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.