Invisibility in Space

[rust]

It didn't help that the 'stealth' aircraft in question was flying low, slow and above all, the same bloody route every day. Sheer bloody stupidity trumps every defensive aid going...

Yes, once the defenders know that some stealth craft is within their reach,
it is only a matter of time to find some method to get a warhead with a
proximity fuse close enough to damage it.

 

[BFalcon]

opening your weapon bays or banking too sharply suddenly makes you much more visible to your hunters...

Never, ever try and attack something in an F-117. Their stealth coverage is poor as it is, particularly with that great big flat bottom. Also, never bank, use your rudders...

Also, fly something better, like an F-22...

Well, in all fairness, the last stealth simulator I flew was the "F-19" years before the F117 was revealed to the world, but they had the key features right about the various flaws, so...

But good advice - will try to remember it if I ever get to fly another sim with decent stealth simulation...

 

[CosmicGamer]

Is your opponent looking in the right direction at the right time to catch you passing in front of a star... ...If you are in the segment of sky being scrutinized, you will almost certainly be spotted. If they aren't in that sensor mode, you might get away unnoticed.

I would think most sensors of the future could either look in all directions at once or scan in all directions fairly quickly. Perhaps this is accomplished by utilizing a sensor array.

 

[SSWarlock]

Why not just "bend" the EM energy around the ship? Researchers have been doing that since at least 2008 using specialized metamaterials.

http://news.nationalgeographic.com/news/2008/08/080812-invisibility-cloak.html

 

[DFW]

Why not just "bend" the EM energy around the ship? Researchers have been doing that since at least 2008 using specialized metamaterials.

http://news.nationalgeographic.com/news/2008/08/080812-invisibility-cloak.html

Could work against active EM like radar. Won't help with passive IR sensors.

 

[SSWarlock]

*ponderponder*

Could a ship's IR sig be "diluted" enough to be useful by cooling the radiators with hydrogen fuel? Kinda like mixing a jet fighter's engine output with cool air?

 

[DFW]

*ponderponder*

Could a ship's IR sig be "diluted" enough to be useful by cooling the radiators with hydrogen fuel? Kinda like mixing a jet fighter's engine output with cool air?

No. The net amount of heat radiated to space doesn't change doing that. Jets can mix it with the air they fly through. In space you can only radiate where you are. What would you do with the LHyd once you used it to cool? It would have to be dumped. To IR sensors (if you were accelerating) you'd look like a bright comet with a tail.

 

[far-trader]

...To IR sensors (if you were accelerating) you'd look like a bright comet with a tail.

Captain "Sensors, contacts?"

Sensors "Just a comet sir."

Captain "Very well, sweep the next sector."

(The PCs sigh with relief, their plan is working, they have gotten by the Ref's little picket patrol... )

Sensors "Sir. That comet... is accelerating, against the gravity well."

Captain "Weapons, get me a targeting solution on that 'comet' and prepare to fire."



:twisted:

 

[phavoc]

*ponderponder*

Could a ship's IR sig be "diluted" enough to be useful by cooling the radiators with hydrogen fuel? Kinda like mixing a jet fighter's engine output with cool air?

No. The net amount of heat radiated to space doesn't change doing that. Jets can mix it with the air they fly through. In space you can only radiate where you are. What would you do with the LHyd once you used it to cool? It would have to be dumped. To IR sensors (if you were accelerating) you'd look like a bright comet with a tail.

I guess an robotic ship would work better, since it would generate less heat. Would it be possible to super-cool your fuel, and then dump your heat into your fuel tanks for as long as it would hold out?

 

[rust]

Would it be possible to super-cool your fuel, and then dump your heat into your fuel tanks for as long as it would hold out?

The normal temperature for liquid hydrogen is ca. 20.28 Kelvin, the
background radiation of the universe is about 2.725 Kelvin. If you cool
the hydrogen below ca. 14 Kelvin, which is still more than 10 Kelvin
warmer than the background radiation, it ceases to be liquid, and you
can no longer use it as fuel.

Therefore the idea to use a robotic ship would not solve the problem,
your entire fuel would still have to be ca. 10 Kelvin warmer than the
background radiation, or your reactor would cease to work.

 

[DFW]

Therefore the idea to use a robotic ship would not solve the problem, your entire fuel would still have to be ca. 10 Kelvin warmer than the
background radiation, or your reactor would cease to work.

Not to mention, you have a nuc reactor. That's a LOT of heat that eventually all radiates from the hull.

 

[atpollard]

TL 14 Thermocouples convert heat to electricity which powers a laser to 'radiate' unwanted heat as a laser beam. If your sensor array is 'lucky' enough to be in the right place at the right time to detect the 15 cm diameter beam ... pop, direct hit to sensors.

 

[DFW]

TL 14 Thermocouples convert heat to electricity which powers a laser to 'radiate' unwanted heat as a laser beam. If your sensor array is 'lucky' enough to be in the right place at the right time to detect the 15 cm diameter beam ... pop, direct hit to sensors.

To quote: "What's the problem? Well, the general problem is that pesky Second Law of Thermodynamics. In this context, it tells you that it is impossible to destroy heat, the best you can do is move it around. So using a thermocouple to convert heat into electricity is impossible.

The specific problem is that a thermocouple does NOT convert heat into electricity. It converts a heat gradient into electricity. The original heat is still there. In fact, the conversion process adds even more waste heat to the original total."

 

[atpollard]

While quite true, isn't it a little late to worry about thermodynamics?

(We've already thrown out Conservation of Momentum and Relativity with reactionless drives that can exceed the speed of light - MD not JD).

Would you prefer a heat pump to cool the ship and heat hydrogen to fusion temperatures to expel a beam of particles?

 

[DFW]

While quite true, isn't it a little late to worry about thermodynamics?

Nope. Only toss out what MUST be. Not at a whim. Otherwise you slide quickly towards playing D&D...

Considering that they already got it right in the CRB, no need

 

[rust]

While quite true, isn't it a little late to worry about thermodynamics?

Well, "solving" this problem by eliminating thermodynamics would lead to
lots and lots of new problems on other fields of the technology of the set-
ting.

For example, my next Traveller starship would have a thermally super-
conductive hull coating and an advanced thermocoupling. Whenever the
ship is hit by a laser, the thermally superconductive hull coating imme-
diately transfers the heat to the thermocoupling, where is is converted
into electricity and used to power the laser which returns the fire ...

 

[far-trader]

...
(We've already thrown out Conservation of Momentum and Relativity with reactionless drives that can exceed the speed of light - MD not JD).

Have we? I don't recall anywhere that it is stated that any Traveller maneuver drive (reactionless or otherwise) can exceed the speed of light. And several sources specifically mention slower than light ships using maneuver drive. Is there somewhere that Traveller says it permits breaking the speed of light?

 

[far-trader]

As for the whole thermodynamics issue, it's a mess. One simple handwave to allow ships to not melt from their own heat emissions is that the jump drive includes a pocket universe heat dump. Thus not only preserving the life and material of the ship, but also permitting a degree of stealth by way of (at least for starships) not being a beacon of heat. No radiators, no venting coolant, just routed through the jump drive and bled into another dimension. As long as you have a functional jump drive and operating power plant.

 

[DFW]

As long as you have a functional jump drive and operating power plant.

AND, you are IN jump space... Otherwise, no. There's NO rule that allows you to "switch on" a J-Drive and just leave open a hole to dump energy into. Complete fabrication on your part...

 

[phavoc]

Would it be possible to super-cool your fuel, and then dump your heat into your fuel tanks for as long as it would hold out?

The normal temperature for liquid hydrogen is ca. 20.28 Kelvin, the
background radiation of the universe is about 2.725 Kelvin. If you cool
the hydrogen below ca. 14 Kelvin, which is still more than 10 Kelvin
warmer than the background radiation, it ceases to be liquid, and you
can no longer use it as fuel.

Therefore the idea to use a robotic ship would not solve the problem,
your entire fuel would still have to be ca. 10 Kelvin warmer than the
background radiation, or your reactor would cease to work.

Well, the idea would be to start off with your fuel as ice, and then as you dumped heat into it, it would thaw and become liquid again. It wouldn't be hard to have a few hundred liters to start off with.

Of course, the easiest way to avoid this would be to ensure your path was coming from some other object that may be generating a heat signature of its own, so you minimize detection possibilities. Space is BIG, and I don't think you could conceivably track every IR signature and run it down.