tharkûn wrote:
You are forgetting the nature of them system. Let's begin with a set up like this:
Cooling mechanism|Heat sink|water|hull
Heat will be conducted from the hull to the water, from there to the heat sink, and then your cooling mechanism will exchange that out into the environment.
So once you get everything done you evacuate the water and turn off the cooling mechanism leaving
Rest of ship|Heat sink|vacuum|hull
Now heat flows from the rest of the ship into the heat sink. However nothing flows across the vaccum to the hull.
Won't the water freeze at some point?
And how would you flash-cool something of starship size and mass?
1. Flood the surface area with a colder liquid.
2. Use laser cooling.
3. Possibly use a transporter to cool the hull further (i.e. beam hot atoms out into a cold bath, cool them, and beam them back into the centre of the hull).
1. This is getting more expensive by the second compared to a conventional ship. You would need massive amounts of cryogenic support.
2. Materials suitable for laser cooling are not necessarily good hull materials.
3. That's mad. What happens if you
Isn't that rather more difficult to do when the medium you're moving through is 1000 times less dense than water and you're moving maybe 1000 times faster than a torpedo?
It's much easier when you have ST technobabble to do it. High strength B feilds would allow you to move the air without heating the hull.
I'm having real trouble thinking of a magnetic field configuration that would do this uniformly, or even effectively. And it wouldn't exactly be energy-cheap.
The hull cannot have a low specific heat capacity, so you must find a material with a horribly low specific heat capacity or you will be towing significant amounts of heatsink.
Or using something with an even greater specific heat capacity. For instance uranium has spefic heat capacity which is 30 times less than that of lithium. Other substances have even higher specific heat capacities, besides which your hull itself can be cooled. Its all relative and most metals have low specific heat capacities.
I can gaurantee you that building a heatsink out of uranium is not a good idea
(I assume you mean other materials have even lower specific heat capacities).
Using the hull as your heatsink sort of defeats the object of the exercise.
Your power plant will supply the engines for a shorter time but at a higher power level, so your heatsink will have to absorb the same amount of waste energy
Unless of course while you make your acceleration burn you dump heated gas out the back.
Well, that will radiate, will it not?
Unless it's a magic engine, that will have be a very large heat sink. And if the engines happen to be pointing at something with a detector when you fire them, you're screwed, heatsink or no.
Nope. The heat of the engines can be ejected with the propellant. The engines only give you away if you don't dump some decoys (basically big cloaked thrusters). Remember unless we are talking about FTL drives, your waste is going to be going at STL speeds. With FTL drives they have to catch up to you before they can do anything ... when they get close ... drop a decoy and then drop to STL and go silent running.
Cloaked decoys. Isn't that rather daft? Aside from the idea of a decoy nobody can spot, you also have to cool them down before the launch too!
I'm talking about thermal radiation from the hull. As for finding the ship, the problem is one of sky area, not volume, unless you believe that lying B5 show, and both uncloaked and cloaked ships will have the same problem.
Fine radiation from the hull. It drops off by the square of the distance as you get away from the hull. Let's say you had a borg sphere 2km across and say the photons have diffused enough after 500 km they are no longer discernable from the background (please note this is a 250,000 fold drop in intensity). Now take the surface of that 1000 km sphere and compare it to the surface area present in a solar system ... yep same problem.
Your emissions are going to diffuse, and they do so with the radius squared. It does not take long for a cold ship to be indistinguishable from the background.
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You wouldn't believe how little radiation you need to make material detectable out there. 10^-26 Watts per square metre per Hertz is considered bright at radio frequencies, for example.
Even with that kind of search area, using sensors based on interferometric principles you could search for a spacecraft electronically. Plenty of things radiate in space, but they tend to be very hot or background, i.e. they don't look like a spacecraft.
only up until the signal is drowned out by the background. And evertything's heat signature in space ends up looking like a sphere, if you cool the hull to close to the ambient background ... you won't look much different.
As I've been arguing, that's really difficult to do at a level that could defeat a reasonable sensor system. You've got a flying ultracold ship with a large heatsink that requires massive ground support facilities, can cloak only once and has to carry cloaked decoys whenever it needs to maneovre. Even if the sensors couldn't detect you, they've certainly made you less tactically effective. Once you close to whatever (suspiciously small) range this cloak is supposed to get you within, as soon as you fire you've had it. You'll be hit at least once, unless you're very lucky or you can guarantee a one-shot kill, which unless the enemy weapons are underpowered will not do much for your stealthy hull. What kind of weapons are so short-ranged that a cloak provides an advantage? Spend the space and energy on making the ship more resilient and resistant.
Now I thought cool objects would be invisible to sensors, so why do you care about maneovreability?
Area effect counter measures
. If they know the direction is being fired from they can take a counter shot on likely trajectories and fry everything within distance. Just because they can't see it doesn't mean they can hit it, especially if they opt for saturation coverage. One of the ways to kill subs is to simply saturate the area with depth charges. Area effect is bitch if it ain't on your side.
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It's volume effect, surely, and isn't it substantially less effective when there isn't a nice dense medium to carry pressure waves?
1) EM In Space: We can detect it now. It's not invisible or undetectable just because space is big and empty.
No but it does get drowned in the background. In an NMR machine you can pick up the radio transmissions from individual hydrogen nuclei ... rarely can you here them next to a commercial broadcast station. As intensity decreases with radius squared ... its a small area where you can detect it from. If your blackbody radiation is the same as the background ... EM detection is not worth much.
We can detect objects now that emit less energy over 50 years in the relevant band than would be required to melt a snowflake, and we do pretty well at filtering out commercial broadcast stations. EM detection is not bad nowadays.
