Try putting it this way: you get friction between the molecules of a macro object as well as between two objects. After all, what else is friction?

Gravity, like any other force, applies friction because the force of gravity is acting slightly differently on the various molecules of the object. Why? Because they're travelling at ever so slightly different speeds from each other, and are at ever so slightly different distances from the larger body.

This is taken to extremes at black holes, where the front of you can be moving much much faster than the back of you. It's called "spaghettification", and it's not fun.

So, yes. Gravity causes friction by attraction.

Umm... This is going back a bit, but why build missiles or fighters?

Accelerated mass, especially if your target is moving, is just as dangerous as a warhead, and on occasion even more so. Think about it. An enemy ship is flying past at say 300m/s. You throw a can massing 0.1kg out of the window (airlock?) and boom, instant carnage. Remember:

Kinetic Energy = 0.5xmx(v^2)

But v is relative. So from the enemy spaceships point of view the can is moving at 300m/s towards them. So the kinetic energy of the can is 4500J. Fine. Thats quite small, but enough to go through some metal sheeting. Upscale it. Suddenly you an the enemy ship are moving towards each other at 300m/s (that is, you're both moving at 300m/s, towards each other.). You drop a 5kg mass. Suddenly the energy is up to 900000J. Fine, that about the explosive power of a small hand grenade. But both of you are still only moving a 1080 km/h. Slow in a high-tech universe. Lets go to 0.433c (0.866c relative to each other.). At this speed, 442 493 668 km/h, the total energy is the same as if the charge was pure anti-matter. Thats a five kg mass. Try ten. Or thirty. Or a ton. Mass is dangerous, matey.

In case any of you think I hauled this out of thin air, try http://www.projectrh...t/rocket3x.html and check out relativistic weapons. Although they require massive amount of energy, it makes fighters and warheads obsolete. Maybe Nova isn't at this tech level yet, but...

(wanders off thinking about possible plug-ins)

Ahh, excellent question. One reason is to close the distance. The whole thing of dropping five kilos of mass in another ships path is completely useless if the other ship doesn't hit it. You'll need to get in front of it, and drop your item. Fighters are an excellent way to do that. Even if they're very small, they could easily carry a twenty pound bowling ball, dodge the items the other ship drops, get in front of it, and drop the ball. Of course, that only works in fighter vs. capital ship. Another fighter could dodge it if it was agile enough. That's why you need powered weapons. You can't just drop balls randomly and hope that the other fighter happens to hit them. With a big ship, the acceleration is low enough that you can accurately determine where it's going. It won't have time to brake or change course. But a fighter would, especially if you're expecting it. To get back to the original point, it'll be really dangerous to be going after the other ship. What if it drops the ball? You can't dodge. You need something else to deliver it, so that you don't get destroyed.

You also have the issue of shields. Typically in sci-fi, explosions and lasers do more damage to shields than blunt objects. Or, at least as far as I've seen. Then again, most sci-fi doesn't throw around steel balls for combat.

@templar98921, on Jul 5 2008, 10:32 PM, said in On Relative Sizes of Spacecraft:

Umm... This is going back a bit, but why build missiles or fighters?

Accelerated mass, especially if your target is moving, is just as dangerous as a warhead, and on occasion even more so.

Who said a missile has to bother with a warhead? You're right it would just be wasted space. But the propulsion system to add that kinetic energy? Not so much.

In fact I think even modern high speed anti-ship deal as much damage from their kinetic energy as from any warhead they have stuck on. Perhaps even more so.

@joshtigerheart, on Jul 5 2008, 11:59 PM, said in On Relative Sizes of Spacecraft:

You also have the issue of shields. Typically in sci-fi, explosions and lasers do more damage to shields than blunt objects. Or, at least as far as I've seen. Then again, most sci-fi doesn't throw around steel balls for combat.

Of course typical sci-fi doesn't really have a scientific basis for a lot of things. If you had some sort of electromagnetic deflection field, then explosions would be less effectual, as without a medium to propagate a shockwave, they are just flinging a whole lot of shrapnel around, which is probably less effective than propelling a projectile. Lasers would not be averted at all by electromagnetic fields alone. This of course, assumes that science fiction force shields are using, you know, real forces.

I think one issue you're not really focusing on is seeing things coming. This is an issue in a couple of cases - one, if you're a light minute away from someone you're gonna be a minute behind on their location, all the time. Two, if they have light based weaponry, you literally can't see it coming. So without some kind of FTL sensor, you have to rely on the first case to protect you from the second, because reactive dodging isn't a possibility. Really, it'd be amazing if fighters ever hit anything at all - you have ships moving at an appreciable fraction of the speed of light and you're not gonna be seeing your enemy much at all.

What I'm going to say ties in with the other thread, too.

If ships got ridiculously huge, I would imagine that the force of gravity acting up them, especially very long ones, would cause tremendous amounts of stress on the hull, so I don't think you really could make them too big, unless you use unobtainium. Even if we discount the actual physical problems of building a huge ship, game play becomes kind of awkward. I seem to remember rEVisited having an option to use ships to scale (based on their lengths). Defenders were practically impossible to see, while Confederate Cruisers were so big that they took up much of the screen. While I think certain scale things should be somewhat observed (perhaps the Thunderhead could be a little smaller and the Fed Carrier be a little bigger), I think the bigger issue has to do with space for weapons. I don't see why some smaller ships have enough space to arm themselves like destroyers or carriers.

@pipeline, on Jul 5 2008, 09:08 PM, said in On Relative Sizes of Spacecraft:

Try putting it this way: you get friction between the molecules of a macro object as well as between two objects. After all, what else is friction?

Gravity, like any other force, applies friction because the force of gravity is acting slightly differently on the various molecules of the object. Why? Because they're travelling at ever so slightly different speeds from each other, and are at ever so slightly different distances from the larger body.

This is taken to extremes at black holes, where the front of you can be moving much much faster than the back of you. It's called "spaghettification", and it's not fun.

So, yes. Gravity causes friction by attraction.

@sheer_falacy, on Jul 6 2008, 02:48 AM, said in On Relative Sizes of Spacecraft:

I think one issue you're not really focusing on is seeing things coming. This is an issue in a couple of cases - one, if you're a light minute away from someone you're gonna be a minute behind on their location, all the time. Two, if they have light based weaponry, you literally can't see it coming. So without some kind of FTL sensor, you have to rely on the first case to protect you from the second, because reactive dodging isn't a possibility. Really, it'd be amazing if fighters ever hit anything at all - you have ships moving at an appreciable fraction of the speed of light and you're not gonna be seeing your enemy much at all.

Another huge problem that I didn't think was a problem until Pipeline noted it and Sheer falacy reinforced.

First of all, gravity sensor would be an essential. Not only will mass based particle be ineffective because of the pull on gravity, but photon or light based weapons (lasers) will also be in effective. Basically, light will be way off by the time it gets to the target. As you mentioned, because light is the fastest thing in the universe, at a "light minute" away the ship will have moved in that one minutes some distance. Further, it is important to note that light at that distance (and greater distances) will not travel in a straight line. Remember in space you have all of these "gravity wells" causing space to curve. Thus the path that light travels, isn't flat it is curved. So to even fire a laser or a mass object you are going to have to a) predict the future movement of the object and its target or b ) have an ai on the system that constantly redirects the object (into the correct path to hit the ship) and c) a gravity sensor to read three dimensional curves in space to adjust for "gravity wells" (planets, stellars, stars, comets, astroides...etc...).

So possibly fighters would have a greater role in that, theoretically, they would get closer to the target to minimize distortion of great distances caused by gravity and curves in space.

This post has been edited by Swithich : 06 July 2008 - 04:59 PM

At the gross levels you'd be working at, merely knowing the masses and distances of all the large objects (asteroids, planets, stars) would be sufficient to build a firing trajectory and speed that will hit a certain point in space at a certain time. A gravity sensor merely to detect the curvature of space for this usage is gross overkill. Spend your money elsewhere. Furthermore, gravity sensors can't even work that way. All you get is curvature that is effecting you right now.

While trajectories do bend, for light this only happens in amounts capable of making a beam miss it's target at huge distances, distances that would render combat pointless, due to the information delay. And for objects, we have been doing this since Sputnik. Plotting a trajectory through bent space is trivial.

re: a, You're going to have to predict the movements of your target at all times anyway, because of the information delay. Use it's last seen vector and your knowledge of it's acceleration capabilities to project potential locations at an arbitrary future moment.

re: b, this is so incredibly inefficient it makes my head spin. Plot the trajectory ahead of time, use those gravity wells to help your weapon hit it's target. You're already fighting one intelligent being, there is no need to waste delta-v fighting a force of nature.

The whole getting close thing was one of the reasons behind my stealth tactics post. Get your launchers close undetected and unload on your target at a distance where response time can be measured in seconds rather than minutes.

Gravity-friction is still a problem, but if you're fighting in a gravity well large enough to cause that problem you're already compensating your firing trajectories for it or you're missing.

Hmmm, it seems that either space fights are going to be really far apart and using super-fast super-long range weaponry to do battle with, such as lasers and other light-based weapons, up close and slow enough for normal weapons to work (most likely applies to early tech space battles). It also looks like spontaneous fleet encounters seem unlikely just because of how fast everyone is moving (assuming you're able to come up with technology to prevent inertial forces and the like from affecting pilots and crew for prolonged periods of time), regardless of the fact that stealth technology doesn't work due to mere thermal and heat emissions by ships. Rather, fights look like they'll only happen in critical locations, like in orbit over a planet.

Or maybe because it'd just be too dang complicated, space combat won't ever exist. Everyone would just skip the whole space part and go to the atmospheric combat, where you won't be having ships zooming around at the speed of light.

The longer this topic goes, the more I think it's impossible to envision what combat in space will really be like.

Actually I think lasers will be the close range weapons and missiles the long ones, since random evasive maneuvers will render lasers worthless at long range, whereas a guided missile can correct its course as it closes in. That and missiles given longer to accelerate can spread their thrust time out longer and end up having more efficient fuel usage.

I think it's going to be a long, long time before ships are legitimately travelling anywhere near the speed of light. FTL if it is possible, counts as "cheating", since you have to figure out how to play a different game than increasing velocity to get the same effect position-wise.

@keldor-sarn, on Jul 6 2008, 10:39 PM, said in On Relative Sizes of Spacecraft:

Actually I think lasers will be the close range weapons and missiles the long ones

I thought I'd pop in for a bit and voice my opinion.

I highly doubt we'll see lasers in common deployment. At most, they'll be turrets on larger ships and space stations mostly for point defense. In the long run though, they won't be useful against other ships because those ships will be heavily shielded against atmospheric re-entry and whatnot. I'd imagine that higher-caliber bullets would be much more effective (especially at close range). Their low speed and energy (compared to lasers) will be more effective against space ships. Especially considering that armor (unless considerable advances are made, which they won't be) is heavy and therefore expensive to ship into space. Missiles won't be as effective due to their low-speed, cost of fuel and engines. You'd be more likely to see high-powered rail-gun type weapons shooting bolts of metal made out of lead.

In short, we'll start seeing the space shuttle armed with weapons similar to those on modern fighter aircraft.

...I should go now...

@joshtigerheart, on Jul 6 2008, 09:49 PM, said in On Relative Sizes of Spacecraft:

Or maybe because it'd just be too dang complicated, space combat won't ever exist. Everyone would just skip the whole space part and go to the atmospheric combat, where you won't be having ships zooming around at the speed of light.

Like a Lethean sub-orbital bombardment!

I am reminded of the VS topics of Trek and Star Wars ( but I won't go into them.) What I mean to bring up is Star Wars. It is said to be a civilization around 10000years old (in space). Certain games and other movies have their civilizations around 1000 in space. But none so old as SW. SW has kept the good old combat method of Ship to system combat.

FTL laser combat reminds me of the old joke "If you are driving your care at the speed of light and you turn your lights on, would they do anything?" In other words, pointless.

Just as an aside that I want to contribute:

What if Tachyon-Based Weaponry or Drives become available?

I would like to underline that Tachyons, as stated in the article, are HYPOTHETICAL. Meaning they're just an idea, but there is considerable study into the particles.

The key to Tachyons is they have what is known as "Imaginary Mass." The best example is when you are out playing tennis. For the infinitesimally short time that the ball is in contact with the racket, it technically has an imaginary mass (I remember seeing this on the History Channel, but I can't remember specifically how it's worded).

With this in mind, if Tachyonic Weaponry/Drives/etc. become used, the projectiles or ships could theoretically reach their destinations almost instantly.

@joshtigerheart, on Jul 5 2008, 09:26 AM, said in On Relative Sizes of Spacecraft:

Stealth in space, while fun, doesn't make much sense. I did some research on it once and discovered that it isn't very likely. If your ships have enough temperature for life support, a reactor that produces a reasonable amount of power, and a thruster able to move your ship fast enough, you WILL get detected. Why? If the spacecraft are torchships (aka they don't have some sort of cold engine), their thrust power is several terawatts. This means the exhaust is so intense that it could be detected from Alpha Centauri. By a passive sensor. The Space Shuttle's much weaker main engines could be detected past the orbit of Pluto. The Space Shuttle's manoeuvering thrusters could be seen as far as the asteroid belt. And even a puny ship using ion drive to thrust at a measly 1/1000 of a g could be spotted at one astronomical unit. The life support for your crew emits enough heat to be detected at an exceedingly long range. The 285 Kelvin habitat module will stand out like a search-light against the three Kelvin background of outer space. And your reactor to power your ship is going to be many times hotter. And if you are hoping to lose your tiny heat signature in the vastness of the sky, well, that won't work either. Current astronomical instruments can do a complete sky survey in about four hours, or less.

Hey Josh, the next time you do some research, copy somebody else's work.

Move along...

This post has been edited by JacaByte : 07 July 2008 - 11:05 AM

I forgot to put a link to that, didn't I? D'oh!

That site has some useful information, but it difficult to read for more then a few minutes at a time and I don't agree with a bunch of things on there. For example, they completely discredit fighters being possible, yet totally ignore the necessity of atmospheric combat capabilities on at least some of your spacecraft.

Mike, if your ships can arrive in places instantly, then we'd never have space combat to begin with. Instead you'd move your troop-carrying transport from Mars to a target location in Alpha Centauri in an instance and begin the invasion.

This post has been edited by JoshTigerheart : 07 July 2008 - 01:15 PM

@joshtigerheart, on Jul 7 2008, 12:15 PM, said in On Relative Sizes of Spacecraft:

That site has some useful information, but it difficult to read for more then a few minutes at a time and I don't agree with a bunch of things on there. For example, they completely discredit fighters being possible, yet totally ignore the necessity of atmospheric combat capabilities on at least some of your spacecraft.

Burnside's Zeroth Law of Space Combat states that as long as Sci-Fi fans want fighter combat in space, that there will be space fighters, because readers are more likely to relate to humans than to computers.

http://www.projectrh....html#zerothlaw

As for your atmospheric-space fighters, you might be interested in the X-15, which was designed for both atmospheric and space maneuvering, and entered the official boundary of space on two occasions...

My excuse for fighters is that the devices required to convert the photons from a proton-antiproton collision are too expensive to be used on a one-shot device, and so it is at least as effective to have a manned craft with an antimatter reactor close the distance before unleashing the weapons, rather than fire fusion-powered missiles at long range. More so if most of the ships come back or if you win the battle and can salvage a lot of vessels, less so if you lose disastrously.

@final-frontiersman, on Jul 5 2008, 07:53 AM, said in On Relative Sizes of Spacecraft:

I have a few ideas on ship size. A cessna 172 can fly at 123 knots (140 mph) and weighs 2.25 tons. A F15-C Eagle can fly at mach 2.5 (1650 mph) and has a max gross weight of 20 tons. A Nova spaceship needs to be able to leave Earths atmoshere so it must be able to achieve 18,500 mph. The space shuttle can do so and weighs 1,600,000 lbs, or 800 tons and can carry 25 tons payload. A fully loaded 747 weighs 800,000 lbs. So, accounting for futuristic improvements such as more effecient engines, but adding weight back on for armor, shields, and weapons, I could see a space fighter being an 800 ton monster easily. Modern naval carriers displace 100,000 tons and carry 85 aircraft. Since going from F15 to space shuttle is an increase of a factor of 40, I believe a space carrier carrying 85 fighters would weigh 4,000,000 tons.

But let me lay down some Nova assumptions
1. Ships of all sizes can land on planets
2. Shields are advanced enough to offer protection from just about anything
3. Even small ships can achieve FTL travel

Now in terms of futuristic starship defenses, here are my basic ideas. Shields in Nova seem to be very similar to the shields in Star Wars, capable of stopping lasers, projectiles, whatever. Also the shields in Nova scale with the ship, the larger ships are able to project stronger shields. My thoery on armor is based on NASA's Deep Impact mission when they crashed a probe in to 9P/Tempel. To protect the probe on final approach to the comet, they used several thin sheets of copper spaced out in layers on the front of the probe. For a few kilograms it could stop a ball bearing moving at 60,000 mph. Now imagine a capital ship layered in dozens of layers of armor that are several inches thick. Anything passing through would suffer from refraction. It would take weapons of catastrophic power to penetrate that kind of defense, especially after defeating an energy shield. It should take an entire swarm of strike craft to take a capital ship down.

As for weapons, small ships would probably try to deliver missile or torpedo based weapons because they would lack the powerplant for excessively overpowered energy weapons. Large ships would use more energy based weapons because they could support the power requirements and that would extend their battlefield endurance. Capital ships would also likely carry missiles and torpedoes as fire and forget weapons for hit and run or nuclear ordnance for orbital bombardment. Capital ships would also be very dependent of point defense weapons for protection.

In space tactics, there would likely be two phases: the stealth phase, and the engagement. In the stealth phase, the opposing sides manoeuvre on each other silently, hunting and hiding. Once contact is made, they turn over to active scanning and jamming. Decoy craft, small pods that broadcast ship like signals, would be effective because visual confirmation of targets would be nigh impossible at space combat ranges.

In strategic terms, even if strike craft could achieve FTL, carriers would be important as a refuel/rearm station in enemy territory. Otherwise the small craft would have to jump all the way home before returning to the action. That would make the carrier the center point of the fleet. As carriers would have obscene defenses, direct combat capital ships would likely be required to engage them. Supercapital ships would likely be rare, as rare as carriers, but medium capital ships would likely be common because of thier survivability and versatility. Fleets would have ships of all sizes up and down the scale to operate effectively in the game of space rock, paper, scissors. Strike craft swarm counters destroyer, destroyer swarm counters heavy cruiser, heavy cruiser counters carrier.

Those are pretty big assumptions. Fighters would have to be designed for atmospheric flight, and larger ships would have to have a massive gravity dampening field in order to keep from plummeting to earth in a ball of flames. I wonder if atmospheric combat would ever be needed or worthwhile, when a ship parked in orbit can turn the whole planet into a nuclear wasteland or selectively eliminate the planet's air/sea/ground defenses with Point Defense. But its nova, lalalala.

@nfreader, on Jul 6 2008, 07:50 PM, said in On Relative Sizes of Spacecraft:

I thought I'd pop in for a bit and voice my opinion.

I highly doubt we'll see lasers in common deployment. At most, they'll be turrets on larger ships and space stations mostly for point defense. In the long run though, they won't be useful against other ships because those ships will be heavily shielded against atmospheric re-entry and whatnot. I'd imagine that higher-caliber bullets would be much more effective (especially at close range). Their low speed and energy (compared to lasers) will be more effective against space ships. Especially considering that armor (unless considerable advances are made, which they won't be) is heavy and therefore expensive to ship into space. Missiles won't be as effective due to their low-speed, cost of fuel and engines. You'd be more likely to see high-powered rail-gun type weapons shooting bolts of metal made out of lead.

In short, we'll start seeing the space shuttle armed with weapons similar to those on modern fighter aircraft.

...I should go now...

Its kinda Rock-Paper-Scissors when it comes to space combat. Lasers are relatively ineffective as a long range offensive weapon, but the best choice for short range Point Defense. Missiles are a decent choice for both PDS and long range. Railguns are useless for PDS, but effective at range.

If there is very little mass involved, a highly accurate laser PDS can vaporise a railgun shell, taking a lot of the bite out of its sting.

@warlord-mike, on Jul 7 2008, 07:59 AM, said in On Relative Sizes of Spacecraft:

Just as an aside that I want to contribute:

What if Tachyon-Based Weaponry or Drives become available?

I would like to underline that Tachyons, as stated in the article, are HYPOTHETICAL. Meaning they're just an idea, but there is considerable study into the particles.

The key to Tachyons is they have what is known as "Imaginary Mass." The best example is when you are out playing tennis. For the infinitesimally short time that the ball is in contact with the racket, it technically has an imaginary mass (I remember seeing this on the History Channel, but I can't remember specifically how it's worded).

With this in mind, if Tachyonic Weaponry/Drives/etc. become used, the projectiles or ships could theoretically reach their destinations almost instantly.

Invoking Tachyonic or Warp-Drive technology opens a very different ballgame. Technically we have to invoke some form of FTL in order to make galactic travel possible, but in turn this means that space combat becomes reduced to simply warping a nuke into the enemy ships bridge and watching them blow up from the inside out, with no way to stop it. So it kinda strips all the fun and romance out of space combat.