Posted by: ollobrains
« on: February 20, 2012, 03:15:51 PM »Stealth probes are an interesting idea to drop em off have em sit idle until something flies nearby and it might give a partial report given its stealtehd nature
You may express contempt for the discussion, but this entire thread is about how to make stealth more realistic;
[snip] . . . the whole discussion comes down to the following points:
A) Stealth for manned Ships is extremely hard in real space. So much for the basis.
B) Stealth in Aurora is too easy to achieve, and excruciatingly boring in that way; Emisions can not only be reduced, but eliminated.
C) The only way to reliably defend against stealth in current Aurora is absolutely humongous Active sensors, as passives become completely useless as soon as an enemy turns of his shields and stops moving.
This implies that the following changes could be useful:
A) A revamp of the range collection, lying somewhere between the current linear and the realistic sqrt range falloff. Maybe half sig=1/3 detection range or something.
A1) Possibly increase range of passives sightly, maybe only for military ships, allowing hide and seek if one raids civies.
B) Giving Crew Quarters, weapon systems, and reactors their own heat signature. While it may be small, and with the current sensor system would still allow to evade detection, it will make passives more useful as theres always a small bit of radiation. Maybe not enough for someone not actively searching, but certainly enough for an Asteroid-Based DTS.
Shields might be able to mask it, but emit stronger EM
C) Allow passives, within a fraction of their range, say, 50%, to give a target id, at a steep hit penalty, for non-homing projectiles.
I have a few Bad Ideas™
[snip]
Perhaps adding a time lag to detect signatures based on 1% chance per sensor per minute + Crew Experience(s) if within passive sensor strength at the target ships signature output.
[snip]
Cloaking could be made to make a flat negative roll on the chance to be detected. Or better yet could cost power to produce a field that when the detection rolls say you should have been detected could cost power to make it remain negative. As well as a flat operation power cost.
[snip]ships with a hyperdrive could have a component added into the engines to generate a place to vent thermal radiation and unwanted materials. Heatsinks can become thermal batteries that need to be drained by venting directly into hyperspace. The downside to this could be that dedicated search sensors such as Deep Space Tracking can detect hyperspace signatures. A Hyperdump™ can be detected but the presence in system can remain unknown. Allowing ships designed from the ground up for power capacity, fuel effency and reduced emissions to perform good stealth missions but not much else since size will need to be kept to a absolute minimum.
drive-by nuclear holocaustinstead of a direct assault by otherwise stealthy ships.
The two-day trajectory is more defended because on your two-day trajectory everyone in the solar system sees you and where you are going, so the defensive fleet is waiting for you, or intercepts you. The idea that there exists a solution to "set up your vectors right" so that interception is impossible doesn't really seem to be a valid assumption.The problem is simple. The stealth ship in question has to remain undetected until it's too late for the intercept to occur. The conventional ship has to come in too fast for the intercept to occur. If the defender can have a fleet on station in 2 days, then the stealth ship must remain undetected until 2 days before it strikes. Actually less, unless you want to lose the ship. I find that sort of thing (over a long mission, no less) hard to credit.
I agree that there is a little bit of hand waving, but if you filter out the existing plasma and only let out the helium that have already emitted their photons to leave their excited state then they aren't going to randomly reignite into plasma once they leave the reactor.The plasma will remain as plasma until after it leaves the reactor. Your problem is twofold:
That's not true. If the stealth ship is detected two months into it's journey then it is two thirds of the way there. It fires up its normal engine and gets there in ten days, the stealth system gave it 20 extra days to play with the Sorium harvesters and begin their escape trajectory. Sure the fact that it has a normal engine and a stealth engine may mean that its shields are halfsize, or it doesn't have as many weapons. But how many weapons do you need to destroy undefended Sorium Harvesters in twenty days?I'm not sure where you're getting this from. You would get 20 extra days, assuming it takes the enemy 30 days to respond. But they will take 30 days to respond from the detection of any ship. Period. Thus, if I can get a conventional ship to the harvesters within 30 days, I can use it, too. Based on the above numbers, it takes twice as long to do something with the stealth drive as the conventional drive. What if I replace the stealth drive with more conventional drives, and use that instead?
Reasonable thrust and specific impulse. A thermal engine can have much, much higher specific power then a non-thermal drive. And why would the two-day trajectory fleet be more defended? If you set up the vectors right, then they can't intercept you in the available time.The two-day trajectory is more defended because on your two-day trajectory everyone in the solar system sees you and where you are going, so the defensive fleet is waiting for you, or intercepts you. The idea that there exists a solution to "set up your vectors right" so that interception is impossible doesn't really seem to be a valid assumption.
Nope. The fact that it is plasma is a function of its temperature. The helium in question will also be plasma, and you will have to use several kinds of magic to neutralize it before you can spit it out. Not to mention keeping it that way.I agree that there is a little bit of hand waving, but if you filter out the existing plasma and only let out the helium that have already emitted their photons to leave their excited state then they aren't going to randomly reignite into plasma once they leave the reactor.
Everyone has agreed that, by nature, a stealth ship is going to suffer severe performance penalties compared to a conventional ship. I believe that detection timescales will be such that a stealth ship offers no advantages over a conventional ship. If it takes the SS three months, and the CS a month, then if the SS is detected a month out, it's no more effective, and more expensive for its combat power.That's not true. If the stealth ship is detected two months into it's journey then it is two thirds of the way there. It fires up its normal engine and gets there in ten days, the stealth system gave it 20 extra days to play with the Sorium harvesters and begin their escape trajectory. Sure the fact that it has a normal engine and a stealth engine may mean that its shields are halfsize, or it doesn't have as many weapons. But how many weapons do you need to destroy undefended Sorium Harvesters in twenty days?
Foolish question on IR (thermal imaging) As I understand it IR cannot be used through object. Example as if your inside a dumpster then the IR signal that will be picked up is a dumpster, not the person in it, unless you are up against the side of the dumpster transferring the heat, then you would see a hot spot.Over the short term, you are correct. Over the long term, you would heat up the dumpster. We just don't notice due to the enviroment being relatively close to your body's temperature already.
What if a spaceship had a large non conductive heat web in front of the vessel that does not conduct heat or is very minimal, with a reflective membrane on the inside to reflect the heat back. then it would hide the main heat of the ship, depend on the web you would get a aurora around the web of IR. Or would you? IR detection relies of IR waves heading towards the sensor. If those waves are not heading towards the sensor then you not pick up the IR or thermal image. It would be no different to say hiding behind an asteroid.That wouldn't really work. Some heat would be absorbed, which would heat up the shield. And as mentioned above, the reflected heat would compound your problems. It might help some, but also as mentioned above, 180 degree stealth isn't terribly useful.
You may not be able to get 360 degree stealth, but you may be able to achieve 180 degree stealth.
Also with all the stars in the night sky producing IR, if you are in front of one would it blind the receiver of an object.Actually, that's backwards. If you're in front of the star, the observer would be more likely to notice a star missing, and conclude that something was there. A star is going to have an angular size much smaller then your vessel.
That depends on your definition of practical. A craft with .1g acceleration may not seem practical when their opponents have 3g acceleration, but for some missions it may be worthwhile. Sending a team on a three-month trajectory to destroy a poorly defended Sorium harvesting fleet can be better than sending a team on a two-day trajectory to destroy a heavily defended Sorium harvesting fleet.Reasonable thrust and specific impulse. A thermal engine can have much, much higher specific power then a non-thermal drive. And why would the two-day trajectory fleet be more defended? If you set up the vectors right, then they can't intercept you in the available time.
The plasma has to be at the site of the fusion, it doesn't have to be anywhere else. Hydrogen is fusing right before your engine nozzle, then sure, you are spitting out a huge plume of helium spray and plasma. However if you are fusing the hydrogen in an internal reactor and using a magnetic screen to divert the flow of plasma so it remains in the reactor while the neutral helium molecules are shot out as thrust then that's completely different. You now have a stealthy engine, albeit a more complicated, lower thrust engine that has huge thermal issues since it's not expelling most of the heat that its reactions produce.Nope. The fact that it is plasma is a function of its temperature. The helium in question will also be plasma, and you will have to use several kinds of magic to neutralize it before you can spit it out. Not to mention keeping it that way.
You have to know where every single picket is to guarantee stealth. You don't need to know where any pickets are to have a better (aka non-zero) chance at stealth. Make sure that your emissions aren't pointing near any planets/moons, comets and pray. Remember that the theoretical goal of stealth is to be perfectly invisible to your enemy, but the practical goal of stealth is to buy you as much time before detection as possible.This assumes that lack of time before detection can enhance the performance of the mission. That is only true for extremely short timescales.
If two months into your three month trip your emission sweeps across a picket you don't know that, but if at that point the enemy fleet around their home planets fires up their engines and heads straight at you or your target then you know that somehow you were detected, and it's time to switch to your "practical" engines. You weren't able to get all the way to your target without being detected, but your stealth systems got you a lot closer than you otherwise would have.
You shouldn't do, if the forums keep to their same friendly aspect and people respect other rights to differing opinions
Foolish question on IR (thermal imaging) As I understand it IR cannot be used through object. Example as if your inside a dumpster then the IR signal that will be picked up is a dumpster, not the person in it, unless you are up against the side of the dumpster transferring the heat, then you would see a hot spot.
What if a spaceship had a large non conductive heat web in front of the vessel that does not conduct heat or is very minimal, with a reflective membrane on the inside to reflect the heat back. then it would hide the main heat of the ship, depend on the web you would get a aurora around the web of IR. Or would you? IR detection relies of IR waves heading towards the sensor. If those waves are not heading towards the sensor then you not pick up the IR or thermal image. It would be no different to say hiding behind an asteroid.
You may not be able to get 360 degree stealth, but you may be able to achieve 180 degree stealth.
Also with all the stars in the night sky producing IR, if you are in front of one would it blind the receiver of an object.
Engines that produce plasma are pretty much the only option on the table for practical space travel.That depends on your definition of practical. A craft with .1g acceleration may not seem practical when their opponents have 3g acceleration, but for some missions it may be worthwhile. Sending a team on a three-month trajectory to destroy a poorly defended Sorium harvesting fleet can be better than sending a team on a two-day trajectory to destroy a heavily defended Sorium harvesting fleet.
That's just impossible. You cannot have a fusion reaction without very hot plasma.The plasma has to be at the site of the fusion, it doesn't have to be anywhere else. Hydrogen is fusing right before your engine nozzle, then sure, you are spitting out a huge plume of helium spray and plasma. However if you are fusing the hydrogen in an internal reactor and using a magnetic screen to divert the flow of plasma so it remains in the reactor while the neutral helium molecules are shot out as thrust then that's completely different. You now have a stealthy engine, albeit a more complicated, lower thrust engine that has huge thermal issues since it's not expelling most of the heat that its reactions produce.
This requires perfect stealth and perfect detection to coexist. I dealt with this earlier in the thread, but, fundamentally, directional radiation is impractical because you have to know where all of the enemy's pickets are. And the picket can be the size of Voyager, with a decent IR camera.You have to know where every single picket is to guarantee stealth. You don't need to know where any pickets are to have a better (aka non-zero) chance at stealth. Make sure that your emissions aren't pointing near any planets/moons, comets and pray. Remember that the theoretical goal of stealth is to be perfectly invisible to your enemy, but the practical goal of stealth is to buy you as much time before detection as possible.
I'm going to regret this, but thoughts and opinions on the above are welcome.
When people say things like "using current technology we have the ability to spot a 0o C ship from 50m kilometers away what sort of field of view are you talking about? Is this a sensor looking out over an entire hemisphere, or a 1 degree cone of sky?Whole sky scan over a couple of days, which is plenty of time at that range.
Also something to keep in mind about engine efficiency is that while the more efficient the engine the less energy is released as heat, the higher the temp of the plume that is released. This may not be that important of a point though, since I am guessing that Steve will have the Thermal Sensors purely based on the power of the heat produced, and not the actual wavelengths of lights produced. (Although designing sensors that were the most sensitive at different wavelengths would be a pretty cool design metric if it wasn't overly complicated, especially since this may allow ways to pick up fighter engines. If fighter engines are less efficient that would mean that the plume was cooler (makes sense, as the plume would be smaller, so the center of the plume would be closer to the nozzle wall, meaning it would have to be cooler), meaning that if your sensor was more sensitive to the lower wavelengths you would see cooler engines (fighters) earlier than their larger ships. Another important point about that is that (As done in The Mote in God's Eye) you can guess from the temperature of the drive how efficient the engine technology is).The temperature of the exhaust is inherently related to the exhaust velocity in gas/plasma engines, which is the rocket equivalent of fuel efficiency. As to actual efficiency, thermal engines (which includes most types explicitly described in Aurora) convert the heat of the gas into motion. That is going to leave a lot of heat anyway. You can't cool it enough to hide the exhaust.
I also think that everyone may be a little hung up on one form of propulsion, the enormous cone of plasma thermal radiation in every direction (even in front of the ship since the plume will be bigger than the ship). Other forms of propulsion may not have the same lack of subtlety. So far the only example of an alternative drive in that of a mass driver, which could work, although it is admittedly low in acceleration. (Although I would add that in addition to the actual projectiles a Railgun would certainly emit some sort of muzzle flash, a Coil Gun may be able to avoid that). Another alternative would be a laser engine, this would take up a huge amount of power, but would only be visible in a small cone along the thrust vector (ignoring reflections off of asteroids, other ships, and even dust. In a Nebula this would be a very visible form of travel), an Ion engine is another example.Engines that produce plasma are pretty much the only option on the table for practical space travel. I find mass drives very iffy for any sort of reasonable propulsion, not to mention venting the waste heat. Lasers are completely impractical for onboard use. 300 MW/N is never going to be adopted by anyone in the forseeable future. And ion engines do produce plasma, if slightly colder then, say, fusion.
For another fairly invisible form of propulsion look no further than alpha radiation. A lower thrust fusion engine may just be able to fuse those Hydrogen atoms and toss the helium atoms out the back at relativistic speeds without the signature plasma tail, if it was being slower and more careful with it's reaction to avoid all the plasma.That's just impossible. You cannot have a fusion reaction without very hot plasma.
Now obviously all of these methods require that the heat from your reactor be expelled in a very targeted way, because if they can see your ship then seeing your exhaust doesn't matter. However, if that can be attained you can also get stealthy movement, albeit much more slowly than a large, high-thrust rocket. I don't know exactly how Steve would model all of this stuff, would it be very hard to model ship emissions as cones (/ triangles in 2d)? The engine emission cones would always be in the direction of thrust, and maybe the thermal radiation would always be aft as well, or maybe you could optionally reorient it. (Or maybe it could just be handwaved as an engine with a smaller thermal signature)This requires perfect stealth and perfect detection to coexist. I dealt with this earlier in the thread, but, fundamentally, directional radiation is impractical because you have to know where all of the enemy's pickets are. And the picket can be the size of Voyager, with a decent IR camera.
Detection is a very important part of the game and this is one those areas where I think fun should take precedence over realism.I know I go out of my way to ensure nothing escapes my sight.