Kinetic Shielding

[Darth Wong]

A lot of people try to find ways to ignore conservation of momentum in collisions without really thinking about how absurd it is. The example I once gave regarding Dune shielding was that according to them, a man wearing a Dune shield could stand in front of a bullet train and it would just stop on a dime when it touched him; "absurdity" is actually an understatement.

Would the kinetic energy actually be transfered to the man, since the shield is a bubble?

Since we all agree that it's absurd to think that the train will suddenly stop, it's obvious that the bubble will start moving, right? And if the bubble starts moving, the man inside it must start moving too, right?

So (and think about this), since the bubble+man have almost no mass in relation to the train, they will both start moving very fast. And what happens to you when you accelerate? Force must be applied. So:

1) When hit by a huge object moving at high speed, you will be accelerated rapidly by the impact.
2) This means a huge force must be applied to your body, since F=ma.
3) There must be some point of application for this force.
4) In the absence of any evidence to the contrary, the only physically likely point for the application of this force is the physical device which generates the shield.
5) The magnitude of the force is such that it would almost instantly kill you.
6) Even if the force were distributed over your entire body (as it is if the train is carrying a huge vertical plate on its front and the plate slams into you), the forces are still more than large enough to kill you.

Is that clear enough?

[HemlockGrey]

Is that clear enough?

Crystal.

[Enlightenment]

You see, the point is that there is a physical explanation for the fact that physical impacts are proportionally more dangerous than energy-weapon hits. And in a universe where ramming is a rare tactic, there would be no need to design or build complex countermeasures against a tactic that they simply aren't likely to see or worry about.

Granted it's irrational to deploy defenses against weapons that no one either uses or plans to use, but then the SW universe is begging the question as to why KE weapons aren't used more frequently. Why chew away at 20tt/sec+ ray shields with turbolasers when the particle shields are substantially weaker and relativistic KE weapons are trivial at SW's tech level? Off the top of my head, 200gt comes out to 8.38e20j--about enough energy to hurl 4235KG at .95c--and more than four times your TESB lower-bracket estimate for the ISD's particle shielding. Perhaps that's not good enough for a one-shot kill but, given the disparity in ray/particle shield strengths, delivering that energy via KE is certainly a better deal than using a turbolaser.

[Darth Wong]

Granted it's irrational to deploy defenses against weapons that no one either uses or plans to use, but then the SW universe is begging the question as to why KE weapons aren't used more frequently. Why chew away at 20tt/sec+ ray shields with turbolasers when the particle shields are substantially weaker and relativistic KE weapons are trivial at SW's tech level?

Are they? Calculate the recoil on a relativistic KE weapon of appreciable mass. At long range, the projectile gets shot down. At close range, you have to maneuver to hit your opponent with it because you can't build something like that into a weapon small enough to spin around; it needs room to accelerate. And you can't put it on a small ship because of the recoil.

Off the top of my head, 200gt comes out to 8.38e20j--about enough energy to hurl 4235KG at .95c--and more than four times your TESB lower-bracket estimate for the ISD's particle shielding. Perhaps that's not good enough for a one-shot kill but, given the disparity in ray/particle shield strengths, delivering that energy via KE is certainly a better deal than using a turbolaser.

Except that now you've got to deal with absolutely enormous recoil and all of the practical deployment issues.

[Connor MacLeod]

Except that now you've got to deal with absolutely enormous recoil and all of the practical deployment issues.

Ok, screw the railgun. shouldn't a particle beam or "plasma" weapon be blocked by particle shields?

[Darth Wong]

Except that now you've got to deal with absolutely enormous recoil and all of the practical deployment issues.

Ok, screw the railgun. shouldn't a particle beam or "plasma" weapon be blocked by particle shields?

Well, whatever blasters are, they are obviously blocked by energy shields, or there would be no point to energy shields.

[Durandal]

Except that now you've got to deal with absolutely enormous recoil and all of the practical deployment issues.

Which they can do quite easily. They can generate artificial conservative forcefields to counteract acceleration of many thousands of g's, after all.

[Connor MacLeod]

Well, whatever blasters are, they are obviously blocked by energy shields, or there would be no point to energy shields.

I wasnt referring to blasters.. I thought we were treating those as massless?

Particle beam and plasma weapons are very distinct from blaster weapons anyhow, so they'd be a different category. I mean, they carry kinetic energy, and don't particle shields handle KE?

[Enlightenment]

Don't think massdriver, think missile. Use missiles propelled by power beamed from the firing ship via laser or microwave.

Given the exposure time of an RKV, shooting one down is going to be much easier said than done, particularly if a portion of those 4 tonnes are devoted to a ray shield generator.

I haven't yet worked the exact numbers but a shooting a .95c RKV with 30 million G acceleration at a range of 2 light seconds gives a one second acceleration run, somewhere between 1 and 2 seconds of travel time and should result in approximately a one second warning for the target ship between the time the light from the acceleration run arrives and the time the missile impacts. Without Jedi precog, destroying a fairly small object in less than a second is going to be a tall order.

[Kurgan]

Not at all; they said that "conservation of momentum does not apply" to Dune shields. If that were true, then the bullet-train stopping instantly at a man's dune shield would be precisely the case. They just didn't think about how absurd it was to say that CoM does not apply.

Then they were wrong (IIRC). Doh!

Were they quoting the canon sources, or was this just their own BS claim?

In the Lynch movie at least, there's no evidence whatsoever that the bullet train thing would work. On the contrary, the shield might survive, but the person inside definately would not!

I always saw the Dune shields as akin to something like medieval armor, or a full body bullet proof vest. It won't save you from everything, but it will prevent certain types of damage from being inflicted on you directly, by dispersing the force throughout the entire surface, than than just in the spot of the blow.

Could you attack a shielded person on two sides for example, simultaneously, and break through? Now that I don't know.

[Darth Wong]

Except that now you've got to deal with absolutely enormous recoil and all of the practical deployment issues.

Which they can do quite easily. They can generate artificial conservative forcefields to counteract acceleration of many thousands of g's, after all.

Yes, but those engines are fixed-axis, and fixed-axis loads can be much higher (you can design a structure to expect loads in certain directions without difficulty; designing one to withstand loads in unpredictable directions, on the other hand, is much harder).

And look at the sheer magnitude of the acceleration you need: millions of G's in order to reach relativistic speed in a reasonable length of time.

[Darth Wong]

Don't think massdriver, think missile. Use missiles propelled by power beamed from the firing ship via laser or microwave.

If the launching platform can target the missile with a laser or microwave over astronomical distances (necessary for acceleration to relativistic speeds), then the enemy platform can target it as well. And since most SW combat takes place very near planets (no need to wander slowly through interstellar space with hyperdrive), I don't think there's enough room to use this kind of weapon.

Given the exposure time of an RKV, shooting one down is going to be much easier said than done, particularly if a portion of those 4 tonnes are devoted to a ray shield generator.

Even at, say, 30,000 G's acceleration, it would take 500s (more than eight minutes) to reach 1/2 c, and the missile would cover nearly 40 million kilometres during that time; if they can still target it with their power-up laser at that range, what makes you think the target ship can't turn it into a vapour cloud? Relativistic missiles don't work either.

I haven't yet worked the exact numbers but a shooting a .95c RKV with 30 million G acceleration at a range of 2 light seconds gives a one second acceleration run, somewhere between 1 and 2 seconds of travel time and should result in approximately a one second warning for the target ship between the time the light from the acceleration run arrives and the time the missile impacts. Without Jedi precog, destroying a fairly small object in less than a second is going to be a tall order.

That's cute, but I don't see how we know this thing can generate 30 million G's of acceleration. Repulsorlift drives seem to be able to do something astounding like that near powerful gravity wells, but I wouldn't extend that an ion drive. Ships running on ion drive are limited to thousands of G's, not millions of G's. It seems unlikely that their missiles can be more than an order of magnitude faster, so the problem remains: very long minimum useful distance, and a powering laser which, if it works, implies that the enemy can probably shoot the thing down.

[consequences]

Simplest thing to do would be to have the missile accelerate to hyperspeed at the target, presuming that the effect we see of ships leaping forward is a massive real space acceleration before ships cross over into hyperspace.

Honestly, I was just wondering if the idea would work at all, I hadn't seen any discussion involving the two mentioned technologies combined.

[His Divine Shadow]

Granted it's irrational to deploy defenses against weapons that no one either uses or plans to use, but then the SW universe is begging the question as to why KE weapons aren't used more frequently. Why chew away at 20tt/sec+ ray shields with turbolasers when the particle shields are substantially weaker and relativistic KE weapons are trivial at SW's tech level?

Well I think it's rather clear that they do protect against them, take the planetary railgun that fired slugs into orbit at the New Republic Destroyer, it downed the shields yeah, it MELTED them after maybe a minute of fire, but the bracings held all the way.

And then there where the quotes where those humoungous mass drivers of old where obsoleted witht the invention of the deflector shield.

[His Divine Shadow]

Anyhow since they have bracings wich can take GT's of force for laser-cannons, let's look at the andromeda weapon, wich is a good example of a high KE weapon, a 1kg missile at .9c would impart 0,6gt·m/s of momentum, I think the shields would be able to take that

The KE of such a missile would be 27MT

[The Nomad]

Slightly off topic, but what would be the effect of the momentum of an Andromeda kinetic missile on an ISD ? Assuming 1 kg mass an .95c relative velocity. How many of them would it take to tear an ISD to shred if they can affect it significantly ?

[The Nomad]

Yups didn't read His Divine Shadow's last reply... sorry

[consequences]

Here's a thought, If the inertial Compensator is only going to work effectively on a single predetermined vector, wouldit be possible to use it to reduce the damage or shield drain you take when you deliberately ram another ship? Or would it just reduce the impact for all concerned and render ramming wholly ineffective?

[Darth Wong]

Let's keep in mind that the shield generator in the main hull is probably much larger and heavier than the one in the bridge tower.

[Connor MacLeod]

Slightly off topic, but what would be the effect of the momentum of an Andromeda kinetic missile on an ISD ? Assuming 1 kg mass an .95c relative velocity. How many of them would it take to tear an ISD to shred if they can affect it significantly ?

Nothing. The According to Destiny's way (along with the Rebel Stand/Rebel Dream duology, which establishes the projectile mass for plasma cannons) The Millenium Falcon can shrug off multiple near-c kinetic impacts from multi-KG plasma cannon rounds without any substantially ill effects.

Then again, you have CRossover_Maniac, who thinks that because of the TESB asteroid incident, that an Andromeda vessel will swiss-cheese an ISD with kinetic missiles

[Connor MacLeod]

Anyhow since they have bracings wich can take GT's of force for laser-cannons, let's look at the andromeda weapon, wich is a good example of a high KE weapon, a 1kg missile at .9c would impart 0,6gt·m/s of momentum, I think the shields would be able to take that

The KE of such a missile would be 27MT

Errr.. a massless beam weapon like a TL has substantially less mass than a kinetic impactor (any kinetic impactor) To impart the same mometnum to a target as the TESB asteroid required a beam in the 300 GT range, remember (check Mike's shielding page.)

[Connor MacLeod]

Let's keep in mind that the shield generator in the main hull is probably much larger and heavier than the one in the bridge tower.

And much more substantially reinforced.

[His Divine Shadow]

Anyhow since they have bracings wich can take GT's of force for laser-cannons, let's look at the andromeda weapon, wich is a good example of a high KE weapon, a 1kg missile at .9c would impart 0,6gt·m/s of momentum, I think the shields would be able to take that

The KE of such a missile would be 27MT

Errr.. a massless beam weapon like a TL has substantially less mass than a kinetic impactor (any kinetic impactor) To impart the same mometnum to a target as the TESB asteroid required a beam in the 300 GT range, remember (check Mike's shielding page.)

What are you erring about? I never mentioned turbolasers, so why do they come into play? The GT bracing thing is from slave-ship