Ground Weapon Yields: Always kT?

The Prime Necromancer · Post by **The Prime Necromancer** » 2004-03-08 04:51pm

Let me start by saying that I am not immediately dismissing the ICS or the calculations of the AT-AT's main guns. I do not claim that the guns on an AT-AT are not *capable* of putting out kT range shots.

However, I question just how often they use that ability, and if it is primarily for strategic, or for tactical purposes. In other words, are yields in the hundreds of kilotons necessary for the average SW combat operation?

In particular, I would like someone to explain why the battlefield of Genosis was not reduced to a smouldering crater by the clash of the two armies. In that battle, missiles with yields of hundreds of kT were apparently used, but with no major affects. The Hiroshima bomb was only about 15 kT, yet it created 980 miles/hr winds at the hypocenter, and leveled nearly everything in a 1.5 mile radius. Now admittedly, the missiles used in SW are apparently focused explosives (how exactly would that work for a nuclear weapon, by the way?) but still, all that energy has to go somewhere.

But noone really seems to have a problem with this, so I'd like to know what the current rationalization for this contradiction is.

Spanky The Dolphin · Post by **Spanky The Dolphin** » 2004-03-08 04:53pm

Because friendly fire is generally considered a bad thing.

The Prime Necromancer · Post by **The Prime Necromancer** » 2004-03-08 08:58pm

Spanky The Dolphin wrote:Because friendly fire is generally considered a bad thing.

Well, yes it is. But that was kind of my point. My question was are 200 kT missiles (like those that the ICS says are on the LAAT) tactical or strategic weapons? Is that kind of energy used often in SW because it is necessary to defeat armor? And if it is, why aren't these missiles also causing massive damage to the surrounding troops and terrain, because a 200 kT missile is not going to deliver all of its energy into the target at 100% efficiency; some is going to be radiated away as waste heat, and the waste heat of a weapon of that scale could very easily approach Hiroshima levels.

Illuminatus Primus · Post by **Illuminatus Primus** » 2004-03-08 09:02pm

One of the major misconceptions is high-energy weapons must be analogous to modern explosives; the 200 kt warheads are "blast-effect" warheads which implies damage without thermal explosions.

The multi-gigaton siesmic charges sheared hundreds of metre diameter rocks in half, with no discernable thermal effects or waste heat.

Gil Hamilton · Post by **Gil Hamilton** » 2004-03-08 09:52pm

Probably because they had their yields set down. They weren't firing multiple kT weapons.

McC · Post by **McC** » 2004-03-08 09:59pm

In other words (I think), it's 200 kilotons of kinetic energy, rather than strictly thermal...although isn't thermal a type of kinetic? My understanding of the distinction between energy types is highly limited.

Seggybop · Post by **Seggybop** » 2004-03-08 10:52pm

Once the energy is expended against the target, what happens to it? Say there's some kind of ultra durable armor plating that will only be penetrated if hit with 200kt worth of KE. After the armor has had all this energy injected into it, I would think its remains would spray everywhere with massive destructive effect. If this isn't happening, what is?

The Prime Necromancer · Post by **The Prime Necromancer** » 2004-03-08 10:56pm

McC wrote:In other words (I think), it's 200 kilotons of kinetic energy, rather than strictly thermal...although isn't thermal a type of kinetic? My understanding of the distinction between energy types is highly limited.

Yes. It's kinetic energy on a microscopic level (the KE of molecules and atoms).

One of the major misconceptions is high-energy weapons must be analogous to modern explosives; the 200 kt warheads are "blast-effect" warheads which implies damage without thermal explosions.

Even if you are correct, I believe that much kinetic energy will still cause thermal effects. Part of the energy will not go where it is intended, and cause the rapid expansion of the atmosphere surrounding the impact point. And we're right back to where we started.

The multi-gigaton siesmic charges sheared hundreds of metre diameter rocks in half, with no discernable thermal effects or waste heat.

It was also detonated in outer space, where there is no atmosphere to interact with.

Illuminatus Primus · Post by **Illuminatus Primus** » 2004-03-08 10:58pm

Well if they can absorb enormous levels of energy before deformation, that's where it is going--destroying the armor.

But as shown above--the seismic charges prove that SW can inject huge amounts of energy into targets without any appreciable thermal effects. And remember: Mike theorized that it was designed as a ground assault weapon.

McC · Post by **McC** » 2004-03-08 10:58pm

The Prime Necromancer wrote:It was also detonated in outer space, where there is no atmosphere to interact with.

Not sure, but I think thermal effects would still be exhibited in space, assuming some kind of radiated transmission.

Illuminatus Primus · Post by **Illuminatus Primus** » 2004-03-08 11:00pm

Some of the pebble/dust fragments would've been melted or glowing if there was enough waste heat such that similar weapons in the atmosphere would have the exaggerated "Hiroshima scale" waste heat effects.

The Prime Necromancer · Post by **The Prime Necromancer** » 2004-03-09 01:49am

Illuminatus Primus wrote: Some of the pebble/dust fragments would've been melted or glowing if there was enough waste heat such that similar weapons in the atmosphere would have the exaggerated "Hiroshima scale" waste heat effects.

I'll conceed that much. But what I really meant by my post was that surely the "blast effect" that comes from a seismic charge would interact with the atmosphere, causing a rapid change in pressure. Something similar should happen with the missiles.

Also, the seismic charge is observed to be *very* different from anything else that has been seen before. What makes one think that this technology is the basis for *all* of their ground missile weapons?

McC · Post by **McC** » 2004-03-09 12:13pm

The Prime Necromancer wrote:Also, the seismic charge is observed to be *very* different from anything else that has been seen before. What makes one think that this technology is the basis for *all* of their ground missile weapons?

I don't think anyone's saying that seismic charge-like devices are the basis for all ground missiles, just that this particular type of weapon is actually intended for surface demolitions use rather than as a spatial weapon, but Jango was improvising to dramatic effect.

Illuminatus Primus · Post by **Illuminatus Primus** » 2004-03-09 03:28pm

And since when do field/repulsor effects appreciably effect the atmosphere?

Repulsors don't compress or blow air underneath vehicles; thermal detonators, which Connor proposed may be an application of the selfsame technology, effect nothing beyond the blast radius.

Obviously SW technologies can significantly reduce collateral damage.

The Silence and I · Post by **The Silence and I** » 2004-03-09 11:39pm

If you watch the seimic charge scene you may notice there is some thermal effect. Pay careful attention to the close-up of the destruction of the large 'roid, there are a few reddened rock fragments, i.e. glowing (This is what convinced me these were not dirty ice of some other wimpy material).
I think it is safe to say that regardless of transfere mechanism waste heat will happen. If you apply 200 kt of K.E. to an armored target it can only become heat and mechanical work, which will become heat anyway: energy must be conserved, if K.E. is added to a stationary target what will happen? Will it randomly chose a vector and fly off at great speed? It can't do that--the energy will become heat or, if the armor fails, some will become work.
This means if you hit a tank with a 200 kt K.E. warhead, it may fail or it may not but either way the armor will heat up VERY significantly and will radiate like crazy, convect heat into the atmosphere, etc. Since we don't see this such energies were not used and may be strateigic only.

Darth Garden Gnome · Post by **Darth Garden Gnome** » 2004-03-10 01:01am

Obviously any number of reasons can be cooked up for why SW weapons, even with their ridiculous yields, did not blow away both armies at Geonosis that day; but there is an obvious reason why the Republic or the CIS wouldn't want them to even if they could: they would have demolished the droid factory and killed all the CIS leaders they could hope to capture/cover the escape of.

Ender · Post by **Ender** » 2004-03-10 04:47am

WRT missiles: We never saw them used against anything other then starships. We already know that the durasteel that makes up the hull of starships is both superconductive and has a high enough specific heat that it can take an insane amount of punishment. Now granted we probably should have seen the hulls heat up and glow as they re radiated the energy, but remember that they penetrated the hull and then blew up; so the inside and crew was cooked, but the outside was preserved. So that explaisnthe missiles.

WRT AT-AT weapons, they only went that high to take out a hardened target, and we saw exactly what one would expect from such a yield.. infact that is how the numbers were generate. Most of the otehr stuff was MJ-GJ level.

McC · Post by **McC** » 2004-03-10 09:14am

Ender wrote:WRT missiles: We never saw them used against anything other then starships. <snip> So that explaisnthe missiles.

The LAATs also used missiles against the wheel droids. This had the effect of blowing the wheel droids apart with only slightly more explosive force than when Jedi blow battle droids apart with Force-pushing/lightsaber strikes -- not with any amount of violence that one would expect from kiloton-range weapons. Any thoughts on that?

Isolder74 · Post by **Isolder74** » 2004-03-10 10:51am

They could be shaped charges with most of the explosive energy being directed only where it is needed.

airBiscuit · Post by **airBiscuit** » 2004-03-10 12:59pm

Sounds to me like those kT yield values are pretty excessive. I am lost on the source of this information. What exactly did it say? I think if you compare the atomic bomb to these figures, you can see how ridiculous this would be, given what we observe in the movies. Even the large explosion of the Shield generator on Hoth had more to do with the generator itself, than the firepower that destroyed it. It was a secondary effect, and even that was not 200kT going off. That would have destroyed the Hoth base and the attacking Empire landing force in one swoop, I should think.

Illuminatus Primus · Post by **Illuminatus Primus** » 2004-03-10 01:02pm

Care to quantify your cute $.02 instead of a host of unsupported claims?

According to AOTC ICS, each missile carried by the LAAT/i has a "blast effect" warhead direction 200 kilotons of firepower in a 2 degree cone. Presumably the warheads have adjustable yields, but I dunno.

McC · Post by **McC** » 2004-03-10 01:19pm

Illuminatus Primus wrote:According to AOTC ICS, each missile carried by the LAAT/i has a "blast effect" warhead direction 200 kilotons of firepower in a 2 degree cone. Presumably the warheads have adjustable yields, but I dunno.

They'd have to have adjustable yields for the wheel droid bit. Since this is from DVD rather than VHS, it's fairly easy to cap, so I'll cap it when I get home from work tonight and post it up. I might end up eating my words, but I'm going to go out on a limb and say there's no way that what hits the wheel droids is 200 kilotons worth of explosive, directed or not.

EDIT: Nevermind, there's no need. Dr. Saxton has it on his site. Image 44. Image 37 might be worth looking at too.

airBiscuit · Post by **airBiscuit** » 2004-03-10 04:43pm

I would have to say that on the battlefield that an adjustable yield would have had to be used, since the explosion radius in picture 44 (see previous post for link) goes not much further than the size of the wheel droids, which is, what? 10 to 20 meters wide? This is what I would expect to see from a conventional warhead, certainly not something in the kiloton range.

Is it possible that the kiloton value is not kilotons of dynamite, but some other material? Or is the ICS supposed to reflect values equivalent to our corner of the galaxy?

Is it possible for a shaped-charge weapon, as this appears to be, to contain all of its penetrative energy into the target, and not kick up a huge blast radius (and I might add, a mushroom cloud)? Hiroshima was 15 KT, destroyed reinforced concrete buildings in a 500m raidus, and kicked up a mushroom cloud that could be seen from 80 KILOMETERS AWAY. Do we see that in AOTC?

I can certainly understand how missiles of this size could *potentially* carry that kind of explosive power, but this falls more along the lines of strategic strikes and not the tactical battle we saw in AOTC. So I guess it remains to question whether these are variable-yield weapons.

airBiscuit · Post by **airBiscuit** » 2004-03-10 05:02pm

Illuminatus Primus wrote:One of the major misconceptions is high-energy weapons must be analogous to modern explosives; the 200 kt warheads are "blast-effect" warheads which implies damage without thermal explosions.

What exactly does this mean?

If you are not making a thermal explosion, then you must have converted it into something else. Is it concentrated heat without expansion? Is it mechanical work without expansion? If it's blast-effect, how is it not explosive?

The multi-gigaton siesmic charges sheared hundreds of metre diameter rocks in half, with no discernable thermal effects or waste heat.

Certainly in space we would not see combustion unless the weapon fed the oxygen necessary for this to take place. Indeed, the explosion couldn't even ignite. Therefore, this is some other effect that allows a shockwave to be produced. The question is, what is it? Gravity waves? The shockwave was certainly not going at the speed of light, so it had to be propagated by something else...perhaps excitation and compression of molecules, although this wouldn't have such a destructive effect since space is very sparse in its molecule count. Maybe it's dark matter.

In any case, you could observe the catastrophic damage observed in a mechanical fashion where asteroids were pulverized over a large radius. So the same would apply to Geonosis. Even if the warheads of the missiles weren't incendiary, which they appear to be, they would still have a mechanical effect on their surroundings, namely, the ground would get kicked up on all sides of it and kick it a thousand feet into the air when you start talking kiloton yields.

Illuminatus Primus · Post by **Illuminatus Primus** » 2004-03-10 05:07pm

What the seismic charge planar waves are is immaterial; point was that it is possible to create highly-localized non-thermal high-energy detonations with SW technology?

What about huge thermal detonators?