Size Matters- or was that Mass?

[AfroBeaver]

Alright, here's a thought that's been floating around my head for awhile and it actually made me curious enough to register so I could post. I should note first off that I have no background in engineering or anything of the sort, I'm a simple guy who's brain enjoys entirely too much free time and comes up with useless crap.

I was reading the 'Size Matters' section in Science over at the main SD.net site and I started thinking about it again. What if, instead of massive, solid slabs of metal as armor they used multiple layers of honeycombed sheets/plates fused/welded together. Now to my limited understanding that would not only reduce the weight/mass of the ship (mass, really since weight in zero G is pretty much zero by default) but it should, in theory increase the protection of the armor even without shield- IE if an asteroid hits the hull of a star destroyer (handwave reason for the shields being down) or a turbolaser shot the honeycomb structures would reduce the overall damage to the ship versus a solid plate.

Would that be true? Aside from reduced weight/mass, would their be any benefit to used fused/welded honeycombed layers of armor? If so, what are they? What about drawbacks?

Like I said, my brain has too much free time and I have yet to find an effective method to keep it from wandering away and getting into places and things it where doesn't belong. That said, sometimes my thoughts amuse me.

[AfroBeaver]

Well shit, got to thinking about it and I forgot to to give any sort of references for calculations.

For the sake of argument let's go with Mike's (seemingly) default elemental metal of Iron for comparison.

Let's compare two slabs of identical dimensions, calling them 1 meter squares both approximately 30 cm thick. For simplicity let's call the solid slab A and the honeycombed slab B.

Since slab A is just a big old hunk of Iron, I'm sure somebody can figure out it's overall mass and other properties pretty quick.
I'm thinking slab B would be composed of roughly one hundred layer of honeycombed iron plating. Since this is theoretically supposed to go on a ship, obviously it can't have holes in it so I'll call the composition as such, each layer of the plating (for now) consists of one 1 mm thick solid iron sheet fused with one 2 mm thick honeycombed grid. The grid is arranged in a hexagonal pattern, with each side of the hexagon being three mm long and .25 (1/4) mm thick. Since the idea behind this is for a less massive armor platting with (hopefully) greater protective qualities, it's likely that the plates would be overlaid in such a away that the hollow spaces of the honeycomb are crisscrossed by underlying layers to reduce the gaps between them (when looking down on them from overhead, if for whatever reason you could see through the solid metal sheets set between each layer).

To my (limited) knowledge this should (should, mind you) increase the overall strength of the armor (a bundle of twigs tied together versus a single branch of roughtly the same size) or at least not reduce it to any significant degree while at the same time leaving more material available to make other ships without reducing their dimensions. More Star Destroyers over everyone! (yeah, we still need a cheesy villain manic laughter smiley- it's just not the same)

Actually this has been a curiosity of mine since I first saw the idea when I was... eight I think? It was a while back at anyrate. I just want to know how well the idea would work. At least in theory.

[AfroBeaver]

For. For everyone, stupid lack of a working edit button. I guess 'over' works as well, but still.

[Sea Skimmer]

Solid vs spaced armor depends on the properties of the threat projectile or beam. Local stiffness is key to defeating kinetic hits for example and so one thick plate will work better then two half thickness plates. However this assumes that the projectile is not damaged or yaw induced by passage through the first half thickness plate. If it is, then the second plate gains a lot. If its not, then the spaced system is worse then useless. The merits are entirely dependent on the properties of the threat and the armor; and the best combinations normally dissimilar materials. For example a very hard layer ahead of a very ductile layer. The first shatters the threat, the second catches it. If you reversed the layers meanwhile, the result would be failure of the armor even though it had the exact same mass and materials.

Spaced armor is very effective against shaped charges because they are inherently unstable and dissipation of the jet intensity is a matter of certainty. On the other hand such a restriction might not apply at all to a magic energy bolt, or so slightly that it makes no functional difference.

So end result is, you want to talk about what's best with weapons that have entirely unknown properties like turbolaser bolts? Nobody can answer that. Best we can do is observe that Starwars has no indication of spaced armor being useful that I've ever seen, and ICS has indicated the Millenium Falcon had its applique armor laid directly on the hull.

Oh and just in general terms, physical size does matter as well as mass. Real materials have properties that are distance dependent, such as elasticity. Make something big enough and you have to take this into account.

[Simon_Jester]

Afrobeaver, welcome to the site, but I would like to point out that the woohooing over how awesome star destroyers are is coming across as a bit odd. The versus debates were mostly resolved five to ten years ago, the content of the main site dates to that era, and we do have actual lives so we're mostly not still all worked up over stuff that happened that long ago.

So relax and be of good cheer, you do not need to exaggerate your love of the ISD to fit in, the site's URL notwithstanding.

Hm.

Nearly all highly energetic weapons known are best modeled in terms of high-energy radiation. A nuclear blast, a relativistic mass driver, a charged particle beam- all these things do pretty much the same things. About the only exception I can come up with is a visible light laser, which could theoretically be hugely powerful and yet not have remotely the same physical consequences on the target as an equivalent-yield nuke or particle beam.

Against this kind of threat, spacing the armor as such accomplishes nothing, because models of physical impacts (including hypervelocity ones that inspire things like Whipple shields) do not apply.

On the other hand, sandwiching layers of dense and low-density materials with different properties might be desirable. Also, anything made out of atoms is inherently treated as ablative at such energy densities, so you may use layering, spacing, and sandwiching to ensure that the material ablates in the fashion you desire. For example, you might want to ensure minimal heat transfer into the interior until the outer layers have fully boiled away.