Unrealistic SCI-FI metals

SyntaxVorlon · Post by **SyntaxVorlon** » 2002-12-29 06:23pm

If you can kill the computer on a nuke then all it is just a big hunk of dense metal or a can of deuterium. If you can kill it's thrusters great there's just a big gas cloud, if you kill it's comp, well, you've got a derelict nuke all to yourself:twisted:

Patrick Degan · Post by **Patrick Degan** » 2002-12-29 06:39pm

SyntaxVorlon wrote:If you can kill the computer on a nuke then all it is just a big hunk of dense metal or a can of deuterium. If you can kill it's thrusters great there's just a big gas cloud, if you kill it's comp, well, you've got a derelict nuke all to yourself

Nukes don't employ computers. The fusing mechanisms tend to be very basic. Simple. You don't need anything more complicated than a device to read proximity to target and that can be accomplished by any number of passive systems or a simple timer.

The likeliest method to defeat a nuke is to breach the casing. You destroy the pressure conditions necessary for the device to work properly. Affect any of the initiator charges and it won't fire at all. Disrupt any of the fissionables and you never achieve critical mass, and again, the thing doesn't fire at all. If you hit the fusing mechanism, well, you've won the ballgame even if you don't affect the device in any other way. But the casing presents the easiest target.

ClaysGhost · Post by **ClaysGhost** » 2002-12-31 06:41am

Passive infra-red systems on large ships could be configured as an interferometer array, rather than as single large telescopes (SLTs?) using CCD detectors. The advantages would be:

* Damage resistance. You can lose array elements and resolution/sensitivity would be barely impacted unless a majority of elements are effected. One hit on your SLT and you've had it. Also, large CCDs would suffer significantly from cosmic ray hits and bad pixels. Individual array elements do not have to be imagers since imaging is produced by processing the output from array elements together.

* Scanning. The array can be "steered" electronically, and can even look in different directions simultaneously. An SLT would have great problems matching the speed and flexibility of this system.

* Resolution. The SLT might be a few metres across, but you could spread array elements out from one end of a hull to another and have a synthesized telescope the size of the hull. Even better, launch simple, disposable sensor buoys and have them move to fixed positions with respect to the ship, and you can gain even more resolution (and damage resistance).

* Smaller detectors would make mass-manufacture more convenient, and smaller reflectors permit easier alignment and adjustment, assuming more exotic light-gathering surfaces aren't used.

The distributed array requires more computing steps to produce an image than the SLT, but not an order of magnitude more steps.

ClaysGhost · Post by **ClaysGhost** » 2002-12-31 06:59am

A dangerous aspect of nukes, particle beams and beyond-UV lasers is the penetrating aspect of the weapon. A volume of armour is affected, rather than just the surface. The most important properties of armour in these cases are density and thickness - you want to prevent as much radiation as possible from reaching the ship's interior.

Consider a beam of neutral particles (neutrons or photons, for example) impacting on armour. To stop the beam, enough armour must be interposed between the beam and interior that most particles have run into one (or possibly several, depending on particle and energy) atoms in the armour. Obviously, thicker armour and denser armour are more effective at absorption. Very little else matters. Worrying about heat transfer into the armour may be pointless if the armour is way too thin or insufficiently dense to stop radiation penetrating the hull anyway.

Obviously, the more armour used, the more mass the ship has to tow, so the sections chosen for radiation shielding might have to be carefully chosen. The best defenses against nukes are definitely distance and preventing detonation, as stated.

His Divine Shadow · Post by **His Divine Shadow** » 2002-12-31 08:35am

Enlightenment wrote:Barring the discovery of physics as we don't know it, it's simply not possible to stealth spacecraft. The problem is heat emission: spacecraft must radiate heat (IR) or they will roast.

Ofcourse if you could controll the emission of that along a specific and narrow path, then you'd have a very effective stealth system, say some kind of system that takes waste heat and uses it to power a low-powered laser that sends away the waste heat as a laser beam.

His Divine Shadow · Post by **His Divine Shadow** » 2002-12-31 08:43am

Darth Wong wrote:Diamond has cleavage planes and near-zero ductility. You would have to be seven kinds of insane to use diamond for any structural or armour application.

What about a find coat of very small diamonds, or diamond dust on top of the hull armor? If a laser hits, shouldn't it refract it sevens ways to sunday or hell or whatever the saying is.

Ofcourse it might just be easier to have an outer mirror layer ontop of the armor to reflect energy weapons, or atleast lasers.

Enlightenment · Post by **Enlightenment** » 2002-12-31 01:44pm

His Divine Shadow wrote:What about a find coat of very small diamonds, or diamond dust on top of the hull armor? If a laser hits, shouldn't it refract it sevens ways to sunday or hell or whatever the saying is.

At the kind of energies involved with weapons lasers, the surface of the armor is going to explode pretty much no matter what coating it has. Furthermore, optics tricks are pointless against non-optical lasers.

His Divine Shadow · Post by **His Divine Shadow** » 2002-12-31 07:50pm

Enlightenment wrote:Furthermore, optics tricks are pointless against non-optical lasers.

Yeah I was wondering about that too.

Post by **Darth Wong** » 2002-12-31 08:02pm

His Divine Shadow wrote:
Enlightenment wrote:Barring the discovery of physics as we don't know it, it's simply not possible to stealth spacecraft. The problem is heat emission: spacecraft must radiate heat (IR) or they will roast.
Ofcourse if you could controll the emission of that along a specific and narrow path, then you'd have a very effective stealth system, say some kind of system that takes waste heat and uses it to power a low-powered laser that sends away the waste heat as a laser beam.

Order from disorder?

His Divine Shadow · Post by **His Divine Shadow** » 2003-01-01 02:20pm

Darth Wong wrote:Order from disorder?

You lost me now, elaborate.

I was thinking along the lines of the refigeration idea, sure overall it'd generate more thermal waste, but that'd be centered in key locations right? The refridgeration units, one could refridgerate the air on the ship into wich the majority of thermal waste ought go and then the energy required to do so ought to be localized, and possibly used to power a small laser or something to carry the shit away.

This doesn't violate any scientific principles does it? Seems to me it's not destroying any energy or something, it's just moving it.

Post by **Darth Wong** » 2003-01-01 02:22pm

His Divine Shadow wrote:
Darth Wong wrote:Order from disorder?
You lost me now, elaborate.

A laser is low-entropy. Waste heat is high-entropy. This is a problem.

Pu-239 · Post by **Pu-239** » 2003-01-01 02:23pm

What about a layer of aluminum, since it is a good conductor of heat, then some ceramic tiles on top of that which gets vaporized to carry away energy?

His Divine Shadow · Post by **His Divine Shadow** » 2003-01-01 02:47pm

Darth Wong wrote:A laser is low-entropy. Waste heat is high-entropy. This is a problem.

If you say it is, well ok then, but don't I get an explanation or something, an analogy, or something along those lines to help me actually understand what you are saying? The cross-language barrier isn't helping either, but I doubt you speak swedish.

beyond hope · Post by **beyond hope** » 2003-01-01 09:02pm

I think I get what Mike's trying to tell you: in order to create a beam from the waste heat, first you have to have the refridgeration system you mentioned to localize the waste heat. Then, you have to have a system to turn that waste heat into power. Then, that power system feeds into the laser. Best thermal efficiency for a laser is something like 20%, so four-fifths of the power you feed the laser gets lost as... more waste heat. The problem is that every step along in that process is building up more heat because heat is a by-product of performing work.

Here's a question: how about a tank of ice water on the ship as a heat sink?

aerius · Post by **aerius** » 2003-01-01 09:18pm

Pu-239 wrote:What about a layer of aluminum, since it is a good conductor of heat, then some ceramic tiles on top of that which gets vaporized to carry away energy?

You do not want aluminum. It may conduct heat well but it's quite weak and has a low melting point. The ceramics aren't going to help since they'll get shattered into pieces or blown away, shortly after which the aluminum gets slagged from the heat and/or gets holes punched through it from the flying ceramic fragments. If a projectile weapon is used it'll shatter the ceramic and punch a clean hole through BOTH sides of the ship. Aluminum makes piss poor armour due to its low strenth, hardness, and toughness.

A better idea would be aluminum plates on top of steel. The aluminum can then act as ablative armour while the steel can stand up to high energy projectiles as well as heat based weapons.

Pu-239 · Post by **Pu-239** » 2003-01-01 09:21pm

I did say layer of Al....

Pu-239 · Post by **Pu-239** » 2003-01-01 09:25pm

Anyways so I've learned ceramic is useless....

Oh for energy weaps

Here
I wonder how you will keep the plasma "sticking" to the hull though. Can you contain plasmas with magnetic fields, since they are electrically charged?
Might it also partially work against nukes since they are energy weapons releasing gamma rays? That is until it gets blasted away, when a nuke hits close.

Post by **Beowulf** » 2003-01-02 02:41am

aerius wrote:
Pu-239 wrote:What about a layer of aluminum, since it is a good conductor of heat, then some ceramic tiles on top of that which gets vaporized to carry away energy?
You do not want aluminum. It may conduct heat well but it's quite weak and has a low melting point. The ceramics aren't going to help since they'll get shattered into pieces or blown away, shortly after which the aluminum gets slagged from the heat and/or gets holes punched through it from the flying ceramic fragments. If a projectile weapon is used it'll shatter the ceramic and punch a clean hole through BOTH sides of the ship. Aluminum makes piss poor armour due to its low strenth, hardness, and toughness.

A better idea would be aluminum plates on top of steel. The aluminum can then act as ablative armour while the steel can stand up to high energy projectiles as well as heat based weapons.

*points to Al armor on armored cars and on some IFVs*

Post by **Darth Wong** » 2003-01-02 02:43am

Beowulf wrote:*points to Al armor on armored cars and on some IFVs*

Which are not built to take a lot of punishment.

Post by **Vympel** » 2003-01-02 02:47am

Darth Wong wrote: Which are not built to take a lot of punishment.

They're soft as shite. Armored cars are vulnerable to small arms fire, while IFVs are at best only protected against 20-30mm autocannon fire along the frontal arc.

Post by **Beowulf** » 2003-01-02 02:52am

Did I say that it was good armor? IT's just that using steel would make the vehicle unacceptably heavy.

Post by **Darth Wong** » 2003-01-02 02:53am

Beowulf wrote:Did I say that it was good armor? IT's just that using steel would make the vehicle unacceptably heavy.

Or it was a matter of cost.

Post by **Vympel** » 2003-01-02 03:09am

Darth Wong wrote: Or it was a matter of cost.

Both cost and weight I think.

In the case of the M2 Bradley, they thought they'd better add on some armor because it was too easily killed.

The M2A1 Bradley IFV weighs 22 tons. The M2A2 which added on applique steel armor plating jacked the weight up to 33 tons, IIRC.

In the end, you're going to have to spend some major cash to make an IFV that can withstand modern weapons- even the 33 ton applique armor Bradley couldn't take a hit from a modern RPG-7 round and survive.

Connor MacLeod · Post by **Connor MacLeod** » 2003-01-02 03:40am

Darth Wong wrote:
Beowulf wrote:Did I say that it was good armor? IT's just that using steel would make the vehicle unacceptably heavy.
Or it was a matter of cost.

Quick question mike.. when you were dealing with Syntax you mentioned some refractory materials (refractory tungsten and ceramics) as well as a "superalloy" - I was wondering if you could elaborate a bit about those (IE what they are/do/used for.)

Post by **Darth Wong** » 2003-01-02 03:57am

Connor MacLeod wrote:Quick question mike.. when you were dealing with Syntax you mentioned some refractory materials (refractory tungsten and ceramics) as well as a "superalloy" - I was wondering if you could elaborate a bit about those (IE what they are/do/used for.)

There are certain exotic metals which are used for applications such as jet turbine blades (didn't you ever wonder what they made those out of?) which require a set of characteristics impossible to meet with other materials.

A jet turbine blade requires high temperature strength and good creep resistance, but it also must have excellent tensile strength, because there's a fuckload of centrifugal force involved here. So ceramics are out, and that means you need something made of metal, but which won't creep at the high temps. Enter superalloys: alloys with lots of alloying elements designed for elevated-temperature strength.

Nickel-based superalloys have good creep resistance up to beyond 1000 degrees C, and good resistance to corrosion as well. Cobalt-based superalloys are even better, but very expensive. Haynes 25 (no, it's not a fucking underwear) is 50% Cobalt, 20% Chromium, 15% Tungsten, 10% Nickel, and a few other sundries. Tensile strength is 135 kpsi with excellent ductility (60% elongation before failure). It's used for jet engines. Stellite 6B is 60% Cobalt, 30% Chromium, 4.5% Tungsten, and a few other sundries. Tensile strength is 177 kpsi. It's used for abrasion resistance (and the M60 gun barrel, IIRC).

MAR-M246 is also used for jet engines, and it's 10% Nickel, 9% Cobalt, 10% Chromium, and a bunch of Tungsten, Titanium, Aluminum, and Tantalum (real smorgasbord). It's good for 140 kpsi, but it's not as ductile as Haynes 25.