[Chooriwrocafn]

The Vorlons will destroy your homeworld, poor Patroklos! Oh noos!

I do think mass drivers provide the best weapons choice for first generation space combat. Better power in/power out ratio, and the technology is relatively simple.

[mybooboo]

Originally posted by Kuciwalker
Consider the range you'd need for a laser to possibly miss. Missiles would probably take hours to reach the target at that range.

Dude, unless you're more than several light-seconds away, they can't dodge the laser.

(They can't deliberately dodge the laser anyway - it hits as soon as they see it. They can only constantly juke around to try and foil your aim. I think it's likely that space combat would take place at very long range, light-seconds or light-minutes apart. Missiles take much longer, it's true and it's already been pointed out that they would be vulnerable to laser defenses.

Stealth missiles are one way round this, but there are others. Dummy missiles, missiles which split into multiple warheads or a cloud of flechettes, or even laser missiles, which close to a range where they can fire off a single use laser blast.

[Soulofpostar]

Originally posted by Patroklos
Oh noos!

I do think mass drivers provide the best weapons choice for first generation space combat. Better power in/power out ratio, and the technology is relatively simple. What are you talking about? Neither assertion is true...

[MinisuipGaicai]

Originally posted by snoopy369
Well, there is if you pack it full of shrapnel A missile full of shrapnel would have to be based on conventional explosives, or something of similar energy density. Increase the energy density a lot (e.g. nuke) and the shrapnel is vaporized. Therefore you've got a weapon with far less damage potential than our hypothetical military space laser.

[Enfotanab]

Originally posted by Kuciwalker
Originally posted by Whoha
I'll grant that, even though the requirements for a laser that has to survive being shot are somewhat different from a warhead that doesn't, but even if they start out equal the warhead still wins at long distance.

At ranges considered "long distance" for a military space laser, I don't think any weapon will be particularly effective. Missiles can continue ballistically without consuming fuel, so they can travel much longer distances.

The energy will be spread a "comparatively" short distance from the ultimate detonation point, which will be the hull of the ship.

And you think force spread over a large area is more effective than force spread over a small area why? Overkill. Most of the energy from the laser will pass through the ship, while the warhead will vaporize the entire ship.

that material would be blown into space and away from the target/laser.

Why would the material be blown into space rather than transferring most of its energy into the rest of the ship (via the explosion)? The energy should be about equal in both directions. Atmosphere behind the plating that just got vaporized will push it out.

[Assentesy]

Originally posted by Dr Strangelove
I think a laser would simply cut through the hull. Laser beams are generally on the order of microns in diameter. That's not going to create much of an explosion, except for the explosive decompression of the compartments opened to space. See above; a military laser is not going to cut through anything.

[cokLoolioli]

Originally posted by Kuciwalker
Missiles can continue ballistically without consuming fuel, so they can travel much longer distances.

Do you know how long it would take a missile going at non-relativistic speeds to hit a target that's "far away" (several light-seconds) for a laser? Do you have any data on how much power it would take to make a military laser that could do significant damage at a distance of a light-second? I don't know exactly how quickly they disperse, but at a distance of a light second I would imagine the laser would be incredibly wide (I read that a laser from here to the moon would have a dispersion radius of a several mile:
http://sunearth.gsfc.nasa.gov/eclips...olloLaser.html
) ... certainly a military laser would be more powerful than the research lasers they're using, but what order of magnitude more powerful would it need to be - and what power source would you need for that?

[Gasfghj]

I'm not sure how this is relevant to the question in the OP, to which I provided the most concise response: lasers have a limited range before the beam is too weak to do damage. Missiles can hit something much farther away, just at decreased effectiveness (given time to target, etc.). That's the real important difference, and explains fully the phenomenon question in the OP.

[Rchzygnc]

Originally posted by Kuciwalker
I'm not sure how this is relevant to the question in the OP, to which I provided the most concise response: lasers have a limited range before the beam is too weak to do damage. Missiles can hit something much farther away, just at decreased effectiveness (given time to target, etc.). That's the real important difference, and explains fully the phenomenon question in the OP. I'm not sure why you went off on a tangent either We agreed at the start here...

[AntonioXYZ]

Originally posted by Kuciwalker
Missiles can continue ballistically without consuming fuel, so they can travel much longer distances.

Do you know how long it would take a missile going at non-relativistic speeds to hit a target that's "far away" (several light-seconds) for a laser? A fairly long time, But so what, its not like the ships will be moving faster than the missiles will.

Overkill. Most of the energy from the laser will pass through the ship, while the warhead will vaporize the entire ship.

Lasers don't cut through ships. When the laser hits it vaporizes the surface it hits, but it doesn't annihilate the surface. The matter is still there and it continues to absorb most of the rest of the laser. Given the duration of the laser (probably a very small fraction of a second), this amounts to almost all of the energy of the laser deposited at one point on the surface of the ship at one instant. Let me first say that this is shaping up to be one hell of a beam weapon. It can deliver atleast a megaton in a 20th of a second. That is damned impressive from every angle.

But there is still no way that the matter will absorb all that energy, and most of it is going out the other side of the ship.

Atmosphere behind the plating that just got vaporized will push it out.

Wrong timescale. That effect takes orders of magnitude longer than the duration of the beam. There are 15 pounds of pressure per square inch exerting a constant outward push on the hull, the instant the hull can't hold it back it is pushing outward. It is anyone's guess how far away the vaporized matter will get before transfering what energy it has absorbed to the ship, but it isn't going to deliver all of its energy there.

[ebookinfo]

Would kinetic weapons (ie in sci fi mass drivers/railguns/coilguns) have any special use if lasers and missiles were available? I'm not specially talking about space combat here.

[Soadiassy]

Originally posted by Dr Strangelove
In that experiment they shined the laser through a telescope. The mirrors and lenses diffracted the beam, as the article said, until the beam was as wide as the telescope. You have to remember that laser beams are generally in the order of microns in diameter, so the beam was widened by certainly more than 10,000 fold. In so doing I'm certain that the original cohesion of the beam was greatly diminished. It's coherence, not cohesion, and you can't "weaken" the coherence. The light stays coherent even as the beam widens.

[Unamannuato]

Originally posted by Whoha
A fairly long time, But so what, its not like the ships will be moving faster than the missiles will.

Why not? That doesn't seem guaranteed at all.

But there is still no way that the matter will absorb all that energy, and most of it is going out the other side of the ship.

... why not? The matter doesn't have time to get out of the way of the beam. Since it's there and relatively opaque to the beam, it will absorb most of the energy. That's why the laser is so powerful, it delivers most of its energy to a single point.

There are 15 pounds of pressure per square inch exerting a constant outward push on the hull, the instant the hull can't hold it back it is pushing outward. It is anyone's guess how far away the vaporized matter will get before transfering what energy it has absorbed to the ship, but it isn't going to deliver all of its energy there.

The vaporized matter isn't going to get much of anywhere in the duration of the laser. The question then is based on how deep the damage went. If only a tiny portion of the surface was initially vaporized, a lot of energy will escape (though a ton will still be transferred through the hull), but the deeper it goes the more energy will be transferred.

[irridgita]

But there is still no way that the matter will absorb all that energy, and most of it is going out the other side of the ship.

Coming back to this, the energy of the laser will go pretty much anywhere but the other side of the ship. If you look at the kinematics you'll see a lot of the energy actually escapes with the vaporized hull material, back towards the source of the beam.

[johnuioyer]

Ship engine -> missile engine. It is pretty well guarunteed.

What does that mean?

A missile would probably be propelled by a rocket, depending on the scale, whereas a ship could be propelled by a much more powerful engine. Or, the engine could provide less acceleration, but the engine lasts longer so the ship can accelerate for longer and escape the missile.

It's notable that occasionally aircraft speeds have outpaced the speeds of the missiles designed to shoot them down.

Ok, I was still thinking about a beam that couldn't do 20 megatons per second, and that you'd have to hold it on the target for an appreciable period of time(a few seconds) for the matter going out. But this is still something that I'd like to see, unfortunately its not going to happen.

What, a laser with that energy density? Why not?

[Les Allen]

Then put that engine on the missile. Of course the ship is going to have the more powerful engine, but it has to move a great deal more stuff.

Big ****ing missile. Not everything can be miniturized. Also, the engine may be significantly more expensive.

The ship can turn tail and run, or move out of the path of the missiles, but not if it intends to engage the missile ship.

... unless it can fire in a direction other than forward.

and depending on which ship has more fuel available the missile ship can just hunt it down and blow it up later.

What does that say about missiles vs. lasers?

Aircraft have gravitational potential energy available to them.

As do air-to-air missiles.

I'll be long dead before any of that exists.

The same is probably true for most of what we're talking about.

[gIWnXYkw]

The big problem is fuel consumption for the missile, hence the ballistic travelling routine. And if you can build a 20 megaton/second laser however, then I can build any damned missile I want.

It's certainly plausible that a missile could be faster than a ship, I'm just saying that it's not necessary (which you were implying).

We're talking at ranges where lasers suffer. Close up there is no way a ship is avoiding or run from a missile. They will have to just try to shoot it down.

Ability to avoid a missile depends more on relative velocity than relative position.

It says nothing. the laser has an effective range, and the missile has a greater effective range.

I believe I claimed that at the outset of the thread...

I'm betting that the aircraft vs missile stuff you are talking about happened from the stance of a missile fighting against gravity towards an aircraft going with it.

Nope. I can't find a cite right now, sorry, but I distinctly recall reading about at least a couple aircraft that, at the time they were deployed were faster than any surface-to-air or air-to-air missiles in existance. I think the SR-71 was one.

If you want I'll look more later.

in any event, it won't be the case in space most of the time.

I don't think you can make a claim like that. It might be the case in space or it might not. We haven't been considering the relative probabilities of each possibility.