Weapon systems, part 0001

[targon]

Some time ago, I've begun to hinder local folks by my knowledge in high energy physics. I still think that "realistic" weapons and armor can't make StP more doomed it's already is. I do remember lot of ways of bringing good things to death, all are worst.


1. Rail guns. Employs electromagnetic force (Amper's law) as way of acceleration. This stuff consists of two sturdy conductive "rails" with small constant width gap inside. This rays are connected to high power pulsed voltage generator (what currently means _huge_ capacitors battery; this batteries generally aren't easy to climb on). Projectile is placed between rails. After pulse, rails are connected via streamer type discharge. This discharge forms Pi-like contour which "want" to remove projectile from itself. Naive estimations may say what theoretical limit of velocity is c, but there are some really nasty plasma ion instabilities what hinder human-kind lust of blood and place ceil near 10 km/s. Real rail guns I've seen made something like 4-7 km/s, or 2-3 times better than chemical guns. Disadvantages: needs huge pulsed power supply, rails become terrible twisted after single shot, projectile becomes heated and deformed. There is huge room for improvement, BTW.
2. Advanced conventional guns. Conventional == stuff with long accelerator barrel which pushes projectile via pressure. Modern chemical guns are near their theoretical limit, and its hard to improve. Bacicaly, it depends on specific energy of gunpowder and molecular weight of its burn products. But barrel itself may be to young to die.

a) Two-stage guns. This stuff is used in high energy physics, especially in America (Russians prefer explosives) and consists of ordinary gun barrel that accelerates heavy piston. This piston then compress light has (H2, He) is so-called high pressure camera. Real projectile is placed in second barrel, just near intake, so it can be "escaped" by working pressure but not before. This projectile can be accelerated as fast as ~10 km/s. Disadvantages: huge size, extremely slow fire.

b) Plasma gun. Rather than gunpowder, we may use other propelent with external energy source, so specific energy limit may be effectively overridden. Disadvantages: needs huge power source, so may fire slow. Barrel will be surely damaged by superheated plasma. Scheme with internal nanite repair is left for readers exercise.
c) Laser or beam acceleration. This stuff is like previous, but we may use rear part of projectile as propelent (much like rocket), with laser or beam heating. Currently, people accelerate thin foils to ~100 km/s. Disadvantages: needs much power, laser beam will be blocked by spreading plasma cloud. This stuff isn't especially "conventional", as it may be used without any barrel. Why I placed it here?


3. Plasma cannons. This stuff isn't as deadly as old Doomers may think. In fact, it's almost harmless. Plasma may be really hot, but its density is too low. Wonder if may be used in any atmosphere. In vacuum, spreading will limit range, too. Concerning Star Trek plasma torpedo: even this stuff isn't total buzzword, it's really hard to implement. Hot plasma tends to cool down really quick (in matter of microseconds), it's intrinsically unstable and hard to control even with lots of huge magnets hoarding around. IMHO, it may be even theoretically impossible to bind this stuff from inside... But, plasma tech may be used inside warheads of missiles (or "drones" in Star Trek science blasphemy).


4. Particle cannons. This stuff may be really nasty way of sending stuff to hell. Particles may be easily accelerated to speeds indistinguishable from speed of light in sense of targeting, so it isn't easy thing to dodge. Currently, "military grade" accelerators may be subdivided into 3 ranges:

a) Electron beams. This stuff may be done huge, pulsed beams may be almost arbitrary energy, end their efficiency is about 50% (without battery). Disadvantages: electron beams tend to collapse, producing "overkill" energy fluxes, electrons have too small penetration depth even against "light" materials, producing too quickly attenuating shock waves (compared to projectiles), it may be deflected using electromagnetic methods.

b) Proton beams. This ones are bigger, more energy intense, and more costly bigger brothers of electron beams. They are less efficient, too. But protons have much more penetration, while they tend to produce so-called Bragg's peak.

c) Heavy ions & friends. Currently, they're junk. While the above accelerators are, in general, "streamers", or, more precise, linear, ions currently can't be accelerated to dramatical energies and needs so-called accelerating rings - bulky, heavy, inefficient. Heavy ions can't be accelerated in much quantities, and while energy flux isn't as bad, total energy is pity.

Common disadvantages: All the above needs really lot of energy to operate.


5. Static cannons. These ones are basically macro-particle linear accelerators,
usually powered by Van-der-Graff statical high (several MV are easy) voltage generators. They accelerate micron-sized particles which are charged beforehand. Achieved velocities may be as high as several hundred km/s, but ROF and general kinetic energy flux isn't as spectacular.


6. Explosive acceleration. Plate placed on big explosive charge may be easily accelerated to several km/s (depends on explosive used, TNT < RDX < HMX~the_best). With some tweaking, this tech may be employed for killing stuff. In fact, it's already used. BTW, thiner plate = more velocity, but long projectile is far better is senses of both penetration and ballistics. This problem may be resolved by specially shaped charge that deforms accelerated plate (in fact, real deformation occurs after acceleration) and makes it "flying fist" rather than flying pancake, but I fear I shouldn't say any further. Use your imagination for details...

Analogous stuff may be performed using so-called electrical explosion of conductors, which occur then conductive media is almost instantly overheated to plasma temperatures via _huge_ current. BTW, electricity makes better energy than chemicals, but chemicals are "encapsulated" energy and easily available at any time, while electricity or likewises must be produced, not-so-easy stored and then used in one unit. Suggestions?


7. Lasers. Lasers definitely are more dangerous in SCSI-fi rather than real life, but it may eventually change (still unlikely, tough). The main problem with laser "fire" is its extremely low penetration depth (~wavelength in metals) and easy blocking by plasma. Inside atmosphere, it causes so-called laser "spark" which is due to avalanche-like heating of air initiated by hot plasma emitted form the target. This phenomenon may even damage or destroy laser itself. Hey, laser may be destroyed by single dust particle sitting on its "face" surface, as it particle will explode, generate cloud of plasma and eat all the pulse energy in deathly dangerous vicinity. So really powerful lasers are placed inside "clean rooms" what is really far relative to battlefield.
If your fire laser and still alive, you mustn't be disappointed by the fact that only first several ns of your pulse are really effective. After this time (more if target is covered by something hard to vaporize, say, tungsten or niobium carbide) laser beam in fact heats cloud of plasma rather than target. It's exactly like earth ionosphere what mirrors long radio waves, but much more dense. OK, target is still heated by cloud's IR radiation, heat transfer and attenuated laser beam, but it not such fun as at beginning. So you must choice: either you make really short pulses (wasting much of laser's energy via so-called "efficiency modulation" technique) or waste pulse energy by heating air and generating nice bright flash. Your desire.
Recently, new kind of lasers was introduced, namely femtosecond lasers (1 fs = 10^-15 s). This stuff hinders matter by different way. It's pulse if to fast to do something with ion lattice, as their time of response is something about ~10^-12 s. Electromagnetic field in this beam is so strong that it can easily stone electrons from atoms. This electrons become really fast and run away from beam like mad. Ions become disappointed by this and also become angry, just after 10^-12 s. This stuff is called "Coulomb's explosion".

So modern lasers are strange creatures, but they're still hardly usable for military. But, this problems may be overridden via either sheer pulses energy or clever and novel techniques that I'm unaware of, like spatial energy profiling and so. Later, I may question my colleagues that are in it. Currently I know that ring patterns are more profitable to use, they are less hindered by plasma and shock wave may be focused at desired depth in target, forming so-called Mach's surface. Periodical wave strobing is also OK, as it cloud may dissolve between pulses.


8. Microwave. Your can toast your enemies from great distances using pulsed microwave energy emmiters. This waves may be aimed using so-called phase lattices. This stuff is fairly [cost]effective, easy to use and not so disappointing as lasers. Microwaves may be stopped by any conductive material, but they tend to use even tightest flaws to break thru. It's great stuff for melting enemy's circuits, cooking brains of their soldiers etc.

9. Sonic. Sonic waves may be dangerous. They may be focused to small surface and bring the power for people - unwanted power. Infra-sonic waves are deadly for living creatures. It's natural precursor for many catastrophic events and wreaks terror even among steel-heart ones. High intensities are in fact deadly. It's almost impossible to insulate from (cause it the same as with "long projectile is better", can your comprehend it? If not, I need to explain this better). But this stuff still needs some media, earth or water if better than air, but air is enough to kill lot of people... kinda neutron bomb without radiation... dirty thing.


10. Nanites. This thing seems to be favorite gadget in StP, but it was mentioned as armor enhancements. BTW, all-eating nanites may become deadly weapon. BTW, I'm still wondering about their energy source, communications and control.


11. Missile/bomb/mine warheads. The main problem with missiles and their ilk is traveling to its prey, which among other things encompasses propulsion problem. But, StP is something about space colonization, so let's say we have pretty good prop in hand. I'm not a rocket engine expert, but I really know how they really work (including real working examples... fear I can't say which examples and how good they are except that they are exciting good in some aspects) and modern propulsion tech are close to its theoretical limit (darned specific energy and molecular weight). So you need something really new. Concerning warheads:

a) Chemical ones, currently 99.9% of net use:

a1) HE - most commonly used, dumb type known several centuries (to Chinese at least). Penetration depth is roughly proportional to caliber and isn't exceptionally fascinating. Warhead may "wait" some time from impact before actually detonate as it may penetrate deeper into enemy structure or unit. BTW, buildings are more easily exploded from low levels and perfectly placed charged or bombs must be somewhere deep, preferably nearby carrier walls. This is also true for killing, say, ships.

a2) Cumulative ones: form tight stream of really fast "heavy metal" (it's fun, but this metal isn't dramatically hot, at least until it strikes something; it's "dissolved" by pressure rather than heat; shock waves in general aren't especially good heaters while they're not really "strong"; without much of math, common explosive wave isn't especially "strong" while air wave generated by a-bomb is). This stream splices thru armour and makes big deals. Warhead can't be rotating. Velocity may be about ~10 km/s, and even more for electrical collapce.

a3) Napalm and friends: Either day is to cold or morning isn't smelly, you may bring more warm to your life using this sticky jelly. In general, napalm consist of some fuel combined with jelly to stick to walls, ceil, skin etc. _Some_ states (NATO and USSR for sure) add some more dopes which makes cure for burns impossible. This stuff is usually employed in special containers what spread it over great territory. Napalm tends to sink even into smallest flaws, easily burns on ceiling, and tends to drop oxygen level dramatically. Isn't especially good against armour.

a4) Volume explosion. Warhead expands great amount of gaseous fuel into air, then ignite. Ka-boom! Great, strong, "long" explosion from that isn't easy to hide.

b) Fission: BTW, a-bombs tend to decrease their size over time, today it may be fitted into 230 mm gun and even less.

c) Fusion: way to dirty, big and lethal, this things may really object minaturisation. BTW, "inertial confinement fusion", dream of at least 50% physicist in high energy physics (hey, this dream is too long!) may eventually lead to production of really small fusion _targets_, but they must rely on some external energy source. For example, attacker may "ignite" it via some beam if it's pretty nearby some sweet victim.

d) Anti-matter? Much a bang for much a buck, this stuff isn't easy to obtain and even harder to store. This thing may eventually become ultimate killer, obliterating entire worlds with suitcase-sized gadget. Dust sized ones may be used for killing tanks or so. Someone knows how to create this stuff en mass?

e) Collapsars? BTW, these ones may be formed by sending lot of matter (or energy) into small volume (its size for spherical geometry is known as Shwarchshield's radius if I spell correctly). This matter/energy will form "black hole". Unless you're sending something really heavy (earth mass fits), this black hole will "evaporate" in matter of fractions of femtosecond, forming storm of high energy particles. So your effectively waste your energy, converting form one form into another, less suitable for destruction. If formed inside target, it may eat atom or two before collapsing, if it's extremely lucky. Any reasonable big black hole must be _*H*E*A*V*Y*_. Moving collapsar may trek thru its victim, eating unlucky sparse particles and will eventually explode, so this stuff may be used as form of "delayed explosion", but it must be really fast in order to travel any macroscopic distance. Gravitation forces isn't as dramatically huge as one may think. BTW, two gravitation acting on pair of electrons placed with 1 m in between is ~ as electrostatical force acting on pair of electrons placed in ~700.000 l.y. So I still thing collapsars as weapon simply can buy the candles.


Almost all of the above needs _LOTS_ of energy to operate. Currently common schema involves huge capacitor batteries. For example, my favorite e-beam is feeded by battery of 20 sections of 7 capacitors in each. Every single capacitor weights something like 32 kg. This accelerators is fairly compact, more powerful have even more disappointing properties.
Please stop crying, now good news. This parameters seems to steadily improve, but I think that it will hinder high-tech weaponry for long time in future. We may use other energy sources. For example, coil "capacitors" are almost 100 times more light, but less reliable and more costly. Explosive generators are also good asset, as they transform chemical energy into electrical pulse of great power (GWts are possible) by collapsing electrical contour from which magnetic field can't escape due to conductive shielding. The same may be used for would-be fusion generators. Use your imagination. I'm already bored and need some time to recharge my batteries.

[Lemmy]

Ack...put some [ b ]bold [ /b ] text in there, and some extra blanklines, maybe one between each number...

[targon]

Done. Any other suggestions, quiestions, proposals?

[Lemmy]

Thanks, lot more readable.

No suggestions, no questions, and no proposals either...i just like the explanation with all the types of weapons.
Very interesting post

[Jeremy Buloch]

Well the Power Source for the nanites could be as follows:
A generator on the command vessel and/or object.
The generator enables a wireless power field. Where the nanites would be powered by a far distance and wont need to have power cells attached to them. This generator would of course need to be near the vicinity to operate the nanites but it would provide a good power source.
-J.B.-

[Michiel]

Very interesting post, indeed. Long too.

How do you know all this stuff, anyway?

About antimatter. It's currently produced by nuclear reactions, so it's extremely dangerous to make and at the time, it costs more energy then it produces. It's a long way from a weapon.

Why is our world so matter-dominated? Why, directly after the big bang, didn't matter and antimatter collide again? I hope I won't make the whole thing sound too startrek , but maybe, in space, there are antimatter-clouds/phenomena that you can harvest and use. Not only as a weapon, but also as a powersource.

[DeathByTheSword]

I have read over a lot of it and this i what i came up with:
(in random order)

missiles/rockets will not work in outerspace. you cant carry the fuel in a rockets to follow a fast moving craft in space. a small alteration in the path of a spaceship and it costs a lot of enegry to alter the rocket...second of all normal way of altering the rocket will not work in outerspace. you will need even more enegry (= more fuel) to do it.
in the atmosphere they work fine

we build a railgun at school and we could destroy a woodenboard...the only problem was that that it could only be used ones by us.....but if some kids can build that in school with simple stuff i believe we can use them A LOT in StP at least in Space...problem if you use them in space.....a year later another ship my be hit by it....so what to use in space?


i have been thinking about that a lot.....we will have enough weapons we can use on the ground...but what kind of weapons are we going to use in space?
the only think I can think of are missiles...but because i already tought of that as in possible....then i think we need to think of very big missiles with the same kind of propolsion as our spaceships will have (never ending I guess)....and the ability to shut down and return to the ship if it fails...and spaceship will not explode.....because all the pieces of the ship will hurt the other ship so the only way to defeat an enemy spaceship is to make a hole in the ship without an explosion....that will directly kill everone on board.....just some toughts if we are going to be realistic then we have a HUGE problem in space combat

[Michiel]

Well, I'm not sure if a 'forcefield' is realistic enough... (Is it possible in theory?) But if there is a forcefield that can stop molecules from passing it, it can be used as a containment-field. In the event of a hole in the ship, a containmentfield can be placed to prevent everyone from dying. (Also, it can lead to 'shields' around the whole ship)

Star trek may be fictional/unrealistic, but it can be a great source for ideas. Tell me if it's really impossible.

But I think a lot of the weapons Targon suggested can be used in space. Using projectiles in space is hard (not impossible), but I'm not sure about the rest of them.

[Rasbelin]

I read through the post by Targon and I have to say it looks very impressive. I didn't come up with anything to add now, but I assume DBTS could be right about his claims, but I'll leave it for someone else. I'll lurk until that.

If we get weapons added for space use too, then I'll get this included in GOD as the basic structure for the weaponry used in StP for both space and planets. That should make it easier to design individual units and weapons.

[DeathByTheSword]

yes but many 'normal' weapons are not fit for space...maybe only lasers but as Targon said they are pretty hard to make

[Blake]

No plenty of weapons are suited for space.
Lasers
Ion Cannons (note: Must fire neutral particles, you cant easily accelerate neutral particles, so accelerate positive ions and combine with electrons...)
Missiles: If the missle can accelerate faster than a spaceship, than unless it runs out of fuel, it can hit the ship. More likely a missile will be fired to intercept a ship, and detonate "in" the ships projected path, leaving a cloud of of shrapnal and stuff for the ship to fly into and destroy itself.
Conventional Guns: There is no reason at all why they cant work in space too, range and projectile velocity is a problem, but at closer ranges they could be effective, especially with some extra *relative* velocity thanks to the target moving, a few bullets that connect could do some nice damage.
Rail Guns: The better design would probably go for very high velocity rapid fire.

By far the greatest difficulty in space combat will be hitting the target, evasive manuveres will be quite important, even against laser fire. Ship design will probably be towards having a very small profile when facing the enemy, making two popular designs a long cylinder (suitable for weapons like ion cannons and rail guns) and wedge shaped battleships which have a farkload of armour plating along the leading edge.

Spheres could also work, but would require a lot of armour plating, altough spheres would probably be the shape of choice if forceshields can be invented.

For very small ships the shape wouldn't matter much because if they get hit, they die, so they'll be taking much evasive manuveres.

Ultimately realistic space combat will probably come down to ever smaller ships with ever increasing firepower.

Ofcourse there is no need to make space combat realistic, altough totally disregarding realism is always foolish.

[DeathByTheSword]

one problem in space there will be no cloud of shrapnel and every accelarated thing needs as much enegry to be stop.....if you fire with a bullet at a spaceship the bullet will go on and on and on....it will not stop....if you explode an spaceship the shrapnel will go on and on and on in every direction and it will hurt your ship too....lasers are ok I think...but as you shoot out something solid and you misses i will go on and on and will hurt totally different things and that is not the idea

[Blake]

but as you shoot out something solid and you misses i will go on and on and will hurt totally different things and that is not the idea

Remove the "will" and replace with might. As in, you might step outside and get hit by the international spacestation after it got punted out of orbit by a coffin launched from a ship of advanced space faring aliens that like to eject their deceased into outer space. (Note: For those who dont wish to do the maths, the probabilites of that happening are not very high)

If a battle occurs in deep space, the cloud of shrapnal will quickly expand so much as to present no additional threat to passing ships, and in fact can not really be descriped as a cloud, rather an expanding shell of debries of extremely low density.... the key to effective usage is detonating the missile at such a time as to make evasion (or countermeasures) impossible, but still having the shrapnal cloud/shell dense enough to give good odds of causing damage.

Battles in orbit could present more of a danger to other spacefarers, but then again using a flak strategy only really works against incoming targets, altough if you happen to know a target is in a particular orbit, you could always deliver a load of junk in the same orbit, but going the *other* direction (good way to destroy a space station?).

Besides it is in human nature to disregard consequences...

It would be interesting to have some space debries factor for planets, a planet which has had many space battles will have a lot of space junk in orbit, and ships in orbit have a higher risk of getting damaged.... and have some sorta ship or something to sweep up space junk.

[Gateway103]

I have been quiet busy/lazy lately, but anyway, I have some little input (hopefully useful) about space combat. The manuverability of space craft, in terms s of turn rate and turn speed, would be dependent to thrust and the velocity at which the craft is travelling at, in a similar fashion as atmospheric aircrafts.

Let's disregard the issue of physiological restriants for a second (not that it isn't important), in general, the faster you are travelling, the more difficult it is to turn. There are issues of structural stress, and even if you are able to turn, your turn radius would be much larger and consequently turn rate slower.

In atmospheric flight, there is a "corner velocity", which is the most optimal for turning, which isn't at slowest velocity, because the aircraft must have sufficient lift and consequently energy to turn. However, in space combat, due to the absence air and strong gravity well, as long as your ships hull can handle it (plus the occupants can), I believe the lower the velocity, the better the turn rate. Nonetheless, it is generally not advisable to slow down to a snail's pace during combat, since you'll make an easy target.

Anyway, what I am getting at is that even if the space crafts can travel at fast velocity (sub-light, say 0.2 C) for linear travel, if you want any serious space combat (i.e. as oppose to a quick flyby exchange), the opposing sides would have to slow down to slow velocity for manuvering and space-version of dog-fight.

And it is precisely at this slower speed, even with much larger range than atmospheric dog-fight, that convention projectile and missile weapons, as well as laser weapons, are usable for combat.

Now you might say, well, these sound only like fighters and small vessels, what about larger vessels? Well, if you have larger vessels, the combat will be more like naval combat in modern era, whereas low profile, as Blake mentioned, would be favored. Nevertheless, for a complete, self-sufficient taskforce, it would necessarily have smaller, faster and more agiles, escort vessels, and possibly also fighters (launched from carriers), that would intercept/engage missiles and enemy forces.

So in conclusion, regardless how fast the ships may travel at (even faster than light), for a serious combat, sub-light, and very small sub-light speed would be necessary (unless you have weapons that travels at super-luminal speed, because at fast velocity, when you see the enemy at position A, they are already gone)

Ok, enough babbling for now ^_^

-Gateway103

[Blake]

Good to see you gateway

Well regarding turnrate you are mostly wrong (but it's a common mistake/misconception that I've seen before by people who really, should know better...). Turning doesn't make much sense in the absence of friction, the only thing that really matters is change in velocity, it doesn't matter if your going at 0.2c or 20m/s, if someone fires a bullet *to intercept you* then all you need to do is accelerate in some direction so that the bullet hits empty space.

If someone fires a missile to intercept a ship, then the only thing that matters is how well that ship can accelerate. Now granted if the ship is going faster, it will run into the missile faster, giving less time to react, but on the flipside it gives the missile less time to reach the ship.

If I seem to be babbling, it's probably because I am.

Anyway, the important thing is, in space the manuverability of the ship does not depend on how fast the ship is going.

An interesting exercise is dodging laserfire (well, I mean as a thought experiment type exercise, dodging laser fire is physically difficult for humans)

Imagine we have a big lasergun, it can hit a target (say the left eye of a rat, it's infinitely accurate and precise) at 30,000,000 m, which is approximately how far light can travel in 1 second (and is comparable with the distance from earth to the moon)

This laser is being fired at another ship which is at the distance of 30,000,000m from the laser. It is aware that the laser will be shooting at it.

Question is, can the target dodge the laser?
Well, you might think that because it's impossible to see a laser beam coming the ship wont be able to dodge. But it can.

Firstly, the lasergun has 1 second old information to work with, so it is obviously shooting at where it thinks the ship will be, it is fairly trivial to determine the velocity of the ship; the location of the ship in 1 second can be accurately determined and the lasergun can greet the ship with a laser beam.

Now all the ship has to do, is not be at the position where the lasergun predicts, which means it needs to accelerate in any direction, because it takes 1 second for the light from the ship to reach the lasergun, and another second for the laser to reach the ship, the ship has 2 seconds to accelerate.

The ability for the ship to dodge depends on how fast it can accelerate, and how large it is, the maximum distance the ship can change position by in the 2 seconds is given by simple kinematics : d = 1/2at^2
If the ship can accelerate at 2 gees then that distance is 21m, so if the ship accelerates in some direction (not directely towards or away from the lasergun) it can be 21m away from where the lasergun fired at.

Whether or not this saves it depends on the size of the ship, obviously if it's a sphere with a radius of 21+m, and the laser was aimed to drill it dead center, it will get clipped by the laser and destroyed, however if it's smaller then the laser will pass harmlessly by.

So basically the first conclusion is that, even the most perfect laser imaginable cant be guaranteed to hit a target doing evasive manuveres, thanks to the speed of light.

The second conclusion, is that the velocity of the target *does not matter* because the laser is aimed at the *expected* position of the ship, and the ability of the ship to be somewhere other than the expected position is determined solely by how well the ship can accelerate.

The third conclusion is, if the laser hopes to hit the target, it has to try to fire somewhere where the ship *can possibly be* (a sphere of radius 21m around the expected position of the ship) and hope that the ship is indeed there, thus at that range hitting targets with a laser comes down to probability, and it would be possible to work out the probability of hitting the target given:
Distance
Size of target (cross section)
Maximum acceleration of target.


The final conclusion is that I probably talk too much.

[Jeremy Buloch]

Yes Good to see you Gateway. I wish you an easy time.
By the way, Blake you dont talk too much.


Now about this topic of ours...

The energy Weapons would be much more beneficial in stellar combat. The energy pulses would hit the vessel and if it misses then the energy slowly disipates. A projectile would have too many risks involved that would make it unsafe.

If we were to use projectile based weaponary then we would have to devise some sort of working system that would go as follows:

Two vessels are in combat and one vessel fires a projectile which misses the other vessel. Later after the battle another innocent vessel is passing through space and is hit by a stray projectile(s). This would have to be implemented into the game in order for it to be realistic, would it not?
-J.B.-

[Blake]

Two vessels are in combat and one vessel fires a projectile which misses the other vessel. Later after the battle another innocent vessel is passing through space and is hit by a stray projectile(s). This would have to be implemented into the game in order for it to be realistic, would it not?

Space is big, spaceships are tiny. The only time that stray shot has even a remote chance of hitting something that feels it (ie not a star or blackhole) is when it's locked in orbit, hence prehaps a "Space Junk" variable would be useful.
- keep a count of the total number of particles in orbit
- calculate the volume of space in the orbit
- from that, determine the chance of a spaceship hitting 1 particle
- use some sorta probability distribution to determine if, and how many particles the spaceship hits.
- throw all that out the window, and use an approximation that works
In practise have some variable that increases each time a spaceship gets blown up in orbit of the planet, it should reduce slowly due to junk falling into the atmosphere. Use some sorta probablistic method to determine how many hits orbiting ships get....

In principle a whole solar system could start getting dangerous if entire planets start getting blown up (a planet worth of debries scattered in a belt around a star presents a significant danger to spaceships). But when talking a single stray shot, nah.

[targon]

Hey, IMHO, your "space junk" fears are fairly irrelivant, as high-tech projectiles will surely leave this humble solar system as they velocity will be reasonable high (~30km/s will do). Missiles even now employ self-destuction if they can't hit the target.

[targon]

I've forgot about some more weapon stuff:
Discharge cannon. Atmosphere only (possible hydro). Employs massive discharge generator coupled with pulse laser. Laser beam forms conductive "thread" that is later used to fry enemy electronics and even armour via strong discharge. Laser may be substituted with some other beam, but electrons, protons and especialy heavy ions tends to deflect and change its directions.

[Blake]

Nah I mean junk leftover from battles, like when a ship explodes, sure some of the debries would escape the orbit, or hit the atmosphere, but some would remain in orbit.... (assuming the spaceship was in stable orbit)

I assume a discharge cannon would only work in atmosphere? ie the laser beam ionizes atmosphere to make the conductive thread.

[targon]

Blake,

Originally posted by targon
Discharge cannon. Atmosphere only (possible hydro).

In fact, I saw its working prototype, so it is't my pure imagination... there are some problems, but we speak about future, right?

Originally posted by Blake
Nah I mean junk leftover from battles, like when a ship explodes, sure some of the debries would escape the orbit, or hit the atmosphere, but some would remain in orbit.... (assuming the spaceship was in stable orbit)

Yep, you're right. Assuming the spaceship was in stable orbit, center of masses of its debris must remain the same orbit (w/o light pressure, atmsphere and other subtile ways of momentum transfer)

[Gateway103]

Originally posted by Blake
Good to see you gateway

Well regarding turnrate you are mostly wrong (but it's a common mistake/misconception that I've seen before by people who really, should know better...). Turning doesn't make much sense in the absence of friction, the only thing that really matters is change in velocity, it doesn't matter if your going at 0.2c or 20m/s, if someone fires a bullet *to intercept you* then all you need to do is accelerate in some direction so that the bullet hits empty space.

Well, it actually does depend on your velocity. Let us assume your ships can produce a constant maximum X amount of lateral acceleration (used for turning), and the linear velocity is constant at V.

Now, the lateral acceleration is your centripetal acceleration, which we assumed to be constant and equal to X. Therefore, by the formula, F = MV^2/R = (4 Pi^2 R M) / (T^2): we see the following,
(1) Since F (i.e. X is constant), then the relationship between V and R (turn-radius) is R = MV^2/X
(2) Also, T^2 (square of period) = 4 Pi^2 R M / X
(3) by (1) and (2) then, T^2 = (4 Pi^2 M^2) / (X^2 V^2), or in otherwords, T is proportional to V (M and X are fixed if linear velocity is constant, and X fixed).

By result (3) then, if the period required to complete a full turn (i.e. 360 degrees) is proportional to V, then the turn-rate, measured in radians/second, is 2Pi/T or proportional to 1/V. In otherwords, if velocity increases, turn-rate is lowered.

This should be intuitive, because if you think about it, turn-radius definitely increases with increasing in linear velocity. And unless your ship is capable of generating and withstanding any arbitary lateral acceleration (providing you, the passenger, can withstand it too), you must move across a longer arclength (i.e. longer path) at the same initial velocity you were in (again assuming only lateral acceleration). So since T = D / V, increasing in D, while keeping V constant, will surely result in increasing in T, and subsequent lower turn-rate.

Now I hope I have illustrate that turn-rate and turn-radius are indeed affected by your initial linear velocity, I wish to discuss more about space combat.
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You are nevertheless correct in that actual space combat at long range (read: lightsecond and upwards) is problematic. However, long range weaponary tend to have short-comings.

1) Beam Weapons
With lasers or other beam weapon capable of luminal speed, there exist the problem of energy dissipation over distance. This is not a trivial matter, and does exist in vacuum. But for 1 light-second, this may be alright (given you have centuries to refine this tech perhaps)

The more serious concern is the energy output of the beam weapon. In your thought experiment, just because the defender is hit with the laser, it doesn't mean it is destroyed. Beam weapons is like a conduit, depositing energy from the attacker to the defender. Therefore, the amount of energy you can put on the defender depends not only on the energy output of the beam (ignore dissipation for now), but also the duration. Just grazing the defender's ship for a fraction of a second probably isn't enough to do much damage, unless you got one very-powerful lasers (probably not on ships due to power generation constraint; but with orbital weapon platforms such as space stations, this is feasible)

And foreseeably, because of movement, energy deposition is spread over an area of the hull, thus lowering the energy density and most likely damage incurred. Also, armouring materials at the surface of the hull would likely to be designed to spread incoming energy as quickly as possible across the entire outer-hull, so again minimize damage. Therefore, beam weapons at long range isn't going to be very effective against agile defenders.

However, if the target is immobile, well, then you may be able to do some serious damage there.

2) Missiles-type
Missiles are more capable of delivering a concentrated energy blast to defender, either via actual impact detonation (difficult against agile target) or proximity detonation (via sharpenal or other means). Missiles are limited to travel at sub-light speed, although they may indeed be faster than ships. Nevertheless, at long range, enemy would have time to pick them off with point-defense weapon platforms (e.g. PD lasers, or more agile escort/picket vessels, including fighters).

Now for closer range however, missiles can be devastating, provided you the attacker isn't too close either.

3) Projectile of sub-light speed
Projectile of sub-light speed suffers the same accuracy penalty as luminal speed beam weapons, and even worse. However, due to the absence of pretty much anything in space, damage potential dissipation due to travelling distance is not significant for moderate range. Therefore, these are most suitable for close-range combat.

Conclusions:
1) Long range combat is feasible, especially against immobile target and/or larger/slower targets. However, against small and agile target, this isn't going to be productive.

2) One possible tactic, however, is to throw long range offensive fire against enemy via larger/slower capital ships, while sending in smaller escort/picket vessels (including fighters) to destroy/harass enemy at mid- to close-range.

3) To counter the battle tactics in 2), enemy must also need to have small escort/picket vessels, to protect their larger/slower capital ships from approaching vessels and missiles (long to close range ones). This is akin to modern naval warfare, whereas you see lots of smaller escort vessels for the core ships (e.g. carriers, troop transports, etc.)

4) From 1) to 3), it is feasible that battle would occur in all ranges, depending on the fleet composition and weaponry of each side. And recall velocity affects manuverability, which is very important in mid- to close-range, conventional weponary (e.g. projectile, beam weapon, and missile-type) would then be adequately effectively (of course if you got some better alien tech, by all means use it).

To close it off, battle only at long range isn't going to be common or productive in general, especially if you want to invade planets and attack orbital platforms (while they are immobile, they have much better defense capabilities, not to mention the likelihood of a local defense response fleet). So the general categories of beam, projectile, and missile weaponries can be useful, at various stages/ranges, depending on the sophistication of the relevant technology as well as opposing defense capability.

-Gateway103

[Leland]

Originally posted by Gateway103 Well, it actually does depend on your velocity. Let us assume your ships can produce a constant maximum X amount of lateral acceleration (used for turning), and the linear velocity is constant at V.

...

Uh, it seems like you define "turning" in space as a change in velocity V to -V. In that case, of course the time spent in the manouver is proportional to the initial velocity. I'm not much of an expert in this stuff, but I don't really see the relevance of this in evasive action... to dodge a bullet/missile/beam, all you have to do is to avoid being in the same place at the same time, and this you can achieve by accelerating in any direction (assuming the guys who shot you assumed you won't accelerate at all). If the shooting algorithm takes into account your initial acceleration at the time they pull the trigger, then the situation gets too complicated for my puny brains though...

Hmm, how come I get the picture that the best way to dodge lasers and dumb projectiles would be to set your ship's engines accelerating in random directions, and then hoping for the best? That might be an interesting thing to see.

[Martin the Dane]

Well I must ask what is the point of turning ratio and radius for a spaceship in combat?

In caombat you want to avoid being hit. So how do you acieve this.

For grund combat you don't use evasive manuvers very much you use trerain for cover, and expose as little as possible of yourself for the shortest possible time. Only when it is not feasible to take cover you use speed and acceleration to dodge bullets.

For naval combat, there is seldom much terrain to use for cover, and since naval vessels generally dont have much in way of acceleration evasive manuvers arn't overly effective.

For air combat, even less cover but you have quite good accelerations, and due to aerodynamics you have to maintain a certain minimum speed relative to the air (airspeed). Traditionally planes have only been able to apply thrust in one direction (ecxept the harrier) so they have use control surfaces to generate lateral acceleration, so the grater airspeed the greater lateral acceleration, for modern aircrafts the turnratio is limited by the ammount of acceleration the pilot can cope with.

Now for space combat, there is still nothing to take cover behind, so the only way to avoud being hit is, as Leland correctly points out, not to be where the projectile/beem/misile "hits", so we have to rely on evasive action, or active defence.
In space there is no airspeed, so unless we operate at relativistic speeds, the absolute velocity is completely irelevant (except for calculating travel time for lightspeed weapons). What is interresting is the relative speeds of the combatants. If they are traveling on a converging cource, thy will for all practical pourpouse be traveling straight for each other, at a given speed, and since spaceships don't have to take drag into account they can be orientated in any direction, so turnratio is irelevant for the purpouse of evasive action. If the aim is to pursue the oponent or escape him, the acceleration is best used either directly towords or away from the oponent, (or rather where the oponent might be at the time of intercept, relative to the current system of coordinates that is) depending on wether you want to prolong or shorten the encounter.
Since the oponent is most likely to use his acceleration to his own advantage, it becomes a question of who has the best acceleration. Here it is interresting to note that if you want to run from an encounter the best cource might be to accelerate more or less straight for you oponent. This might get you closer to him, but since you will then have the greater speed relative to him, you will spend less time inside his sphere of attack. An added bonus is that if he causes you to explode he will moste likely be hit by the debree, so he will be more reluctant to shoote.

Oops there I got into my speculations on space tacktics, and not the dynamics of space combat. Well my point is that turnrate has no meaning in space combat.

As you have no fixed system of coordinates, and don't have any aerodynamics to take into account tactics changes and becomes a question of being where _you_ want to at the time _you_ decide - relative to your oponent. The same goes for your weapons, being it projectiles, misiles or beams.

[Gateway103]

Let's me try again.

Space Combat
-no cover
-no fricition

To dodge incoming fire
-random bursts of acceleration in various direction (i.e. evasive manuvering)

Note about hitting target
-Space is big, difficult to hit directly with projectile/missile/beam weaponry.
-Solution? use proximity/pre-set detonation for missiles. And use a boresighted projectile/beam emitter.
---proximity detonation: the warhead detonated if it is within certain distance away from the target.
---pre-set detonation: more like bombs, it'll travel a certain distance, pre-set by the attacker, then detonate. This works in the hope that enemy will be near when it detonates (like depth charge against submarines)
---boresighted cannon: guns and cannons don't concentrate all their firepower on a single point, or a small area. Surely the damage potential is higher for concentrated fire, but it is much easier to completely miss the target that way. Hence, modern cannons/guns (not hand guns, more like guns on aircraft) has a larger envelope area in which they funnel their projectile into. For example, F-16 is boresighted to about 6 foot, meaning the gun is adjusted to fire a burst that will put 80% of the rounds inside a 6 foot diameter circle. This makes it easier to hit if you aim correctly, despite enemy manuvering. Beams are a bit different, but that's not within the scope of this post
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Now, turn-rate and turn-ratio
-On the surface, many seems to think it has little or no impact in space combat. However, as noted above, direct hit is difficult, thereby you are trying to just put your firepower near where enemy may be.
-Attached in the zip file are 2 files, a diagram and an avi, please load the diagram first.

Diagram
In the diagram, you see two sets of attack. The upper one involves a fast moving target, the lower one involves a slower moving target. Both frames are considered to be relative to the attacker, therefore the attack is considered fixed.

Both target starts out at the same initial position. As indicated before, turn-rate and turn-radius is larger for faster moving vessels, and slower vice versa.

edit: Note, the faster moving vessel, because its higher momentum, would have higher structural stress when accelerating, relative to the slower vessels at the same acceleration. And this diagram assumes the ships are accelerating at their respecitve maximum possible acceleration, hence everything else being constant (ship size, geometry, thrust, mass), the faster ship would have a lower max acceleration than the slower ship. I forgot to mention is earlier, sorry for the inconvenience.

In the upper depiction, Target is moving quickly away from the Attack, but because of its high linear velocity, after some arbitrary time, the probability envelope is as indicated. The probability envelope is given the initial velocity of the target, and the maximum lateral acceleration it can generate, where the target can be in. I.e. , the target may not carry out acceleration in only one direction, but rather doing something, in that case, it'll be inside the boundry of the blue area (actually a volumn if you rotate it about the yellow axis, but drawing 3D is a bit harder on Paint)

Similarly, in the lower depiction, Target is a slower moving target, but with better turn rate and turn ratio. The probability envelope is again depicted.

Ok, now recall that we are not really trying for a 100% direct hit (too difficult), but rather near the target. Assuming your missile detonation kill radius is fixed, and your boresighted cannon a fixed damage envelope. Now consider a missile fired along the yellow axis and detonated somewhere on the axis inside the probability envelope (pre-set or proximity). Due to the shape of the probability envelope, the target can not be very far away from the axis, as oppose to the lower example. Therefore, the target in the upper case is more like to be damaged.

Similar effect works for beam weapon too.

movie
For a hopefully clearer demonstration, please load up the avi movie file.

In the movie file, two defenders started at the same location, but with different linear velocity, travelling directly away from the attacker. Again, all the motion is relative to the attacker, and let's assume the attacker to be stationay. The orange ball you'll see appearing are missiles, where cyan lines are beam weapons. Blast radius is indicated as enlarging balls, (should be sufficiently obvious which is which, despite my poor skills).

Just look at the movie and you'll see that turn-rate and turn-ratio does affect combat survivability, and in an important way.

Of course, this is a very crude model, in actual combat between two armed sides, both parties are doing evasive manuvering, travelling towards/away/passby each other, carrying out counter-measures, as well as firing against each other, making the calculation that much more complicated. Nevertheless, the same principle holds.

-Gateway103

[vovan]

I figure it would be easier for the people to see if they didn't have to download the large file. So, I converted it into a much smaller animated gif (hope you don't mind )

[vovan]

And, of course, the diagram:

[Leland]

This is so counter intuitive that my brains won't accept it. I mean, if the slower ship can accelerate "upwards", why can't the faster ship do the same? After all, in their own frames of reference boths ships have zero velocity. furthermore, since the pursuing missile has lower velocity relative to the faster ship, I would expect it to be able to dodge it.

Uugh.

[Gateway103]

First, thanks to vovansim for convertin the diagram and avi file , I wonder why I didn't think of that

Second, to addreadd Leland's inquiry.

You are right that in their own reference frame the individual ships have zero relative velocity to themselves, so intuitvely they should both be able to dodge the missile.

But an underlying assumption I made, which I forgot to state (sorry, sorry, don't lock me up ), is that there are more structural stress on the faster moving vessel, hence its lateral acceleration must be slower than the second slower vessel so as not to break itself apart (sorry, I factored it in during render, but forgot to mention it in either post... guess that's what happen when you start rendering near 1am in the morning...) So that's actually what is depicted in the movie, the faster vessel having a necessarily lower lateral acceleration.

[I'll edit the above post to include this assumption sorry]

And you are right, if they are of same lateral acceleration (say with some tech to reduce stress), you would intuitvely expect the faster ship to doged as well.

Once again... I am very sorry for the confusion

-Gateway103

[Martin the Dane]

Well I must admit it Gateway you have a point, but it does not hold.

First speed in zero-g and zero-athmosphere does not result in stress, only acceleration does that. So the only important factor here is the acceleration, and we have setablished that it is applied lateraly to the ships current movement.

Let's take an example:
One Attacker A and two targets B1 and B2.

Initial state:
A is moving at Va=10km/s B1 is moving at Vb1=14km/s B2 is moving at Vb2=12 km/s all in the same direction.

We transform the coordiane system to A, so now we have Va=0, Vb1=1 Km/s, and Vb2=2 Km/s.

Since A is clearely loosing ground A fires 2 shots running at 10 Km/s relative to A. The distance to both targets at firing is 1000 Km so the shots will take ~111 seconds to catch-up with A1 and ~125 seconds to catch-up with A2.

If both targets keep going as they did they will then have ~111 and ~125 seconds to live respectively.
And due to the speed of the shot they canot outrunn it by accelerating.

So both B1 and B2 accelerates laterly at full trhust 10g (close to the limit of the pilots I dont think we have to consider stress on the ships, as they can most likely tolerate far more than the crew).

When the shots get to where B1 would have been it has moved ~111*111*10m=~123 Km sideways.

When the shots get to where B2 would have been it has moved ~125*125*10m=~156 Km sideways.

If both shots explodes when they reach the spot where the targets should have been (T1 and T2) B2 has the best chance of escape. since he has put ~26 km more between himself and the blast than B1 has.

Since the attacker most likely knows this, he will probably use multiple spreading shots so now the angles O# between the lines A-B# and A-T# comes into play. (See the attached image)

If I remember my trigonomy-lessons right, O1 is 6.3 and O2 is 7.1 degree, so the faster ship not only gets the benefit of distance but also of the greater angle.