WH40K - Ciaphas Cain, Caves of Ice (SDN)

[Mr. Oragahn]

Ciaphas Cain: Caves of Ice - analysis and discussion thread

OK, this one is unusually long, in comparison to other threads. 4 pages to wade through, this time we're clearly dealing with big weapons and thus, big numbers.
The CC series appears to give good ranges for infantry weapons. Kill zones for lasguns and else are around 300 meters, with the possibility of reaching good hit ratios at greater ranges.
Artillery spam in conjunction with infatry fire helps. Orks seem to rush like twats most of the time.

Page 22-23

- the cargo hauler Cain is riding in takes fire from Ork ground weaponry shortly after entering the atmosphere. Even accounting for probable reentry speeds (at least 8 km/s, but possibly as high as 13+ km/s) and the fact the Orks do not evidently understand (or care) about the concept of effective weapon's range, this is still many kilometers/tens of kilometers distant.

Or perhaps "effective" as I fly through a barrage of enemy fire concentrated on few converted cargoships into dropships, indeed.
That's crossing fingers for *some* shots to connect with targets, but like a walk out into the rain, I have little chances of avoiding getting wet.

Also, according to Cain, it would have taken hours for the hauler to abort its current trajectory and return to orbit - the life support would give out long before they could return.

A rather sluggish ship.

It should be noted, I believe, that the shuttle here was implied to be running on promethium (like alot of 40K vehicles of that size.) Not unreaosnable for a shuttle, however its chemical reactions would have to be extremely powerful - as Mike has noted numerous times, it takes a minimum of 60 MJ/kg to escape an earthlike gravity well (far more than modern gasoline or diesel) This, along with other evidence, tends to suggest Imperium chemical explosives and engines are probably alot more powerful than our modern equivalents (potentially at least - efficiency is still an issue.)

Refined promethium, perhaps yes.
We later find two posts touching on this subject, on page 2:
http://bbs.stardestroyer.net/viewtopic. ... 8#p2372688
http://bbs.stardestroyer.net/viewtopic. ... 9#p2374759

Of use, a piece from Iron Hands:

Gdolkin turned his head to survey the battlefield passing beneath them through an armacrys porthole and considered the enemy they were about to face.
The thick black smoke rolling into the skies from the burning promethium refineries - kilometres of petrochemical production plants all washed with flames - obscured the view through the porthole momentarily.

Petrochemical. Burning. This will be of importance later on.

Page 32

- Cain comments that Ork axes, crude as they are, can shear through Astartes armour when driven by ork muscles. This either comments on the nature of 40K materials science, Ork Strength, or both.

Doesn't sound that good. A melee weapon is just as good as its (weakest) materials, and no matter the strength of the Ork, if the weapon isn't as tough as the armor, it would bend, break or literally shatter, the greater the Ork blow the more violently.
So the question is what's crude about these axes? Perhaps the fact that they're mere axes, with no fancy monomolecular edge or force field.
That or the weirdo Waaagh unquantifiable buff anything gets when numbers don't look nice enough, I suppose.

Page 33

I don't suppose they even knew what hit them: suddenly struck by the concentrated fire of a couple of score of lasguns, not to mention the unrelenting hail of heavy bolter fire, there was nothing much left of them apart from some unpleasant stains on the snow within seconds. Sulla ambled over to inspect the mess, and spat a small gobbet of ice on it.

There are 10 orks total (as mentioned by Cain on page 31), minus 2-3 already destroyed by the heavy bolter. There were also 3 squads or so disembarked (30 lasguns), probably plus the command section (andother 5-6 ppl IIRC) as well as the Chimaera with its heavy bolter (only one is mentioned, and the others probably weren't offloaded yet.)
The quote implies that the gunfire (lasguns plus the Chimaera's bolter) basically exploded and/or vaporized the orks in a matter of seconds.

The problem is, though, we dont know the actual ratio between lasguns and bolter fire. given above, its likely though that the bolters could only take out a 2-3 orks "in a few seconds", possibly a few less. which means that 4-6 orks were destroyed by the Valhallans.

Assuming 4 orks, and a mass of around 200 kilos per ork (about 2-3x more massive than a huhman, which may be conservative since other sourcese like Ghostmaker imply 400+ kilos for an ork), is 800 kg. Assuming 70% water composition, is 560 kg.

Conservative: Assuming the lasgun fire merely boiled that much water (boiling point), a minimum of ~200 MJ must be injected (remember, lasguns cauterize as well as explode, hence the conservative term) Assuming 40 lasguns ("a couple score", even though i mentioned above only 30, 35 with the command section were probably actually there and Cain might have been rounding up.) and 3 seconds worth of fire, we come out with a sustained output of 1.67 megawatts per lasgun.

Assuming total vaporization of the 560 kg mass, the energy input becomes 1.5 gigajoules (boiling point plus vaporisation) Again assuming 40 lasguns over 3 seconds comes out to 12.5 megawatts per lasgun.

Note that at least SOME vaporization should be considered liekly, so the low end is EXTREMELY low. It also ignores inefficiencies, number of orks destroyed, any armour the orks were wearing, etc.

Like always, his definition of conservative leaves something to be desired.

The heavy bolter was mounted on a turret. It's a heavy automatic weapon with a high rate of fire, that fires explosive self-propelled shells.
Connor puts too much emphasis on the lasguns, while only a handful scores of them ever fired, compared to the unrelenting hail of HB fire.
That and seconds, in the heat of battle, could have easily been far more than three mere seconds. Some of those few Orks were at knuckle range, so even any partial vapourization would largely prove problematic to the Imperial troops.
Flash vapourizing, at the very least, 560 kg of water, implies some safety issues. Taking into consideration the complete spectrum of overpressures and eardrum ruptures would be interesting to begin with, considering the energies involved and a battle taking place at melee range. Then comes the burns caused by hot vapour. It's rather hard to imagine hundreds of megajoules deposited into something fleshy less than two meters away, at best, from someone's face that is barely protected, and not suffer.
However, if vaporized meant turned into cold mist instead of hot vapour, it works much better.

Page 55

Either luck or the Emperor was with me, because she'd left it on full auto. As my panic-spasmed hand locked on the trigger a hail of las bolts sprayed the chamber, blowing chunks of ice from the walls and defeaning us with the roar of ionising air and ice flashing into steam. The creature screamed and fled, even more terrified than I was, and as the power cell died and relative silence descended on our ringing ears, Penlan stirred.

- Two details of interest. First, full-auto on a Valhallan lasgun seems to empty the power pack in a matter of seconds. We know the powerpack was full, but we dont know the exact number of shots. If we assume it took 4-5 seconds, and assume 50 shots (40-60 shots per pack seems to be average), the rate of fire on a lasgun seems to be around 600-720 RPM. If the timeframe is shorter, the rate of fire could go up to 800, 900, or 1200 RPM. or more.

The other interesting detail of note is that the lasgun impacts cause ice to "flash into steam" (there is mention of ice blowing chunks in the wall too.)

The mention of the ionization actually reminded me that I wish I had found a figure about how much air a single las-bolt would ionize.
With ionization energy in mind, and taking a look at the width of a typical lasgun beam, we may get an absolute and sure lower end for the weapon's power output. Something about turning x atoms of oxygen and nitrogen into ions, within y cubic centimeters, over a given distance of several hundred meters.
If we consider maximum range before the beam is too weak, we'll get an idea of the beam's muzzle power, considering that the laser will have to ionize up to x meters of nitrogen and oxygen, after breaking their molecular bonds. That said, my memories on that stuff are waaaay diluted, to say the least, so either someone else will do it, or I'll have to recollect enough data to remember how doing this right.
Also, the "roar" from the ionized air is rather curious. One would think a maelstrom of "cracks" would be more deafening that, well, what could artistically be considered the sum of thunder-like echoeing "booms".

I took a glance around the chamber. It looked bigger from down here, and the hail of las bolts had melted a number of small pits into the walls. Something seemed to be embedded in one, and I tried to focus on it, to stop my head spinning.

- here, Cain mentions that the lasgun had melted "small pits" in the wall, though above he mentions chunks of ice and vaporization (IE steam.) The best answer would probably be that all three (to varying degrees) occured. Note that some vaporization would be needed for fragmentation (blasting chunks), while you could expect some vaporization along with melting (if the ice/water reaches boiling point, which is likely.)

Yet weapons were discharged, apparently.

Page 56

It was a human hand, severed at the wrist, the stump scored with viscious bite marks.

- This provides us with our best estimate of the dimensions of the holes melted/vaporised in the ice. "hand sized" implies at least 10 cm in diameter, but the hand is open, so this is probably conservative (I'd say less than 20 cm.. so maybe 10-15 cm.)

Assuming a perfectly hemispherical crater 10 cm in diameter would melt/vaporise about .25 kg worth of ice per shot. 15 cm would melt/vaporise .8 kg of ice. According to the stats provided on SD.net, we can infer roughly .51 MJ/kg for melting, and 2.71 for melting/vaporization (at least.) This means melting is between 122-475 kilojoules per shot, while vaporization would be 650 kilojoules and 2.2 Megajoules per shot. The actual value falls somewhere between those to.

This seems rather low for lasgun values compared to other calcs I have done, but we know most lasguns have variable charge settings (even though Valhallan lasguns are never mentioned as having them it is a reasonable supposition.) It may also be that the lasgun accepts a lower overall "per shot" output for a much higher rate of fire.

Who ever said the pits were hand sized, or that they even melted or vaporized that much ice?
They just saw a hand embedded into an ice wall, paying more attention to the surroundings, after the shooting at the ambull.
See:

I took a glance around the chamber. It looked bigger from down here, and the hail of las bolts had melted a number of small pits into the walls. Something seemed to be embedded in one, and I tried to focus on it, to stop my head spinning. Then my brain finally interpreted what I was seeing, and I regretted my curiosity at once.
'Looks like we found our missing miner,’ Penlan said, with what I felt was rather unseemly relish.
'Almost,’ I agreed. It was a human hand, severed at the wrist, the stump scored with vicious bite marks.

Not only pits were only melted, but the violence of the reaction itself would cause surrounding ice to shatter, and the very fact that one could recognize a hand and not bits of fingers spat out of the newly made hole is largely due to the fracturing blast precisely not reaching that far.
Clearly his values don't match what he thinks happened.

But the most amusing part here is that the correct interpretation of the text may allow for greater pits if we wanted to, because at no point the book says the hand was revealed through a hole or anything, but just that they saw it stuck in the ice after paying more attention to the walls.

[Mr. Oragahn]

Page 2.

Page 62

- at this point the Ork GArgant is 200 kilometers to the west. upon request by Cain, the Pure of Heart relays that it has a "high thermal signature, which indicates combustion process of some kind." It has a metallic shell that is mainly ferric in composition. and is eighty metres tall.

80 meters high and ferric. These bits are of great interest, notably if crossed with other references.
Later on, we learn that it weighs thousands of tonnes, and even near the end of the book, we learn that the Gargant has a one meter thick plating. It takes around 60.97 GJ to vaporize a m³ of iron.

Page 73

- Jurgen's melta is stated as being capable of vaporizing an ambull along with a "fair sized chunk of the wall behind it." and again notes that the weapon was designed for punching through tank armor, although it is quite effective against powerful targets (or engaging groups of enemies ast short range, including Orks.)

I don't recall offhand any specific information about how massive ambulls are, but I'd guess they're probably larger than orks or humans by several times (say maybe half a ton to a ton) in which case vaporisation would require close to several gigajoules of energy, plus whatever portion of the wall is vaporised (which could double or triple the output, since the melta is probably going to vaporise at least a similar volume in ice as the creature itself.)

This would also be roughly consistent with Necronlord's meltagun calcs as per below (and we know from other sources that Meltaguns, like lasguns, have variable settings, so the difference in power could be attributable to that.)

As usual with meltas, let's just be cautious with energy figures based on hypothetical literal vaporizations.
The devastating effects are not to be denied, but the mechanism, and thus the energy figure... that's a whole other thing, especially when the weapon cheats physics in the way energy is deposited into the target.

Page 81

His voice was drowned out by the abrupt hiss of the melta as Jurgen fired into the wall, instantly flashing a dozen cubic meters of ice into steam, which condensed almost instantly in the subzero temperatures, filling the narrow passageway with mist.

The infamous "meltagun calcs" as originally performed by Necronlord. Necronlord's original calcs are somewhat consevative (inefficiencies, latent heat of fusion, specific heat, etc all add some energy to the calc, but its still accurate to within an order of magnitude.) It can safely be said that a meltagun can achieve double-digit gigajoule outputs easily (but this is probably close to the maximum for the weapon - multimeltas reach triple digit GJ in Storm of Iron and are are definitely more powerful.)

It should also be noted that some people have equated the output of 20-30 gigajoules of enerrgy as resulting in a bomb-like blast. This is not neccesarily true - the pressure wave (if any) will depend heavily on the duration of the vaporisation as well as how "concentrated' it is (bombs develop high pressures due to the fact they generate large amounts of gasses in very short timeframes and in very small volumes.) Given the "area effect" nature of a meltagun, and the "sustained" nature of the beam, small volumes and rapid timeframes are unlikely. Furthermore, the described operation of a melta (at least some of them anyhow) tend to suggest that the "heating" of the ice would be much more uniform than ti would be if, say, a lasgun was melting it (the latter would have to heat a very small area and rely on work heating to vaporize the rest of it, which tends to lead to more "explosive" effects - a meltagun does not need to rely on work heating nearly as much to achieve the same results.)

The energy output is, however, quite substantial, and could pose a risk to exposed flesh, especially in confined spaces. In this case, though, there are some possibly mitigating circumstances. For example, due to the mentioned "sub zero temperatures", that some of the people were up to 100 meters away along the tunnels (either way), time was allowed for others to get clear, that a third opening was created a bit later, and that all the Valhallans were heavily bundled up in flak armor, greatcoats, and winter gear, brief exposures to the high temperature steam would unlikely be a significant problem (And given the warning, they can take further protective measures such as, turning away, covering their faces, etc.)

Another possibility is that 40K humans are not quite like us (ie modern humans) - there is circumstantial evidence that they are taller/heavier, ,stronger, and faster as a rule, so they could also have greater durability as well (the fact that the Valhallans are likely to be heavily bundled due to the enviroment is a bigger saving grace here.)

We understand it's pretty much vital for Connor and else to prove that the release of energy would be long and more or less constant.

But let's remember bits from "Ciaphas Cain: For the Emperor".
For the death of Kelp, by Jurgen's melta, Connor said "bear in mind this also occurs over about half a second or less, so that can at least double or triple the figure too."
That, between the moment Jurgen fired, and Kelp got killed.
Earlier on, quite a similar weapon in terms of magnitude of damage, a hellgun, from the same man, Jurgen, flash steamed parts of the guts of a Patriarch (old genestealer pureform).

So why suddenly pretend that we're dealing with a "sustained" beam? More, the book clearly speaks of ice instantly flashed into steam. Instant, flash. Is that not clear enough?
When this would typically warrant an interpretation in favour of greater figures, notably for power outputs and excess of energy, why is it blantantly ignored here, if not to get away from the obvious lacking blast and the issue it represents?

Also, if we use the references to the speed of the reaction, from Connor's half a second or less, to the flash-steam implied rapidity, you could easily obtain a power of 40 gigawatts or more for a yield of 20 gigajoules. With 30 gigajoules and a speed reaction even faster than half a second, you could literally be just one order of magnitude close from the terawatt range!

And of course, no cracks in the ice, no collapse of the ceiling, nor other adjacent walls or else.

The melta weapon clearly has residues of heat, but its mechanism is not spreading heat naturally. Once again, it does not undermine its capacity, but it heavily puts into doubt any claim of non-exotic mechanism.

Page 91

- one of the Imperial Guardsman with cain manages to take down an Ambull with full auto lasgun fire. The result leaves the body "riddled with the cauterised craters of las bolt impacts" and that identification was impossible (Cain wondered if it was the same one he'd wounded before) because there wasn't enough left intact to tell (although the head was untouched.) Clearly, he didnt totally vaporize or incinerate the creature, but he did severely burn it. It is also worth noting that it is not mentioned that he needs to replace his clip, so he may not have totally used up his ammo.

Unfortunately, its very difficult to accurately measure the amount of damage done. Cauterising is mentioned, but no exact volumes of damage are implied. If we assume the aforementioned "500-1000 kilo" mass for the Ambull, and ssume about half the body was burned (cauterised), and that all of a 40 shot clip was used up, you might get 1-3 megajoules per shot (roughly.) All in all, its more useful as a supplementary bit of evidence than direct, calculable evidence.

Of course how could Cain even make a comparison between this carcass and the one which had fled? Remember, they shot widly across the room, and then noticed blood on the floor, which allowed purchase for the famous line from Predator (if it bleeds...).
Clearly, no one knew, before seeing the stained floor, that the creature had been wounded.
Let's also remember that the Commisar was surprised by the creature, pressed the trigger in spasms and panic, and this went very fast. The creature ran away.
Oh, and the men down there were using torchlights. Oh, I guess Connor didn't think it was worth pointing out?

Obviously, and at best, Cain's memories of the beast would be random and partial. Pretending that the creature could not be identified because of the size of the wounds is ridiculous.

Page 93

According to the Magus Biologos they [ambulls] can see heat rather than light. Rather an odd concept, I have to say, ,but having looked through a tau blacklight system recently I can attest from personal experience that such a phenomenon can be achieved by technosorcery, so I suppose its not beyond the bounds of possibility that it might also occur in nature.

This is in regards to the ambull's ability to see in the dark (the means by which made no sense to Cain, he claims.) From what I understand some people take this to mean that Cain (and by extension the Imperial Guard as a whole) do not understand or utlilize infrared or night-vision systems. However, we know of ample (earlier) cases that demonstrate this false (such as the Ghosts novels.)

We also know from page 62 that Cain IS familiar with thermal scanners (and another incident with Sentinels in Triator's Hand reinforces this, IIRC.) so again the idea that Cain or the Guard have no idea about them is patently false.

It wasn't Cain who had this thought. It's from a note by Amberley Vail, of the Ordo Xenos. And what appeared odd was that a feral creature would come with such a sense, while it's generally attributed to the making of technosorcery.

Page 98 - Cain wonders if he shouldn't have told Jurgen to acquire something safer than the melta, such as a hellgun or flamer. This seems to suggest that the valhallan general stores (like we saw in "For the Emperor" have hellguns available. Perhaps these were leftover or recovered from the losses among their storm trooper regiments? (Then again, Jurgen is supposed to have an unusual scrounging ability, so this may merely mean that. A normal human brain (IIRC) masses around 1.3-1.5 kilos. Thus brain mass can be considered 1/3 to 1/4 the overall body mass. (That could mean an Ambull brain masses around 2.5-3 kilos at least, possibly as much as ten kilos.) Assuming cauterization takes place, and ignoring vaporisation, cauterisation would require at least 670-800 kilojoules per shot, assuming a 2.5-3 kg brain. At 10 kg, the energy is ~2.7 megajoules.

It shoudl be noted that like the prior calc I did on the ambull, this is not a precise calc, and should not be presented as such. (I've noticed that certain parties are prone to presenting some of my calcs are firm calcs, despite the fact I indicate that in some cases there are assumptions involved.)

When did 1/3 or 1/4 of an overall (human) body mass result into 1.3~1.5 kilograms? We're not small dogs.
And ten kilos for a brain?
The Sperm Whale (don't ask) has a brain six times the size of the human brain, and weighs 7.8 kg on the average, as seen here.

Page 134

The unmistakable hiss of the melta opening up behind me made me turn, just in time to see my aid cut down a small group of the creatures that had evidently been following the first with a single ravening blast of thermal energy.

- Melta takes down an "small group" assuming 2 orks (500 kg?) this probably takes around a gigajoule (assuming vaporisation, described in too many sourcees to count)

Page 139

In less than a second, he [an ork struck by a gauss weapon] seemed to dissolve; skin, muscle, and skeleton whipping away to vapour, leaving only the echo of a howl of inhuman agony to mark his passing.

- As I discuss later, the Gauss weapons do not seem to be thermal at all, despite the statement of "vapour." Various sources (Inquisitor sourecbook, the Necrons codex) tend to describe them more as some sort of "molecular" or "atomic" disruptor device (the Codex implies magnetic field/force field disruption.) of some kind, with little to no thermal results.

Out of purely academic interest, completely vaporising (or more accurately, ,cremating) an ork (Assuming 200 kilos, although it could possibly be twice that) would require at least 500-600 megajoules of energy. Odds are its probably much more (several gigajoules.) Note however that cremation would leave ashes behind as well as water vapour, and he wouldn't "dissolve".

In other words, take the use of terms such as vapour and vaporization with pincers.

Page 147

The heavy weapon hissed once more, flashing the intervening curtain of snow into vapour, and reducing the ork leader and the two standing next to him to a rank pile of gently steaming offal. The sole survivor turned, blinking in what looked like stunned stupefaction, its left arm hanging limp and charred from flash burns, then turned and bolted

3 orks, probably vaporised. Assuming 200 kg for the escorts (and 300 kg for the leader, thats at least several gigajoules easily (minimum). If we more conservatively assume boiling rather than full vaporisation, its only 52 megajoules. I'm leaning towards full vaporisation (and probably under-rating the mass involved.) This calc probably puts the meltagun's output at very close to what the "ice vaporisation" calcs before indicate.

A "pile of gently steaming offal", again? What's the fixation on offal??

And of course Connor is leaning towards full vaporization. Nevermind that the energies in question would certainly not leave a neat pile of gently steaming offal, because of tremendeous blast effects, the fact that three creatures were destroyed and not just one (how can the remains even turn into one single pile is anyone's guess), if it truly were pure thermal energy and not some of the pink unicorn's fancy mechanisms at play here.

Page 159

- a shot from a laspistol and a lasgun blow away most of an ork's head. Assuming cauterisation occurs (likely, no blood mentioned) and that an Ork head masses around 10-15 kilos ("Ghostmaker" indicates that ork heads are about twice the size of a human's, and this is conservative: head mass generally represents 7-8% of total body mass, and orks can mass up to 400 kilos, again according to Ghostmaker.) going with the conservative "boiling point" estimate, we're probably talking at least 2.7-3 megajoules, minimum, for the combined shot.

Assuming a lasgun is 3-4x more powerful than a lasgun,a nd that they are on comparable settings, a laspistol works out to at least 600-700 kilojoules, and the lasgun works out to about 2-2.5 Megajoules per shot.

If a head is literally pulverized in a single shot, wouldn't the neck and perhaps the uppermost region of the thorax be shredded and bleed like hell?
After all, even mere bullets push flesh apart when penetrating a body, and even Connor pointed out that lasgun impacts are similar to bullet impacts (although this seems to vary depending on the author).
Let's also notice the idea that although cauterization is not mentioned, assuming it would still be is fair?
Gaunt Ghost first novel has a reference of lasgun impacts leaving mists of blood or some such. That said, the Gaunt novels were written by some author who didn't know much of WH40K's background apparently.

[Mr. Oragahn]

T3H HUGE FIREPOWER

Page 166-167

Nothing in our inventory would even come close to doing the job, but an astropathic message to the nearest naval unit would bring a task force here within weeks, and a flotilla of battleships ought to be enough to level the continent. A couple of barrages from their lance batteries would be enough to excise this cancer, however deeply it was buried.

Of course the planet would be rendered uninhabitable for generations, but no one in their right mind would be willing to set foot here once the necron presence was known in any case, so the question was moot.

Ah, the most (in my opinion) precise and impressive example for 40K starship firepower. Many calcs to follow:

Off the bat, some variables to address: A "flotilla" of battleships in Battle Fleet gothic is defined as a squadron. By BFG, this means 2 or 3 Battleships. In other words, a couple of lance volleys from a couple of battleships will wipe out a continent and render a planet uninhabitable. But the latter part is purely a secondary effect!

Anyhow, assuming at least 1e9 megatons (low end.), 3 battleships, and that a "couple" of salvos means 2 - the firepower works out to roughly 167 teratons per salvo.

impressive, yes, but more than likely a drastic underestimate. For one thing, later on Cain mentions "sterilizing" the planet, which implies drastically gerater firepower (tens of billions of megatons.) For another, consider just how deeply buried under the planet the necron tomb is, at LEAST 3 km, possibly tens of km deep. That's a huge volume to attack. Cratering a continent-sized target would require tens of billions of megatons. Melting or vaporising that much ice would be even MORE insane (and more likely - lances are sustained beam weapons and melting/vaporising is what they do.) Assuming a 3000 km diameter "continent, 10 km depth, and complete melting would equate nearly 10 billion megatons of energy.

Assuming 10 billion (20 billion sterilization? double that) megatons, 2 battleships, and 2 salvos - 2.5 billion megatons per salvo. REalistically this is probably more accurate, short term extinction, much less sterilization (which would be needed to completely eradicate the Necrons taint.) AT the very minimum, one billion megatons should be expected per salvo (pulierizing a large crater into the continent ought to require at least 4-5 billion megatons, easily.)

In any case, the statement makes it clear the planet is STILL Habitable, at least in the long term. This means it didnt lose its biosphere, atmosphere, etc, suggesting that the energy is definitely under e11-e12 megatons (And hence battleship firepower is no more than 250 billion megatons.)

Before we start anything, it must be known that Connor presented a rebuttal to arguments that surfaced at SBC, when he presented his own revised calculations.
Caves of Ice Battleship bombardment calculation: Revised edition goes into greater details to support the scale of firepower claimed for Imperium ships.
Trying to follow the tracks of Connor throughout SB's history, I found some old and short lived threads:
How much damage can 40k Shields take (oct 2005), and Posleen vs IG (sept 2005).
These threads make numerous references to other pieces of blurb, calcs being hard to find, and contain trademarked arguments for inflationism, one of them being that ships are said to have weapons that can lay waste to an entire continent, which still represents a considerable total of energy, but says nothing of time, and thus nothing of power, and actually nothing really about what waste is supposed to mean.
There is a much more recent thread: Warhammer 40k Weapon Yields.
The thread Connor talked about could easily be this one: Yuuzhan Vong in Warhammer 40k (feb 2007), with the "moron" apparently being that Abanim folk.

So, before going into the sterilization part, what did Connor understand here?

He didn't consider the possibility that there were two separate clauses defining two independent statements instead of one. If you look at it, what you have is:

• "... a flotilla of battleships ought to be enough to level the continent."
• "A couple of barrages from their lance batteries would be enough to excise this cancer, however deeply it was buried."

Connor argued that Cain thought the whole continent would need to be leveled to take care of the Necrons, and assumed this would be done with a couple of barrages of lances, while both sentences are separate.
Case by case:

• Several ships, less than a fleet, could concentrate their firepower on a continent, over an unknown amount of time, to level it. Generally, leveling is merely done via blasts, and doesn't imply thermal vaporization.
• The Necron structures, tombs, were located in a giant cave only. This "cancer" was a very localized point on the planet's map, and that's all the couple of barrages from a same flotilla is about: destroying this Necron spot. Although it would still be impressive to look at, there is nothing phenomenal here, notably since they're firing multiple times at an ice sheet, with many cannons times several ships, and that such ships tend to be around one kilometer in length, more or less, some several times more, and their reactors take around a third of the whole ship's volume.
  
  Get rid of the city-sized cave, and you're finished with the Necrons here.
  I won't bother with Connor's long winded and really unnecessary red herring about sterilization, because I merely need one quote to tell you what Cain actually had in mind when he spoke of sterilization.
  
  Cain viewed the hundreds of thousands of Necrons, their ice tombs and their portal as a cancer... this cancer.
  Take an analogy with a human body. Once you have destroyed a cancer, the body is safe. You don't need to destroy the whole body to do so, if you happen to have the tools to excise it with precision (here, the lances, capable of digging without wasting too much energy into pointless cratering, and that especially when dealing with ice instead of rock).

Now consider this:

The portal,’ Kasteen said, the coin dropping. I nodded again.
'Hundreds of thousands of them would be let loose on the galaxy. We simply can't allow that to happen,’ I paused for a moment, letting the implications sink in. 'We have to call in the Navy to sterilise the whole site from orbit. It's the only way to be sure,’
'You can't do that!' Pryke and Ernulph both shouted at the same time, then broke off to boggle at one another, completely taken aback to find themselves in agreement for once.
'I can, and will,’ I contradicted them. This facility is under martial law, which means the commissariat is the final arbiter of what can or cannot be done,’
'Have you any idea of the economic value of this installation?' Pryke asked, recovering first.
[...]
'On the contrary,’ Ernulph replied. 'I don't think you can risk not sending anyone back,’
'Explain,’ Kasteen said, although in a sudden agony of panic I realised what the magos was driving at. The worst of it was that he was right, damn it, and the spasming of my bowels told me who was by far the most likely candidate to get stuck with the job.
You said it yourself,’ he said triumphantly. The portal's still active. Even if you called in your naval strike it would be left intact and functioning for months before a flotilla could get here, possibly even years. The necrons would be long gone,’

Initially, Cain considered that a flotilla could be there within weeks. This is not the case, he's contradicted by Ernulph. However, later on the fleet is expected to arrive, and we know that Cain and the Valhallans spent a couple days at best on this planet.
But more important, it is that Cain had one target in mind: the Necrons and their portal, all located in one spot.

Abanim was actually making a good point about how deep the Necrons could be.





If this wouldn't be enough, then let's see what happens, much later, when some Necrons manage to get very close to the surface:

'Look, sir!' Jurgen pointed to the pictscreen, which I'd left tuned to one of the upper levels. A torrent of liquid became momentarily visible, filling the width of the gallery, sweeping all before it, tearing chunks of ice the size of Baneblades from the walls as it came and tumbling them casually ahead of itself. Then the pictcaster was ripped from its mounting, and the screen went dark. I switched to another just in time to see a party of necron warriors, far closer to the surface than I would have thought possible, trapped by the onrushing tsunami, picked up and thrown around like so many rag dolls. If I believed them capable of emotion I might have thought they stood dumbstruck before it before turning to flee, but it engulfed them all the same. I wondered if they'd fade away, smashed to pieces by that irresistible tide of pure promethium. Much good would it do them if they did; their tomb was at the lowest point of the tunnel complex and would surely flood in time, even though Logash had calculated that it would take the torrent around twenty minutes to seep down that far. Not that they needed to breathe, of course, but at the very least it should stop them using the portal until they found some way to pump the chamber out, by which time with any luck the Navy would be here to sterilise the planet. All in all, I felt, a rather satisfying result.

8 million litres of pure promethium were liberated from the storage tanks, at the surface. It took 20 minutes for the fluid to get to the lowest point, through the tunnel maze.
Early, we learn that sometimes, the tunnel floor would raise gently (low slope).
The lowest level of the mine was three kilometers below the surface, presumably from the valley's floor. Add a bit of more sloped tunnels, and you could argue that the tomb was four kilometers below the overall frozen planet surface. And that's assuming the shock of the tide wouldn't make a tunnel collapse.
The greater ice depth comes from Cain ruminating about the bedrock they finally put a foot onto, wondering what the planet looked like when it was warmer, and he considered that among other things, where they were could have been a shore, with tens of kilometers of ice more down from that level.
At no point is it said they went deeper than those three kilometers.

Let's make a quick calculation here, which will be easily modifiable with different factors.

Ice density: 917 kg/m³.
It takes 3017 joules to sublimate 1 gram of ice (1 cc), and therefore 3.017 MJ/kg.

How big was the cavern? It was said to be city-sized, but by the book, Cain and co don't appear to spend eons to get from the cavern's wall to the portal, and back.
Assuming the portal is somewhere close to the center of the cavern, and assuming the cavern was roughly hemispherical, with a width of 5 km, the lances would need to carve something like 7.854 e10 m³ of ice (assumed depth, 4 km).
I'm not removing the cavern's own empty volume there.

The necessary energy to sublimate such a cylinder of ice is 217.288 e18 J.
Roughly 52 gigatons. This shall provide more than what's really required to douse the cavern in plasma.

In reality, I don't see why so much ice would need to be sublimated to reach through a couple of kilometers down. All that would be needed would be to dig some beam-wide holes down there, focused onto the target, and input the energy into the Necron structures directly.
This, obviously, would dramatically lower the numbers.

Now make that only a good dozen 20 meters wide beams, you must remove 1.2566 e6 m³ of ice per beam. Multiplied by a dozen beams and assuming they don't overlap, that's 1.508 e7 m³ as a total.
That is precisely 5208.223 times less than the former figure.
The energy figure becomes: 41.72 e15 J, or 9.97 megatons.

No time reference is ever given by the way.



The "Promethium Flood" case will be tackled later.
For the moment, let's take a look at another extract from the same book, CoI, that helps understand the very punctual nature of the Necron cancer.

'Is that it, then?' Kasteen asked, her eyes riveted on the scene of destruction below. Even from orbit the dust cloud could still be seen staining half the planet, and in spite of all the horrors I'd endured down there I couldn't help feeling a spark of regret at the scar across the face of the pristine world I'd first looked upon from this very spot a few short days before.
'I hope so,’ I said, although the twist of apprehension in my gut didn't fade entirely until we'd dropped back into the warp and were well on our way back to the safety of the Imperium.
Although, of course, where the necrons are concerned nowhere is ever remotely safe, as we now know to our cost. At least that particular nest appears to have been dealt with, even if no one can ever go back to check; the first thing Amberley did when my message finally caught up with her was to place the whole system under Inquisitorial quarantine. 1

1. Subsequent examination of the site showed no signs of an active necron presence, although if anything was left of their installation it would have been buried far too deeply to have left much trace of anything I for one would not be at all keen to start digging holes to find out for sure.

So we know that this contained multi-gigaton explosion is considered to have been enough to destroy, or at least bury all of the Necrons. Clearly, this would be have been terribly short in order to level an entire continent resting under 3~4 km of ice or more.

Therefore, in the best conditions, if Cain, at some point, really considered digging out the whole continent and burning it, it was certainly not part of the "couple barrages" part of the operation, since the "couple barrages" would take care of that nest, of that cancer.

On the sterilization part, if it wasn't obvious enough that they didn't intend to literally go down to burn every single square centimeter of the planet, I'm still amazed about how Connor arbitrarily places the cursor somewhere between "let's melt all the ice and down a couple of kilometers through the rock" and never go down to the most far fetched interpretation of this operation, that is, liquefy the whole crust, just to be sure.
From the moment Connor decides they don't need to go that far, anyone can pull the cursor back and say that they don't even need to blast the whole ice up either.

As for the uninhabitable part, the planet itself was extremely hostile. Death was assured without a special tough gear when wandering outside, and people had to live and work inside shelters and other buildings.
Any amount of firepower, regardless of time, that will be enough to level a continent, is ought to severely damage a biosphere for eons. But when said environment is already barely friendly, you don't need much more.

[Mr. Oragahn]

Page 3





Sorry for the long quoting cascade, but this one is a "gem", and must be presented.

Only the upper limit is 250 petatons, the actual calcs are 2.5 petatons per salvo.

Precisely. To be perfectly honest, I doubt they're anywhere close to 250 Petatons in reality. I suspect either single or very low double digit Petatons per salvo. I'd only endorse the use of the 250 petaton figure if you're running across a particularily annoying asshole (and if it came to that tehre's more excessive ways to generate firepower calcs for 40K.)

Quite true. There is the single missle Exterminatus from Tactica Imperialis, even though its directly stated that its not just one big explosion, it still causes a huge amount of destruction.

Eisenhorn mentions "continent destroying" ordnance, and The old Rogue Trader source has this little gem:

In theory, there is no reason why any of the grenade or missile types shouldn't be available in lager support versions. It would be possible to manufacture a missile of any size: from a weapon little larger than a normal launcher shell, to one capable of wiping out a city, ,province, or continent."

That included barrage and melta and plasma warheads as well as virus bombs and such. The fun bit of that is that they also note that such weapons can bombard planetary targets from millions of miles away :D

Firing a missile at a planet to cause a mass extinction event can be done from outside the system. It can be done from outside the galaxy for all I care, as long as you can plot a course.
What matters is how long it takes them to get there, and any faction that has access to FTL sensors, or even well tuned sensors, will be able to pick the rockets up, and millions of miles away, that's at the very least 3.2 million kilometers.
Easily intercepted.
That's not counting on some events which point to a rather average targetting capacity for Imperium missiles, so I suppose we must be impressed here, but in reality, there's nothing formidable at all about such a range.

Notice, of course, that nothing is said about the size of the continent wrecking missile. It would either need to be large to carry enough boomz, or large enough to carry enough fuel to ram a planet at near c after crossing the system.
The quote itself is self-defeating if you actually bother reading it properly, since it says there's no limit to the size of the missile: "any size", or in other words, let's build a missile the size of a medium to large starship.

Edit: Oh yeah, and how could I forget this one?

"Their anti-ordnance defence turrets have weapons larger than those carried on Titans, their barrels over ten metres long, dozens of the point-defences studding the hull of a ship the size of a cruiser. Their broadsides vary, sometimes having huge plasma cannons capable of incinerating cities, other times its mass drivers that can pound metal and rock into oblivion. Short-range missile batteries can obliterate a smaller foe in a matter of minutes, while high-energgy lasers, which Jamieson tells me are called lances, can shear through three metres of the toughest armour with one devastating shot. Most cruisers carry huge torpedoes as well, loaded with multiple warheads charged with volatile plasma bombs, carrying the power to unleash the energy of a small star on the enemy. It makes my humble laspistol look like a spit in an ocean. More like a hundred oceans, actually. " - 13th Legion, page 134-135

"energyt of a small star" is almost certainly TT range.

How can one focus on the hyperboles and analogies, yet completely ignore the bit about "huge plasma cannons capable of incinerating cities"?
Perhaps when it's too obvious, it's easy to miss? It takes a couple of megatons to incinerate cities.

Oh, and the "energy of a small star" bit. Fantastic. A star has a luminosity. It gives information about its power.

Now, the energy... isn't that silly? Really? Let's hear a definition of a star's energy.
Google "star energy" once, and observe how the first page has nothing scientific to provide.
"Stellar energy" addresses the principle behind how the energy is produced. There's nothing else to say about that, and certainly not any figure to be used until you start talking about power, which is not the case here.
The principle described on several pages is about nuclear fusion, so at best, energy of a small star, would be a reference to the levels of energy you obtain with nuclear fusion (with hydrogen, generally two orders of magnitude less than with perfect annihilation of matter), and anything found in a small star would point to similar reactions, but with a lesser power output.

Had it been power of a small star, there would have been much less arguing , although it would still be deeply ridiculous.
But frankly, such levels of power would make any Exterminatus with fancy and exotic weapons completely pointless.
You don't need Exterminatus special weapons --that fail to destroy anything that's deeply burrowed btw-- when your ships can throw some petatons per lance at a planet. That's absurd. Petaton energy weapons will do far more damage to the planet and its environment than thousands of those virus bombs and other oddities.

But I guess that was too obvious as well.

Page 191

- Cain here reiterates that they would be outnumbered "hundreds to one" and that "hundreds of thousands" of necrons would be loosed on the galaxy. He also says they must call the Navy in to sterilize the whole site from orbit. Note that later on (page 240), Cain mentions sterilizing the whole world. The two are not mutually exclusive, ,however (though I am sure some people will try to treat it as such.)

Indeed they're not mutually exclusive. Destroy the cancer and the planet is clean again.

Page 219

On cue, my aide unleashed another blast from his melta into the centre of the group, cutting a swath through them as efficiently as before. Once again the necrons caught by the full force of the blast were simply annihilated, flashing into vapour as thoroughly as the victims of their own terrible weapons, while the ones at the fringe of that ravening burst of energy staggered, limbs and torsos seared and softened like candle wax.

Here, it suggests that the melta is actually VAPORIZING the Necrons (or at least mostly vaporizing them) while others surrounding take not-insigifnicant melting damage from proximity. No doubt they just teleport away after, of course.

Again, Connor ignores the part about the reaction's speed (flash), yet is not puzzled by the fact that Necrons barely grazed by the beam, but standing next to those hit squarely, don't literally fly across the room.

Page 220

- Cain refers to the cavern that the warp portal is in as "city sized", suggesting that it is quite large and open. And it is quite likely not the only one. All told, I would not be surprised if the Necron base had a dozen or more such caves ten or more kilometers in diameter.

This also does suggest, with regards to the bombardment calc, that they have to melt a not-insigifnicant amount of crust in and around the caves to actually fuck them up (nevermind the ejecta and secondary effects we know about.) Probably at least hundreds if not thousands of meters deep (minus all the city-sized empty spaces, of course.) Small wonder Cain mentions bombarding them "however deeply buried", eh?

The quote was:

That's it,’ I said, watching it pulse like the beating of a diseased heart, and fighting down the surge of dread which suddenly suffused me. The portal.' The glow intensified for a moment, with an accompanying thunder crack of displaced air which rumbled and echoed through that city-sized cavern as though presaging a tropical downpour.

That said, there is no other identified cavern such as this one, and considering that it didn't take ages for Cain and co to sneak into said cavern, avoiding Necron patrols, and return to the entrance, the claim of "ten or more kilometers in diameter" is totally absurd.

[Mr. Oragahn]

Promethium Flood Case

Page 228

- according to the tech priest Logash (survivor of the Necron assault that wiped out his companions), there was "eight million litres" of promethium stored in the fuel tanks. However, its worth noting they actually flooded the tunnels below (which, as noted, extend for kilometers down), and eight million litres does not quite seem... enough to bury the necrons (as happens.) Given the fact that the mines extend down for many kilometers easily, its quite likely that billions (or possibly trillions) of litres is more likely. (By my estimates, assuming a 3 km radius and 10% empty space, the mines probably need about 2 billion tons of promethium.

Also note that, given the later "FAE" commentary, the much GREATER quantity of promethium makes more sense. I'm pretty sure only 8 million litres would yield a fairly unrealistic energy density for mere chemical reactions (terajoule range, in fact.) Billions of liters (trillions if the explosion later is VERY big) yields much more plausible densities (e7-e8 J) Of course, we know that since promethium-filled ships can reach escape velocity, they must have an energy denstiy much better than modern gas as it is. Given that Logash is demonstrably not in his right mind (if not insane) by now, we can reasonably believe that his figure is inaccurate.

Either:
- Logash was wrong and wanking; an in-universe explanation. Rather weak.
- The author had a good idea of what prometheium was, and was convinced of the power of this element, which doesn't mean it's right. An unlikely solution, but Connor would happily jump on this one to claim "exotic super-fuel!"
- The author threw numbers around, which doesn't help taking other events at face value. Indeed, if we know the author to be terribly wrong on what petrochemicals that merely burn would be capable of, there's no reason, really, to think he has any idea about anything he wrote regarding energetic figures.

This one is very problematic. You'll have to remember the note from Iron Hands picked earlier on.
When the tunnel network was flooded with the promethium, we knew that it created the equivalent of a tree-like bomb several kilometers wide:

We found him in the shuttle's main cargo bay fussing over the stowage of the small amount of equipment he'd been able to salvage; under the circumstances Kasteen had decided to abandon our vehicles and stores and use the space we saved to bring up another couple of platoons at a time. Riding back here would be hideously uncomfortable, but far better than still being around if the necrons stirred again.
'So you could still set the charges off from here?' I asked, raising my voice slightly to carry over the babble of voices from the troopers beginning to file in to the echoing hold. A few of them had evidently been in a similar situation before, unfurling their bedrolls into improvised acceleration couches as they settled. Federer nodded. 'Oh yes. You'd just need a sufficiently powerful transmitter. You could even do it from orbit if you wished.'
'That might be safer,’ Kasteen suggested. 'After all, it's going to be a pretty big bang.'
'Oh yes,’ Federer's face lit up with what I can only describe as unhealthy enthusiasm. 'Huge. Massive in fact. On the order of gigatonnes,’ His eyes took on something of a dreamy quality.
'We didn't place anything remotely that powerful,’ Kasteen said, looking vaguely stunned. 'We'd have blown ourselves to pieces along with the gargant,’ Federer nodded, his voice taking on something of the quality of Logash discussing ambulls.
'That was before the commissar flooded the mine with promethium,’ he explained. 'The liquid will have settled to the bottom levels by now. That means the upper galleries would be full of vapour. In effect you've created an FAE bomb several kilometres wide,’
Assuming the explosives you placed weren't washed away by the flood,’ I said. Federer shook his head.
We anchored them pretty firmly. We were expecting a gargant to tread on them, don't forget. We allowed for stresses in the region of..,’
'Never mind,’ I said, cutting him off before he could get properly started. Once enthused, as I knew from experience, he was hard to bring back to the point. 'If you say it'll work I'm sure it will,’
'Oh yes,’ he said, nodding eagerly.

FAE stands for Fuel Air Explosive. "A type of bomb which releases a volatile gas before detonation to magnify its power and area of effect."
The upper galleries would be filled with vapour, as the aftermath of a torrent of fluid gushing through the tunnels.

1 liter is 1000 cc, and one cubic meter is 1000 liters. We have 8000 m³ of promethium here.

Gigatonnes for the magnified explosion. That's in the (4.184+n) e18 J range. Globally, we'd get in the order of petajoules per cubic meter, based on tank volumes.

2 gigatonnes is 8.368 e18 J. -> 1.046 TJ/L. -> 0.25 kT/L.
999 GT is 4,179.816 e18 J. -> 522.477 TJ/L. -> 124.875 kT/L.

Even if that's not counting the promethium that's left to harvest, since, you know, they're blowing up the mine as well, which is built where there's hydrocarbons to pick, this still is a rather hard problem to solve.
Benzene, for example, is a colourless liquid, highly flammable, a natural component of petroleum, and releases 41.8 MJ/kg under a complete combustion.
Density is 0.8765 g/cm³ at 20°C, 876.5 kg/m³. It could be slightly greater at 0°C.
At best, that's 36.64 gigajoules per cubic meter.

Eight thousand cubic meters would deliver 293,101 GJ (70 KT, several times Hiroshima) if we were dealing with a complete combustion of benzene. We're like at least eight orders of magnitude short of the gigaton range, if we were speaking of gigatons of TNT.

Is there another solution? In that giga-tonnes means something less obvious than the energy equivalence to billions of tons of TNT?
Well, as much as it sounds forced, awkward and unpleasant, we can at least try.

So say we are dealing with a bizarre formulation for force (see here), where one tonne-force would be 9806.65 Newtons, or 9806.63 kg·m/s², which would be 9806.63 kg·m/s over one second only.
A gigatonne-force would be 9,806.63 e9 kg·m/s, or 9.807 e12 kg·m/s.

More creatively, as put by JMS, a gigatonne is 1 e12 kg. A gigatonne per meter per second would be 1 e12 kg·m/s. That would be for the momentum.
8 million liters of benzene would weigh 6,400,000 kg.
The explosive velocity of something akin to benzene may be worth a couple thousands meters per second:

Abstract

We report results on flame acceleration and transition to detonation of benzene–air mixtures at room temperature. Flame acceleration experiments were carried out in a 150-mm-diameter, 3.6-m-long steel tube. The entire length of the tube is filled with circular orifice plates (blockage or obstructed area ratio of 0.43) spaced one diameter apart. The fuel concentration was varied between 1.7% and 5% by volume of benzene in the fuel–air mixture. Three regimes of propagation were observed: (1) a turbulent deflagration with typical flame speeds less than 100 m/s, (2) a “choking” regime with the flame speed corresponding to the speed of sound of the combustion products, 700 to 900 m/s, and (3) a quasi-detonation regime with a wave speed ranging from 50% to 100% of the Chapman-Jouguet value.

Source

Clearly the speed of sound in the relevant products would be rather different than that of typical air at sea level (343 m/s). I'm rather surprised the values for case (2) could be that high but well, if that's so.
Obviously, as alluded to in the abstract above, more benzene means a speed largely outpacing 700~900 m/s.

On another note, although this is only half useful because we're dealing with compounds, we can still look at mixed benzene explosives.

If we tried to speak of the explosive momentum, we'd reach a figure in the e9-e10. We're still below the gigatonne momentum threshold, which itself could be worth hundreds at the highest values (e14).

But we need a force, and thus an acceleration. This is where the rate of reaction would be rather useful, for F = m.a.
Considering the description of the setup, likened to a Fuel Air (mixture) Explosive, we can safely consider that we'd be dealing with the equivalent of a detonation (and not a deflagration).
The reaction rate of the charges themselves would play a large role in that, and luckily, we learn that the demo(lition) charges were melta charges, which would easily imply a high reaction rate.

The placement of several charges in that network of kilometer long tunnels, filled with promethium, which a large quantity vaporized, would mean most of the fuel would largely fully react due to the shockwave passing through it at speeds well greater than that of sound.

Admittedly, this far fetched rationalization would only work if there was evidence that most of the reaction could occur within few milliseconds.
There would need to be a considerable degree of mixing between air and promethium to allow the reaction of most of this mass to reach above the level of deflagration. But that is the way a FAE works. The fact that promethium was flushed into the tunnels at a fast pace would help create the much necessary air-mixture.

Now, we could assume that promethium is more energetic than benzene for one. It would push the figure a notch up, and perhaps provide the equivalent of a hundred of kilotons or more.
Would that amount of power fit with the described effects?

'It didn't go off...' I began to say, then a gout of ice erupted from the plain at the mouth of the valley. Mazarin did something to enhance the clarity of the image, and in front of our eyes a vast, growing crater spread to engulf the nearby metal warriors. They tumbled into it like broken toys, more and more of them as the ground crumbled away faster than they could flee, and Federer punched the air as though he'd just scored the winning goal of a scrumball match.
That would have seen off the gargant,’ he said cheer fully.
That it would,’ I agreed, awestruck at the amount of devastation he'd wrought. But that had only been the prelude. Deep in the bowels of the pit a sudden flare of light erupted as the promethium vapour trapped in the caverns below ignited. A gout of flame fully a kilometre in height burst from the rupturing ground and raced across the snowscape at the speed of thought, melting the fleeing warriors in an instant, throwing blazing fissures ahead of itself as it went.
There were other explosions now too, the entire sur face of the valley erupting like pyroclasts, vaporised rock, ice, and necrons forming a low, looming cloud riven with thunderbolts as electrostatic discharges of incredible power jumped between the particles. The refinery disappeared, sliding into the hellish inferno below, and vanishing as though it had never been...
'Brace for impact!' Durant called out, as though this were just a minor inconvenience, and the Pure of Heart was suddenly picked up and shaken like a child's toy by the titanic shockwave as the very atmosphere of the planet bulged under the force of the energies released. Even the crew grabbed for handholds, and I found myself bracing Kasteen, who had fallen back against me (something I had no complaints about at all).
'Just a minute,’ Mazarin called, playing the controls in front of her like the keyboard of a forte, and the shuddering gradually ceased. She grinned again, and I began to suspect she enjoyed the chance to push the limits of her engines.
'Lucky we were so high. If we'd been down where the atmosphere's thicker it would have been a bit trickier.'
'Is that it, then?' Kasteen asked, her eyes riveted on the scene of destruction below. Even from orbit the dust cloud could still be seen staining half the planet, and in spite of all the horrors I'd endured down there I couldn't help feeling a
spark of regret at the scar across the face of the pristine world I'd first looked upon from this very spot a few short days before.

For some of the effects, like the erupting flame jet, the fact that it was formerly compressed through ice, an explosion worth of dozens of kilotons wouldn't be out of league of the observed effect.
However, for the observed effects, the collapse, the crater and implication of massive amounts of ice that's vaporized, and the fact that the blast was rather dangerous at a lower altitude, we'd be expecting many megatons of energy to be released down there.

That, and the other problem, being that I can't really picture 8000 m³ of fuel to be enough to fill all the network!
The volume itself being kinda silly in how low it is (20 cubed). That sounds rather miserable for a refinery.

If this was not enough, while we could argue that gigatonne could be a bizarre unit if only Logash knew what he spoke of, the fact that Kasteen immediately understood what it meant largely disproves the "bizarre unit" theory.

Then, a likely solution is that he slipped, and said liters instead of tons. Eight billion kilograms, if we used benzene as a point of reference for a low end (41.8 MJ/kg), we'd get 334.4 e15 J.
Assuming promethium would somehow be more energetic (still within realistic proportions though) and considering that more promethium than what the refinery held blew up along what was leaked into the tunnels (again, the refinery wouldn't be built there if there weren't pockets of fuel to harvest), we could probably reach more than ten thousand petajoules.

The problem, though, being that even if promethium weighed 1 kg/m³ or a bit more (the tech-priest Logash had to perform "stabilisation rituals" on the tanks), the tanks would be worth billions of cubic meters. That's millions of thousands of cubic meters.

Eventually, promethium might be hyper-compressed.
See here and here). Considering thath the experiment produced ultra-dense deuterium which was "a million times more dense than frozen deuterium", we're within the bounds of million times more matter contained within 8000 m³.
We would "merely" need to believe that Logash would have to reprogram the tanks and valves to carefully spill the promethium back to its natural density, into the mines.

That's purely speculative though, but then we have our nice gigatons fireball, and everybody's happy. ^_^

[The Dude]

I'm just going to comment on a few things, theres really to much here for me to bother wading through it all.

OK, this one is unusually long, in comparison to other threads. 4 pages to wade through, this time we're clearly dealing with big weapons and thus, big numbers.
The CC series appears to give good ranges for infantry weapons. Kill zones for lasguns and else are around 300 meters, with the possibility of reaching good hit ratios at greater ranges.
Artillery spam in conjunction with infatry fire helps. Orks seem to rush like twats most of the time.

The Ork's prefer close combat over everything else, why? IIRC it was bred into them by the Brain Boyz.

Doesn't sound that good. A melee weapon is just as good as its (weakest) materials, and no matter the strength of the Ork, if the weapon isn't as tough as the armor, it would bend, break or literally shatter, the greater the Ork blow the more violently.
So the question is what's crude about these axes? Perhaps the fact that they're mere axes, with no fancy monomolecular edge or force field.
That or the weirdo Waaagh unquantifiable buff anything gets when numbers don't look nice enough, I suppose.

It probably just pertains to it's means of manufacture and lack of finish. If you go by some of the pictures out there of Ork weapons and kit, it has the appearance of being slapped together, rather then the Imperium's weapons which are treated almost as an object of reverence
and worship.

[User1350]

Ciaphas Cain: Caves of Ice - analysis and discussion thread

Also, according to Cain, it would have taken hours for the hauler to abort its current trajectory and return to orbit - the life support would give out long before they could return.

A rather sluggish ship.

It should be noted, I believe, that the shuttle here was implied to be running on promethium (like alot of 40K vehicles of that size.) Not unreaosnable for a shuttle, however its chemical reactions would have to be extremely powerful - as Mike has noted numerous times, it takes a minimum of 60 MJ/kg to escape an earthlike gravity well (far more than modern gasoline or diesel) This, along with other evidence, tends to suggest Imperium chemical explosives and engines are probably alot more powerful than our modern equivalents (potentially at least - efficiency is still an issue.)

Refined promethium, perhaps yes.
...

I would note that even twice the energy/mass of modern propellants give jumbo jet mass ratios for SSTO. From how long it would take to return to orbit, it looks more like somewhat better fuel in terms of ISP efficiency combined with partially relying on suspensors to get to orbit.

[User1350]

...

Page 81

His voice was drowned out by the abrupt hiss of the melta as Jurgen fired into the wall, instantly flashing a dozen cubic meters of ice into steam, which condensed almost instantly in the subzero temperatures, filling the narrow passageway with mist.

The infamous "meltagun calcs" as originally performed by Necronlord. Necronlord's original calcs are somewhat consevative (inefficiencies, latent heat of fusion, specific heat, etc all add some energy to the calc, but its still accurate to within an order of magnitude.) It can safely be said that a meltagun can achieve double-digit gigajoule outputs easily (but this is probably close to the maximum for the weapon - multimeltas reach triple digit GJ in Storm of Iron and are are definitely more powerful.)

It should also be noted that some people have equated the output of 20-30 gigajoules of enerrgy as resulting in a bomb-like blast. This is not neccesarily true - the pressure wave (if any) will depend heavily on the duration of the vaporisation as well as how "concentrated' it is (bombs develop high pressures due to the fact they generate large amounts of gasses in very short timeframes and in very small volumes.) Given the "area effect" nature of a meltagun, and the "sustained" nature of the beam, small volumes and rapid timeframes are unlikely. Furthermore, the described operation of a melta (at least some of them anyhow) tend to suggest that the "heating" of the ice would be much more uniform than ti would be if, say, a lasgun was melting it (the latter would have to heat a very small area and rely on work heating to vaporize the rest of it, which tends to lead to more "explosive" effects - a meltagun does not need to rely on work heating nearly as much to achieve the same results.)

The energy output is, however, quite substantial, and could pose a risk to exposed flesh, especially in confined spaces. In this case, though, there are some possibly mitigating circumstances. For example, due to the mentioned "sub zero temperatures", that some of the people were up to 100 meters away along the tunnels (either way), time was allowed for others to get clear, that a third opening was created a bit later, and that all the Valhallans were heavily bundled up in flak armor, greatcoats, and winter gear, brief exposures to the high temperature steam would unlikely be a significant problem (And given the warning, they can take further protective measures such as, turning away, covering their faces, etc.)

Another possibility is that 40K humans are not quite like us (ie modern humans) - there is circumstantial evidence that they are taller/heavier, ,stronger, and faster as a rule, so they could also have greater durability as well (the fact that the Valhallans are likely to be heavily bundled due to the enviroment is a bigger saving grace here.)

We understand it's pretty much vital for Connor and else to prove that the release of energy would be long and more or less constant.

But let's remember bits from "Ciaphas Cain: For the Emperor".
For the death of Kelp, by Jurgen's melta, Connor said "bear in mind this also occurs over about half a second or less, so that can at least double or triple the figure too."
That, between the moment Jurgen fired, and Kelp got killed.
Earlier on, quite a similar weapon in terms of magnitude of damage, a hellgun, from the same man, Jurgen, flash steamed parts of the guts of a Patriarch (old genestealer pureform).

So why suddenly pretend that we're dealing with a "sustained" beam? More, the book clearly speaks of ice instantly flashed into steam. Instant, flash. Is that not clear enough?
When this would typically warrant an interpretation in favour of greater figures, notably for power outputs and excess of energy, why is it blantantly ignored here, if not to get away from the obvious lacking blast and the issue it represents?

Also, if we use the references to the speed of the reaction, from Connor's half a second or less, to the flash-steam implied rapidity, you could easily obtain a power of 40 gigawatts or more for a yield of 20 gigajoules. With 30 gigajoules and a speed reaction even faster than half a second, you could literally be just one order of magnitude close from the terawatt range!

And of course, no cracks in the ice, no collapse of the ceiling, nor other adjacent walls or else.

The melta weapon clearly has residues of heat, but its mechanism is not spreading heat naturally. Once again, it does not undermine its capacity, but it heavily puts into doubt any claim of non-exotic mechanism.

At several seconds, it's enough to damage people through blast, damage them through overpressure, and steam boil them alive. It would have to be a very long time, or a very large cavern to get away from that.

The second thing, it confusing homo-40k with homo-superior has been very over done. Game rules are something one should be very cautious about, but height/weight for the various people of the Imperium in Dark Conspiracy doesn't fit that mold. Planets with people larger than current norm do exist. These people are over represented in the elite of the military. Actually nice worlds have people that would be pretty average for non-immigrant first world populations (childhood nutrition). But, the majority or them are poor saps from hive worlds. As for them being better, faster, stronger, tougher, on average, it doesn't seem to work that way.

Page 93

According to the Magus Biologos they [ambulls] can see heat rather than light. Rather an odd concept, I have to say, ,but having looked through a tau blacklight system recently I can attest from personal experience that such a phenomenon can be achieved by technosorcery, so I suppose its not beyond the bounds of possibility that it might also occur in nature.

This is in regards to the ambull's ability to see in the dark (the means by which made no sense to Cain, he claims.) From what I understand some people take this to mean that Cain (and by extension the Imperial Guard as a whole) do not understand or utlilize infrared or night-vision systems. However, we know of ample (earlier) cases that demonstrate this false (such as the Ghosts novels.)

We also know from page 62 that Cain IS familiar with thermal scanners (and another incident with Sentinels in Triator's Hand reinforces this, IIRC.) so again the idea that Cain or the Guard have no idea about them is patently false.

It wasn't Cain who had this thought. It's from a note by Amberley Vail, of the Ordo Xenos. And what appeared odd was that a feral creature would come with such a sense, while it's generally attributed to the making of technosorcery.

I'd note that light amplification or other sensors is a couple handfulls out of 3000 for the Ghosts. They have a few sniper scopes, one person with cyber-eyes, and at least one general sensor pack.

As of a few Cain books, his regiment isn't even that well equipped.

[User1350]

As for the bombardment in 'Caves of Ice', mixing and matching specifics from different theoretical incidents is very sloppy.

[Mr. Oragahn]

As for the bombardment in 'Caves of Ice', mixing and matching specifics from different theoretical incidents is very sloppy.

I can't figure out if it's a positive or negative criticism here, and if it's directed at my post or not. Believe me, I tried to focus on CoI as much as possible, with the less extrabook references possible.

[User1350]

As for the bombardment in 'Caves of Ice', mixing and matching specifics from different theoretical incidents is very sloppy.

I can't figure out if it's a positive or negative criticism here, and if it's directed at my post or not. Believe me, I tried to focus on CoI as much as possible, with the less extrabook references possible.

Apologies, it's on Connor.

[Mr. Oragahn]

Bumpin' this since it seems a bit of clarification is needed. I've seen myself being referred to on this SciForums ST vsd W40K thread.

To reply to Ricery and HeartlessCapitalist, my methodology is as rigorous as it can get. If one should retain something about my analysis of quotations, it's that at several times, I had to provide the complete context of quotes people at SDN or SBC gleefully forgot to include, or didn't want to include in glaring cases of cherry picking, which in the end explained why their out of context quotes could be understood the way the did understand them.
That's without counting the god awful numerous times when they simply didn't properly understand the little quotes they had to begin with!

Now, the case of Caves of Ice is very simple: Cain knows that the cancer (the Necron activity) is localized, and they damn know where it is. It's several kilometers below the surface, down that promethium mine.
The other fact is that the AdMech guy drools at the idea of being able to generate a gigaton level explosion, and that single explosion precisely does destroy the Necron menace.

The problem with Connor is relatively simple: he believes that his CoI calc is the cornerstone-like demonstration of the rightfulness of his position on WH40K firepower. And yet he made a rather simple mistake in conflating two independent statements.
The final nail in his erroneous judgement is in taking literally Cain's claim that the planet would be sterilized. I explained it.
You will find everything about the sterilization parts in this post. There are two instances of the verb sterilize, and it's important to understand what Connor did.

Finally, concerning about our friend Ricery, I wouldn't be too worried about his "rebuttals" and his capacity to understand anything of importance.
Just two examples - and I will limit myself to that because I don't want to pollute this thread more than what is just enough to clarify the situation about this individual - to understand what I'm talking about (his own words are coloured):

http://forums.spacebattles.com/showpost ... stcount=69

4.184 GJ = 1 KT 41.84 GJ = 10 KT 418.4 GJ = 100 KT 4,184 GJ = 1 MT 41,840 = 10 MT 418,400 = 100 MT 4,184,000 = 1 GT 41,840,000 = 10 GT. 41,840 terajoules is more like it. It would take 418,400,000 GJ to produce 400,000 TJ, which is below 100 GT.

All wrong. Let's start with 4.184 TJ = 1 KT.

http://forums.spacebattles.com/showpost ... tcount=330

To match 20 gigatons, you would need hundreds of millions of tons of hydrogen.

I guess being wrong by nothing less than six orders of magnitude is not important.
Let's try at 580 tonnes, that would be better.
One can only imagine the mass of Tsar Bomba according to him.

So, see.
I think we're safe. :D

[Mith]

Something I shamefully missed earlier.

There is a difference between barrage and volley--yet Connor seems to equate the two here.

Allow me to explain:

vol·ley   /ˈvɒli/ Show Spelled
[vol-ee] Show IPA
noun, plural -leys, verb, -leyed, -ley·ing.
–noun
1. the simultaneous discharge of a number of missiles or firearms.
2. the missiles so discharged.
3. a burst or outpouring of many things at once or in quick succession: a volley of protests.

A volley is typically used for the simultaneous discharge of a ship's weaponry. This does not have to include all of its weapons at the same time, but can be. This, in Connor's context, could mean devistating firepower. Could.

It does not however, as this word is barrage:

World English Dictionary
barrage (ˈbærɑːʒ)

— n

1. military the firing of artillery to saturate an area, either to protect against an attack or to support an advance

2. an overwhelming and continuous delivery of something, as words, questions, or punches
3. a usually gated construction, similar to a low dam, across a watercourse, esp one to increase the depth of water to assist navigation or irrigation
4. fencing a heat or series of bouts in a competition

— vb
5. ( tr ) to attack or confront with a barrage: the speaker was barraged with abuse

[C19: from French, from barrer to obstruct; see bar 1 ]

Barrages have no sort of time limit or limit of firing as a volley might imply. In other words, there is absolutely no way to quantify what Cain just said. Barrages can last for hours if need be and regularly did in many wars. Hell, barrage doesn't even make sense in the concept of time (such as 'several'), but rather makes more sense in targets. As in the navy would target multiple areas to barrage. Or it could mean a requirement to cease fire and reload, recharge, or what else.

[Mr. Oragahn]

The formulation isn't gracious, for sure.
A couple barrages is hard to define in time because we just don't know how long a barrage can last.
However, you say that there could be several barrages, as one barrage per different target, but the context makes it more sound like they'd be concentrating their firepower on the known location of the underground Necron tombs. Cain knew where they were. They were in that large ice cave.
So I see how one can equate barrage with volley.

But in fact there's no reason to do so, since a barrage is generally understood as a bombardment session of undetermined duration, and generally it's meant for a continuous bombardment.
Indeed, there can be several bombardment sessions. We know they need to reload weapons, and lances of various types (laser or plasma/fusion, or a mix of both if we go with what Andy Chambers once wrote) and other mass drivers may need to cool down or charged. Again, Chambers once mused that a turn could be between 15 minutes and one hour. You generally get only one attack phase per turn.

All this is in total agreement with what I said at the end of the calculation regarding the bombardment of the Necron tombs:

In reality, I don't see why so much ice would need to be sublimated to reach through a couple of kilometers down. All that would be needed would be to dig some beam-wide holes down there, focused onto the target, and input the energy into the Necron structures directly.
This, obviously, would dramatically lower the numbers.

Now make that only a good dozen 20 meters wide beams, you must remove 1.2566 e6 m³ of ice per beam. Multiplied by a dozen beams and assuming they don't overlap, that's 1.508 e7 m³ as a total.
That is precisely 5208.223 times less than the former figure.
The energy figure becomes: 41.72 e15 J, or 9.97 megatons.

No time reference is ever given by the way.

Your clarification is a good addition.

[Mr. Oragahn]

To highlight the whole importance of understanding the meaning of barrages, I found this post from Orsai, in the long and constantly growing ST vs Eldar & Tau thread:

Through unknown means which doesn't tell us anything.

Well, Cain sure seems to think that a few lance volleys would render the planet lifeless (well, "uninhabitable for generations" is the phrasing he uses, but close enough).

If that isn't rewriting what the text says, I don't know what it is. It probably explain why they just can't clean their eyes and warp their head around the real essence of the text.

It says "a couple of barrages", which at best identifies a quantity, not a duration, since there's no known duration regarding what a barrage means.
Why should we be surprised that Orsai is among those who keep defending the same inflated figures?
They just don't get it. Or perhaps they don't want to let it go. Your pick.

It also goes without saying that by Connor's calcs, it would be quite a stretch to consider that the planet would be uninhabitable "for generations" (only). When you count in generations and not centuries or millennia, it's quite obvious that the extent of the damage brought upon this world would be limited.

The firepower necessary for nuclear winter added to the hostile milieu of the planet, so much that you can't live on its surface without conveniently insulating gear to survive the permafrost and minimal vegetation environment, is sufficient to explain why you'll make this world a shit hole for a couple multiples of 25 years.

Besides, if you recall correctly, the text said:

"Nothing in our inventory would even come close to doing the job, but an astropathic message to the nearest naval unit would bring a task force here within weeks, and a flotilla of battleships ought to be enough to level the continent."

Meaning that anything less than such a flotilla would not be capable of leveling a continent. Otherwise there would be no point even thinking than more than one large ship would be necessary!
And yet Connor's calcs put the firepower of a single battleship at 1.25 billion megatons per salvo - after a "drastic underestimate" "low end" of 55.66 TT per battleship, he said "2.5 billion megatons per salvo" involving two battleships - a range sufficient to flash vaporize any large nation in one single broadside, to a considerable depth?
Dividing by zero pales against the silliness of their logic.