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Hi, I was trying to come up with more realistic idea of space craft in the far future. I thought all these ideas right now like in starwars, etc arn't that real. There would be the military flag/mother ships that would be more of a huge armored block that had immense power to move very fast to get around, and it would be a platform for launching small fighters and carrying lots of weapons. This ship wouldn't be able to land on planets due to its size and armor so no slimness needed. This ship would sorta be like a space station that moves :) Then there would be aero dynamic looking ships that are a style for alot of movies, these would be the more private enterprise ships and ofcourse there would be the planetary defense military ones. But mainly private owners. The fighters from the mother/flag ships would be aerodynamic for planetary assaults and be controlled by ai(and/or remote controlled). The mother/flag ships may also launcher other man controlled larger ships, eg retrieval, battle maybe etc This is what I am thinking for a game, but I want to know if my ideas are flawed and could be improved upon. Thanks

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The further ahead in time you get, the harder it is to design 'realistic' spacecraft, because no-one has a clue where technology will be then. I would use your imagination, rather than trying to work out everything so that it fits together.

Also, bear in mind, that if you do go down the realism route, you're going to have to compromise at some point - huge great big motherships probably aren't realistic to begin with, regardless of their form or function.

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"Realistic" space combat would probably be incredibly bland when you take one thing into account.
There is no significant drag in space, therefor projectiles have infinite range.

Combat would begin after you leave the port. Even if the enemy is also just leaving port on anothet planet. Why not launch your ordinance immedietely? The projectiles are obviously going to have a higher acceleration than the ship that launches them, and therefor they will arrive soonest if you shoot immedietely, instead of flying halfway there in your craft, then launching.

And so, combat would be a game of shooting various things and waiting 75 years for them to arrive and..miss, as technology has discovered some way to counter them as they were in-transit. Maybe you could arc your shot around the moon to sling-shot it and take a few years off.

If you were contesting a particular body, then there is no reason you couldnt do that from a few million miles out. No need to send fighters to physically bump into the enemy.

If you are going to solve the problem with laser weapons of some kind, then you have all sorts of other issues. If it's going to be realistic, then the laser is going to go on nearly forever. There is nearly no matter to diffuse the light in space. So, you are left with the same problem as above... just the projectile speed happens to be the speed of light.

What happens if you sign a cease fire after launching your weapons and they wont arrive for 50 years? Hope for another war to break out before they hit?

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Original post by Ajare
huge great big motherships probably aren't realistic to begin with, regardless of their form or function.


How come?

I thought that because there would be enough resources to construct such a thing, it would be protected against alot of natural disasters and almost anything, it could generate huge amounts of power.



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Original post by CombatWombat

The projectiles are obviously going to have a higher acceleration than the ship that launches them, and therefor they will arrive soonest if you shoot immedietely, instead of flying halfway there in your craft, then launching.


If you are going to solve the problem with laser weapons of some kind, then you have all sorts of other issues. If it's going to be realistic, then the laser is going to go on nearly forever. There is nearly no matter to diffuse the light in space. So, you are left with the same problem as above... just the projectile speed happens to be the speed of light.



Well I thought if you could get ships closer to fire speed of light missiles they would be harder to shoot down,

i'm not sure about lasers as main weapons, i heard a discussion somewhere, all you have to do is mount lasers and your safe, or some kind of high heat resistant armor.


With these huge ship idea, I'd like to hear more any pro's or con's..

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Aerodynamics only comes into play if you start battling in the atmosphere of some planets. Otherwise it had no effect. You could have multiple types. one that is aerodynamic which can enter/exit an atmosphere and then other fighters which have to stay in space.


If you want to know what a realistic space fighter would look like, take a look at the TV Series called Space: Above and Beyond. It's a very nice military sci-fi series. It's nothing like the series i have listed below.
There are many websites out there dedicated to it so you should get some info you might want.


Most other Sci-fi series have carriers because the small fighters lacked room / power for the long range engines. Well.....

Star Trek, shuttles didn't realy have much in the way of weapons, they only had limited armour and warp drive capability.
And the Defiant isn't all that small if people can walk around like they do in it.

Star Wars, It was the empire who didn't have fighters with hyperdrives. So they always needed a star destroyer around or a base.

Babylon 5, they needed cruisers to hold fighters for the same reason.


The medium sized ships had the ability to travel long distances while also being fast in normal space. They also had decent firepower as well.

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Trying to bring real science into space games is always a bad idea...

I would suggest: make a list of the groups of people who will have spaceships, ie military, merchants, civilians, etc. Then, for each group, make a list of the ships that they would use, based on functionality - don't worry about their design yet.

Now, and I know this because I have tried myself, if you try to design the ships themselves from scientific principles, even taking into account their different purposes, you will find that they all look the same, and that any large ships will probably be, yes, large ugly cubes. Not much fun for a game, if you ask me.

Rather, I would work on simple principles - the more powerful the ship the larger it is, the faster the thinner it is, but stick to a basic spaceship-like look for all of them. You have to be aware of people's expectations - if you try to do something too different from what they know, it will confuse them.

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Original post by johnnyBravo
Well I thought if you could get ships closer to fire speed of light missiles they would be harder to shoot down,


And how do you get such ships closer?

Answer) fly there. At significantly less than the speed of light. And therefor in the grand scheme of things, it takes longer for the projectiles to get there, which means more time for the enemy to counter the attack.

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Original post by CombatWombat
There is no significant drag in space, therefor projectiles have infinite range.

That's not really accurate. A weapon's range is not determined simply by how far it can physically reach. The range of a weapon is the distance at which it can reliably hit a target, so factors like sensor range and resolution become more significant than the ballistic properties of the projectile, as does the ability to predict the movements of the enemy. You might very well fire off a projectile that will take years to arrive on target, but unless you know that the target will actually be there at that time, then what's the point? That's the advantage of closing the gap in ships first.

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A missile can certainly go infinitely far, but unless it has fuel when it reaches the enemy, it is simply a sitting duck for his defenses to deal with. Not necessarily active defenses, either : The simple expedient of moving his ship in unpredictable ways will generate a miss. So unless your missiles have infinite fuel, they do not have an infinite range. I suggest David Weber's Honor Harrington universe as a look at this, particularly On Basilisk Station and Honour of the Queen. Of course, this doesn't apply if you are shooting at an immobile target, but then you're not talking about ships anymore.

About the Huge Mothership (tm), what happens if a nuclear missile hits it? I don't care how much armour you've got, a nuke is going to leave a fairly major hole. Even if you could build a ship capable of surviving a nuclear hit, why whould you? It would be far more cost-effective to build ten or twenty smaller ones with zero armour. So one gets hit, who cares? You've got nineteen to shoot back with. This was one of my major beefs with Master of Orion; you start out with nukes, and soon build ships that can take such hits easily. Yeah, right. There are defenses against nukes, such as pulling a mountain over your head, but they are not very practical for spaceships.

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Original post by Plasmadog
That's not really accurate. A weapon's range is not determined simply by how far it can physically reach. The range of a weapon is the distance at which it can reliably hit a target, so factors like sensor range and resolution become more significant than the ballistic properties of the projectile, as does the ability to predict the movements of the enemy. You might very well fire off a projectile that will take years to arrive on target, but unless you know that the target will actually be there at that time, then what's the point? That's the advantage of closing the gap in ships first.


If you have the technology to be flying around in space, I make the assumption you can do simple things like look through a telescope. I would assume you would also be able to build a weapon with it's own sensor and terminal-phase manuevering systems, like an ammraam missile on a bigger scale it would guide to the general area via the launching vehicles direction, and then once close enough for its own sensor to work, guide itself.

The point I'm trying to make, is what is the difference of a projectile and a ship in space? The ship/projectile can sort of be looked at as a two-stage vehicle, where the first stage is nearly obsolete. Faster response times of having a launch vehicle in the area of conflict are nice, but how long does it take to actually get there? Probably hundreds up to millions of years. (Again, why a 'realistic space combat game' would be a terribly boring thing). Why not just shoot first and not get out of bed?
If the advantage of the ship is to "close the gap" as you put it, then you have the same problems with the enemy moving, etc. He probably wont even be there when you arrive, and the war will have been over for several generations. Using any sort of jump, wormhole, ftl type thing defies the "realistic" part, and even if it were possible, there would be no reason not to use said technology on the projectile directly instead of the vehicle. (shoot, bullet opens wormhole, exits 'subspace' ontop of the target instantly)

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You have to be really careful how you apply "realism" to spaceships/space combat. Why would you risk lives when you could easily make an unmanned ship or missile? It's not like it'd be hard to do. There's not a lot of complex physics in space. No pesky air resistance, gravity or other messy things screwing up your AI. It just has to take into account it's relative speed, its position and heading, and then use its sensors to keep track of it's opponent.

I'd just build a swarm of missiles, program them to hit whatever target I decide, and send them off. They can probably accelerate/manouver much better than manned ships, and you'd have a hard time defending against all of them. Then when everything you have has been blown to pieces, I could fly in and take possession of the remaining debris and ruins. If they can get up near the speed of light, they'll be practically impossible to detect and destroy. And they don't have to carry any real payload, since at that speed, practically anything can cause a lot of damage. So all you need is an engine, a fuel tank and some navigation system, and you have a weapon that's basically impossible to defend against, and doesn't even risk the lives of my own soldiers.

Of course, that's a fairly obvious strategy, and my opponent would probably do the same. That means we could both get killed. Not very much fun.

Anyway, about your original suggestion. Would a big huge armored ship really be worth it? Do you think its armor would actually help it? (How would it "move very fast" anyway? It sounds like it'd have a lot of mass, meaning lots of inertia) But wouldn't most sci-fi weapons be able to blow it to bits anyway? If I fire a small slug at it at, say, 80% of the speed of light, I doubt you'll have much left of your ship. Would it make more sense to use lots of smaller faster and lighter armored ships?

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Here's my take on "realistic" spacecraft (say within the next 100 years or so). I'm positing real world physics here, so no reactionless drives.

1) The ships will be fairly small.
2) They will have few to no human crews.
3) Combat will take place at extremely long ranges using energy weapons.
4) Combat will take place at relatively slow speeds.
5) *Fighters will not be used in space-to-space battles

Explanations:
1) Small ships will require less fuel and hence can travel further. I posit that solar sails or laser sails will be the main method of intra-solar travel, while traditional chemically propelled or maybe atomic detonation devices will be used for high speeds burns. In my own game system, I have posited a reactionless drive system that utilizes the Zero Point engery field (google it). Some physicists believe that this real field is what causes inertia. If we can create a drive system that can tap into the ZPE, then you could conceivably "push-pull" through this modern day "ether" that's the ZPE.

2) The quickness of decision-making simply won't allow for human crews to be that efficient anymore. If you posit robotic technology, then having human crews becomes even less sensible. The reaction time of a computer controlled ship will be far greater than that of a human. Taking into account a slightly reduced Moore's law, and/or quantum computers, and you can have decision-making computers that can decide and interface with ship controls far faster than a human crew could (even if they could somehow jack-in). Add in the maintenance upkeep and logistics for human crews (life support, food, crew quarters) and it just doesn't make sense.

3) The range at which ships can detect each other purely through passively radiated EMF signals (whether infrared or something else) will make sneaking up nigh impossible. Hence, combat will take place at incredibly long ranges. Given that the primary weapon systems will be energy weapons for several reasons (not needing to stock ammunition, not having explosive ammunition on board, and the weight/volume savings), we now have the premise for #4.

4) Combat will be slowly paced because if your ship is moving fast, it can't turn fast. If you can't change your vector quickly, then your enemy can better predict where your ship will be from momment to moment. Since most weapons will be energy weapons at extreme range, this will give only a split second to make course corrections. This supports yet another reason why human crews are unlikely...ships without human crews can perform high-G moves that humans wouldn't be able to take.

5) Because of the long ranges, fighters are somewhat useless. Most fights will be over by the time the fighters made their acceleration burn to get within firing range of the target. However, fighters will probably take on an important planet-based role. The asterix is there because it's possible for them to be of use in ambush situations. In my own game world, thanks to the ZPE engines that produce extremely little heat (ZPE energy usage can "violate" laws of thermodynamics because the energy is coming from "outside" of the system) fighters can be almost powered down and lay in wait.

So you won't see the fancy Newtonian-approved acrobatic displays of ships blasting each other with humans barking orders to one another. Instead, it will be a very cold, calculating and quiet affair like space itself.

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This is just a general post on the topic.

By 'realistic' I'm going to assume, like everyone else seems to, that you mean slower-than-light. I'll also assume that reactionless drives (as someone else pointed out) are still beyond the horizon. So, we have two huge constraints right there. Two direct results would be:

1. Ships would avoid planets like the plague. A planet means a relatively huge gravity well to contend with, which would place even worse constraints on fuel and maneuverability (mainly from a lower orbit to a higher one).

2. The farther away from the enemy at which you can win, the better. In space, time is fuel, and both are precious. Ship commanders will need at all times to conserve their reaction mass (whatever it may be) as much as possible.

Drives requiring reaction mass would mean that the fuel-to-mass ratio would be as low as possible (i.e. maximum fuel and minimum mass). Depending on what kind of reaction mass you're working with, this is more or less of a constraint.

At relativistic speeds, the amount of mass something has is not as important as how fast it is going. This is true for even subrelativistic speeds. I once read that an object the size of a pencil eraser orbiting Earth collided with a satellite and vaporized(!!!) it. So, drones (the likely weapon in near-future space combat, basically a guided missile) are likely to be as small as possible.

Furthermore, these drones will be (as many others have suggested here) unmanned. There are two reasons for this: an unmanned vehicle can undergo vastly higher accelerations than a manned one, and a manned vehicle requires much more mass (life support, actual person(s), etc.) than an unmanned one.

Even better, a drone wouldn't necessarily have to make accelerations from (essentially) rest to relativistic speeds. A probable tactic would be for a ship travelling toward a star system at relativistic speeds to release some drones before it decelerates. That would allow the drones' onboard fuel to be dedicated entirely to maneuvering and (possibly) deceleration.

A projectile travelling close to the speed of light would be very difficult to detect, because at any point at which one could detect it, it would actually be much closer. However, I wonder if a projectile's accuracy rate is inversely proportional to its speed. That is, I wonder if it would be just as easy for a ship to move out of the projectile's course.

Finally, shields would be vastly preferred to armor. Armor is always passive, while shields can be either active or passive. Furthermore, shields can have much longer range than armor. In fact, shields would be a necessity on *any* relativistic ship, because there could be many objects in space which could destroy the ship while it is travelling at relativistic velocities. Another consideration is, given the speeds at which drones would travel, it is likely that any armor would be rendered meaningless. So, the probable configuration would be little or no armor, mainly just to keep the ship structurally intact, and as much shielding as possible.

Another tactic for such ships would be to 'mine' the area around it to a certain range. This could be an extension of its shielding system, whether permanent or temporary. The permanent version would be a constellation of small objects moving with the ship a certain distance away from it, hopefully to catch any objects which could collide with the ship before they would reach it. The temporary version would, again, be for the ship to release these objects only upon decelerating to non-relativistic speeds.

Hope that's some stuff for y'all to work with.

- Rob

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Original post by RobAU78
1. Ships would avoid planets like the plague. A planet means a relatively huge gravity well to contend with, which would place even worse constraints on fuel and maneuverability (mainly from a lower orbit to a higher one).


I'd disagree with this one, at least as far as combat is concerned. I'd go as far as to say that combat will simply never happen except within a fairly short distance of a planet.

The reason for this, is that planets are really the only points likely to be of interest to anyone, and therefore the only place where forces are likely to clash. Deep space is so unbelievably vast that the chances of two forces clashing randomly is essentially nil, and it's so empty there's no other reason for them to fight in it.

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Original post by Sandman
I'd disagree with this one, at least as far as combat is concerned. I'd go as far as to say that combat will simply never happen except within a fairly short distance of a planet.

The reason for this, is that planets are really the only points likely to be of interest to anyone, and therefore the only place where forces are likely to clash. Deep space is so unbelievably vast that the chances of two forces clashing randomly is essentially nil, and it's so empty there's no other reason for them to fight in it.


Of course you're right that "planets are really the only points likely to be of interest to anyone." However, I don't think two (or more) species would have to fight over a planet *near* that planet. They would certainly have to have forces within the general vicinity (i.e. in the planet's solar system), but the farther they are from the point of interest at which they can achieve victory (likely the total annihilation of the other's/s' forces), the better. So, I agree that there would be little (if any) conflict in deep space, and most battles would take place "in-system," as it were. But I still think that the major battles would not take place *in orbit* around contested planets.

- Rob

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Original post by Dauntless
4) Combat will be slowly paced because if your ship is moving fast, it can't turn fast.

Umm, why not? That may be true of atmospheric aircraft that turn by essentially trading speed in one direction for speed in another, but spacecraft do not work that way. Even the concept of "turning" doesn't really translate well to spacecraft. If a spacecraft thrusts at an angle to it's current velocity vector, the only factor governing how quickly that vector will change is the amount of thrust that can be applied. Of course, the ship may first have to rotate itself before it's able to thrust in a new direction, but the ability to do that quickly is a function of the shape of the ship and the placement and power of the thrusters. The current speed makes no difference whatsoever.

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Original post by CombatWombat
The point I'm trying to make, is what is the difference of a projectile and a ship in space? The ship/projectile can sort of be looked at as a two-stage vehicle, where the first stage is nearly obsolete. Faster response times of having a launch vehicle in the area of conflict are nice, but how long does it take to actually get there? Probably hundreds up to millions of years. (Again, why a 'realistic space combat game' would be a terribly boring thing). Why not just shoot first and not get out of bed?


I think you are assuming combat between enemies who are in different solar systems, while I and Plasmadog were speaking of combat inside one solar system. In which case, millions of years is certainly an overstatement; you can reach Mars from Earth in (IIRC) two years even on a highly efficient orbit.

Even between solar systems, though, I think you don't want to be launching robots. By the time they get there, the enemy's technology will be vastly improved; how could your ancient, steam-powered robots compete? You would have to send an entire microcosm of your society, capable of improving its weaponry en route, so it would stand a chance when it arrived. Which might make for an interesting RPG, if a part of the Fleet decided it didn't want to die in a war declared five generations ago.

But getting back to combat inside one solar system, I think it's not so trivial as all that to hit a target - even a planet-sized one - at distances of AU. There are limits to how good a brain you can build for your missile, if you want to build them in sufficient quantities to fight a war; whereas humans can be produced in nine months by unskilled labour. Why not send along a few human brains to direct your missiles, cope with enemy surprises, and accept his surrender, then?

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Plasmadog-
Even though space offers no friction as a counter-resistance against the hull of the ship, you still have to account for the acceleration of the thrusters versus the inertia of the ship's own mass as well as the equal but opposite force generated by the thrust accelerators. Apply too much acceleration against a weak structual part of the ship, and you'll snap it in half. The inertial mass of the hull itself acts as a counter-resistance to the acceleration. Imagine this for a second. You have a super-hero trying to lift a battleship off the ground. Assuming he's strong enough, there's a problem with this....the ship would either crack in half, or the hero would just act like a nail driving through the ship. In this case, it's obvious that gravity is acting as a downward force. But relatively speaking, that's no different than if the hero was pushing forward (Newton's second law IIRC). So when the ship has to burn its thrusters at an acute angle to make a steep turn, that acceleration still has an equal but opposite force. If that opposite force is applied to the ship's weak structural side, that could be bad ( depending on how the ship was designed....I guess the safest structure for a ship would indeed be a sphere).

In fact, in gravity situations, frictional forces actually help you turn. Think for a moment of how hovercraft turn versus a car. The frictional forces of the tires on the pavement act as a gripping force that actually improves handling. The hovercraft on the other hand has almost no friction, and you can think of hovercraft as a 2d "gravityless" environment. Hovercraft turn by pointing their fans in a different direction. And the handling characteristics of hovercraft are pretty poor. Same thing for aircraft...the air drag and air resistance actually can help the turning characteristics (to a degree). Obviously, it can't do very acute turns, but

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Guest Anonymous Poster
Great discussion everyone!

I expect combat would play out something like a cross between sub warfare and WW2 carrier fights. I expect a standard warship would be a medium sized craft that has few offensive weapons itself. Most weapons would be carried by smallish remote drones. Stealth would be crucial - victory would go to the sid that remains undetected the longest. Given the relative success of the f117 stealth fighter I don't think it's unreasonable to assume that ships would be able to remain undetected as long as they don't emit a significant EM signal. The mothership would fly a straight course, making an absolute minimum of EM noise. Drones would be spread out around the mothership in a wide (100Km?) cloud, scanning for enemies. When an enemy is detected, weapon drones would be switched on to attack the enemy mothership. I'd send in a few nukes first to try to melt or EMP-knockout any drones in the area, then send in a few high velocity slugs to try to puncture the mothership. Since these slugs rely on kinetic energy instead of a warhead that could be detonated before it reaches you, they would be very hard to stop. At that point the mothership would have to rely on agility to try to dodge them. I expect combat would be short and very deadly.

I think large ships would be mostly limited to civilian transports, and possibly military transports. Big ships are presumably easier to detect from a long distance, and it's really hard for me to imagine shielding that could withstand even a single direct or close hit from a fusion warhead.

Sandman - while space is largely empty, there are zones of space with different gravity potentials (I think that's the word). Basically, there are bands in space where the gravitational attraction of different bodies (the earth and moon for example) interact and either combine or cancel each other out. Travel along these bands is much more energy-efficient than a course ignoring these bands. So these provide some sort of 'terrain' in space, like roads. I'm not sure how they are shaped (tubes?), but I do know that they are constantly shifting as the planets and moons move.

Dauntless - I disagree that high speeds limit manuverability. Think of it this way, when you are lining up a shot, you know the position and velocity (vector) of the target. Given that, you can estimate the weapon's time to target, and thus the target's position when the weapon arrives. Let's say your rocket will take 1 minute to reach the target, and that the target's thrusters can accelerate it at a speed of 10 m/s. From a sitting position, the target will move roughly 60*10 meters. That means that your target's expected position after a minute is a sphere .6Km in radius. That's from a standstill. Now assume the target is already moving at 1,000 m/s. Again, the engines can *change* the speed 10 m/s every second. Assuming the same 1 minute for the weapon to close, the target's expected position is again a sphere .6Km in radius, but the sphere is offset from the target's current position by 1,000m/s*60s = 60,000 meters. My point being that when evading incoming fire, the only things that matter are acceleration and time to make use of that acceleration - not the target's current speed.

-jake

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Let's say your rocket will take 1 minute to reach the target, and that the target's thrusters can accelerate it at a speed of 10 m/s. From a sitting position, the target will move roughly 60*10 meters. That means that your target's expected position after a minute is a sphere .6Km in radius.


I'm not a math major so correct me if I am wrong, the above calculating assumes a max SPEED of 10 m/s. Wouldn’t an acceleration of 10 m/s give you something much larger (no friction in space)? Something like 18300 m?

Aside from that I think the biggest problem is not how far away the target is but how fast the projectile is traveling in relation to the target.
You are standing on a high way and a motorcycle is barreling down on you at 100 mph. If you time it right, at the last second you can step/jump either left or right and the motorcycle will wiz on by. It's turning radius prevents if from being able to make a curse correction fast enough to hit you at the last second.

[Edited by - Kars on October 13, 2004 2:02:45 PM]

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Guest Anonymous Poster
My math was way off, sorry, but hopefully my point is clear

If you accelerate 10 m/s for 60 seconds, you will go much further than 600 meters, something more like 18 kilometers
-j

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Everybodies already touched on most of the important topics, but I'll throw out a few thoughts too.

Inertia will be one of the biggest things you need to consider when designed "realistic" spacecraft. It affects how quickly they can accelerate, decelerate, and rotate. The faster something is, or the more massive something is, the more inertia it has, and thus the harder it is to maneuver or change velocity.

Ships will be designed to make the optimal use of space and resources as possible. On earth, we have things like air, water, or ground that affect the design of function of a craft. Space has few constraints like this. There's no reason to be aerodynamic, for example. On the other hand, the function of the ship will determine its design.

For example, a ship that would be required to rotate and move quickly might be designed something like a giant "jack" - a center sphere or structure that houses the engines and computers, while struts extend in every direction with thrusters on the ends. By placing these thrusters out away from the center, rotational torque is increased, allowing the ship to rotate much faster than if the thrusters were towards the center.

Ships won't have human crews, and that's been discussed already. In short, computers will be advanced enough to do whatever they need to on their own.

To house humans will be a complete waste of resources - humans require air, food, water, and large amounts of empty space. Humans generate waste. To keep temperatures regulated will take excessive amounts of energy. Ships will need additional shielding to protect the humans from radiation, further adding to the weight and/or energy requirements of the ship.

Future ships will get rid of humans entirely and use all that extra space and energy for more productive things, like better computers, faster engines, or more weapons.

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Quote:
Original post by Ajare
huge great big motherships probably aren't realistic to begin with


Well now that's just stupid. Haven't you ever seen an Imperial Star Destroyer? Those things are BIG.

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Original post by RobAU78
1. Ships would avoid planets like the plague. A planet means a relatively huge gravity well to contend with, which would place even worse constraints on fuel and maneuverability (mainly from a lower orbit to a higher one).


Unless your ship is equiped with any of the hundreds of gravity-nullifying systems.

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Dauntless - I disagree that high speeds limit manuverability. Think of it this way, when you are lining up a shot, you know the position and velocity (vector) of the target. Given that, you can estimate the weapon's time to target, and thus the target's position when the weapon arrives. Let's say your rocket will take 1 minute to reach the target, and that the target's thrusters can accelerate it at a speed of 10 m/s. From a sitting position, the target will move roughly 60*10 meters. That means that your target's expected position after a minute is a sphere .6Km in radius. That's from a standstill. Now assume the target is already moving at 1,000 m/s. Again, the engines can *change* the speed 10 m/s every second. Assuming the same 1 minute for the weapon to close, the target's expected position is again a sphere .6Km in radius, but the sphere is offset from the target's current position by 1,000m/s*60s = 60,000 meters. My point being that when evading incoming fire, the only things that matter are acceleration and time to make use of that acceleration - not the target's current speed.


I agree absolutely with what I put in italics. It's not speed that truly matters, but how you use your acceleration. But in fact, it's not good to just slam on the accelerator either, since it is acceleration that causes the forces which could affect the weak parts of the hull. So really, it's acceleration + vector changes with respect to time that's important.

Plus, you have to consider all my other constraints. In my scenario, the majority of weapons will be energy-based, and hence time-to-target will be on the order of a few micro-seconds to at most a few seconds (depending on how good your scanning margin of error is to be used as a targeting system, this will determine the maximum range that combat can take place in). Given that fact, the indeterminate position of a target is greatly reduced. If a ship is moving very fast, then the only way it can rapidly change its vector (and hence it's direction) is by rotating the ship, and applying a maximum burn. This is the point I tried to make earlier in that depending on how you design the ship...these rapid turns can be hazardous to the structural integrity of the ship (one way to alleviate this problem is to mount the main thrusters on "turrets" placed near the center of mass of the shiprather than only at the rear of the vessel...this could allow for more rapid turning, but having the thruststers in such a manner would also mean that they probably wouldn't be as powerful as rear-mounted thrusters).

So to recap in a nutshell,
1)a ship moving with a high velocity can not rapidly change directions or apply too much acceleration
EDIT- It can't change direction or speed quickly (which is the definition of a vector) because if you're moving fast, you have to accelerate fast to change either your direction of movement, or your speed...and that's the problem. Not to mention rotational torque and other stress factors involved.
2) If you can't rapidly change directions or speed (change vector), your opponent can guess where you will be much better
3) If your opponent can predict where you are better, he can hit you more easily.

Therefore, slow to medium velocities will be more common because then although the toral displacement over time may be less than at high velocities, the ability to constantly change vectors creates a more unpredictable end displacement (i.e., you can sum more vectors in a period of time at slower speeds than you can if you move fast).

Also, I think kinetic weapons will be rare in ship to ship combat. Today's Aegis systems on USN vessels can blow missles out of the sky. Because of the slow time it takes for the missles to get there there's ample time for them to be shot down, or simply run out. As for high velocity railgun types, the slower speed and hence greater inaccuracy of the weapons (round time-to-target is greater, and hence target has a more unpredictable end position) will make them less desirable. Add in the fact that your ship's position will constantly be minutely affected due to the recoil (and even just a micro fraction of a degree can make a difference when you're trying to hit something on the order of tens of thousands of meters away), storage space for ammo, and the volatile nature of the ammo (just look what happened to HMS Hood) and I think kinetic weapons will be rare. One way to make missle systems better is simply to swamp your opponent with them so that he's unable to shoot them down. Drones and missles make great fiction, but I doubt they'll be that common once energy technology becomes feasible and reliable (so kinetic weapons systems might be common in the early stages of going to space).

[Edited by - Dauntless on October 13, 2004 4:31:30 PM]

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