Concepts: Today's similarities and differences to the HV

tlb wrote:A space ship is NOT a submarine, it only has to contain one atmosphere of pressure; whereas every 10.3 meters (33.8 ft) of depth adds another atmosphere of pressure. The workings of a space ship can easily handle vacuum; they would not respond well to salt water, which is both conductive and corrosive (consider a plasma conduit for example).

Theemile pointed out the problems of generating movement in air, these are compounded in water. In addition to the problem of pressure that I have repeated, ThinksMarkedly questions the orientation of a spider drive ship when laying in water.

penny wrote:True. A spaceship isn't. An LD "is." If it is designed to be. I don't fret over niggling little details. Certainly not pressure. This is a ship that has tractors that juggle gravity. A gravitational field around the ship can counteract pressure.

That is purest nonsense, an LD is every inch a space ship. Also tractor beams in NO way constitute a "gravitational field around the ship" that can "counteract pressure". They do NOT "juggle gravity", they either pull or push in discrete beams (so no bubble wall).

PS: The people who designed Oceangate Titan also seemed to consider pressure a "niggling little detail".

tlb wrote:A space ship is NOT a submarine, it only has to contain one atmosphere of pressure...

penny wrote:True. A spaceship isn't. An LD "is." If it is designed to be. I don't fret over niggling little details. Certainly not pressure. This is a ship that has tractors that juggle gravity. A gravitational field around the ship can counteract pressure.

Ever heard of Jack of All Trades?

Master of none.

There's something to be said about a ship that expensive being able to fulfil multiple roles. It might have the volume for all the necessary bits of equipment, and it may have the mass in the armour for the pressure. But that doesn't mean the compromises required for it are a good idea.

Specifically on the landing on a planet, won't that make it easier to find and target? Can it fire energy weapons from underwater without losing power through dissipation? Of course the same would apply to anyone trying to fire on it, in reverse, but if it can't threaten anyone in orbit, it's out of the fight anyway.

If you want to defend the planet, don't land a ship. Just build weapon emplacements.

ThinksMarkedly wrote:Specifically on the landing on a planet, won't that make it easier to find and target? Can it fire energy weapons from underwater without losing power through dissipation? Of course the same would apply to anyone trying to fire on it, in reverse, but if it can't threaten anyone in orbit, it's out of the fight anyway.

Plus the grounded / submerged ship is at the bottom of a giant gravity well; but anybody orbiting overhead is on top of it. If their energy mounts won't work well (and they won't, even through atmosphere) but they do need to engage they can always drop KEWs on it. (A favor the grounded ship can't return)

(Because, my goodness, an entire warship is definitely a legal target under the Edict -- yes, yes, presuming the local government has refused to surrender. But if they have surrendered you don't need to fire on the ship; and if it's an uninhabited world so there's no local government there's also no rules against kinetically bombarding it)

And even a ship entirely submerged in water isn't going to appreciate chunks of metal at low fractions of c slamming into the area around them.

Jonathan_S wrote:Plus the grounded / submerged ship is at the bottom of a giant gravity well; but anybody orbiting overhead is on top of it. If their energy mounts won't work well (and they won't, even through atmosphere) but they do need to engage they can always drop KEWs on it. (A favor the grounded ship can't return)

I thought about kinetic weapons but discarded writing about them. Given the acceleration missiles are given by their launchers, a ±1 gravity will be meaningless. So yes, a grounded ship could fire a KEW up, but a) it's no different than a weapon emplacement anyway, and b) it's going to cause huge damage due to the hypersonic pressure wave to a planet it's supposedly trying to protect.

And even a ship entirely submerged in water isn't going to appreciate chunks of metal at low fractions of c slamming into the area around them.

Indeed, the pressure wave just by a near miss may be more than the structural integrity of the ship can withstand. You don't want dented armour, but more importantly you don't want all those fragile protuberances sticking outside the hull like sensors and spider tractors to get damaged.

ThinksMarkedly wrote:

Jonathan_S wrote:Plus the grounded / submerged ship is at the bottom of a giant gravity well; but anybody orbiting overhead is on top of it. If their energy mounts won't work well (and they won't, even through atmosphere) but they do need to engage they can always drop KEWs on it. (A favor the grounded ship can't return)

I thought about kinetic weapons but discarded writing about them. Given the acceleration missiles are given by their launchers, a ±1 gravity will be meaningless. So yes, a grounded ship could fire a KEW up, but a) it's no different than a weapon emplacement anyway, and b) it's going to cause huge damage due to the hypersonic pressure wave to a planet it's supposedly trying to protect.

I'd assumed a grounded ship wouldn't be able to fire KEWs. Certainly the one we have the best description of wouldn't appear to work well from the ground for the same reason normal missiles wouldn't -- lighting up a wedge of that size in the atmosphere anywhere near your ship isn't going to be good for the grounded ship or for the surrounding county.

Shadow of Freedom wrote:The Mark 87 “Damocles” Kinetic Strike Package was a containerized weapon system designed to fit into any standard shipboard magazine and sized to deploy through a counter-missile launch tube. The KSP could be configured with several different types of payloads, but the most common variant—like the one which had been deployed from Quentin Saint-James’ number three CM tube shortly after she’d entered orbit—carried a rack of six of the Royal Manticoran Marine Corps’ M412 kinetic penetrators. Each penetrator was a six hundred and fifty kilogram dart fitted with its own small, short-lived but powerful impeller drive, a capacitor ring for onboard power, and a guidance package. By controlling acceleration rates and times, the M412 could produce an effective yield of up to one megaton

But even if you could fire one upwards the odds of it hurting a warship over a hostile world seems very low. It's certainly not going to penetrate the wedge; but also in HotQ we saw a BC's sidewall tank a couple of kinetic impacts that ludicrously exceed what an orbital bombardment KEW can do.

Honor of the Queen wrote:Two of them vanished in sun-bright fireballs that shook Thunder to her keel as twin, 78-ton hammers struck her sidewall at .25 C. For all their fury, those two were harmless

A relativistic kinetic energy calculator says each impact would have been about 59 gigatons; 59,000 times more than a Damocles KPS's impactor can manage.
(FWIW if we ignore relativity each missile's calculated kinetic energy would still 52 gigatons)

So, for a KEW to even damage a warship in orbit either the warship would have to have it's wedge offline (unlikely around a hostile planet), it's sidewalls down (also unlikely), or have to be oriented were you can manage a down-the-throat (or up-the-kilt) shop.

I think your instinct was right and we can safely ignore the possibility of upward fired KEWs from a grounded ship.

Jonathan_S wrote:I'd assumed a grounded ship wouldn't be able to fire KEWs. Certainly the one we have the best description of wouldn't appear to work well from the ground for the same reason normal missiles wouldn't -- lighting up a wedge of that size in the atmosphere anywhere near your ship isn't going to be good for the grounded ship or for the surrounding county.

I don't see any reason why a purely kinetic weapon could not be fired. The gravitic/electromagnetic drivers that kick missiles out of the tubes are powerful enough to impart significant velocity to the missiles, well above that of escape velocity for the planet. How much we don't know for sure, this is an area where numbers are lacking and I expect will remain so, lest we try to poke holes at the ability of the ship to launch 22 tightly-packed missiles with wedges much larger than their ships, let alone the distance to their brethren.

But my thinking is that if a ships can kick missiles out, then a dedicated kinetic launcher could fire projectiles out of the gravity well too.

Shadow of Freedom wrote:The Mark 87 “Damocles” Kinetic Strike Package was a containerized weapon system designed to fit into any standard shipboard magazine and sized to deploy through a counter-missile launch tube. The KSP could be configured with several different types of payloads, but the most common variant—like the one which had been deployed from Quentin Saint-James’ number three CM tube shortly after she’d entered orbit—carried a rack of six of the Royal Manticoran Marine Corps’ M412 kinetic penetrators. Each penetrator was a six hundred and fifty kilogram dart fitted with its own small, short-lived but powerful impeller drive, a capacitor ring for onboard power, and a guidance package. By controlling acceleration rates and times, the M412 could produce an effective yield of up to one megaton

This is not purely kinetic. This is a guided penetrator. Do we know whether its impeller drive shuts down before hitting the atmosphere? It could continue, as we've seen impeller-propelled grenades and MANPAD-launched missiles in-atmosphere. And if it does work after entering the atmosphere, there's no reason it couldn't start from inside the atmosphere - though the difference is that it is densest at the bottom, thus the start of the flight.

But even if you could fire one upwards the odds of it hurting a warship over a hostile world seems very low. It's certainly not going to penetrate the wedge; but also in HotQ we saw a BC's sidewall tank a couple of kinetic impacts that ludicrously exceed what an orbital bombardment KEW can do.

The wedge would be a problem, though one assumes that ships that are moving into firing position on a planet, either for energy strikes or kinetic weapons, must not obscure their target with their wedges in the first place. That ship could be attacked.

Honor of the Queen wrote:Two of them vanished in sun-bright fireballs that shook Thunder to her keel as twin, 78-ton hammers struck her sidewall at .25 C. For all their fury, those two were harmless

A relativistic kinetic energy calculator says each impact would have been about 59 gigatons; 59,000 times more than a Damocles KPS's impactor can manage.
(FWIW if we ignore relativity each missile's calculated kinetic energy would still 52 gigatons)

We know sidewalls are tough but can be penetrated. "Were harmless" does not necessarily imply all such weapons are harmless under all conditions, or that continuous fire couldn't bring the sidewalls down. A planet has far more mass available for it to fire upwards than any ship or fleet is ever going to have. It might not be a good idea - sustained fire on a fleet might cause hurricane-force storms that damage the infrastructure it's trying to protect in the first place.

ThinksMarkedly wrote:I don't see any reason why a purely kinetic weapon could not be fired. The gravitic/electromagnetic drivers that kick missiles out of the tubes are powerful enough to impart significant velocity to the missiles, well above that of escape velocity for the planet. How much we don't know for sure, this is an area where numbers are lacking and I expect will remain so, lest we try to poke holes at the ability of the ship to launch 22 tightly-packed missiles with wedges much larger than their ships, let alone the distance to their brethren.

But my thinking is that if a ships can kick missiles out, then a dedicated kinetic launcher could fire projectiles out of the gravity well too.

Shadow of Freedom wrote:The Mark 87 “Damocles” Kinetic Strike Package was a containerized weapon system designed to fit into any standard shipboard magazine and sized to deploy through a counter-missile launch tube. The KSP could be configured with several different types of payloads, but the most common variant—like the one which had been deployed from Quentin Saint-James’ number three CM tube shortly after she’d entered orbit—carried a rack of six of the Royal Manticoran Marine Corps’ M412 kinetic penetrators. Each penetrator was a six hundred and fifty kilogram dart fitted with its own small, short-lived but powerful impeller drive, a capacitor ring for onboard power, and a guidance package. By controlling acceleration rates and times, the M412 could produce an effective yield of up to one megaton

This is not purely kinetic. This is a guided penetrator. Do we know whether its impeller drive shuts down before hitting the atmosphere? It could continue, as we've seen impeller-propelled grenades and MANPAD-launched missiles in-atmosphere. And if it does work after entering the atmosphere, there's no reason it couldn't start from inside the atmosphere - though the difference is that it is densest at the bottom, thus the start of the flight.

So the ship is on the ground (or in the water) and on its side to make the CM tube point upward. The ship could have an active sidewall on the upward side and fire through a gunport.

However the ship should certainly NOT be submerged in the ocean when it tries this, because salt water will flood the tube and could enter all sort of things. In particular there are the plasma channels and the plasma capacitor ring and the guidance electronics on the penetrator. If the water gets into the ship's plasma channels, there is massive damage that can be done.

ThinksMarkedly wrote:I don't see any reason why a purely kinetic weapon could not be fired. The gravitic/electromagnetic drivers that kick missiles out of the tubes are powerful enough to impart significant velocity to the missiles, well above that of escape velocity for the planet. How much we don't know for sure, this is an area where numbers are lacking and I expect will remain so, lest we try to poke holes at the ability of the ship to launch 22 tightly-packed missiles with wedges much larger than their ships, let alone the distance to their brethren.

But my thinking is that if a ships can kick missiles out, then a dedicated kinetic launcher could fire projectiles out of the gravity well too.

You're likely right that we're not going to get numbers on the velocity a missile/cm launcher can impart. Though, given how fast even SDMs accelerate, Earth's escape velocity (11.2 KPS) is essentially a rounding error (equivalent to an extra 2.48 thousandths of a second of drive). A launcher that imparts that on an SDM would give it an extra 0.028% (extra 2,016 km) of powered range compared to the 7,302,960 it'd have firing from rest.

So maybe they can throw a projectile hard enough to reach escape velocity.

ThinksMarkedly wrote:

Shadow of Freedom wrote:The Mark 87 “Damocles” Kinetic Strike Package was a containerized weapon system designed to fit into any standard shipboard magazine and sized to deploy through a counter-missile launch tube. The KSP could be configured with several different types of payloads, but the most common variant—like the one which had been deployed from Quentin Saint-James’ number three CM tube shortly after she’d entered orbit—carried a rack of six of the Royal Manticoran Marine Corps’ M412 kinetic penetrators. Each penetrator was a six hundred and fifty kilogram dart fitted with its own small, short-lived but powerful impeller drive, a capacitor ring for onboard power, and a guidance package. By controlling acceleration rates and times, the M412 could produce an effective yield of up to one megaton

This is not purely kinetic. This is a guided penetrator. Do we know whether its impeller drive shuts down before hitting the atmosphere? It could continue, as we've seen impeller-propelled grenades and MANPAD-launched missiles in-atmosphere. And if it does work after entering the atmosphere, there's no reason it couldn't start from inside the atmosphere - though the difference is that it is densest at the bottom, thus the start of the flight.

My assumption was that the short-lived impeller shut off before it hit (much of) the atmosphere; and so its terminal effects were purely kinetic. Basically the impeller is primarily to let you easily dial the required yield (up to an impact speed of 3.600 KPS (0.012 c) -- way more than you'd expect a CM tube to fire anything.

Though it occurs to me that having the impeller on the submunition also gives you more cross-range flexibility without having to fire at extremely slant angles through the atmosphere. You can use the CM tube to fire the main Damocles round out sideways until it gets sufficiently overhead of the target(s). Then the submunitions separate, aim, and kick on their impeller just long enough to reach the desired velocity for the selected dial-a-yeild impact energy.

ThinksMarkedly wrote:

Jonathan_S wrote:But even if you could fire one upwards the odds of it hurting a warship over a hostile world seems very low. It's certainly not going to penetrate the wedge; but also in HotQ we saw a BC's sidewall tank a couple of kinetic impacts that ludicrously exceed what an orbital bombardment KEW can do.

The wedge would be a problem, though one assumes that ships that are moving into firing position on a planet, either for energy strikes or kinetic weapons, must not obscure their target with their wedges in the first place. That ship could be attacked.

Jonathan_S wrote:>>>>>>Honor of the Queen
Two of them vanished in sun-bright fireballs that shook Thunder to her keel as twin, 78-ton hammers struck her sidewall at .25 C. For all their fury, those two were harmless
<<<<<<
A relativistic kinetic energy calculator says each impact would have been about 59 gigatons; 59,000 times more than a Damocles KPS's impactor can manage.

We know sidewalls are tough but can be penetrated. "Were harmless" does not necessarily imply all such weapons are harmless under all conditions, or that continuous fire couldn't bring the sidewalls down. A planet has far more mass available for it to fire upwards than any ship or fleet is ever going to have. It might not be a good idea - sustained fire on a fleet might cause hurricane-force storms that damage the infrastructure it's trying to protect in the first place.

Yes, sidewalls can be penetrated - by weapons with sidewall penetrators, which (IIRC) use the wedge of the missile to specifically interact with the grav effects of the sidewall to try to force an opening large enough for the warhead to slip through. We don't know what level of kinetic impact it might take to overwhelm them (other than, more than a couple of SDMs have at near terminal velocity (reaching 0.25c with the 46000g a normal missile can pull takes 165 s and 6,136,515 km -- so there's not enough distance between ground and any likely orbit of the hostile warship to get up to that velocity even if you were firing a missile and not a kinetic round)

And, circling back to the first item, if a missile tube was able to throw something anywhere near that fast it'd cease to be a rounding error and would majorly add to the range and terminal velocity of missiles. But that'd be incompatible with the several descriptions of battles where the given numbers wouldn't work if the launcher imparted more than a rounding error's worth of velocity. (But if the launcher is, as it seems, only capable of that rounding error's worth then such a projectile has no hope of overloading a sidewall from kinetic energy alone)

So I think we can safely say that a sidewall would easily block the kinetic effects of any round fired from ground to orbit. (Mind you though, nothing seems to stopping someone from building a launcher capable of throwing a laserhead up to orbital altitudes -- but now we're very much out of the realm of pure KEWs)

tlb wrote:So the ship is on the ground (or in the water) and on its side to make the CM tube point upward. The ship could have an active sidewall on the upward side and fire through a gunport.

However the ship should certainly NOT be submerged in the ocean when it tries this, because salt water will flood the tube and could enter all sort of things. In particular there are the plasma channels and the plasma capacitor ring and the guidance electronics on the penetrator. If the water gets into the ship's plasma channels, there is massive damage that can be done.

Um, unless it has a spherical bubble sidewall a ship can't have a sidewall active without a wedge active. And activating a wedge while you're on the ground (or in the ocean) is going to end.... badly.
(Even trying to run a spherical sidewall when much of it would be cutting into the ground/ocean seems likely to be really bad -- assuming the generator is able to bring it up at all)

So I don't think a landed ship is going to have any sidewall protections.

(But that doesn't affect whether or not it can fire something from a CM tube)

tlb wrote:The ship could have an active sidewall on the upward side and fire through a gunport.

Jonathan_S wrote:Um, unless it has a spherical bubble sidewall a ship can't have a sidewall active without a wedge active. And activating a wedge while you're on the ground (or in the ocean) is going to end.... badly.

While I will agree that a sidewall without a wedge is not nearly as strong, I find it strange to hear that a sidewall requires a wedge. For example a buckler is a sidewall that is not attached to a wedge. More importantly every gun range uses a sidewall as a backstop (even those on planets) and clearly those do not require a wedge.

It seems to me that on a ship, they use the same nodes, but they have different generators. So what's the situation?