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)