[Thaeris]

It seems we were on slightly different tangents, Battuta.

I did not call you stupid, I have no basis to do that. Nor would I, for that matter. I said your statements had some problems. This is where our misunderstandings must have come into play.

My focus is in terms of the plausibility of an actual design... or if it could in any way be made plausible. Thus, I'm referencing the thruster/engine positions in relation to the center of mass, etc., etc. I get the impression you are questioning combat fightercraft in space in general, which is a different matter. Correct me if I'm wrong.

As far as the TIE goes, I've often heard of the "aetheric... or whatever you call them... rudders," though I've not read any material on how that crap (which it undoubtably is) is supposed to work. Actually, a good deal of the SW references I've seen do mention thrusters, so no, my comments were not invalid. My statements were directed moreso at the general configuration, which is quite reasonable.

Lastly, I apologise if I've offended you.

-Thaeris

[General Battuta]

The design cannot be made plausible without the invocation of magical or currently unavailable and non-foreseeable technology. The ship simply has no room or allowance for 'real' engine, weapon, defensive, or control systems (the latter because it makes room for a human pilot.) Run the timescale a little forward and you hit the technological singularity which makes predictions difficult.

We should probably start a new thread on this if we're going to keep discussing it, though.

[NGTM-1R]

Stealth does not exist in space. People will be able to see you from across a star system, no matter what you're flying. Just the fact that the interior of your ship must be almost 300 kelvins hotter than space just to keep you alive will make you extremely easy to spot even if you're running with engines off. And when you do cut engines on, you have a huge neon "I AM HERE" sign coming out your exhaust nozzles.

Have to argue this point. There are lots of infrared objects out there. They're called stars. The infrared universe is actually pretty crowded. As long as you're not observably moving against the background universe, or even just moving along with the ecliptic on reasonable orbit for an asteroid or something, you can be stealthy. (For that matter, approaching from sunward.) There are also ways to cheat on this, like creating baffles to hide most of your drive flare. Depending on how you design your ship, it may not even be necessary. FS capital spacecraft, for example, presumably have a ridiculous number of hulls and even more compartments which aren't in use in combat. They don't need heatsinks at a certain point; they can empty everything outside the main areas of atmosphere and cool the external hull artificially or by radiation.

Also there's the range issue to consider. You are emitting a very small relative signal, in a very big place. There is every reason to believe that you could be undetectable halfway across a solar system, even if you were under weigh and actively radiating, because it takes a really big friggin' antenna to pick you up at that distance, something that would be constantly getting shot away on a combat ship and so isn't likely to be added.

And given light lag, even detecting someone at that distance, they still have a relative degree of stealth.

[Akalabeth Angel]

"There ain't no stealth in space:"

http://www.projectrho.com/rocket/rocket3w.html#nostealth

[NGTM-1R]

What he's declining to mention, again, is antenna size and complexity.

Simply detecting something is also not good enough. You have to classify it as an active spacecraft and a hostile.

[Akalabeth Angel]

What he's declining to mention, again, is antenna size and complexity.

Simply detecting something is also not good enough. You have to classify it as an active spacecraft and a hostile.

To quote the page (since I don't know anything really):

What Sensors Reveal

When the enemy spots your ship by the exhaust plume, it not only knows that a ship is there, it also knows the ship's exhaust velocity, engine mass flow, engine power, thrust, acceleration, ship's mass and ship's course. Not only can it tell a warship from a cargo freighter with all that information, but it can also tell the class of warship, and maybe make a good stab at determining which particular member of that class it is.

In more detail: as mentioned above, propulsion system's exhaust velocity is revealed by the doppler shift in the emission lines, mass flow is revealed by the plume's luminosity, the thrust is exhaust velocity times mass flow, acceleration is revealed by watching how fast the plume origin changes position, ship's mass is thrust divided by acceleration, and ship's course is revealed by plotting the vector of the plume origin.

This means that painting the ship with camouflage in an attempt to disguise its identity is pretty pointless.

Remember the light-speed lag. Light moves quickly, but not at infinite speed. It takes about eight minutes to travel one astronomical unit. So if you are in orbit around Terra and you observe a spacecraft near the Sun with a telescope or radar, you are actually are seeing where the ship was eight minutes ago. By the same token, if you change course it will be eight minutes until the Sun-grazer ship will know.

[NGTM-1R]

And as we were posisting stealth mainly in the context of running silent with your engine off, you miss the point. Next please.

Also these things become significantly less likely again at range. This is a rather unwarrented application of the principles behind unique sonar signatures of ship propulsion to space combat. At the ranges at which combat occurs in FS, most of those things are reasonable. At interplanetary ranges, and failing to consider the possiblity a ship will not always be running at max thrust/design choices/other factors, not so much.

Also antenna size, fragility, and complexity were not addressed.

[c914]

Stealth does not exist but "stealth" (in marks) exist as exit on B-2 F-117 and F-22 it a ability do minimize your profile at enemy scanners. In space ship stealth ability mostly will depend on which side of system star your enemy is or does it hide in shadow of a planet and other objects. Our solar stem is a HUGE empty space which in you can run silent just like subs. Even if enemy find your engine trails when you change your course due to light speed restrictions your data  always will be late for few hours.

Only two thing will be sure where they are, planets and installation orbiting them. Other spaceship will move separately, silent, and covered. Gathering together when major assault will be ordered (just like wolf packs in WWII)

[Tomo]

So if the vehicle is manoeuvring via reaction mass, it cannot be stealthy. While you cannot necessarily know the 'peak' output of a given engine using exhaust plume alone, you can determine the technology class once you've observed them for a very short time - photon drives sparkle off dust particles, ion plumes look like x, chemical rockets look like y.
(Photon drives are probably the most stealthy, assuming that the drive is not pointed towards an observer.)

Unless your blackbody emission exactly matches the emission of your background, you will be inherently detectable by passive sensors because all anyone has to do is look in the low-frequency electromagnetic domain and watch for anything that doesn't match the background.

This detects all radiating objects. Yes, you may not immediately know the precise nature of an object, but if you (or a friendly) been there before you can know what use to be there and compare it with what's there now.

Sensor range is only limited by the resolving power of your (radio) telescope.

If we accept Einstein's Gravity Waves, then the radiation doesn't even matter as you can use the gravity waves of any moving object. This is probably harder due to the ludicrous amount of background waves, but not impossible.
(On the other hand, we've not detected gravity waves yet so they may not exist.)

[Akalabeth Angel]

And as we were posisting stealth mainly in the context of running silent with your engine off, you miss the point. Next please.

Oh, I see well let's look at the webpage for that then shall we?

The maximum range a ship running silent with engines shut down can be detected with current technology is:

Rd = 13.4 * sqrt(A) * T2
where:
Rd = detection range (km)
A = spacecraft projected area (m2 )
T = surface temperature (Kelvin, room temperature is about 285-290 K)

If the ship is a convex shape, its projected area will be roughly one quarter of its surface area.


So take what a Deimos? Which is roughly 700 by 200 by 222 metres?
So one quarter of the surface area is 150,443 m2

Rd = 13.4 * (388) * (81225)

So detection range for a Deimos with engines silent is 422,305,020 km or basically 3 AU.

So given current tech it's not detectable halfway across the solar system, but it is detectable a damn long way away.

And what does attenae size have to do with anything? You think ships aren't going to mount sensors?? How many ships in a realistic universe are going to survive one  battle to care about whether their detection systems are intact or not?? Detection I imagine would be done with telescopic lenses, ie like the Hubble etcetera. Just put it behind a strong clear material.

Stealth does not exist but "stealth" (in marks) exist as exit on B-2 F-117 and F-22 it a ability do minimize your profile at enemy scanners. In space ship stealth ability mostly will depend on which side of system star your enemy is or does it hide in shadow of a planet and other objects. Our solar stem is a HUGE empty space which in you can run silent just like subs. Even if enemy find your engine trails when you change your course due to light speed restrictions your data  always will be late for few hours.

Only two thing will be sure where they are, planets and installation orbiting them. Other spaceship will move separately, silent, and covered. Gathering together when major assault will be ordered (just like wolf packs in WWII)

The data will be a few hours late but when engagement times are measured in  days if not weeks or months does it really matter?? They'll see your burn, your course corrections, etcetera and so on.

[NGTM-1R]

Oh, I see well let's look at the webpage for that then shall we?

Numbers are unsourced and almost certainly wrong. Sure, Chandra can do that. Chandra is in no way practical for a combat ship to carry.

And what does attenae size have to do with anything? You think ships aren't going to mount sensors?? How many ships in a realistic universe are going to survive one  battle to care about whether their detection systems are intact or not?? Detection I imagine would be done with telescopic lenses, ie like the Hubble etcetera. Just put it behind a strong clear material.

Antenna size has everything to do with it, as Herra explained. Don't strawman on me, I'm not on you. We're not talking about a realistic universe, either, and you said as much by comparing the Deimos. We're talking about FreeSpace. It's not practical for FS ships, or indeed any combat ships, to carry huge, unwieldly, easily damaged supercooled batteries of CCD cameras in the infrared range or whatever. (Chandra is the size of a small truck, or a smaller FS fighter.) Hubble doesn't have lenses. It's not a refractor, it's a reflector, it has mirrors. No possible clear material in existence could hope to stand up to the kind of weapons fire we are talking about. And you've only opened yourself to poor field of view by bringing in Hubble-like detectors.

[Akalabeth Angel]

Numbers are unsourced and almost certainly wrong. Sure, Chandra can do that. Chandra is in no way practical for a combat ship to carry.

Well I give the webpage weight on the fact that the two people talking on there are much bigger geeks than you or I.
I'm no science wiz myself. One of the guys most frequently quoted creates boring tabletop boardgames which go for the most realistic space combat possible. Though he does like to think of himself as a greater authority than he is I think.

Antenna size has everything to do with it, as Herra explained. Don't strawman on me, I'm not on you. We're not talking about a realistic universe, either, and you said as much by comparing the Deimos. We're talking about FreeSpace. It's not practical for FS ships, or indeed any combat ships, to carry huge, unwieldly, easily damaged supercooled batteries of CCD cameras in the infrared range or whatever. (Chandra is the size of a small truck, or a smaller FS fighter.) Hubble doesn't have lenses. It's not a refractor, it's a reflector, it has mirrors. No possible clear material in existence could hope to stand up to the kind of weapons fire we are talking about. And you've only opened yourself to poor field of view by bringing in Hubble-like detectors.

Well if you're not talking about a realistic universe then basically you can do any "handwavium" to make stealth possible. Having stealth in a universe is fine if it's consistent with the backdrop and doesn't break suspension of disbelief. Realistic combat is probably fairly boring unfortunately, which is why we have movies like Star Wars and kickass games like Freespace.

Anyway I don't really want or need to debate this. Both our time could be better spent creating new content for Freespace instead (or some other worthwhile endeavour). In many ways talking on the forums is a way to procrastinate doing what should be done, for me at least anyway.

[NGTM-1R]

On the contrary. We are creating new content for FreeSpace by hashing out the rules and functioning of the universe.

[Scotty]

And as we were posisting stealth mainly in the context of running silent with your engine off, you miss the point. Next please.

Oh, I see well let's look at the webpage for that then shall we?

The maximum range a ship running silent with engines shut down can be detected with current technology is:

Rd = 13.4 * sqrt(A) * T2
where:
Rd = detection range (km)
A = spacecraft projected area (m2 )
T = surface temperature (Kelvin, room temperature is about 285-290 K)

If the ship is a convex shape, its projected area will be roughly one quarter of its surface area.


So take what a Deimos? Which is roughly 700 by 200 by 222 metres?
So one quarter of the surface area is 150,443 m2

Rd = 13.4 * (388) * (81225)

So detection range for a Deimos with engines silent is 422,305,020 km or basically 3 AU.

So given current tech it's not detectable halfway across the solar system, but it is detectable a damn long way away.

And what does attenae size have to do with anything? You think ships aren't going to mount sensors?? How many ships in a realistic universe are going to survive one  battle to care about whether their detection systems are intact or not?? Detection I imagine would be done with telescopic lenses, ie like the Hubble etcetera. Just put it behind a strong clear material.

Hold it!  Did you just use Room Temperature for the "Surface Temperature" of a ship in the vacuum of space?  I suggest you rework that.  The hull temperature of a ship not very close (in astronomical terms) to a star would be hovering about just above absolute zero.  Remember that planets are only still hot (comparatively) due to their atmospheres.

Space is about 2.725 Kelvin at any given place/time.  I will grant that it might be a little warmer than that, but not by much with no atmosphere to trap the heat.  Call it 5 Kelvin.

Using that in your equation come to just under 130,000 km.  Extremely viable for stealth purposes, considering that space is enormously empty.

[Akalabeth Angel]

Hold it!  Did you just use Room Temperature for the "Surface Temperature" of a ship in the vacuum of space?  I suggest you rework that.  The hull temperature of a ship not very close (in astronomical terms) to a star would be hovering about just above absolute zero.  Remember that planets are only still hot (comparatively) due to their atmospheres.

Space is about 2.725 Kelvin at any given place/time.  I will grant that it might be a little warmer than that, but not by much with no atmosphere to trap the heat.  Call it 5 Kelvin.

Using that in your equation come to just under 130,000 km.  Extremely viable for stealth purposes, considering that space is enormously empty.

The ship is going to radiate heat will it not?

All objects emit infrared radiation. So the ship will have to be at room temperature (or higher depending on the power systems) and will be radiating that heat into space.

[Herra Tohtori]

Thermodynamics doesn't work like that.

I could write a long post about heat transfer through matters of all sorts (basically the thermal conductivity of the wall of the space ship would be the key to determining the outside temperature of the surface in complete vacuum), but for experimental confirmation, go and see if your house's outside walls are at room temperature during wintertime. If they are, I recommend investing in something called insulation.

Space ships have good insulation because they do not want to waste energy into something like heating when they can get that as a side effect of running any devices, and in most cases space ships need to spend energy on actively cooling the ship instead.

Basically, every spaceship (like everything else, duh) needs to be in thermal equilibrium in order to not freeze or overheat. That means it needs to radiate the same amount of energy as it is receiving from the outside, plus all the excess heat that the systems are producing.

The amount of energy received depends largely on how close to a sun the ship is. For reference, Moon's surface can reach up to 107 degrees celcius during daytime, although Moon's albedo is not exactly the best of all materials. Suffice to say that on the lit side, ship surfaces are hot, on the dark side they are cold, and this has far more relevance to surface temperature than anything that is within the ship. This is not exactly a problem, since every object in space finds it's thermal equilibrium and therefore it would not exactly make it any easier or harder to separate a ship from, say, an asteroid of similar size.

The problem for space ships and stealth comes from excess heat produced by the ship's systems and appliances, and that is the only thing that can basically separate a ship from any lump of rock as far as detection goes.

However, the excess heat usually is transferred away via radiators that radiate the energy into space. Alternatively, the excess heat can be stored in heat sinks when running at stealth mode, sort of like submarines go into silent mode when trying to specifically avoid detection by passive sensors.

And even when using radiators, the ship can simply turn so that the radiators are on the non-visible side to potential observers.

The fact is, there are ways to minimize the EM signature for a limited period of time. Even completely neutralize it, should the need arise, for a while. Simply turn everything off, put a sweater on and use glowsticks for lighting and emergency oxygen supply for breathing.

Radar signature can be masked likewise - just make the ship's surface indistinguishable (via radar signal analysis) from an asteroid.

[Akalabeth Angel]

And even when using radiators, the ship can simply turn so that the radiators are on the non-visible side to potential observers.

Right you have to radiate waste heat.

You're assuming that

A - the ship knows where potential observers are
B - that observers don't have "all the angles covered" (or at least enough to make the tactic unviable).

Any radiators would also need a fairly large surface area to be effective due to the lack of any substantial medium in space if I'm not mistaken.

[Herra Tohtori]

The odds of being in the field of view of even one infra-red sensor in the system are really small. You are underestimating how big space is.

The odds of being in two simultaneously are even smaller.

[Tomo]

Thermodynamics doesn't work like that.

Irrelevant information.
In space, there is only one way to get rid of your waste heat, and that is to radiate it.

The interior of the craft will be at around room temperature at the very minimum, assuming that the crew inside are alive and relatively comfortable.

Each of your crewmembers will be creating several watts of waste heat all the time, and therefore heating up the spacecraft.
That's before the reactor or other power source comes into the equation.

The skin temperature of the vessel is only defined by the difference between the rate of heat radiated from the skin, and the rate of skin heating by internal conduction.
The latter is much larger than the former at reasonable skin temperatures, so it'll be roughly the same temperature as the internals unless refrigerated.

[Dragon]

I think the best take on stealth in space was the technique used by Minbari from B5.
Instead of trying to reduce amount of signals coming from their ships, they emited additional ones which scrambled enemy sensors and made getting a lock on them impossible.
You may know that Minbari are here, but you won't know how many, what class and where they're going, not to mention you won't be able lock your weapons on them, at least until you get clear visual contact. (correct me if I'm wrong about that, as I haven't watched B5 and I just read about this somewhere, most likely in some thread on TBP board)
Also, that's the matter in which FS also was pretty realistic, as true stealth was only used in a nebula, Lokis in ST and Shivans at the beggining of FS1 were visible on radar, but they weren't identyfied, they most likely seemed like "strange signal" to ship's computer and were so unstable that it wasn't able to aquire a clear lock. Those were the only cannon instances where stealth was used, every other instance is fan-made (I think that using stealth fighter outside of nebula would produce "strange signal" effect on hostile sensors and won't hide the ship completely).