.

Materials science is a highly disruptive real-world technology.

MEMS, nanomaterials, and currently unknown composites are very real and in twenty years they will have changed planet Earth beyond recognition.

Nano-assemblers are a long way off even if they're possible.

Super-strong materials are practical and will arise. In fact NASA has been wanting to use currently available super-strong plastics for a long time, but NASA doesn't have enough funding to do more than pay its bureaucrats.

Super-strong, super-small materials are not necessarily possible.

Suppose that you had a pressurized super-thin blade. It would definitely be sharp. Would it be able to cut through steel, while remaining man-portable? I don't know, and I don't think anyone else does either.

There are lots of cool cutting technologies. Nano-carbon cutting blades might be a real-world tech in the future. However, it seems likely that other forms of technology will be easier to develop.

E.g. near-infrared lasers, water jets, sonics.

 

[robject]

"Materials science is a highly disruptive real-world technology."

I'm going to have to remember that quote. Thanks, again!

 

[Anthony]

If you have a strand of 100 GPa wire (high end estimates of carbon nanotubes) and you wish to have a breaking strain of, say, 1,000N (which means a strong person might break it with a solid tug, but not easily), it must have a cross-section of 1e-8 m^2, corresponding to a wire about 0.11mm in diameter. If you are applying that force along, say, a 20 cm area (reasonable for a garrote or some such) that corresponds to 1,000N over an area of 2.2e-5m^2 or a total pressure of 45 MPa.

That will not cut any hard armor material. It won't even cut soft steel. Monowires as useful weapons are pretty much fantasy.

 

[Icosahedron]

Originally posted by Anthony:
If you have a strand of 100 GPa wire (high end estimates of carbon nanotubes) and you wish to have a breaking strain of, say, 1,000N (which means a strong person might break it with a solid tug, but not easily), it must have a cross-section of 1e-8 m^2, corresponding to a wire about 0.11mm in diameter. If you are applying that force along, say, a 20 cm area (reasonable for a garrote or some such) that corresponds to 1,000N over an area of 2.2e-5m^2 or a total pressure of 45 MPa.

That will not cut any hard armor material. It won't even cut soft steel. Monowires as useful weapons are pretty much fantasy.

Oohh, a mathematical analysis. I like that, thanks. Obviously I need to swot up on my force, pressure and area. Dunno where I'd find a table of how much pressure is needed to cut different materials, though.
What effect would that 45MPa have on flesh, for example?

Would a simple analysis of a bulk quantity like pressure break down at the molecular level?

Veltyen, I like the memory metal blade.

Hunter, I think I've figured out how to do a hard(ish) science light sabre.

 

[redwalker]

Suppose that you had a pressurized super-thin blade. It would definitely be sharp. Would it be able to cut through steel, while remaining man-portable? I don't know, and I don't think anyone else does either.



Originally posted by Anthony:
If you have a strand of 100 GPa wire (high end estimates of carbon nanotubes) and you wish to have a breaking strain of, say, 1,000N (which means a strong person might break it with a solid tug, but not easily), it must have a cross-section of 1e-8 m^2, corresponding to a wire about 0.11mm in diameter. If you are applying that force along, say, a 20 cm area (reasonable for a garrote or some such) that corresponds to 1,000N over an area of 2.2e-5m^2 or a total pressure of 45 MPa.

That will not cut any hard armor material. It won't even cut soft steel. Monowires as useful weapons are pretty much fantasy.

Correction: I don't know, and I think Anthony knows.

Folding sword-blades, allowing a "switchblade sword" effect, might be possible with means other than nano-wires. One problem is that carbon materials can be very strong when they are stiff, but stiff materials make the "switchblade sword" effect hard if not impossible to engineer.

 

[atpollard]

Originally posted by Anthony:
If you have a strand of 100 GPa wire (high end estimates of carbon nanotubes) and you wish to have a breaking strain of, say, 1,000N (which means a strong person might break it with a solid tug, but not easily), it must have a cross-section of 1e-8 m^2, corresponding to a wire about 0.11mm in diameter. If you are applying that force along, say, a 20 cm area (reasonable for a garrote or some such) that corresponds to 1,000N over an area of 2.2e-5m^2 or a total pressure of 45 MPa.

That will not cut any hard armor material. It won't even cut soft steel. Monowires as useful weapons are pretty much fantasy.

A tunneling electron microscope (big) can be used to form, manipulate and break bonds on the molecular level. Is it not plausible that a nanoscale wire (sub-micron not mono-atomic scale) might be energized in some way to create a localized field which disrupts molecular bonds on "contact". Could a nanoscale field "part" the armor without relying on a test of brute mechanical strength.

If one were to bond a diamond crystal matrix to your 0.11 mm nanotube wire, it could concentrate the force on a smaller cross sectional area and increase the pressure.

I am personally no great fan of wire swords for my space heroes, but (unlike many Traveller concepts) they seem at least plausible but currently unobtainable.

 

[far-trader]

"If you cut a persons molecules do they bleed?"

No, seriously, I'm wondering with this idea of super fine slicing (mono molecular anyway) if you are even making an effective weapon. Won't a cut so fine self-heal with no damage done whether it be in armor, bone, or tissue?

 

[redwalker]

Originally posted by far-trader:
"If you cut a persons molecules do they bleed?"

No, seriously, I'm wondering with this idea of super fine slicing (mono molecular anyway) if you are even making an effective weapon. Won't a cut so fine self-heal with no damage done whether it be in armor, bone, or tissue?

If a cut is so fine that tissue heals behind it, you've invented matter interpenetration. (Possibly mesons are involved, in a Traveller universe.) Quantum effects are IIRC not necessary: it's possible for gold and lead to swap atoms across a boundary, and hydrogen can seep through iron.

Blades, whether relatively blunt or sharp, are inclined planes. They separate the tissues at the edge and on one side of the edge.

A monowire that could pass harmlessly through meat would be so fine that electron repulsion no longer operated. I'm pretty sure that's a practical impossibility -- but I'm not a physicist.

Leaving aside the issue of a perfectly cylindrical wire, consider what happens when you have a monowire edge backed up with an inclined plane of greater thickness. At that point, you have a very sharp, and possibly very durable, knife blade.

A blade that is very thin and very stiff would probably be very effective for cutting.

 

[Straybow]

It is already possible to create molecular-thickness edges on blades. They're called "razors" and have been around for millennia.

A nanotube might be slightly smaller in cross section than a metal crystal or glass/obsidian molecule, but less than an order of magnitude.

Of course, once you have a "force field" that magically enhances the strength of the molecular edge it won't chip as easily, but it still can't slice effortlessly through hard matter.

Adding a microscale oscillating "saw" motion might help some, but even that will have limited effect on metal, ceramic armor, and the like.

 

[far-trader]

Originally posted by Straybow:
It is already possible to create molecular-thickness edges on blades. They're called "razors" and have been around for millennia.

Umm, thousandths of an inch (razor sharp) is not molecular, not even close. Molecular scale is more like billionths of an inch I think. Correct me if I'm wrong.

 

[far-trader]

Originally posted by Straybow:
Of course, once you have a "force field" that magically enhances the strength of the molecular edge...

...you also have "force field" armor that can't be penetrated by anything

 

[sinbadsam]

Originally posted by Theo D Lite:
I think Larry Niven had a mono fillament (sp?) sword in one of the Ringworld books. This was from memory something that extended the fillament in some sort of "field" to maintain rigidity. I do recall that it used to have a small "marker ball" at its extreme end so the user knew where it all was.

Ahh the Variable Sword. Yes I recall those well, IIRC under a Scouts supplement, you could get one as a retirement benefit. It was much fun, "where did the ball go....Dude get back up???"

 

[Straybow]

Oops, correct. It is crystal dimension that limits the sharpness of metal blades. For molecular sharpness we have asbestos fibers. Glass fibers and asbestos will both worm through cell walls but only asbestos cuts DNA strands.

Anyway, you still have to contend with inter-atomic forces (weak, EM) that prevent solid objects from penetrating each other. The monofilament is only as strong as one such bond, while the material surface has multiple bonds resisting the wire.

The idea that a force field has the near-infinite strength necessary to permit a monofilament weapon is going a bit too far.

 

[Pagan priest]

IIRC, there have been mono-molecular blades availabe here on Earth for some time now. Carefully napped obsidian ends up with a brittle edge that is mono-molecular. TL0

 

[BlackBat242]

Straybow & Red Walker...
"E.g. near-infrared lasers, water jets, sonics."
"Adding a microscale oscillating "saw" motion might help some,"

There is, in Science Fiction, something called a vibro-blade.

I have never read a good description of exactly what it is or how it works... does anyone have one?

 

[Andrew Boulton]

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