Discussion Solving the problems of space combat in Orbiter

[Urwumpe]

Seems reasonable. Maybe it doesn't even worth to do raytracing, just checking the distances to a primitive (to nearest poly and its vertexes, if it's convex) will be enough.

Well, just distances could result in strange effects in directed energy weapons (AP projectiles, HEAT jets, Lasers), it makes more sense for area effect weapons (which directed energy weapons turn out to be. As secondary effect).

Shrapnel clouds for example are better modeled as cones or spheres.

 

[Usonian]

As for space combat, I think we won't see any "fighter" like craft like in the movies- there isn't really any use for them.

Certainly anyone who "plays" with Orbiter must know that anything resembling Battle Star-Trek-Wars-Gallactica dogfighting or capital ship maneuvers and bombardment is out of the question. The only things in space worth fighting over are planetary systems, and within planetary systems the effects of orbital mechanics are fairly overwhelming -- especially so on low planetary orbit. You can't just turn, excellerate and stop any which way you care to. Fire a missile and it will go lower and faster, or higher and slower, but remain pretty much in the "fighter's" original orbital plane. Space "dogfighting" would involve the same sort of limited launch windows and slow, meticulous plane alignments as normal rendezvous and docking maneuvers. And why expend all that extra fuel launching the weight of a pilot, consumables and reentry vehicle?

Orbiter is all about simulating real orbital and interplanetary spaceflight, completely ruled by Newtonian physics. I'm not sure a realistic spaceflight model lends itself to an exciting, multiplayer combat game. Still, realistic explosions and damage would be nice -- peaceful spacecraft blow up all the time.

 

[Ghostrider]

And why expend all that extra fuel launching the weight of a pilot, consumables and reentry vehicle?

'Cause space-fighter riding babes in tight suits are HOT.

 

[T.Neo]

You make a good point.

peaceful spacecraft blow up all the time.

:rofl:

(I'm sorry, I read that and I just had to.)

 

[Zatnikitelman]

Actually, would the current Galactica's dogfighting be that far from reality? In the show, the ships launching fighters are already basically 0 rvel already. Now granted over 30km or so you have to take Orbital mechanics into account, but for close-in maneuvering, isn't just turn, burn, and shoot? Hmm, I guess I'll build a lightweight SC3 vessel and test its maneuverability using realistic settings for stuff.

 

[Hielor]

Well, what about defining a generic damage model for Orbiter?

Basically, we just search for ways to project energy on a target. This can be kinetic energy and mechanical forces (also shock waves), or radiation (lasers, masers, nuclear mines).

As suggestion for the start: A library which defines solid primitives (cylinders, spheres, hollow cylinders, hollow spheres, etc). Each primitive gets modeled as receiver for the minimal set of damages we could possibly find.

Another part of the library then takes a damage profile (for example a kinetic kill vehicle) and and "ray traces" it's damage. If the number of primitives and damage rays is low enough, this can be done in real time. As the damages would not always propagate through the full spacecraft during one time step, we could even do divide and conquer.

Would be no true FEM model of a spacecraft, but somewhere close.

I think a generic damage model would be more than what's needed. Assuming you intend to limit your game to a certain set of spacecraft, designing those spacecraft to have specific damage models would result in a more realistic experience, IMO. A spacecraft designer knows what a wing is, and can make it look good for when a wing gets blown off. A generic damage model would probably not be able to do the same.

 

[Usonian]

'Cause space-fighter riding babes in tight suits are HOT.

Touche' mon ami! You win... well played. Praise the Lord and pass the hydrazine!

 

[Andy44]

Actually, would the current Galactica's dogfighting be that far from reality? In the show, the ships launching fighters are already basically 0 rvel already. Now granted over 30km or so you have to take Orbital mechanics into account, but for close-in maneuvering, isn't just turn, burn, and shoot? Hmm, I guess I'll build a lightweight SC3 vessel and test its maneuverability using realistic settings for stuff.

Yes, it would be very far from reality. Starting witht he low rel vel you mentioned, the fighters are launched past each other and must waste lots of dv just to turn around.

Then there is the matter of Vipers and Raptors entering atmo, landing, and taking off again to return to starships far far away without having to refuel.

Then there is the matter of humans outflying Cylon Raiders which are pure bio-machines, and should have much higher tolerance for G's, faster processing and should almost never miss.

Then there is the matter of needing manned fighters at all, when unmanned drones would do nicely, and when a vessel the size of Galactica with handwavium artificial gravity and FTL technology should have energy weapons of immense power, making manned fighters pretty silly.

BSG is a great show, I love it, but aside from some nods to real physics to make it feel more realistic, it's still the Star Wars-style fantasy which it was inspired by in the 1970s.

BTW, only 4 episodes left, finally!

 

[tgep]

We're actually working on solutions to this in the RTF Fleet. By trying to combine realism ( ie physics ) with actual weapons designs.

So far, we have Chainguns, MK-82 SnakeEye Retarded bombs, and two diffrent types of missiles that can be loaded of fighters and on the big ships.

For the missiles, the next step is determining an auto-guidance algorithem that will guide a weapon to the preselected target chosen from what will be the DRADIS.

DRADIS is the key to our plans as it will scan the local area ( just like the sencor MFD ) and enable you to lock on to a target to fire your missile at.

After that, the next step will be determining WHERE the weapon hits and what kind of damage it does.

 

[Eagle]

Lol, with Battlestar's handwavium about anything's possible.

Pretty much the big problem with spacecraft combat is how lethal weapons are and that it tends to follow the 'If you can be seen, you can be shot' rule. And you can see pretty far in space.

Of course reality is never as wonderfully theoretical as theory. AMRAAMs do not have 100% kill rates despite being faster and more maneuverable than any manned plane. Don't expect realistic space combat to be easy or the least forgiving. But people (or aliens ) are inventive enough to find a way.

----------More stuff---------
Andy44, I wouldn't so much call it a waste of delta v just that to go out and back takes four times the delta v as going out. Depending on the drive system the feasibility changes. But hey, sure looks impractical now.

On a side note I've found that you can maneuver really well using only the main, hover and rotational engines. Hover corrects side drift main engines give more speed where you want to go. Set up a croquet course with a bunch of hoops and fly through the circuit as fast as you can in a Battlestar Viper or DeltaGlider variant or ship of your choice. Relative velocity differences between rings makes it much fun.

I'm trying to find an article I read earlier about cooling a spacecraft with a laser instead of radiators. Something where the spacecraft excites a microwave laser with its own infrared heat. The maser beams energy off into space. All I can find is the other kind of laser cooling where a laser is beamed onto an atom to cool it down.

 

[Drake]

I'm trying to find an article I read earlier about cooling a spacecraft with a laser instead of radiators. Something where the spacecraft excites a microwave laser with its own infrared heat. The maser beams energy off into space. All I can find is the other kind of laser cooling where a laser is beamed onto an atom to cool it down.

Hey Eagle,

I don't know of any papers, but physicist Dr. David Brin wrote a story where a laser was used to cool a spaceship - it needed the refrigeration since it voyaged into the sun. The name of the book is Sundiver. He has a blog on which you could post the question. Either he or one of the others there might be able to get you a resource if it exists.

The principle is sound - you need a temperature differential between the thing you have pumped the heat into and the heat sink. There is no physics principle which prevents you from turning heat energy (e.g. IR) into light/laser energy, which you then send out into the universe.

 

[Linguofreak]

Hey Eagle,

I don't know of any papers, but physicist Dr. David Brin wrote a story where a laser was used to cool a spaceship - it needed the refrigeration since it voyaged into the sun. The name of the book is Sundiver. He has a blog on which you could post the question. Either he or one of the others there might be able to get you a resource if it exists.

The principle is sound - you need a temperature differential between the thing you have pumped the heat into and the heat sink. There is no physics principle which prevents you from turning heat energy (e.g. IR) into light/laser energy, which you then send out into the universe.

Actually, there is. The second law of thermodynamics states that entropy must always stay the same or increase. A hot substance has high entropy. A cool substance has low entropy. A laser has really low entropy. So putting heat entropy into a laser beam makes for a huge entropy drop. To satisfy the 2nd law of thermodynamics, entropy has to increase by an even greater amount somewhere, which means that something within your system has to get hotter. Since you're trying to cool your ship, which involves an entropy drop, and since any entropy drop neccesitates an entropy increase somewhere, which means heating something else up, the laser is a bad thing, since it just makes the entropy drop all the steeper, which means you have to create and dispose of all the more hot gas.

Laser cooling in the lab works by shooting two lasers tuned to a very specific frequency through a substance in opposite directions. The short story is that the entropy in the heat of the substance goes into scattering the lasers, which cools the substance.

So basically, you don't want to fire the laser away from what you want to cool, but you want to shoot two carefully tuned lasers in opposite directions in opposite directions *through* what you want to cool.

 

[Eagle]

Bah, I jacked another thread.

Linguofreak, it doesn't violate thermodynamics, otherwise a radiator wouldn't work. The universe gets a little hotter from the laser (which increased total entropy). The laser has enough energy to lase merely because the ship is hot enough. And the ship can never be cooled below the excitation level of the laser.

This means that you would likely use a mix of infrared absorbers and something else that lases lower in the infrared or microwave spectrum.

Thanks for bringing up Sundiver. I read it a few years ago, pretty good book, but it does have a good bit of handwavium. (FTL and artificial gravity)

Its worth noting exactly what happens in a gas laser, I'll use a CO2 laser. A flash bulb (usually ultraviolet) excites nitrogen molecules in the chamber. These excited nitrogen don't tend to shoot off the absorbed photon in one go, so they stay excited. The nitrogen molecules bump into and heat up the CO2 molecules to a similar temperature. The CO2 then lases out. The CO2 can't get rid of all of its energy in a single photon so it says a little hotter compared to before it was excited and the N2 doesn't give all of its energy to the CO2 either. That is the waste heat. The CO2 laser is still cooler than it would have been if you didn't take the cap off the end and let the laser beam out.

 

[Linguofreak]

Bah, I jacked another thread.

Linguofreak, it doesn't violate thermodynamics, otherwise a radiator wouldn't work. The universe gets a little hotter from the laser (which increased total entropy).

Actually, the universe gets a little cooler from the laser. An object is not "hot" unless it has both energy and entropy. A laser beam is basically an object in which all the particles (photons, in this case) are moving in the same direction at the same speed. In the same way, an ice cube cooled to absolute zero and accelerated to an arbitrarily high speed will have all of its water molecules moving at the same speed in the same direction. It will still be very cold, no matter how fast it's moving. (Note that this doesn't say that things won't heat up when the ice cube/laser hits something. But that has nothing to do with the entropy changes involved in the creation of the laser/ice cube).

Basically what you're trying to do is like trying to keep your refrigerator cool by using the temperature gradient between the inside and outside of the refrigerator to operate a device that sucks in air from inside the refrigerator, cools it off, and pumps it out of the refrigerator. The first problem is that you would be better off trying to pump the cool air back into the inside of the fridge. The second is that the only way you can get energy from the temperature of your environment (or more accurately, from the temperature differential between your refrigerator and its environment), is by letting the temperature of the refrigerator get closer to the temperature of the environment.

Basically, a radiator gives off "hot light," the light goes off in whatever random direction it chooses, and thus has very high entropy. A laser gives off "cold light" with very little entropy, even if it has alot of energy.

So if the ship is hotter than its environment, a laser might work for cooling the ship off, but a radiator will work better. It doesn't try to cool off the energy it emits before it emits it, so you dump more heat overboard for a given amount of energy dumped.

If the ship is colder than its environment, you simply cannot use a laser to keep it cool. You may be able to use a radiator, *if* you have some other source of energy than the temperature differential between inside and out (This is basically how an air conditioner or fridge works, but both require a source of power, you can't just run them off the temperature difference between inside and out).

 

[Sky Captain]

Using fighter like craft to attack large space battleships like in sci fi movies is a stupid idea. If we look at realistic technology then larger ship will be able to mount a more efficient engine, carry more propellant, have lot`s of electrical power to power large long range lasers and since both fighters and battleships operate in same medium there is no reason for fighters to have superior performance, in fact most likely battleships will be able to outperform fighters because of their larger and more efficient systems. Also if we stick to realistic technology then fighters will most likely be stuck with chemical rocket engines while battleship will have thermonuclear pulse drive and several hundred km/s worth of delta v.

Fighters also won`t be able to mount long range laser weapons because of their small size and lack of enough electrical power so they will have to get very close to atack a battleship while the battleship will have probably several hours to shoot approaching fighter swarm out of the sky with it`s long range energy weapons.

In space since you can see really really far IMHO basic rule of space combat will be if you have weapons of longer effective range than your opponent with everything else beiing more or less equal then there is high probabilty that you will win the engagement.

 

[Hielor]

Using fighter like craft to attack large space battleships like in sci fi movies is a stupid idea. If we look at realistic technology then larger ship will be able to mount a more efficient engine, carry more propellant, have lot`s of electrical power to power large long range lasers and since both fighters and battleships operate in same medium there is no reason for fighters to have superior performance, in fact most likely battleships will be able to outperform fighters because of their larger and more efficient systems. Also if we stick to realistic technology then fighters will most likely be stuck with chemical rocket engines while battleship will have thermonuclear pulse drive and several hundred km/s worth of delta v.

Fighters also won`t be able to mount long range laser weapons because of their small size and lack of enough electrical power so they will have to get very close to atack a battleship while the battleship will have probably several hours to shoot approaching fighter swarm out of the sky with it`s long range energy weapons.

In space since you can see really really far IMHO basic rule of space combat will be if you have weapons of longer effective range than your opponent with everything else beiing more or less equal then there is high probabilty that you will win the engagement.

SPACE FIGHTERS are useful simply for the fact that they are capable of destroying large BATTLE STATIONS which are always vulnerable only to attack by smaller vessels because the station designers do not feel they are a threat.

 

[Ghostrider]

Fighters also won`t be able to mount long range laser weapons because of their small size and lack of enough electrical power

Well, why DEWs then. A fighter would either launch missiles from medium-long range or use kinetic weapons at short range, either conventional shells or gyroshells. Any laser powerful enough to damage the target by impulse would require one hell of a powerplant and some heavy radiator, but a smaller one could help damage sensor and electronics, and as countermeasure against incoming missiles. But why lase your enemy when you can pump him full of steel...

 

[Urwumpe]

Also, fighters have a stealth advantage: Many small objects are harder to detect than a single large object. If this buys you a few seconds of surprise, this can be worth a lot. But still, this would be far away from the usual space combat in movies. Maybe a bit closer to Babylon 5.

 

[Zatnikitelman]

Plus, it may only take one fighter that slips through to do significant damage and either allow other fighters to finish the job, or the capital ship to blow the other capital ship to pieces. The advantage here is a distributed attack. A single ship, if one system is crippled, the entire ship might be crippled.

 

[Eagle]

But that has nothing to do with the entropy changes involved in the creation of the laser/ice cube).

That is like saying that a radiator wouldn't work if you put a color and polarizing filter and a long tube in front of it. You might lose some efficiency, but it still works. The stimulation at the chosen frequencies of the maser might make up for the polarization inefficiencies and frequency change to make it practical, but it might not. If it gives off light (energy) and is powered from the energy of a hot object, it cools the object.

Also the laser ice cube is not a real object. Laser beams diverge significantly at a distance equal to its initial beam diameter squared. Its going to get spread out across space-time curves and quantum changes. It is a different phenomenon, but pulsar jets are highly columnated and still increase the universe's entropy.