950 replies to this topic

[Theodor Kling]

Just found another one, jump ships this time:
Despite the Kearny-Fuchida Drive beeing used for and probably refined for centuries ( actually pretty close to a millenium) and not even the horrors of the first two succesion wars beeing able to make it lostec, it is not reliable enough to risk jumping into an uninhabited system for most skippers.
Same goes for the solar sails, or any other important part of the jumpship that has been manufactured and seen widespread use all this time.
Oh the time they could save when actually taking the shortest route to a destiantion instead of the shortest available using only inhabited systems...

[Vitzkrieg]

Melcyna, on 06 August 2012 - 12:02 AM, said:

...

thus far, ALL of their distances indicate that this is within reasonable distance to acquire a firing solution for the massive ships with a light based weaponry.

and incidentally in the case of aiming with 'lag' on their distance based on light speed, calculating the CORRECT LEAD to hit the target is TRIVIAL since the movement is predictable, all you need to know is how far exactly is he to calculate the correct offset.

....

That is what the original argument the poster had about 'random evasive movement' came for....

basically randomizing the pattern to ensure that no lead can be calculated on the firing solution to realistically hit the target... but to do this within a million kilometer at least require that the ship is capable of sufficient acceleration to move the entire bulk of the mass out of the way within seconds.

I know this is from a while back in the thread, but I though I'd put some numbers here to help ball park what an "effective" range would be on a laser in space battles.

So if you're engaging at 300,000,000 m (one light second), that means the target has 2 seconds of juke time to avoid your shot. Assuming the best case scenario, that right as you pull the trigger they pull a maximum thrust maneuver to accelerate in a direction and hold it for the whole 2 seconds, that means we can use the simple "constant acceleration" formula.

distance displaced from where they're expected to be is = 1/2 * acceleration * time^2

distance = 2 * acceleration

So if you could pull 3g's in your ship, that would mean you could shift approximately 30m in that time frame, meaning a shot at the center of mass of a 60m wide sphere would barely miss.

The basic things we can take away from this are:

• The size of the ship is very important for effective targetting distance since acceleration is capped by human limits (This might encourage small "fighters" that had a small cross section and a small weapon loadout)
  
• Your chance of hitting someone falls off dramatically after a few light seconds due to the squaring of the distance the enemy can move in relation to time. (Shoot twice as far away, the enemy can move 1/4 the speed and still dodge)
  
• Ships that can rapidly accelerate in any direction at full impulse are the best combatants, meaning ships with omni-directional thrusters or a small mass and the ability to rotate quickly. (This also biases towards small fighters)
  
• The above number is a best case scenario. If you're randomly juking in many different directions in order to be unpredictable at all times, chances are high that your net displacement from where the enemy gunner targeted is probably significantly less than this.

Sadly I don't know the dimensions or accelerations of dropships and the like off the top of my head, so I can't turn this into a proper fighting distance, but someone who does might be able to ball park it. Suffice to say it'd be near impossible to miss at any distances inside the moons of a planet though if you had a simple targeting computer. Our moon is not even 400,000 km away, or .001 light seconds away.

My mistake, I messed up the units. The moon is 400,000 KM away, or 400,000,000 meters, or about 1 light second. So as far as laser timing goes the moon would be at the edge of where a very nimble and small ship could dodge at least some lasers.

Pew pew

Edited by Vitzkrieg, 20 August 2012 - 07:45 AM.

[Melcyna]

Unless if their computer is SO PRIMITIVE that our World War 2 gunnery computer actually exceed their capability... which given the way their targeting is horrendously bad at may not actually be too far off the mark. Ancient electromechanical computers... actually doing better work at it's job than BT's ... 'stormtrooper' targeting computer.

In all seriousness though, even if we take the absolute worst case scenario of gunnery... ie: dropships incredibly agile and designed specifically to be maneuverable in space and distances of even several dozen light seconds, then basic gunnery would just bracket the target ship with multiple shot, the same way naval ships do it back in WW1 and WW2 when they engage ships at long distance at several dozen kilometers (which was quite far for dreadnought era guns) with their main gun battery.

If one shot may barely miss by a few dozen meters, then standard gunnery logic is to fire several shot each dispersed to cover displacement of several dozen meter from the center point at the target's distance.

One of them would then have a high chance to hit unless the target did a drastic maneuver the likelihood of which depends entirely on how much the ship can pull such maneuver and either remaining intact or keeping it's crew intact.

Fighters probably are not exactly gonna be hit if they remain in acceleration at the same distance, but fighters are not the concern... only the dropship is really... if the enemy doesn't have capital ships of any form (including Q ships).

[Vitzkrieg]

Yep, I thought about the bracketing bit and it certainly would allow you to hit with at least something in each volley at the ranges where they could dodge a single hit.

Also I realized something else I hadn't considered before, that probably makes the whole previous argument about dodging lasers moot. At the ranges we're talking about for a lot of these engagements (say the moon example of one light second, which I'd done wrong before), if the actual laser can't be pointed with perfect precision, it'll likely miss or at least spread itself out over so much of the target as to be ineffective.

Let's say you've got a pretty solid mount for your laser that dampens out most of the ship's vibrations and can be tweaked by the 10th of a degree. That still means that your shots would have a spread of almost 525km at one light second! Even at only .01 light seconds away, or 3,000 km, you'd be hitting at +/- 5km!! Upgrading to .01 degrees of targeting precision still leaves you at 500m spread, which isn't exactly reliable

tan( anglePrecision ) = deviation/range

So yeah, given the general targeting and precision of the BT universe, I suspect naval duels would actually have to be at very close range to be very effective.

I don't have the time to do it yet, but I want to poke around the math of your torpedo minefield idea and see what kind of velocities they could get up to, and how hard they'd be to shoot down with a laser AMS kind of system....

[Theodor Kling]

Hej I never thought about vibrations on the ships. Sure, I doubtet BT targetign systems , and I also doubt their ability to focus a laser ( 1 lightsecond weapon range is pretty optimistic looking at their tech..no matter how big the target) ..but even with real good targeting compensating for ship vibrations ... how could I overlook that Vitzkireg?!
Not BT, but still woth mentioning in this context is Star Trek: Their Phasers are said to have 1 lsec effective range, torpedoes up to 11.6 lsec
(according to Star trek The Next Generation: Technical Manual)
Add to that that Star Trek knows artificial gravity and the great inertial dampeners, allowing their ships insane accelarations, and manuvering at relativistic speeds. And they more ofthe nthen not manage to aim for specific spots on the enemy ship!
Vitzkrieg gave us a good idea how hard it would be to hit a BT dropship. Which is way slower and has way lower turn rate.
Not to mention fighting with both ships beeign at warp
So Star Trek targeting computers must be insaneley good.

[Melcyna]

No need for the targeting computer to compensate the vibration

In the real world this is the reason why guns are mounted on gyro stabilized mount.

Usually the degree in which the mount can mitigate vibration or other negative movement of the ship depends on how big the mount space is... but generally speaking the stabilizer is usually capable enough that minor vibration will not affect the gun accuracy, but the early stabilizers are usually not capable of discarding the effect of more extreme movement (ie: like a sudden acceleration, such as when the ship is hit by a powerful kinetic impact)

Ships as early as WW2 feature these...
http://www.navweaps....mm-78_skc31.htm
and gyro stabilization or other means of gun stabilizer are STANDARD feature of pretty much all modern vehicles that expect to be able to fire on the move.

Naval stabilizers are probably among the most advanced because in the SEA you receive so many vibrations and force of various kind (waves, wind, etc) that otherwise accurate gunnery is VERY unlikely.

In the WW2 era, the stabilizers helped massive guns to accurately hit targets at several dozen kilometers (provided one can range them properly and bracket them).

In modern era the stabilizers are part of what allowed ship board point defense guns the ability to hit something as small and as fast as an anti ship missile flying low.

Without stabilizers, you might as well be shooting the empty air...

Most military vehicles nowadays also stabilize their sight in addition to the guns to help the crew to find their target and stay on it.

Alternatively when the gun are too large, or the space is insufficient to stabilize the whole gun, we stabilize the sensors instead and then use the gyro reading to measure the vibration and other negative movement... the targeting computer then simply hold it's fire until the firing condition is EXACTLY what is required..

This is possible because vibration are random, so any micro movement that shifts the gun off alignment in one direction would inevitably shift it back micro seconds later, the targeting computer simply waits until this occurs and fire the gun when the parameter is in line.

Edited by Melcyna, 20 August 2012 - 08:29 PM.

[Clay Pigeon]

Sug, on 03 August 2012 - 06:53 PM, said:

Why are these aliens considered canon while stackpole explosions are not?

IMHO neither should be. Novels shouldn't be canon.

[Cody Machado]

-people are still people.
COME ON FURRYS GIT YOUR S*** TOGETHER!

[Hoytmandoo]

Melcyna, on 04 August 2012 - 08:54 AM, said:

Whoever control the space in between controls EVERYTHING that goes in and out of the planet, and are free to drop whatever weapon they want to it... who needs WMD? they can just drop a solid rock sufficiently precise onto the military base on the planet and it'll do just fine... a rock large and dense enough dropping from orbit onto the base is just as good as a lance of mech in destroying it.

Agreed, with the rock though, if it is big enough (which isn't even all that big) It can be equal to hundreds of times the power of hiroshima, basically leveling an entire city along with the countryside and any cities close by

[Melcyna]

True, but that's the advantage of kinetic bombardment...

we can scale the damage to what we need by simply altering the mass and velocity of the projectile... small enough, and the weapon can be scaled down enough to be of anti personnel use or anti vehicle, large enough and it can be more lethal than thermonuclear warhead.

The concept is not new... as far back as the 60s during the Cold War both US and USSR brainstormed whole concepts of what to do with spaceborne weapons...

One of the idea which was later developed further into the orbital kinetic weapon concept is to station satellites in orbit holding tungsten based rods that can be jettisoned and dropped onto earth as high precision kinetic weapon.

The weapon can be scaled for anything...

For anti personnel the idea they considered was using the tungsten rod as an atmospheric entry canister, and then dispersing thousands of small flechette when the rod is near enough to the target zone, saturating the area and guaranteeing death or fatal injury to any personnel not under hard cover or armored vehicle.

For anti tank the idea is the same but instead of flechette, we disperse guided rods similar to a downscaled version of the main canister rod effectively releasing multiple armor penetrating rod similar to the one fired from the tank APFSDS shells but coming directly from the sky.

For anti bunker and fortification, even simpler... they just drop a solid guided tungsten rod the size of the canister above. The impact is estimated to be equivalent to a bunker buster for a telephone pole sized tungsten rod.

The weapon concept though wasn't cheap back then, at that time we could hardly transport stuff into low earth orbit economically much less bring the whole weapon and satellite into position for low cost.

And the effectiveness of the weapon is technically not that high compared to regular weapon (anti personnel flechette and anti tank weapon can be fired from artillery for a fraction of the cost for example) but it does have the advantage of being capable of dropping pretty much anywhere on the field.

This however is of little relevance when one has large scale space borne capable transportation.

Edited by Melcyna, 20 August 2012 - 09:50 PM.

[SakuranoSenshi]

Melcyna, on 20 August 2012 - 09:04 PM, said:

One of the idea which was later developed further into the orbital kinetic weapon concept is to station satellites in orbit holding tungsten based rods that can be jettisoned and dropped onto earth as high precision kinetic weapon.

I know people who swear there are fleets of these things in orbit... I suspect, however, they are wearing their tinfoil hats too tightly. The concept, nevertheless, is entirely sound.

[Theodor Kling]

Melcyna, on 20 August 2012 - 09:04 PM, said:

The concept is not new... as far back as the 60s during the Cold War both US and USSR brainstormed whole concepts of what to do with
spaceborne weapons...

Yeah.. but let´s nto forget, that the same kind of people porposed stuff like Project Orion

Concerning vibrations: Might be you´re right..might be not. A spaceship got to deal with a different set of them compared to a naval one. It lacks of corse the impact of waves and currents on the hull. But I can´t imagine a thruster set capable of maintaining several g for days ( mostly just 1g for all practical purposes) for something as massive as an Overlord not te send some immense vibrations through the ship. Not to mention maneuvering thrusters.
On the other hand the ship IS massive, and by that gets a lot of inertia, making it more stable again... great now I don´t know who´s right

[Vitzkrieg]

Melcyna, on 20 August 2012 - 07:12 PM, said:

-- Stuff about vibrations and computers --

Yep, I agree with everything you're saying Melcyna. My point is just that at 30,000 km vs 12 km, even the smallest deviation from where you want to be targeting, and I mean a hundredth of a degree, you'll miss by kilometers. This could be caused by either imprecision on the part of the targeting motors, or a vibration in the ship, or anything else that could distort your aim. The raw amount of precision required to make a shot at the distances we're talking is staggering.

So I don't know how stable a BT gyro is, but this would be a very plausible reason why you don't see light fights at extreme ranges. Even if you know where they're gonna be, it doesn't mean you can make your laser go there. (and since these lasers seem to fire over a non-trivial duration, trying to keep them on a specific location to burn through would be even MORE problematic. You can't just score a lucky hit like you can with a battleship shell).

Anyway, that's my 2 cents

[SakuranoSenshi]

With BT science and technology? They're lucky they hit anything in space without "Dragon ramming" it. ;-)

[gautrek]

Oh and another thing that annoys me about battle tech.How the f*** are you supposed to relaod systems like the LRM20's.There is no way that you can make a system to full reload anything like an LRM20 unless you take the whole pod off to do it.Or the other way is to have very short missiles that allow it(wait a minute that would explain the crappy ranges in the missiles).Oh and why would you have short,medium and long range missiles.You just have one missile with a range of as far as it will go and use that down to a close as you can.
The same with having AC's in the arms and the ammo stored in the body.
The whole concept makes no sense in RL.

[Melcyna]

Vitzkrieg, on 20 August 2012 - 11:44 PM, said:

Yep, I agree with everything you're saying Melcyna. My point is just that at 30,000 km vs 12 km, even the smallest deviation from where you want to be targeting, and I mean a hundredth of a degree, you'll miss by kilometers. This could be caused by either imprecision on the part of the targeting motors, or a vibration in the ship, or anything else that could distort your aim. The raw amount of precision required to make a shot at the distances we're talking is staggering.

So I don't know how stable a BT gyro is, but this would be a very plausible reason why you don't see light fights at extreme ranges. Even if you know where they're gonna be, it doesn't mean you can make your laser go there. (and since these lasers seem to fire over a non-trivial duration, trying to keep them on a specific location to burn through would be even MORE problematic. You can't just score a lucky hit like you can with a battleship shell).

Anyway, that's my 2 cents

Agreed, though to correct something we don't just fire and hope for a lucky hit with naval gunnery (or any gunnery involving assets costing a good chunk of military budget really), we fire with the BEST available targeting solution that gives the best probability of a hit, call it educated guess if you'd like... so it's not quite luck.

In the case of bracketing, the idea wasn't that we simply saturate the area... the idea is that we calculate the largest possible deviation the target can realistically make (which can be estimated from intel and confirmed or measured with ranging equipment) and fire at the extreme ends of these bracket and in between such that one of the shots has a very high probability of hitting the target.

Now if vibrations is a SERIOUS concern...

then aside of gyro stabilized mounting, the other course of action that real equipment use to mitigate it is isolating the potential source of the vibration itself and separating them from direct contact with the main hull structure by putting buffer in between to absorb the vibration.

Again, the tech is not new here... been used in naval and even building construction (those buffer they put on the large generator base mount? yep... those are vibration dampener/buffer) since last century and later used in aerospace industry as well because not surprisingly, there are plenty of situations and conditions where they need vibrations mitigated when concerning a vehicle that may be destroyed by as much as a dent on critical component.

The same stabilizer we use to keep our high power telescope steady to see halfway across the galaxy? Yep, same tech we can use to stabilize a laser weapon to do pretty much the reverse... sending light at the target instead of receiving one.

It's technically not impossible that their tech is very PRIMITIVE that they don't know how to stabilize it properly, but generally speaking if they know how to construct multi hundred megajoules laser then they most certainly had to know at least the basic method of stabilizing it.

Theodor Kling, on 20 August 2012 - 10:27 PM, said:

Yeah.. but let´s nto forget, that the same kind of people porposed stuff like Project Orion

Concerning vibrations: Might be you´re right..might be not. A spaceship got to deal with a different set of them compared to a naval one. It lacks of corse the impact of waves and currents on the hull. But I can´t imagine a thruster set capable of maintaining several g for days ( mostly just 1g for all practical purposes) for something as massive as an Overlord not te send some immense vibrations through the ship. Not to mention maneuvering thrusters.
On the other hand the ship IS massive, and by that gets a lot of inertia, making it more stable again... great now I don´t know who´s right

Technically project Orion WAS based on working principle... ie: one way or another it can be done, the only question is if we SHOULD do it in consideration of it's byproduct.

Similar to project Pluto, the working mechanism does WORK, but should it be DONE is another separate matter.

ie: the problem is much larger on the political side than engineering, the concept was pursued as far as it was because it was valid engineering wise.

Edited by Melcyna, 21 August 2012 - 02:53 AM.

[Hal Michelson]

Just to toss something into the naval combat discussion, you are looking at 1 Lsec the wrong way. 1 Lsec is actually 2 Lsec in practice because we have to use an EM sensor (or eyeball, both SoL limited tools) to position the target and then to fire a speed of light weapon to intersect it. 1 to see, 1 to hit so a total of 2 seconds. Your probability cone gets really large really fast at any distance at all.

[Melcyna]

True, and someone else already mentioned that before as well...

on the flipside though the largest difficulty in gunnery when trying to make a firing solution that requires a lead (ie: when your weapon travel time is not instantaneous) is to identify his exact position and distance and where he is going.

Once you actually know his range and velocity at least to some degree (so you know his last general path at least) subsequent firing solution iteration are much simpler since you now know his last known average trajectory and can use the old information to estimate his new position.

This technically wouldn't hold of course if the target is capable of such rapid acceleration that it's capable of rendering information glimpsed mere seconds ago to be completely obsolete by the time you can fire the weapon.

but fortunately here we have several advantage:
our primary target would be fairly large vessels, and in the case of dropships they get further limitation on top of that... in that they are as their name imply, essentially a transport vessel. The cargo they carry will complicates attempt to maneuver since they add to the mass of the ship itself (which will limit how maneuverable they can realistically make any sort of change in velocity) but more importantly it guarantees that the ship can never accelerate faster than their cargo can withstand else the whole point of the dropship would be moot since the cargo will not survive the trip.

Given a human tolerance to G force is rather limited, even in the event that the ship is capable of such acceleration it's unlikely that it can actually make any sort of complex maneuver of significant degree at all that will be sufficient to evade a weapon with travel time in mere seconds.

The second part is that we KNOW the one direction a ship like a dropship will generally be moving closer towards (even if it's not moving there directly in straight line)...

ie: the target planet... because let's face it, if it's moving away from the planet in question.... then the defender is gaining time and more chance to further intercept the dropship.

This helps to cut down the possible volume in which the ship may be located while plotting it's trajectory and possible maneuver path. He may attempt to zig zag his way (as much as one can try to imagine a dropship that has most of it's primary thrusters in it's rear can possibly zig zag anyway with just attitude thrusters), but he definitely had to be zig zagging TOWARDS the planet, not away... ie: it's much less likely that he will try to decelerate or accelerate in any direction that gives negative approach rate to the planet.

Edited by Melcyna, 21 August 2012 - 03:47 AM.

[Raledon]

Another form of space-warfare is the Railguns:
Using electromagnetics to push objects at high speeds, we can easily make a long barrel that shoots very fast objects.
According to current tech, it's possible to shoot once evey 6 seconds a projectile accurate to hit a 5meter target over 370 KM (on Earth) using 10.64 MJ.
With the tech to build lasers, fiddling with the numbers a bit to GJ(1000 MJ) shouldn't be hard, thus pushing object way faster than 6000 m/s (current muzzle speed). While on flight at a decent fraction of light speed, it shouldn't be hard to actually change the course of the projectile (with current tech, it'll take 50 seconds to hit a 1ls away) to hit the target. The shots should be cheap enough (again, with tech to shoot lasers. Also note that the US Navy currently considers this a better, cheaper option) to slug the whole area, so even if the target "dodges", a hail of bullets are still coming.

Also, Zig Zag is not a solution. Taking into account you can't move TOO fast (you gotta decelrate before entering the atmosphere or lodging to a space station), and that the whole targeting process may take a couple of sec (out of choice), if you move in any kinda of predictable maneuvre, it's possible to time the shot to hit you. Zig Zaging means that you are moving around your main course, but not on it, so timing shots on your main course have high chances of hitting you.

Edit: I forgot, space is exellent isulation. This gives us the option to use superconductors, allowing us to use a giant magnetic field in the railguns, cancelling the overheating. This will also reduce most of the shots cost to the material cost, and we all know that 1 ton of metal doesn't cost that much (we don't even care which as long as we can throw it), and throw as many slugs as we can.

Edited by Raledon, 21 August 2012 - 07:11 AM.

[Dhrakyn]

Humans are devolving. Stupid people breed at a much higher rate then intelligent people. Using this logic, the Battletech universe is much easier to understand.

-W