AW Amazon Affiliate Store

confused by self-publishing? Find your way to self-publishing success in just 5 easy steps with this free how-to guide!

Editing for authors: because every writer needs a good editor.

If this site is helpful to you,
Please consider a voluntary subscription to defray ongoing expenses.


 

Welcome to the AbsoluteWrite Water Cooler! Please read The Newbie Guide To Absolute Write

Page 1 of 22 123456711 ... LastLast
Results 1 to 25 of 527

Thread: Realistic Space Warfare

  1. #1
    On Mac's double secret probation. Dommo's Avatar
    Join Date
    Apr 2008
    Location
    Oklahoma City, OK
    Posts
    1,917

    Realistic Space Warfare

    I'm an engineer by trade and training, and I'm annoyed at the unrealistic aspects of space warfare that seem to be everywhere in books and in movies. So, in my annoyances I turned to the interweb to find out some answers that I really need to know, and this site just happened to have everything AND have the math and physics to back it up.

    http://www.projectrho.com/rocket/rocket3x.html

    It's fascinating and totally alien from any form of warfare we currently know. If anything it might perhaps be closest to submarine warfare, and by close I mean close like a mouse is related to us in that it's a mammal.

    I like the site because it answers many questions, like "What would a nuke do in space, would it still create an EMP?" and "How useful are lasers?" Things of that sort. Everything is analyzed and a good number of the folks who did the posting were people who have expertise in the systems described.

    Definitely worth looking at for anyone who has a desire to write any hard sci-fi that may involve space warfare.

  2. #2
    Very cool. Thanks for the link!

  3. #3
    On Mac's double secret probation. Dommo's Avatar
    Join Date
    Apr 2008
    Location
    Oklahoma City, OK
    Posts
    1,917
    I got onto this tangent, because I can't STAND movies that try to pass themselves off as realistic.

    Sunshine, Armageddon, and the list goes on and on.

    Star Wars and Star Trek, I tend to consider fantasy, as opposed to real sci fi, so they don't really bug me all that much. It's the ones that try to play off as though they're real, that make me want to go and kill something.

    In space it just needs to accepted that there will never be dogfights. Fighters will NOT exist in space, as if you look at the hard physics, there is no real reason. You'd be better off with unmanned vessels that could accelerate in ways that would kill any living occupants. The most lethal weapon that will EVER exist, will probably be relativistic kill vehicles.

    They will be the nuke of the space era. They won't be used, because there is no defense against them(they travel at speeds that make radar detection or any other form of detection impossible), and they will be absolutely devastating. If I know the orbit of an enemy planet, they're dead. An impact from a decent sized RKV would literally liquidize the crust of the target world, and sterilize the planet. No need for a fancy Death Star. I just need a rock, and the ability to make it move very fast. If a civilization is capable of interstellar travel then they're capable of hurling rocks at other worlds.

    In a twisted sense this may actually make space either insanely hostile, where civilizations are nomadic and move around in huge colony ships that can move unpredictably(to protect themselves from RKV attack), or very peaceful, as civilizations would exist in a perpetual state of mutually assured destruction.

    It's fascinating when you look at this kind of warfare, because the more you do, the more alien it becomes.

  4. #4
    Company Man MattW's Avatar
    Join Date
    Dec 2005
    Posts
    6,325
    Great link and calculations that make me feel 21 again (as in a bored physics student).

    I propose the the kill vehicle may have flaws as well - it may be susceptible to a passive net of mines or deceleration measures located ~1000AU out from any system of value. Only authorized gravitational disturbances or approach paths can circumvent the countermeasures. That isn't exactly plausible scientifically, but we're not talking near future here anyway.

    The dance of attack and defense will always continue...
    "We can't solve problems by using the same kind of thinking we used when we created them." -- Albert Einstein

  5. #5
    Bored Fanatic Straka's Avatar
    Join Date
    Dec 2007
    Location
    Connecticut
    Posts
    1,415
    I always thought rail guns would be ideal for space combat. No recoil and a lot of velocity.
    A WOLF ON THE LOOSE: A new weekly adventure e-serial now available on Amazon.

    http://www.awolfontheloose.com/


  6. #6
    practical experience, FTW
    Join Date
    May 2005
    Location
    Sweden
    Posts
    166
    Quote Originally Posted by Dommo View Post
    I got onto this tangent, because I can't STAND movies that try to pass themselves off as realistic.

    Sunshine, Armageddon, and the list goes on and on.
    I can't imagine that anyone ever tried to pass off Armageddon as realistic. It's wildly unrealistic. The Core is another example of movie science not only going wrong, but going missing completely.

    Star Wars and Star Trek, I tend to consider fantasy, as opposed to real sci fi, so they don't really bug me all that much. It's the ones that try to play off as though they're real, that make me want to go and kill something.
    I would love to see movies and TV series on the hard SF level about our future in space, including interstellar travel.

  7. #7
    Company Man MattW's Avatar
    Join Date
    Dec 2005
    Posts
    6,325
    Quote Originally Posted by TMA-1 View Post
    I can't imagine that anyone ever tried to pass off Armageddon as realistic. It's wildly unrealistic. The Core is another example of movie science not only going wrong, but going missing completely.


    I would love to see movies and TV series on the hard SF level about our future in space, including interstellar travel.
    Pish. Hard SF will only get in the way of story and the drama between tanorexic space-twins and the d-bag pilot boyfriends. No mumbo jumbo about vector maneuvering.
    "We can't solve problems by using the same kind of thinking we used when we created them." -- Albert Einstein

  8. #8
    On Mac's double secret probation. Dommo's Avatar
    Join Date
    Apr 2008
    Location
    Oklahoma City, OK
    Posts
    1,917
    Relativistic kill vehicles will be the nuke of the future.

    The only real defense is to move around a lot. This is why I figure if I write a sci-fi verse that's realistic, if the universe is hostile, then every civilization is going to be living in large colony ships that move around constantly. The only people on planets will be miners/farmers and such. The bulk of people would be living in space purely out of safety reasons.

    Planets are just utterly defenseless against an attack of that nature. Given that nothing can travel faster than light, any form of detection system is useless against a projectile that's moving at a significant fraction of the speed of light. Think of it like this. Radar only works because planes and missiles move VERY slow compared to the speed of light, that's what allows for accurate tracking. When you have a ship or vehicle moving at some significant portion of the speed of light, radar is no longer usable. It'll tell you where a ship WAS, but not where a ship IS. The best it can do is give you an idea as to it's heading. That's why ship to ship combat, will probably take place at reasonably close ranges (say less than a lightsecond or so), because at any distance beyond that, there is no way to accurately target anything.

    I figure as far as ship weapons go lasers will be of limited use, and will primarily be effective at closer ranges. Even with high energy lasers that are in the x-ray range, they'll only be effective up to a range of about a light second or two, and the other big problem is radiating heat from them. Space is a vacuum, so heat transfer is a real problem, and lasers generate A TON of heat. As point defense weapons they will probably be useful, or at close range where evasion is impossible.

    Kinetic weapons(rocks/bullets/etc.) will be very effective depending on the situation. They lose no effectiveness with range, and can be used to deny your opponent certain movement options(since you can't exactly turn a ship on a dime at 5% the speed of light), which can put an enemy vessel in a position where you can more easily predict their movements. At high velocities, a 1 ounce rock and hit a ship with the force of an artillery shell, and could easily tear apart a vessel. As a planetary attack weapon this will be the king.

    Missiles/torpedoes, will probably be the primary killers. Armed with a nuclear warhead, they can kill anything within about 500-1000 km when they go off depending on how large they are(the nukes irradiate the vessel, instantly killing the crew). The strength is that you can send out a bunch of missiles and have them take up most of the likely movement paths your enemy might be able to use. Even better, is that these will NOT destroy the enemy ship, and would allow for you to capture them after letting them cool off for a week or two(the neutrons from the nuke cause the ship to temporarily be radioactive making it deadly to any one inside).

    I'll have to start outlining some stories now that this has got my mental gears turning.

  9. #9
    Dragon of the Multiverse AW Moderator Zoombie's Avatar
    Join Date
    Dec 2006
    Location
    Some personalized demiplane
    Posts
    40,754
    Hmm...

    My universe isn't really explored outside of a single ginormus space ship that goes around eating planets. It doesn't eat them to destroy them (though that destroys them fairly well), but rather takes the planet apart to make raw materials. The ship is home to lots and lots and lots of aliens and humans that have lost their homeworld (as planets are, as we've begun to notice, quite fragile).

    But the universe outside...well, there's no FTL travel, and I'm not sure how hostile alien races are to one another. There arn't a lot, cause a huge hunk of them were killed off in the War of Time (A war we didn't even notice, partially cause we were still slinging artillery shells at one another in the muddy trenches of World War One and partially becuase it was waged mostly out of the space/time continuum).

    And I think I've just chucked reality out the window now...
    Purgatory Wars (high fantasy erotica)

    The Murder Stroke: Avaliable Now!
    Riposte: Avaliable now!
    The Cross Guard: Avaliable Now!
    The Blood Groove: Avaliable Now!

    Worldshard (steampunk erotica)

    Cadre: 40k/40k

  10. #10
    practical experience, FTW
    Join Date
    Mar 2005
    Location
    The right earlobe of North America
    Posts
    35,996
    Quote Originally Posted by Zoombie View Post
    My universe isn't really explored outside of a single ginormus space ship that goes around eating planets.

    But the universe outside...well, there's no FTL travel,
    Uhhhh . . . how exactly does a ginormous space ship travel around eating planets without FTL travel?

    caw

  11. #11
    Dragon of the Multiverse AW Moderator Zoombie's Avatar
    Join Date
    Dec 2006
    Location
    Some personalized demiplane
    Posts
    40,754
    By being built by beings who are very very patient and can wait decades between planet eats...

    Also, it takes a while to eat a planet.

    Also, they've got magical engines that provide constant thrust. Which is part of the plot: The engines and how much energy they have in them.
    Purgatory Wars (high fantasy erotica)

    The Murder Stroke: Avaliable Now!
    Riposte: Avaliable now!
    The Cross Guard: Avaliable Now!
    The Blood Groove: Avaliable Now!

    Worldshard (steampunk erotica)

    Cadre: 40k/40k

  12. #12
    banned as an incurable tosspot dmytryp's Avatar
    Join Date
    Oct 2006
    Location
    Stranded in Omaha
    Posts
    7,207
    Quote Originally Posted by Dommo View Post
    Relativistic kill vehicles will be the nuke of the future.

    The only real defense is to move around a lot. This is why I figure if I write a sci-fi verse that's realistic, if the universe is hostile, then every civilization is going to be living in large colony ships that move around constantly. The only people on planets will be miners/farmers and such. The bulk of people would be living in space purely out of safety reasons.

    Planets are just utterly defenseless against an attack of that nature. Given that nothing can travel faster than light, any form of detection system is useless against a projectile that's moving at a significant fraction of the speed of light. Think of it like this. Radar only works because planes and missiles move VERY slow compared to the speed of light, that's what allows for accurate tracking. When you have a ship or vehicle moving at some significant portion of the speed of light, radar is no longer usable. It'll tell you where a ship WAS, but not where a ship IS. The best it can do is give you an idea as to it's heading. That's why ship to ship combat, will probably take place at reasonably close ranges (say less than a lightsecond or so), because at any distance beyond that, there is no way to accurately target anything.

    I figure as far as ship weapons go lasers will be of limited use, and will primarily be effective at closer ranges. Even with high energy lasers that are in the x-ray range, they'll only be effective up to a range of about a light second or two, and the other big problem is radiating heat from them. Space is a vacuum, so heat transfer is a real problem, and lasers generate A TON of heat. As point defense weapons they will probably be useful, or at close range where evasion is impossible.

    Kinetic weapons(rocks/bullets/etc.) will be very effective depending on the situation. They lose no effectiveness with range, and can be used to deny your opponent certain movement options(since you can't exactly turn a ship on a dime at 5% the speed of light), which can put an enemy vessel in a position where you can more easily predict their movements. At high velocities, a 1 ounce rock and hit a ship with the force of an artillery shell, and could easily tear apart a vessel. As a planetary attack weapon this will be the king.

    Missiles/torpedoes, will probably be the primary killers. Armed with a nuclear warhead, they can kill anything within about 500-1000 km when they go off depending on how large they are(the nukes irradiate the vessel, instantly killing the crew). The strength is that you can send out a bunch of missiles and have them take up most of the likely movement paths your enemy might be able to use. Even better, is that these will NOT destroy the enemy ship, and would allow for you to capture them after letting them cool off for a week or two(the neutrons from the nuke cause the ship to temporarily be radioactive making it deadly to any one inside).

    I'll have to start outlining some stories now that this has got my mental gears turning.
    Well, I have a couple of problems with this. Although I agree that missiles and maybe rail guns are going to be the obvious culprits of weapons, you can't discard guns similar to Nautilus as defensive and offensive weapons (ranges would be of concern, of course). EMP generators can be an effective killer at close ranges, too. Destroying life support of a ship in space would be equal to killing everybody aboard.

    As for the relativistic vehicles -- I disagree. Light moves faster and yet we are able to detect it and see its course and origin. Relativistic Doppler effect would be still available and I believe other means of detection would be developed. Since we are talking combat at signifficant distances, avoiding this would be easier than purely energy based weapon or a missile with a tracking system that moves slower. Too much speed would also mean problems of maneuvering (it's not simple at all to fight a helicopter with a plane). And the last problem would be -- it would take a hell of a lot of energy to hurl something large enough at relativistic speed especially if you want a large acceleration.

  13. #13
    On Mac's double secret probation. Dommo's Avatar
    Join Date
    Apr 2008
    Location
    Oklahoma City, OK
    Posts
    1,917
    Any civilization capable of interstellar travel, is capable of making RKV's. If I can get a vehicle up to about half the speed of light, I've pretty much got an RKV. Remember radar has a net speed of 1/2 the speed of light, as it has to travel out and back, while my RKV is only going one way. This means that if my RKV exceeds 50% light speed, it's game over, because by the time your radar picket detects it, it's already past the picket.

    Heck, a 1kg mass at like 99% the speed of light will impact with 130 megatons worth of TNT. Try detecting my baseball sized sphere of tungsten that I fling across interstellar space. Assuming that scales up linearly, with mass(which I'm not sure if it does or not, I'd have to look at the formulas), I could said say strike with a 100 tons of tungsten at you, and it would be about 5 m^3 in size. and it would strike with enough power to liquidize the surface of an earth sized planet. Something that small is practically invisible to detection. If I'm really evil, I design my RKV to explode so that it showers a planet with fragments, and makes it impossible to stop all of them from hitting.

    I do agree though that EMP would be pretty effective, but that can be dealt with with conventional shielding methods. My point with lasers is that they are EXTREMELY dependent on targeting ability, and they are limited by heat issues. Kinetic weapons allow you to just dump masses of gravel out of the ship and let it scatter in your opponents general direction, and they don't have a limited range do to diffraction(the best possible laser which uses gamma rays is only good out to about a light second). If you're just killing enemy merchant ships, I can throw a rock at an enemy ship at 10% light speed, and vaporize them from across the solar system if they keep a constant heading. You can't do that with a laser.

    I think though that Missiles will be the bread and butter though in terms of ship killing. General purpose killing goes to KE weapons, and defense is the realm of lasers.

    PS: Read the site that I linked to. The go into a lot of depth on all different weapon systems.
    Last edited by Dommo; 06-08-2008 at 07:10 PM.

  14. #14
    banned as an incurable tosspot dmytryp's Avatar
    Join Date
    Oct 2006
    Location
    Stranded in Omaha
    Posts
    7,207
    Look, you are missing several key points.
    1. The time it took the incident radar beam to reach the vehicle doesn't matter. The scanning is continuous and only the reflected beam brings information. And it still goes at the speed of light. Through doppler effect (the red shift) you can then easily calculate the speed of the vehicle, direction etc.

    2. This weapon would be only effective against static targets. And for static targets defensive capabilities are much easier to concieve (for example automatic laser systems).

    3. This kind of weapon is seemingly for a ranged sneak attack. Because in relatively close range battle between ships it would take too much time and energy to accelerate these things. And targeting isn't that good. Let's say the battle happens among the distances of five light seconds and you have these things going at half the speed of light and say additional three seconds for acceleration. That leaves the target ship eight seconds to move out of the way the moment it sees the launch. Or even better, based on the data of the launch and acceleration direction, for an automated system to calculate its course and destroy it. Eight seconds is a lot.

  15. #15
    New Fish; Learning About Thick Skin
    Join Date
    Sep 2007
    Location
    pittsburgh
    Posts
    23
    Probably a few more points, anything you get going that fast will probably destroy itself, just from all the stuff that's already in space. I would put my big ship in a asteroid field. Also at any good fraction of light speed something the size of a pea could go right through anything that isn't designed for such collisions. This would make near light speed velocities impossible unless you had a massive shield and knew where every significant chunk was even in deep space.

    An rkv might work if it was real big or if there were a bunch of small one's, just to make sure it even gets there. But with big ships they'll probably take hits from things the size of watermelons at near light speed as a matter of course, which means ungodly solid shields or some form of energy or plasma shield, probably both, since we're already experimenting with plasma shields. And with small ships a moderate collision even if the ship was undamaged might kill everyone inside anyway, from the deceleration.

    And with shields the ships might be undetectable, the shield may just absorb all the energy, maybe even bend it around.
    Last edited by Roanoke; 06-09-2008 at 12:48 AM.
    Wips
    58,487/90,000+
    56,234/90,000+ into a rewrite 9,230/90,000
    4,792/90,000
    1,072/??????
    ...Now if I just had some titles...
    ...And some time to work on these...

  16. #16
    practical experience, FTW nevada's Avatar
    Join Date
    Mar 2006
    Location
    Calgary, Alberta, Canada
    Posts
    2,590
    okay see, i'm a science reject but it seems to me that you guys are failing to see the point of science fiction. The "fiction" bit. Yes it has to be realistic but who says they can't have faster-than-light travel? We do a lot of things scientifically now that only 50 years ago would have been thought of as impossible.

    Why wouldn't jets such as the ones in Battlestar Galactica not have some sort of inertial dampener so that accelaration and G-forces would not be felt by the pilot?

    Sure you can say that with what we know "now" it's not possible, but what about with what they'll know in 100 years? 500 years? Look back 500 years and see how fantastically different things are. Do you think the speed of light is really going to be a barrier 500 years from now? Less than 120 years ago people thought trains would be the end of the world. Cows in the field next to the trains would stop giving milk. The dairy industry would be crippled. As far as I can tell, the one time i was on the train, the cows didn't even notice.

    Seriously, remember the fiction bit.

  17. #17
    Ah-HA! Smiling Ted's Avatar
    Join Date
    Nov 2007
    Location
    The Great Wide Open
    Posts
    2,455
    Quote Originally Posted by Dommo View Post
    In space it just needs to accepted that there will never be dogfights. Fighters will NOT exist in space, as if you look at the hard physics, there is no real reason. You'd be better off with unmanned vessels that could accelerate in ways that would kill any living occupants. The most lethal weapon that will EVER exist, will probably be relativistic kill vehicles.

    They will be the nuke of the space era. They won't be used, because there is no defense against them(they travel at speeds that make radar detection or any other form of detection impossible), and they will be absolutely devastating. If I know the orbit of an enemy planet, they're dead. An impact from a decent sized RKV would literally liquidize the crust of the target world, and sterilize the planet. No need for a fancy Death Star. I just need a rock, and the ability to make it move very fast. If a civilization is capable of interstellar travel then they're capable of hurling rocks at other worlds.

    In a twisted sense this may actually make space either insanely hostile, where civilizations are nomadic and move around in huge colony ships that can move unpredictably(to protect themselves from RKV attack), or very peaceful, as civilizations would exist in a perpetual state of mutually assured destruction.

    It's fascinating when you look at this kind of warfare, because the more you do, the more alien it becomes.
    Although the RKV itself may not be detectable in time, the energy expended to accelerate the rock might easily be detectable. It takes a lot of time and energy to accelerate something to 20% of c, and that energy will be detectable before the RKV arrives - the heavier the RKV, the earlier the warning.
    "Crazy visions you got. Come with me to barber, we bleed you, you see right, everything good. I buy for you first leech."
    - The Wrong Sword


    And Read The Blog!

  18. #18
    On Mac's double secret probation. Dommo's Avatar
    Join Date
    Apr 2008
    Location
    Oklahoma City, OK
    Posts
    1,917
    dmytryp

    Even if the radar is constantly scanning, it's impossible to target an RKV. It'll tell you where the RKV was, but it won't tell you where it IS. Space is such a huge place, that as long as my RKV keeps moving around a bit, you're never going to stop it. If it's a big object, even if you hit it, it'll fragment and still destroy the target.

    How are you going to hit it with a laser? You can try to lase where you think it'll be, but the chances of you actually hitting such a tiny object, that is shifting around is astronomical. Your missing the point, because even if I know a course and heading, if the time lag is significant between where it was and where it is, I can't target it.

    The counter to an RKV is simple. MOVE. As long as you are on something that isn't a relatively static object, or predictable in motion you're safe. Unfortunately on a planet, that's impossible but on a space station, or something like that, it can easily be done.

    It's like trying to target an airplane with sonar(like a high subsonic airplane). It's not going to work. The only way a bat pulls it off, is because relative to the speed of sound insects are SLOOW. Ever try playing a first person shooter, with a huge amount of lag? It doesn't work too well, even when I try to extrapolate where an opponent is going.

    Nevada, it's because I've found that many novels use "inertial dampeners" and stuff as a way to drive the drama. It's a lot more dramatic when you have WW2 style dogfights, then when you have a relativistic battle between fleets where the battle might be over in the course of a second or two. Battlestar Galactica uses the nature of it's battles to drive the drama. It'd be a boring show, if every time the Cylons showed up, that the battles would be over in 2/10ths of second, and random ships would be vaporized with no survivors. That's largely why many shows veer out of the realistic.

    Heck if they made a realistic movie about modern air combat, you'd see the same thing. Two groups of planes flying toward each other, one sees the other first, fires it's missiles that hit 95% of the time, and the other group of planes just blowing up with firing a shot. Or if you looked at an engagement between two modern naval fleets, the battle would be over in the course of a few minutes, in much the same manner. It makes for boring cinema and television. Space combat when it happens is going to be a magnification of these forms of warfare.

    Smiling Ted, I agree. That's why I personally as the president of a space faring civilization would treat them as a nuclear weapon is treated now. I may know who shot the nuke at me, but it doesn't mean I can stop it. It's like if russia shot an ICBM at the USA. We may well see it, and watch it come in before it vaporizes a city, however we still know who shot it. That's the drawback to this weapon. Unless you are really really sneaky about where you launch one from, it's easy to figure out who pulled the trigger. In that case it just means who ever shot the RKV, is going to get a bunch in return.
    Last edited by Dommo; 06-09-2008 at 04:00 AM.

  19. #19
    banned as an incurable tosspot dmytryp's Avatar
    Join Date
    Oct 2006
    Location
    Stranded in Omaha
    Posts
    7,207
    I really dn't want to argue, so this is going to be my last post on the subject.
    Quote Originally Posted by Dommo View Post
    dmytryp

    Even if the radar is constantly scanning, it's impossible to target an RKV. It'll tell you where the RKV was, but it won't tell you where it IS. Space is such a huge place, that as long as my RKV keeps moving around a bit, you're never going to stop it. If it's a big object, even if you hit it, it'll fragment and still destroy the target.
    You really should stop moving the goal post. Either these are inanimate objects (like rocks) hurtled at great speed. And then they are smaller, harder to detect, need less energy to get to said speed, but can't chnage their trajectory. Or these are ships (don't have to be manned ships), which are larger, have propoltion systems and can change their course. Me personally, I'd go with rocks. Change corrections at these speeds would be painfully slow anyway (remember time dilation) and energy demanding (due to the increased mass). So, basically there is no "shifting" around. They run on the trajectory they were sent.

    Second, relativistic speed aren't some magical number (not a number at all as there is no definite limit) that suddenly renders radar useless. If you scan continuously (like any radar does), you are tracking a moving object and getting a trajectory. We are talking space, so, even 0.5c isn't terribly fast in terms of distance covering. If you can calculate the trajectory, you can calculate where it is going to be.

    Third, you don't have to destroy it completely. Either you push it out of the course (which would be somewhat energy consuming since we are talking increased mass), or you fragment it enough to burn away in atmosphere/plasma shield/whatever.

    Quote Originally Posted by Dommo View Post
    How are you going to hit it with a laser? You can try to lase where you think it'll be, but the chances of you actually hitting such a tiny object, that is shifting around is astronomical. Your missing the point, because even if I know a course and heading, if the time lag is significant between where it was and where it is, I can't target it.
    But this is excatly how Nautilus or any other anti-missile system works. It calculates the trajectory of the missile and shoots where it will be when the anti-missile weapon arrives. The idea that because your weapon moves at 0.5c you for some reason can't do this has no legs. Light (laser/emp or whatever) is still faster. Do you think the Patriot missile is signifficantly faster then the missiles it intercepts? It doesn't even have to catch the projectile. Only intercept it.

    Quote Originally Posted by Dommo View Post
    The counter to an RKV is simple. MOVE. As long as you are on something that isn't a relatively static object, or predictable in motion you're safe. Unfortunately on a planet, that's impossible but on a space station, or something like that, it can easily be done.

    It's like trying to target an airplane with sonar(like a high subsonic airplane). It's not going to work. The only way a bat pulls it off, is because relative to the speed of sound insects are SLOOW. Ever try playing a first person shooter, with a huge amount of lag? It doesn't work too well, even when I try to extrapolate where an opponent is going.
    As I said, this weapon would be useless in ship-to-ship combat. As for shooting some planet from enough distance -- maybe, but again you'd have enough of a variety of defenses -- alert stations, orbital sattelites etc.
    As for why you can't do it -- computational capabilities. As you said, you try to extrapolate, but your brain lacks the needed computational accuracy and speed. Targeting computers on the other hand... And even with our poor human brains there are people who are able to shoot down rapidly moving enemies.

    EDIT: I didn't get your point at first, so this is an addition. The reason why sonar with high subsonic plane wouldn't work isn't speed differences, but distance. Once you get the relevant info, your plane is out of range. Not so in space. Also, there wouldn't be any lag. The incident beams are sent continuosly. You'd only be getting the info from hours/days/whatever ago, but this would happen anyway with cosmic distances. Let's examine a scenario -- you have alert stations around Pluto that see an object eading to earth at 0.5c. They pass the info about the trajectory to orbital stations and those have hours until the object gets their to target it.
    Thanks for the discussion
    Last edited by dmytryp; 06-09-2008 at 03:37 PM.

  20. #20
    Wahoowa Tburger's Avatar
    Join Date
    Apr 2008
    Location
    Deep South
    Posts
    788
    I'm not disagreeing with anyone; this is an excellent discussion thread (because I'm 1/3 the way through with my own space combat book) and I am learning a lot. It just occurred to me: how about overwhelming any defenses with hundreds of thousands of rocks?
    Bio/bibliography: Campbell Award Profile

  21. #21
    On Mac's double secret probation. Dommo's Avatar
    Join Date
    Apr 2008
    Location
    Oklahoma City, OK
    Posts
    1,917
    Please explain how you'd target a .8 mach plane with sonar please, and if you can do that, I'll give you the possibility of targeting an RKV. To target something you need to have a huge difference in the speed of the object being targeted, and the method you use to target. Sonar works for submarines, because a sub can go maybe 40 knots balls to the wall, and sound moves through water at thousands of meters per second. That speed difference is good enough to give an accurate targeting picture.

    The same is the case with a laser defense system shooting down artillery shells, or the Airborne laser shooting down ICBM's. The speed of the Radar used to target the artillery shell, is HUGE compared to the speed of the shell itself. That's why the patriot missile works, because it's method of targeting something is WAAAY faster then the target. You can make accurate trajectory predictions, because the time lag is small. If I change the speed of my RKV by say 10 m/s. That is enough over interstellar distances to completely throw off any sort of laser because by the time it gets to where you are, it may well be a 1000 km from where your laser is pointing.

    The reason I was saying .5 C was a magic number, was because at that speed, by the time radar reflects off of the RKV and comes back to the station, the RKV would already have passed the radar picket. Obviously, I'd want my RKV to go at least 86% the speed of light(at that speed it's damage is equivalent to an equivalent mass of antimatter annihilating). You seem to not be understanding what I'm saying.

    The point in a nutshell: Targeting ONLY works if the speed of the targeting method is FASTER than what's being targeted by a significant amount(like say 10x faster at the least). If you don't have that speed difference in your targeting method, it's pretty much impossible to accurately hit anything, unless you get lucky.

    Anyway, off that topic.

    I read a short story once Tburger where the RKV was a large asteroid, and at a fixed distance(I think it was like 5 or 10 light seconds from the target), it was designed to break apart in order to make it very difficult to stop. It showered the world it was after with millions of small rocks. I like the idea personally of sending hundreds of small rocks(say like the size of a beach ball or something of tungsten) because they'd be harder to detect by sensor than something bigger, and due to their density I could get a lot of mass in a tiny package.

    The other thing is that if you do use this method of attack, make sure to do it from a random uninhabited part of space that can't be connected to whatever civilization you're representing. The drawback of this weapon type is that it can be tracked to it's source(or at least a good general direction, since you could sort of relay the things around a star system, before kicking on the engines). Anyway you put it, this kind of weapon has the same drawback that nukes have here, in that it's easy to track the missile back to who shot it.

  22. #22
    banned as an incurable tosspot dmytryp's Avatar
    Join Date
    Oct 2006
    Location
    Stranded in Omaha
    Posts
    7,207
    Quote Originally Posted by Dommo View Post
    The point in a nutshell: Targeting ONLY works if the speed of the targeting method is FASTER than what's being targeted by a significant amount(like say 10x faster at the least). If you don't have that speed difference in your targeting method, it's pretty much impossible to accurately hit anything, unless you get lucky.
    Look, there is no scientific bases for this claim. You are hand waving. The method of tracking has to be faster and contuninuous, that's all. Oh, and the distances have to be large enough to give you time to react.
    I'll give you a blow-by-blow explanation (this also explains why you're wrong with your 0.5c figure). Let's say your RKV is a light hour away from target. It meets incident radar beams from an hour ago. Then, as it moves closer, it meets beams from 59 minutes 59 seconds ago and so on. The radar sending them, didn't know the RKV was coming -- it was continuously scanning (say a sweep a second). Now, half an hour later it starts to recieve back the reflected beams. They have a red shift that is going to tell the computer your RKV's speed, and their progresion is going to tell it the trajectory. If the RKV doesn't have an engine, its trajectory isn't going to change and the computer will predict where it will be in twenty minutes. As for your contention about changing speed, this is true with every weapon. If the missile suddenly changes its speed, the calculations will be wrong.
    Take a look at the site you yourself provided for a glimpes of the problems to do what you are proposing (propultion wise). And consider something else, too. If it takes the RKV 5 seconds to change its speed, how much time passes on the outside to give the defenses time to adapt?

  23. #23
    On Mac's double secret probation. Dommo's Avatar
    Join Date
    Apr 2008
    Location
    Oklahoma City, OK
    Posts
    1,917
    If I'm hand waving, explain how to target a plane using sonar. Do it. It's common sense. If what you say was true, then we'd use sonar to track missiles and jets(subsonic). As I said, to get an accurate targeting solution, you need to have a targeting method that's a lot faster than what your target is. I could easily use sound to say where something was, but that's it.

    With sonar I can tell you where the plane has been, I can tell you where it's possibly going to be, IF it stays on a constant heading. But I can't target the object with any high level of precision. All I can do is ballpark the location that it'll be in. RKV's are no different.

    If my RKV is coming it 90% the speed of light, and you have a radar system that can detect things at a range of 1 light hour, then by the time my RKV is detected by your defenses, you'd have exactly 6 minutes to come up with a targeting solution based on it's position almost an hour ago. All I have to do, is slightly change my velocity or direction(say I laterally thrust my projectile, so that it moves about 10 km to the right) in that light hour distance. Even at taking into account time dilation on my RKV. My little missile, would have around 2 and a half minutes to move around, and I would definitely have my little planet killer on a randomized movement path to the extent that it could still hit the target.
    http://www.1728.com/reltivty.htm

    That's more than enough time to make it pretty much impossible to take it out, unless you get miraculously lucky trying to take out my Volkswagen sized chunk of tungsten that's about liquidize the surface of your home world. In the end, it's a sort of balancing act between screaming in an RKV so quickly, that it only gives a planet say a tenth of second to react, versus going slower but making the missile more capable of changing it's trajectory.
    Last edited by Dommo; 06-09-2008 at 05:03 PM.

  24. #24
    practical experience, FTW
    Join Date
    May 2005
    Location
    Sweden
    Posts
    166
    Quote Originally Posted by nevada View Post
    okay see, i'm a science reject but it seems to me that you guys are failing to see the point of science fiction. The "fiction" bit. Yes it has to be realistic but who says they can't have faster-than-light travel? We do a lot of things scientifically now that only 50 years ago would have been thought of as impossible.

    Why wouldn't jets such as the ones in Battlestar Galactica not have some sort of inertial dampener so that accelaration and G-forces would not be felt by the pilot?

    Sure you can say that with what we know "now" it's not possible, but what about with what they'll know in 100 years? 500 years? Look back 500 years and see how fantastically different things are. Do you think the speed of light is really going to be a barrier 500 years from now? Less than 120 years ago people thought trains would be the end of the world. Cows in the field next to the trains would stop giving milk. The dairy industry would be crippled. As far as I can tell, the one time i was on the train, the cows didn't even notice.

    Seriously, remember the fiction bit.
    Absolutely, but it depends on what sort of SF you want to write. You can write fantasy in a hitech-looking universe and therefore ignore any science you don't like. Or there's SF where you actually try to be consistent with the science, even with speculations involving non-mainstream hypotheses.

  25. #25
    banned as an incurable tosspot dmytryp's Avatar
    Join Date
    Oct 2006
    Location
    Stranded in Omaha
    Posts
    7,207
    Dommo, this is from the site you linked:
    Iain Paterson did some calculations which produced some surprising results.
    I had this image of putting a relatively small payload on top of a bloody massive conventional booster and firing it of -- the poor mans R-bomb i guess -- but after looking at some calculations this doesn’t look likely.
    From the kinetic energy equation and Tsiolkovsky’s equation you get:
    E = 1/2 * Mpayload * (Vexhaust * ln(R))2
    E = 1/2 * (Mtotal / R) * (Vexhaust * ln(R))2
    Differentiating with respect to R and setting equal to zero gives the mass ratio that gives the maximum energy. Canceling terms gives that:
    R = E * 2
    Vfinal_Ideal = 2 * Vexhaust
    This is rather surprising to me though I suppose it makes sense: at higher velocities there is a greater kinetic energy per mass but it requires a huge amount of fuel to get to that velocity. After reaching this velocity any additional acceleration REDUCES the energy impacted on the target so you might as well shut off the engines and let it coast.
    I worked it out for other cases as well, for 2 ships that are approaching each other before one fires a missile you get
    R = e(2-γ)
    where γ (gamma) is the ratio of the approach velocity to the exhaust velocity although this again gives that the missile should impact with a relative velocity of twice its exhaust velocity.
    The final case is for relativistic velocities (although being fired from ships that are stationary with respect to each other otherwise the maths is really nasty!) and you get:
    R = ((c + Vexhaust) / (c - Vexhaust))2
    Vfinal_ideal = 2 * Vexhaust / (1 + (Vexhaust / c)2)
    note that for V«c, Vf = 2 * Vexhaust. And for V~c, Vf = c.
    So is it just me or does this completely defy the concept of the poor-mans R-bomb so that instead it requires some sort of some handwavium total-conversion drive?
    Also this shows that to be effective a kinetic-missile must have a high exhaust velocity, not just a lot of fuel. While I suppose in order to evade point defense they need to be going faster but every extra second of thrust would reduce the damage inflicted to the target.
    Isaac Kuo agrees:
    Mr. Paterson is optimizing a more plausible scenario. His "poor man's R-bomb" is constrained by a particular exhaust velocity, and the question is how to squeeze the maximum kinetic energy into the payload. I'm not sure whether his analysis is correct, but it seems plausible.
    The optimum energy efficiency would actually be reached at an terminal velocity equal to the exhaust velocity. But that doesn't seem to be the objective of the poor man's R-bomb. The poor man's R-bomb seems to be limited by loaded mass rather than energy budget. You don't use any sacrificial propellant at all, you just use pure fuel at the maximum exhaust velocity you can manage all the way.
    Mr. Paterson writes: So is it just me or does this completely defy the concept of the poor-mans R-bomb so that instead it requires some sort of some handwavium total-conversion drive?
    His conclusion is essentially correct, if we assume the poor man's R-bomb must be internally powered.
    Still, this is nothing new to those of us who have seriously considered the problem of fast interstellar propulsion. We gave up on the idea of internal power for fast interstellar propulsion years ago, on the pretty obvious grounds that no fuel has a sufficient (usable) energy density. If you want to reach high relativistic speeds, you should use external power--either in the form of a laser beam or particle beam or "runway" track or relativistic kinetic impactors.


    So, this is concerning taking a volgswagen sized projectile to even get it to the speeds we are talking about, not to mention "move around a little" before the target.
    As for tracking planes with sonar -- the analogy is bad because the distances and time to react don't scale up and, of course, the fact that the plane has no problems moving would be a problem as opposed to a rock flung at relativistic speed.

Page 1 of 22 123456711 ... LastLast

Bookmarks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Custom Search