Relativity

cthia wrote:Which is my point in the debris thread. Missiles routinely operate in a veritable minefield of debris.

tlb wrote:But they also have active particle shielding, which I think is like a repulsion beam directed straight ahead that deflects objects from contact with the missile body.

cthia wrote:It requires a lot of energy that a missile doesn't have access to to deflect an object traveling at a significant fraction of light, or if the missile is traveling at a significant fraction of light.

In fact, have you ever tried to alter the plane of a gyroscope? It's a hard pill to swallow that missiles can alter their vector even a little, once at speed. Let alone warships "crabbing away" from their original vector, once maximum militarily velocities are achieved.

tlb wrote:But we are told that can happen, aren't we? As for warships crabbing away, it is easy to just direct their acceleration in a different direction; the hard point is that it will take awhile before the velocity component perpendicular to the original velocity has an appreciable magnitude compared to that original magnitude.

Its simply another item to add to the archives of the hardest pills to swallow.

cthia wrote:

cthia wrote:Which is my point in the debris thread. Missiles routinely operate in a veritable minefield of debris.

tlb wrote:But they also have active particle shielding, which I think is like a repulsion beam directed straight ahead that deflects objects from contact with the missile body.

cthia wrote:It requires a lot of energy that a missile doesn't have access to to deflect an object traveling at a significant fraction of light, or if the missile is traveling at a significant fraction of light.

In fact, have you ever tried to alter the plane of a gyroscope? It's a hard pill to swallow that missiles can alter their vector even a little, once at speed. Let alone warships "crabbing away" from their original vector, once maximum militarily velocities are achieved.

tlb wrote:But we are told that can happen, aren't we? As for warships crabbing away, it is easy to just direct their acceleration in a different direction; the hard point is that it will take awhile before the velocity component perpendicular to the original velocity has an appreciable magnitude compared to that original magnitude.

Its simply another item to add to the archives of the hardest pills to swallow.

Changing the plane of a Gyroscope is hard because it is spinning extremely rapidly. Since neither ships nor missiles are doing so, that difficulty doesn't mean anything.

Actually, missiles are spinning. You first see this when young Horor is doing a gunnery exercise.

kzt wrote:Actually, missiles are spinning. You first see this when young Honor is doing a gunnery exercise.

Do you mean Honor or Abigail Hearns in The Service of the Sword?

"Got it!" Chief Vassari barked suddenly, and the laser designator "opened fire" before the words were fully out of his mouth.
Abigail watched the plot's sidebar, and her face blossomed in a huge smile as the rest of her crew began to cheer and whistle. The computers had identified the repetition of one of the earlier fly-bys, and Vassari's fire plan had instructed them to synchronize the mount's pulse rate with the recognized spin rate of the target. It meant that they weren't pumping out the maximum possible amount of destructive energy, but what they were pumping out was precisely timed to catch the drone at the moment that it turned the open side of its wedge towards the ship. The energy-on-target total shot up like a homesick meteor, and Abigail wanted to cheer herself as the laser designator systematically hammered the drone.

tlb wrote:But we are told that can happen, aren't we? As for warships crabbing away, it is easy to just direct their acceleration in a different direction; the hard point is that it will take awhile before the velocity component perpendicular to the original velocity has an appreciable magnitude compared to that original magnitude.

As soon as the ship stops accelerating, it's in an inertial frame of reference. It change its attitude as easily as if it were stopped relative to the planet.

Making a 90° turn cannot take less than stopping. Stopping means applying acceleration in exactly the opposite direction of the current velocity vector. To make a turn, you need to apply it at an angle, which means the component that is cancelling the acceleration in the current direction of motion is smaller.

It would be interesting to see calculated what possible motion curves. For example, if there's an object directly ahead of you and not accelerating, what acceleration do you apply so you maximise distance?

kzt wrote:Actually, missiles are spinning. You first see this when young Horor is doing a gunnery exercise.

You missed the 'extremely fast' part. Even toy gyroscopes are generally over a thousand RPM.

tlb wrote:But we are told that can happen, aren't we? As for warships crabbing away, it is easy to just direct their acceleration in a different direction; the hard point is that it will take awhile before the velocity component perpendicular to the original velocity has an appreciable magnitude compared to that original magnitude.

ThinksMarkedly wrote:As soon as the ship stops accelerating, it's in an inertial frame of reference. It change its attitude as easily as if it were stopped relative to the planet.

Making a 90° turn cannot take less than stopping. Stopping means applying acceleration in exactly the opposite direction of the current velocity vector. To make a turn, you need to apply it at an angle, which means the component that is cancelling the acceleration in the current direction of motion is smaller.

It would be interesting to see calculated what possible motion curves. For example, if there's an object directly ahead of you and not accelerating, what acceleration do you apply so you maximise distance?

At ninety degrees to current direction gives you maximum deflection at current forward speed. By going past ninety you might add a bit of time before passing the object with almost the same deflection, but that bit of time might be minuscule at relativistic velocities.

A couple of points.

o The kinetic energy of a missile is moot if it can't hit the target.
o The faster a missile goes (ie c-fractional), the more difficulty it will have at maneuvering and hitting something - even if that something is an SD.
o Nothing really hits the wedge or the sidewall, any object "hitting" them is teared apart due to the gravity shear in the stress band.
o Matter subjected to intense gravitational shearing tend to be converted into radiated energy rather quickly.
o Interaction with a wedge or sidewall puts a stress on the generators.
o You could take out parts of a sidewall with enough kinetic force, but see the first point.
o The functioning of TWTSNBN has nothing to do with trying to overpower a wedge etc, it only pushes the projected field out of alignment which overloads the generators when they try to get the field back into alignment.

zyffyr wrote:

kzt wrote:Actually, missiles are spinning. You first see this when young Horor is doing a gunnery exercise.

You missed the 'extremely fast' part. Even toy gyroscopes are generally over a thousand RPM.

It is impossible to change the attitude of a missile traveling over 93% of light speed enough for something to be targetable. Especially when that something is more maneuverable. It would require more energy than the missile has access to.

P.S. If God doesn't intervene, man is going to blow himself up one day.

cthia wrote:It is impossible to change the attitude of a missile traveling over 93% of light speed enough for something to be targetable. Especially when that something is more maneuverable.

I'd agree if you'd said the vector of the missile.
But the attitude is just the direction it's pointing. It's no harder to change the attitude of a missile moving at .93c that it is to change one at rest.

Well, at least in the missiles reference frame. Time dealation would make it look somewhat more sluggish to an outside observer.
Still, if the target ship would see a missile at rest take, say, 5 seconds to rotate 90 degrees then I think it'd see it take about 7 seconds to make that same rotation at .93c.


The difference is that the higher your base velocity the less deflection you achieve for the same amount of lateral acceleration. The acceleration produces the same lateral velocity and so the same lateral deflection over any given interval. But that gives a far different "slope" when the base velocity is so much higher.