Analyzing WH40K: Roks and other quantification odds and ends

[Sean0931]

The mono-edged weapons is from "Deus Sangunius". I don't have the book (borrowed it from the library), so meh. I'm gonna stop postin here, the text box flickering up and down is REALLY doing my head in.

What browser are you using? You're at least the second person to report this problem, but I haven't been able to duplicate it yet. (As an interim fix, you might consider just C&Ping to and from a text editor window, e.g., Notepad or Wordpad if you're a Windows user).

I'm not a very good debater, so if you want a debate, go to Spacebattles.com and have a debate there, that's where most of the veteran 40kers are. I see your points, but from the multitude of 40k books i have read, I can't agree with them.

e.g. The idea that a modern tank could even hurt a titan, when we have seen them take nearby nuclear blasts (Titan), suvive a global firestorm (HH) and other generally huge forces.

Actually, there's a famous case where a tank survived a nuclear test unscathed at 500m from ground zero.

I don't on the whole think a modern tank would have much chance to hurt a Titan. WH40k armor doesn't do well against kinetic penetrators, but while a modern kinetic penetrator may be able to pierce Titan armor at good incident angles (much like a Vanquisher KE penetrator) it may not do very much damage.

edit: One quote from space hulk is "A Space Marines bolter can rip through eight inches of plasteel as if it were tissue paper". Bolter Shells are often descriped as having RPG-7 like effects (Vapourising torsos [Storm of Iron], blowing man sized holes in Rockcrete walls [Night Lord, I think, though this is high end] outright bodily destruction [Ragnar's claw "There was nothing left of him save his boots"] bolters, and even heavy bolters are next to useless against Russes.

Actually, that would be a very good benchmark. A Bolter is a 19mm weapon.

Let's compare this with a a couple kinetic penetrators.

M829A2 has a 22mm penetrator. At point-blank, it'll punch through around thirty inches of steel, AFAIK. With about three quarters of the area and a little over a quarter of the penetration, we're going to be talking somewhere in the 1-2 MJ (1.4 off the cuff, but there are a lot of potential fudge factors here) range for the bolter round to similarly penetrate.

Not too shabby - impressive, even - but an RPG-7 HEAT round will penetrate over a foot of steel armor (for the oldest model of RPG-7 HEAT round), and a high explosive round will tend to kill everybody within 25-30'. Penetrating 8" of plasteel doesn't mean a Space Marine with a bolter will be able to blow up a modern tank with a shot; however, the bolter has a much higher rate of fire than the RPG-7.

On the whole, I'm more impressed by Space Marines' technology than that of the Imperial Guard - their vehicles have more effective armor, for example. There's no small amount of variation in Imperial military technology.

But the quote says "Like tissue paper". Surely that implies extreme ease? You wouldn't say an RPG can penetrate a foot of armour "Like tissue paper" because it won't go much further than a foot. Also, we have no idea how much tougher Plasteel is than regular steel (from the context in which it is described, we can safely assume it IS tougher.)

[Jedi Master Spock]

But the quote says "Like tissue paper". Surely that implies extreme ease?

Generally, either the armor holds, or it doesn't. Any through-penetration event will be very violent. I wouldn't put much stock in "like tissue paper." Especially if this incident is a bit of an outlier.

You wouldn't say an RPG can penetrate a foot of armour "Like tissue paper" because it won't go much further than a foot. Also, we have no idea how much tougher Plasteel is than regular steel (from the context in which it is described, we can safely assume it IS tougher.)

Actually, we do have an idea.

Plasteel may be forged by hand:

Not being front line combat troops, the garrison auxilia were not generally issued with any form of body armor, and this trooper has corrected this with hand-forged plasteel plates. These will provide rudimentary protection in battle, especially in hand-to-hand combat, but also against lasgun rounds.

Conventional steel may substitute for plasteel in construction:

Due to its STC roots the Rhino can be constructed using locally available materials. Most Rhinos are constructed of a bonded ceramite layer over a cast plasteel hull, although others use carbon composite compounds or conventional hardened steel, depending on their origin.

From that, it's not going to be terribly far off from conventional steel.

Adamantium armor peaks at close to 5x the toughness of conventional steel; we know this from Land Raider armor. So we know that plasteel is less than that. Moreover, the Leman Russ's armor is at most 200mm (turret; front is 180mm), and the thing is made of cast plasteel - and it is not as well protected as the Land Raider according to the fluff.

If the frontal armor of the Leman Russ is equal to the Land Raider's armor (as it is in the game mechanics), then the Land Raider having protection equivalent to 300-365mm of conventional steel armor suggests that plasteel armor is around 1.5-2x the toughness of conventional steel armor.

The problems? Now we have Space Marine bolters able to pierce Land Raider armor, since they can pierce 200mm of plasteel, which means they can pierce Leman Russ turret/frontal armor. Also, the Land Raider is, IIRC, tougher according to the fluff.

So that's why I'm approaching that quote dubiously. Perhaps there's as big of a difference between plasteel armors and normal structural plasteel as there is between steel armors and soft mild steel, but in all cases we're looking at bolters being authoritatively stopped by Land Raider armor that is equivalent to 300-365mm of conventional steel - when the most basic RPG-7 HEAT round will pierce 330mm of modern conventional steel armor, and more advanced versions will pierce 500-700mm or so.

[Sean0931]

But if that were the case, hotshot, or even regular high power lasgun rounds should be able to penetrate Land Raider and Russ armour easily. They are stated as having a 19 megathule magaizine (Author stated that this was a corruption of the word joule, it wouldn't make sense for 40k to use measures other than joules when they regularly use watts). Hotshot lasgun rounds (Which empty the whole magazine in one shot) are useless against all but the lightest armoured vehicles. Lascannon rounds are may times the power of these, but they still do not always penetrate Russ armour. I know these are two types of damage mechanism, but the idea that imperial vehicles armour are an order of magnitude better against energy weapons is, quite frankly, ridiculous. To be honest, I think you just don't like 40k, and are an obscene minimalist. The idea that an empire who have starships that can survive multiple hundred gigaton internal explosions, thanks to the grade of materials that they use, and that can take teratons, at least onto their bare hull, have vehicles that are pathetic compared to modern day vehicles, is laughable.

I also direct your attention to this: http://bbs.stardestroyer.net/viewtopic. ... c24140b407

[Mr. Oragahn]

But if that were the case, hotshot, or even regular high power lasgun rounds should be able to penetrate Land Raider and Russ armour easily. They are stated as having a 19 megathule magaizine (Author stated that this was a corruption of the word joule, it wouldn't make sense for 40k to use measures other than joules when they regularly use watts). Hotshot lasgun rounds (Which empty the whole magazine in one shot) are useless against all but the lightest armoured vehicles. Lascannon rounds are may times the power of these, but they still do not always penetrate Russ armour. I know these are two types of damage mechanism, but the idea that imperial vehicles armour are an order of magnitude better against energy weapons is, quite frankly, ridiculous. To be honest, I think you just don't like 40k, and are an obscene minimalist. The idea that an empire who have starships that can survive multiple hundred gigaton internal explosions, thanks to the grade of materials that they use, and that can take teratons, at least onto their bare hull, have vehicles that are pathetic compared to modern day vehicles, is laughable.

I also direct your attention to this: http://bbs.stardestroyer.net/viewtopic. ... c24140b407

On the same hand, for several lasgun and laspistol quotes and calculations, we see that texts may be taken a bit to the extreme:

---
Laspistol
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Inquisition War Omnibus - Ian Watson, Black Library, Page 550
"By contrast, laspistols were silent in operation. If the aim was inaccurate, the scalpel-blade of energy soon dispersed. Whener a las-pulse met its target: such lacerating flare-up, such a scream of agony, if the victum still had the breath and lungs and heart to scream. Perhaps ten of the pilgrams had fled. A score more lay dead or dying, almost all thanks to the laspistols."

This seems to indicate that laspistols are easily capable of vapourising the water content of a human heart and lungs in a short time. A low end estimate of this firepower is 0.75 to 1.1 megajoules.
Source Thread This is a post from a debate thread, but calcs are in there. This calculation is updated as part of the Lasgun Analysis thread below.

You certainly do not need to vapourize most of the water content of a human heart and lungs in a short time. You just need to rupture them and that can be done with far less energy. These organs are still remarkable fragile.

It's also the same people who interpretated "petals of flame" the size of a large continent or such to indicate teratons per salvo, yet completely ignored that these petals of flame didn't even pierce the cloud layer.

Scout Armour is composed of carbon-titanium. Space Marine power armour is composed of ceramite, described as ceramic material. They may be hyper compressed materials, but they're still not handwavium material.
Plasteel and this ceramite are used for the composition of Terminator Armour, plus adamantium.
And ceramite does exist.

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Caves of Ice - Sandy Mitchell, Black Library, Page 159
Lasguns can be fired fully automatic, one handed. This indicates almost negligable recoil. This contradicts other sources, especially the lasguns used by the Tanith First.
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Caves of Ice - Sandy Mitchell, Black Library, 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.

This of couse, means it also includes a bolt from a laspistol.

This calculation largely hinges on the lack of mention of blood. Is blood always mentionned?
Besides, I'd like to know how you can cauterize flesh, even if it's tough (I believe an Ork's neck is quite tough indeed), when the weapon delivers its energy in a flash instant, and that this power is more than likely to blow things out of the way and rupture tissues, instead of leaving them in place and heating them up neatly? In my opinion, the force of material expansion has more chances to reach farther and deeper down the skull and the neck than the heat itself.
The edges may "smoke" (which is not mentionned either, perhaps we should therefore backpedal into a much lower estimation, huh?), but they'll be the tips of petals of blossomed and dangling flesh.

There are several cases which also point to large amounts of force or energy, but it seems enthousiasm takes precedence over accuracy in a couple of interpretations.

[l33telboi]

The whole cauterization thing is mostly just a trick to get the figures as high as possible, and it's gotten abused to the point of ridiculousness.

I remember one mention of a bolter round hitting someone in the face and leaving a crater there. What was the conclusion? "Oh well, since there's no mention of blood, let's assume it was cauterized, oh, that means about 7 megajoules of energy". And this from an explosive shell.

When's the last time you've seen something like a 120mm tank cannon round hit someone in the face and only leave a crater? When’s the last time you’ve seen a high-explosive round cauterize a wound?

Similarly, there was a mention of a gauss-rifle (or railgun) round that nearly cut someone in half. The calculation? "Let's assume there was a hole cauterized in the person large enough so that he'd be cut in half!" How in God's name is a slugthrower supposed to cauterize a wound, rather then, y'know, blow the person apart? Magic? Wizards?

Sometimes I wonder what would happen if I were to apply similar calculations to the franchises I usually work with.

[Jedi Master Spock]

But if that were the case, hotshot, or even regular high power lasgun rounds should be able to penetrate Land Raider and Russ armour easily. They are stated as having a 19 megathule magaizine (Author stated that this was a corruption of the word joule, it wouldn't make sense for 40k to use measures other than joules when they regularly use watts). Hotshot lasgun rounds (Which empty the whole magazine in one shot) are useless against all but the lightest armoured vehicles. Lascannon rounds are may times the power of these, but they still do not always penetrate Russ armour. I know these are two types of damage mechanism, but the idea that imperial vehicles armour are an order of magnitude better against energy weapons is, quite frankly, ridiculous.

Not at all. Fact of the matter is that laser weapons can be a rather energy-inefficient way of piercing armor; you basically need to vaporize it, do so violently enough to expel matter from the surrounding hole, and quickly enough not to lose too much energy into the surrounding material. A substantial fraction of energy will even be reflected, and depending on the beam duration, target movement, attacker movement, etc, a beam is likely to be dispersed over a larger surface area. And WH40 las weapons are generally not narrow-focus pieces.

As Wikipedia even sees fit to mention, laser cutting is energy intensive compared to mechanical cutting - and this is in carefully controlled environments.

It is with good reason that, in debating Thanatos, one of my lines of evidence regarding lascannon yield was the ability to pierce Land Raider armor. It would take 171 megajoules to vaporize a 10 cm diameter plug of steel 365mm thick - and that looks to be about the diameter of a lascannon beam. Bullets that kill people quite well are available at 1/1000th of the energies Connor ascribes to lasguns.

Moreover, in the case of (say) Land Raider armor, around half the thickness is dedicated to insulation. We can make the case that WH40k armor is designed to resist thermal and shock effects and not kinetic penetrators - and the evidence supports this, with Vanquisher rounds and Tau railguns piercing Imperium tank armor quite well. 20th century conventional armor is actually quite bad vs thermal attacks; steel has a very low specific heat. Depleted uranium, used in modern Chobham armor, has a nasty tendency to turn incendiary when superheated.

The analysis of the Vanquisher round is actually quite solid. We have pictures of it in cross-section, we have multiple citations talking about the mass/velocity of Earthshaker rounds, we have multiple citations talking about how the Earthshaker's recoil is borderline excessive, and the physics of kinetic penetrators (along with the basic kinematics of recoil) is very well studied indeed.

Even then, the Vanquisher round is not less potent than modern tank rounds (close to three times the KE); it is simply less advanced in design (low L/D ratio, no stabilizing fins), winding up with similar penetration but more destructive power. Which, for a WH40k vehicle's thinner armor, designed more for thermal and HE weapons, is overkill - and the way a Vanquisher AP round almost always makes it through AV 14 on a hit in the game reflects that quite well.

To be honest, I think you just don't like 40k, and are an obscene minimalist. The idea that an empire who have starships that can survive multiple hundred gigaton internal explosions, thanks to the grade of materials that they use, and that can take teratons, at least onto their bare hull, have vehicles that are pathetic compared to modern day vehicles, is laughable.

As pointed out on the first page, there's a lot of variation on the starship figures:

The great Sky Fortress bore Rogal Dorn and the remnants of the Imperial Fists to the inner palace. The loyal old general was determined to stand and die with his Emperor in the final hour. The Sky Fortress raced away from the palace in a desperate attempt to reach Jhagatai Khan and return him to the palace. It was destroyed by a blaze of fire fron the Death ́s Heads Titan Legions. Even in death its commander wrought havoc on the enemy, bringing the crippled vehicle down into the entre of the Chaos Horde. It seemed as if a new sun was born on Earth as the plasma reactor exploded, blasting out a crater three kilometres across. Those within the palace knew they were cut off; now they were truly alone. Only a miracle could save them.

A teraton explosion would not leave a three kilometer crater. Nor would a gigaton explosion. The Sky Fortress's core reactor exploding is much closer to Castle Bravo's two kilometer crater - placing it in the 10-100 megaton order of magnitude.

Moreover, there are many problems in scaling down the starships that are, in some cases, close to a billion times the size of the tanks we're talking about - not the least of which is that in WH40k-land, the ground units get a lot more attention and are therefore more consistently described than the starships. It's more appropriate to go from the ground vehicles to the starships than vice versa, and even then it's not a very good idea.

I also direct your attention to this:

Seen it before. I would recommend reading these three threads to cover the most recent major WH40k debate on this board. SDN figures - while generally maximalist - are still not far off from the ones I have used when it comes to las weapons. The difference is largely that on SDN, Connor et al tend to consider the highest figures a "minimum" springboard for speculating up into higher ranges, while I consider the lot to include both low and high outliers and try to err on the generous side, when in doubt, since I usually find myself on the "against" side in these debates. (A product not of personal dislike of WH40k, which I have occasionally considered taking up as a money-wasting hobby, but rather of the excessive claims being made.)

In fact, I cited Connor's collected work (which makes up much of the material in the thread you cited) on WH40k in the closing statement of my formal debate with Thanatos:

Eighth: You've had about a month to come up with some kind of quantifiable lascannon event pointing to >2 GJ yields, and haven't come up with a single one. If there's any evidence pointing to that, it's buried deep among all the evidence that suggests a lascannon is somewhere at or below 2 GJ that we've both rifled through. It's not as if this is a particularly unusual conclusion; this is the same sort of order of magnitude that debaters seem pretty willing to accept.

For example, Connor MacLeod on SDN, pretty clearly interested in promoting higher WH40k numbers, gives "high triple digit MJ to low single digit GJ," "in the hundreds of MJ easily," "las cannon have a minimum energy output of hundreds of megajoules", and once - for the example we discussed at greater length earlier, the Tau battlesuit case - concluding 2-4 GJ by treating the battlesuit as an inert solid brick of steel. If there was anything resembling solid evidence for lascannon yield >2 GJ, I feel like it should have seen the light of day by now.

I rest upon eightfold path of lascannon yield certainty. The lascannon has an effective yield of no more than two times ten to the ninth kilogram meters squared per second squared.

I would not have done so without actually having read through a number of threads on SDN. (As is usual, when talking about maximum yields, I also discussed minimums; this is an estimate of order-of-magnitude precision, i.e., 200-2,000 MJ, and one I still stand by.)

[Enosh]

Similarly, there was a mention of a gauss-rifle (or railgun) round that nearly cut someone in half. The calculation? "Let's assume there was a hole cauterized in the person large enough so that he'd be cut in half!" How in God's name is a slugthrower supposed to cauterize a wound, rather then, y'know, blow the person apart? Magic? Wizards?

you are confusing stuff, what exacly are you talking about?
gauss weaponry is the fancy thing that necrons use and that takes stuff apart at a sub atomic level.

railguns are used by the Tau and from what i remember they fire plasma projectiles (not sure on this one), I am kinda bad at Tau fluff (since I never gave a shit about those little buggers) but I know that they (railguns) are also vehicle mounted and thus certanly not rifles, unless you are talking about pulse rifles, which are certanly plasma projectiles

[Dabat]

There are a lot of read intensive posts in this thread, I have started a few posts and found myself so bass-ackwards that I could not finish them. I hope this is not confusing to you all.

First. Yes there will be blood. Any laser weapon that hits a human will cause a lot of damage. We are not talking about from the heat itself here (well, not all of it) but anything that can vaporize water more then a few centimeters deep will leave terrible bloody wounds. I have seen what happens when a mere 300 grams vapor is introduced inside of a body*. A las shot with even half the vaporization would easily do enough damage to amputate a limb.

*It was caused by a self defense weapon for use against aquatic predaters, it was essentially a knife with a tube leading from near the tip to the handle, inside the handle was 300 grams of compressed air. If the hole it left in the shark was less than 30 cm across I will eat my shirt, headband or bra; your choice.

Crap, of course, I need to go again.... >.> I am posting this now because if I don't I know I will never get around to it. ><

[Sean0931]

OK, my last post here, i think

I found this thread very interesting

http://bbs.stardestroyer.net/viewtopic. ... =tanksharp

[l33telboi]

you are confusing stuff, what exacly are you talking about? gauss weaponry is the fancy thing that necrons use and that takes stuff apart at a sub atomic level.

I’m talking about Tau weaponry. I recall their rifles electromagnetically propelling slugs, making them either gauss guns or railguns. I'm guessing railguns by your post. Necron gauss guns have little to do with ‘real’ gauss guns. They’re more like NDF weaponry if memory serves.

railguns are used by the Tau and from what i remember they fire plasma projectiles (not sure on this one), I am kinda bad at Tau fluff (since I never gave a shit about those little buggers) but I know that they (railguns) are also vehicle mounted and thus certanly not rifles, unless you are talking about pulse rifles, which are certanly plasma projectiles

The slug in question was a rifle, not a vehicle mounted weapon. I’m not sure what you mean by 'plasma projectiles'? The slugs turning into plasma because of the friction generated by the air resistance is possible, but I'm guessing that's not what you're referring too.

[Enosh]

The slug in question was a rifle, not a vehicle mounted weapon. I’m not sure what you mean by 'plasma projectiles'? The slugs turning into plasma because of the friction generated by the air resistance is possible, but I'm guessing that's not what you're referring too.

Pulse Rifles are the basic weapon of the Tau Fire Caste. The Pulse Rifle is the standard pulse weapon, however all pulse weapons operate on the same principle. A particle is propelled by an induction field. The particle breaks down and creates a plasma 'pulse' which shoots out of the weapon at an incredible rate. Damage is caused by the extreme heat and electrical charge of the plasma. This is classed as a Plasma weapon, but unlike Imperial versions they are much more reliable and use more failsafes and cooling mechanisms. This makes them a lot safer and much more sensible to use on the battlefield en-masse. They are much weaker than the Imperial Plasma Gun, but the bonuses of extra safety easily outweigh this reduction in power.

The Tau pulse rifle is longer ranged and more accurate than the Imperial Lasgun.

http://wh40k.lexicanum.com/wiki/Pulse_Rifle

so catorisation is not something handwaved in

[Jedi Master Spock]

Yes - it may be odd, but Games Workshop moves away from the normal meaning of a Gauss weapon.

*It was caused by a self defense weapon for use against aquatic predaters, it was essentially a knife with a tube leading from near the tip to the handle, inside the handle was 300 grams of compressed air. If the hole it left in the shark was less than 30 cm across I will eat my shirt, headband or bra; your choice.

For reference, folks, 300g of compressed air will create a bubble larger than a human diver when it's near the surface - and you need less than 200g of water flashed into steam to create similar vapor pressures. Water has a lower molecular weight.

It's a little more dramatic when you inject the vapor rather than creating it on the surface going inward, but you learn something new every day. I didn't know divers carried something like that, but I can believe that one blew a hole that size in a shark.

OK, my last post here, i think

I found this thread very interesting

http://bbs.stardestroyer.net/viewtopic. ... =tanksharp

A few interesting details worth noting in that thread. I had not thought to estimate the density of plasteel (MKSheppard is estimating 4 g/cc), but I can believe it is lighter than conventional steel (and more corrosion resistant, to boot). This means impressive things regarding its utility - but quite little regarding the thickness required to grant some level of protection.

And we should note, that makes its resistance being greater than that of conventional steel quite a bit higher.

However, I am disappointed to go through three pages of posts and find that many people discussing a tank sliding on the ground without once discussing a coefficient of friction.

So let's do their work for them. I'm going to assume the ground is a bit wet. Coefficient of sliding friction on wet meadow for tires can be estimated as typically 0.15-0.2. If it's particularly muddy, treads will experience a similar low control.

"Several" should, in this context, be taken to be 2-3m - quite enough distance to feel dramatic lurching from a static situation. The braking work by friction is therefore 0.3-0.6 * mg, i.e., about 600,000 N given the tank is 62 tons and gravity is Earthlike. We therefore would expect 180-360 kJ of kinetic energy initially on the tank, i.e., 2.4-3.4 m/s. And in those two sentences, I've provided better justification for estimating the sliding speed than given in that entire thread.

And here's what none of them bring up: If the tank is on uneven ground and not at the lowest point, we may deduct from this total the change in GPE. A simple altitude change of 30 cm could erase the need for the incoming shell to provide anything but the tiniest brief jolt of force needed to finish overcoming the strained coefficient of static friction.

It's an incident that Connor makes much of, but doesn't really mean much at all. And being much less specific than, say, the muzzle velocities discussed in the Imperial Armour series, should be considered less important in analysis.

[Dabat]

*It was caused by a self defense weapon for use against aquatic predaters, it was essentially a knife with a tube leading from near the tip to the handle, inside the handle was 300 grams of compressed air. If the hole it left in the shark was less than 30 cm across I will eat my shirt, headband or bra; your choice.

For reference, folks, 300g of compressed air will create a bubble larger than a human diver when it's near the surface - and you need less than 200g of water flashed into steam to create similar vapor pressures. Water has a lower molecular weight.

It's a little more dramatic when you inject the vapor rather than creating it on the surface going inward, but you learn something new every day. I didn't know divers carried something like that, but I can believe that one blew a hole that size in a shark.

Sorry for poofing in my last post. Sadly it seems now that one of my cats needs to be put to sleep. I'll finish the rest of that post later.

The knife is devestating, 1/10th of the tissue damage would be enough to cripple someone for life, and 1/2 is enough to pretty much gaurente death without advanced medical care, I am at work atm, so i am doing these figures in my head and they may be off, but, according to the fluff, the damage caused by 150-200 grams of vaporized water is what we should expect from a high powered las rifle shot, which fits rather well with the 19mJ power pack hypothisis. (If i did my numbers wrong, please let me know)

As to the knife, the weapon is not a new idea, but to my knowledge it only came into use recently, and there were some legal and ethical concerns which kept it from from being widely reported on. And, for the record, not all of those legal concerns were were from the knife's use on animals.

[Mr. Oragahn]

I'm unearthing this, but I noticed, in the very first post, that Roks... are shielded?

[User1350]

And Spock, Imperial tanks having armour incapable of taking 18mj is frankly ridiculous. How many 40k books have you read? For example, in "Honour Guard" a Leman Russ is slammed 6 metres sideways by a kinetic round (stated) which failed to penetrate (Its stated that the enemy tanks had the energy to penetrate but as they were mostly basic kinetic rounds, not SABOTs, they couldn't harm the Russes. A Vindicator round is stated to be "Hypersonic", too, and recoil isn't an issue because any race with fighters and ships capable of pulling multiple-hundred G turns (Double Eagle) is going to have some serious inertial damping technology, unless their ships can be crewed by the pink mush left of the crew members.

...

The most common effect of 40k plasma hand-weapons impacting on a human is total incineration (Too many occurrences to count) which is a multi-gigajoule feat. Plasma weapons aren't useless against tanks in 40k, but they normally need a lot of shots to weaken the armour of imperial tanks to penetrate (Chaos tanks are usually lower quality, Chaos Russes are actually very rare). Leman Russes are also very advanced. In most 40k literature (Which is highest canon, btw, the novels "Portray the best image of the universe" and codex fluff and rules are secondary.) we see Leman russes with auspexes, radar and thermal imaging systems as standard, with gyro-stablised weapons, targeting software and "Target discriminators". IG armour crews are also extremely well trained, apparently. I'd like to see any modern armour units preform the "Pincer" manure without a single case of friendly fire or crash.

EDIT: This is an empire 38,000 years in the future, containing at the very least a million worlds (Another aside: There are several references to being able to visit a world of the imperium every dar for a lifetime and not managing it [Wolfblade, Sabbat Martyr ], so in my opinion, it is likely that the "Million worlds" is just the major capital worlds. After all, the IOM has some serious terraforming technology, and there are 100 billion stars in the galaxy, most of which have at least one planet.). and ships capable of "Reducing continents to ashes". Its unlikely that our modern day tanks will be in the same ballpark as theirs.

It's not like 40k is "Over the top" either, people who think it is have obviously never heard of the Culture, Hyperions FORCE: Ground or the Xeeleeverse.

Generally 'Blown Across the Room' is not a useful method to calculate something.

Having read Double Eagle, I don't recall any 'multiple-hundred G turns'.

I also don't recall the core material becoming somehow secondary canon.

Any sensor is called Auspex. Not all Auspex are equal.

Being far in the future does not in itself make something more powerful.