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This came up in a different thread, relevant posts quoted below. I thought this was sufficient to spawn its own thread.

Firstly, I think Chaos warships have a firepower comparable to Imperial ones.

Here are the quotes:

Haighus wrote:

Aecus Decimus wrote:

 Haighus wrote:
Modern nuclear bunkers would require a direct nuclear hit to take out, and even then, I doubt it would be guaranteed.

Fortunately a mere nuke is trivial compared to 40k weapons. There are direct canon quotes that starship weapons are capable of destroying entire continents with a single salvo. The only possible issue is collateral damage, not a shortage of firepower. https://www.reddit.com/r/40kLore/comments/frggzr/naval_combat_range_and_firepower/

Now add shielding of a kind we know to be able to resist the scale of artillery found on warships (void shields)

If the fortification has so much shielding over such a wide area that it can survive a continent-destroying broadside from an orbiting warship then what exactly are marines going to do against it? Even titan weapons can't breach that level of shielding.

There will be damage, but the structural integrity and function of an installation will be unlikely to be harmed unless the marines or defenders are trying to harm it.

The concrete structure of a bunker may still be intact, the delicate computer systems are unlikely to survive marines firing automatic RPG launchers everywhere (on top of their heavy weapons). And nobody cares if you capture the concrete shell of a building when everything of value inside it is lost.

Also, the gaining intel from eating brains thing is absolutely canon, and has been for >30 years. One of the marine implants is explicitly for this purpose, and the initiation rites for many chapters involve eating corpses after this stage of implantation to celebrate and test the new skill.

It's stupid as hell and relies on GW having no idea how brains actually work. The only sensible thing to do is to reject it as non-canon nonsense.

That would require an absurd level of firepower, to destroy an entire cave system. Modern day nukes would likely struggle to, er, blow up mountains. Rock is pretty hard to blow up. 40k easily has the tech for some rebels to hermetically seal off deep portions of the cave to prevent them dying from the overpressure or the O2 beimg sucked out.

Every weapon in the battleship’s arsenal was prepared and oriented down at the surface; torpedo arrays filled with warshots that could atomise whole continents in a single strike, energy cannons capable of boiling off oceans, kinetic killers that could behead mountains through the brute force of their impact. This was only the power of the ship itself; then there was the minor fleet of auxiliary craft aboard it, wings of fighters and bombers that could come screaming down into Dagonet’s atmosphere on plumes of white fire. Swift death bringers that could raze cities, burn nations.
-Nemesis

or

A mighty Repulsive-class Grand Cruiser with powerful reactors and heavy armour in sloping facets of adamantine and ceramite scores of metres thick, the vessel carried a weight of armament and ordnance that could reduce a continent to ruins with a single salvo.
-Black Crusade

A mere cave is no issue at all.

I am pretty confident that the above BL quotes are hyberbole. The same Repulsive-class grand cruiser, with a single broadside, struggles to destroy a stationary, unshielded Imperial cruiser hull at point-blank range. An Imperial cruiser is 5km long, and only about 500m thick along much of it's length. Yet, we are supposed to believe that the same firepower is capable of devastating a continent? Australia is the smallest continent on Earth, and the majority of it (Australia proper) is 4000km wide. Nearly a thousand times longer than an Imperial cruiser, which can survive the firepower of a Repulsive cruiser without shields (although likely heavily crippled).

It really doesn't add up.

Also, void shields don't block everything- attack craft attacks somehow circumvent them, for example. A person can walk through a void shield, but couldn't shoot a laspistol through one. It isn't clear at what velocity the shield kicks in and blocks a given attack.

BobtheInquisitor wrote:BFG established torpedoes to have hundreds of gigaton yields. Further sources continued using high-end weapon yields fitting in the era of the Star Wars Incredible Cross Sections “Biggatons” firepower calculations. These numbers are consistent among many sources from the time, back when Warhammer 40k lore was consistent and more thought-out.

You don’t have to take my word for it. People have already gathered and collated all the references, and they show their math:

http://bbs.stardestroyer.net/viewtopic.php?p=2092582


Automatically Appended Next Post:
Even more:

http://bbs.stardestroyer.net/viewtopic.php?f=4&t=123079


Automatically Appended Next Post:
The second one is an even better source since it links to various specific source analyses.

I have spent some time over the last few days picking through those links. I firmly disagree that the figures are "more consistent", and it appears to me that they fall into two broad camps. Both involve devastating firepower, but one is several orders of magnitude higher.

The lower level is that capital ships have the firepower to glass cities and destroy emplaced defenses buried hundreds of metres deep with sustained firepower. This is supported by sources like Execution Hour and the BFG rules (where ground defenses are tough but will be destroyed by sufficient firepower). The gigaton yield on torpedos is consistent with this level of firepower.

The step up is the kind of firepower in the above quote, and most famously in Caves of Ice. This is firepower that can destroy continents and make worlds uninhabitable to humans in a salvo or two. Making a planet uninhabitable in particular requires enormous amounts of energy to be dumped into the planet.

The difference is the timespan- sustained bombardment vs one or two salvos. This could be explained by differences between cruisers, grand cruisers, and battleships, but I don't think BFG supports this with some cruiser variants having a short-ranged firepower equivalent to battleships. The primary advantage of battleship-grade weaponry seems to be the ability to project that firepower effectively over much longer ranges.

I personally think the lower level of firepower, whilst still devastating, is the kind supported by the lore and games more, because orbital bombardment is a common device in the setting. It allows weapons to be used at an operational or even tactical level, which the higher yields do not- you cannot have a field army if the planet will be made uninhabitable following a couple of lance strikes. The latter also makes most exterminatus-grade weapons* pointless- they offer very little over simply firing a few volleys of standard void weaponry, and avoid sacrificing those weapons. I'd also be inclined to treat Commissar Cain (Caves of Ice) as an unreliable narrator on warship power, but he isn't alone in that grade of assessment.

Having a level where warships are terrifyingly powerful, able to destroy any structure on a planet given sufficient time, but not so powerful that they cannot support ground armies or to invalidate the class of weaponry designed to kill planets, makes most sense to me. I'd personally put the higher firepower levels down to wifely believed propaganda.

However, clearly both perspectives have support in the background. What do others think?

*Weapons like virus bombs, that destroy the biosphere but not the fabric of the planet. The weapons that can do the latter are rare and apparently beyond the capabilities of the Imperium to reproduce, like fully-functional cyclonic missiles.

I’d agree the lower powered representations are more accurate.

After all, vast as The Imperium is, actually destroying planets remains a rare and very final sanction. I mean….what point Exterminatus if every bombardment is a de facto Exterminatus, because it shatters a continent, and the environmental impact that will bring with it,

As for Imperial and Chaos cruisers? It might help to keep in mind Chaos Crusiers were once Imperial Cruisers, just from a different time, suited to a different tactical view.

Now, how much of the shift that lead to the modern (as such things can be measured in the setting) Imperial Fleet is precisely because they’d now be going up against Traitor Ships? Good debate to be had there.

Though…..is there anything in the background to suggest, confirm or deny variable yields from shipboard weapons?

If memory serves, most shipboard weapons are plasma based. So it does seem they may be able to moderate the yield. In a space battle? Ramp it up. When targeting ground based targets, only dial it up to the desirable yield?

In fact, I’d say that probably makes the most sense, overall. As per the video I shared (but cannot vouch for the accuracy of) which explains how Nukes act differently in and out of atmosphere? Ships may carry much smaller yield torpedoes or warheads for planetside strikes, with the Really Effing Big Ones being used solely for space?

 Mad Doc Grotsnik wrote:
I’d agree the lower powered representations are more accurate.

After all, vast as The Imperium is, actually destroying planets remains a rare and very final sanction. I mean….what point Exterminatus if every bombardment is a de facto Exterminatus, because it shatters a continent, and the environmental impact that will bring with it,

As for Imperial and Chaos cruisers? It might help to keep in mind Chaos Crusiers were once Imperial Cruisers, just from a different time, suited to a different tactical view.

Now, how much of the shift that lead to the modern (as such things can be measured in the setting) Imperial Fleet is precisely because they’d now be going up against Traitor Ships? Good debate to be had there.

Though…..is there anything in the background to suggest, confirm or deny variable yields from shipboard weapons?

If memory serves, most shipboard weapons are plasma based. So it does seem they may be able to moderate the yield. In a space battle? Ramp it up. When targeting ground based targets, only dial it up to the desirable yield?

In fact, I’d say that probably makes the most sense, overall. As per the video I shared (but cannot vouch for the accuracy of) which explains how Nukes act differently in and out of atmosphere? Ships may carry much smaller yield torpedoes or warheads for planetside strikes, with the Really Effing Big Ones being used solely for space?

Variable yield is one way of squaring the circle.

I think there is some support for this for Astartes bombardment cannons, at least.

Lower estimates of firepower are correct.

I cite as evidence from the 13th Black Crusade book from BL, which described the destruction of the penal planet St. Josmane's Hope (which is still described as destroyed even with the latest version of the background fluff). The Imperium ended up having to send a strike team to overload the generator grid to destroy the planet in a timely manner, as ships equipped for Exterminatus were not available in a quick enough time frame and sustained bombardment by multiple Imperial Navy Nova Cannons would have taken too long. Nova Cannons are at the upper end of standard Imperial Navy weaponry yet even they would have required long sustained bombardment to destroy the planet. That points to a lower total firepower than excessive hyperbolic claims.

Imperial ship batteries are a range of weapon types that are aggregated in BFG. The background description of the Murder class cruiser which was the mainstay of Battlefleet Obscurus before being replaced by the Lunar class was described as having some of the best plasma cannon batteries ever produced by the Mechanicus. These were firepower 10 range 45cm batteries in BFG rule terms. The Tyrant class cruiser has batteries of 4 firepower 45cm range and firepower 6 30cm range, and is described as having rediscovered "superfired" plasma weaponry therefore the range 45cm weapon batteries are these plasma batteries. It would therefore be reasonable to conclude that a considerable portion of the firepower value of weapon batteries in Imperial warships come from plasma weapons. The artwork and stories are fond of depicting loading of massive shells into batteries by chain gang or the like. These can still be true as there are many guns of varying size depicted on the broadside of an Imperial warship, so those "macro cannon" batteries may be some of those other smaller guns that make up a smaller fraction of the total firepower value.

 Mad Doc Grotsnik wrote:
I’d agree the lower powered representations are more accurate.
As for Imperial and Chaos cruisers? It might help to keep in mind Chaos Crusiers were once Imperial Cruisers, just from a different time, suited to a different tactical view.

Now, how much of the shift that lead to the modern (as such things can be measured in the setting) Imperial Fleet is precisely because they’d now be going up against Traitor Ships? Good debate to be had there.

The BFG rulebook gives a good sense of why the shift happened and it has more to do with technological decline than trying to tailor against traitor ships. The Imperium's shipbuilding technology is declining gradually over time. We can see this again in the Murder class vs. Tyrant class. The Murder was built between M33 and M37. The Tyrant dates from M39, but can reach the 45cm range with only 4 firepower whereas the Murder does 45cm with 10 firepower. The Murder is also faster and has 2 prow lances.

In short, the Imperium relied more and more on the school of design that settled for slapping on slabs of armor for an armored prow and using the lower tech torpedo weapon systems as it became harder to construct the older ships. The older ships were faster, had longer range weaponry in greater numbers, and had more high energy lance weaponry. Later Imperial designs can at best only partially match the performance.

The same can be seen in the battleships. The old Desolator battleship has 60cm lances in its broadside weapon mounts and is fast for a battleship. The Apocalypse also has lances but is slower and has an armored prow. Its lances are normally 30cm with the option to boost to 60cm at the cost of a critical hit to itself as power relays burn out under the strain.

Rules wise you have Rogue Trader which had stats for a Macro Cannon and Defence Laser. Ships mount multiple batteries of them. Further cyclone missile launchers were adapted from the short range point defence weapons used by warships against attacking fighter craft.

The BFG rulebook has a gunnery captains log of shooting targets planetside in support of ground operations. It was clearly based on WW2 battleship fire support logs.

Epic had actual starship/ground forces interaction. A spaceship could make a pass over the battlefield and then be out of position to the extent they could do it only once.

A lunar class cruiser could deliver a lance strike that did 'titan killer' (no save allowed) damage that hit on a 2+and would destroy (if it hit) a superheavy like a baneblade or unshielded warhound titan roughly 44% of the time, and break (a morale failure from coming under heavy fire that means the unit loses its turn(s) and isn't much use for anything) a further 39% of the time. So be destroyed or knocked out of the fight 82% of the time if hit.

The broadside was a 'macro' attack so any troops hit wouldn't get a save unless they had heavily reinforced armour - and that armour would lose part of their save (so no save for marines or hammerheads, a superheavy would get one 4+ save rather than a 4+ save with a re-roll). It would use a blast template with a diameter of 12cm which is enough to roughly cover a 40k game. Bigger or better ships like marine strike craft would get a 2nd or 3rd template.

Iracundus wrote:
Lower estimates of firepower are correct.

I cite as evidence from the 13th Black Crusade book from BL, which described the destruction of the penal planet St. Josmane's Hope (which is still described as destroyed even with the latest version of the background fluff). The Imperium ended up having to send a strike team to overload the generator grid to destroy the planet in a timely manner, as ships equipped for Exterminatus were not available in a quick enough time frame and sustained bombardment by multiple Imperial Navy Nova Cannons would have taken too long. Nova Cannons are at the upper end of standard Imperial Navy weaponry yet even they would have required long sustained bombardment to destroy the planet. That points to a lower total firepower than excessive hyperbolic claims.

Imperial ship batteries are a range of weapon types that are aggregated in BFG. The background description of the Murder class cruiser which was the mainstay of Battlefleet Obscurus before being replaced by the Lunar class was described as having some of the best plasma cannon batteries ever produced by the Mechanicus. These were firepower 10 range 45cm batteries in BFG rule terms. The Tyrant class cruiser has batteries of 4 firepower 45cm range and firepower 6 30cm range, and is described as having rediscovered "superfired" plasma weaponry therefore the range 45cm weapon batteries are these plasma batteries. It would therefore be reasonable to conclude that a considerable portion of the firepower value of weapon batteries in Imperial warships come from plasma weapons. The artwork and stories are fond of depicting loading of massive shells into batteries by chain gang or the like. These can still be true as there are many guns of varying size depicted on the broadside of an Imperial warship, so those "macro cannon" batteries may be some of those other smaller guns that make up a smaller fraction of the total firepower value.

I suspect plasma batteries are rarer to be honest, the shipyards likely to be able to produce plasma weaponry are probably restricted to the more advanced worlds, particularly forge worlds. I suspect laser batteries to be the most common, we know the Sword class uses these and they are very reliable (like much Imperial laser tech). I certainly doubt that a Lunar class built over a feral world would have plasma weaponry, but that was an exceptional case. I also suspect that individual ships typically have the same kind of weapon battery across the ship, with the BFG quote refereing to the variety across ships, not within a particular ship. However, we do have some old (John Blanche?) artwork showing a battery of what appears to be a mix of plasma and macrocannon weaponry.

Of course, there isn't any lore to confirm this at present, and the unique nature of each individual ship means there will be a huge amount of variety.

 Mad Doc Grotsnik wrote:
I’d agree the lower powered representations are more accurate.
As for Imperial and Chaos cruisers? It might help to keep in mind Chaos Crusiers were once Imperial Cruisers, just from a different time, suited to a different tactical view.

Now, how much of the shift that lead to the modern (as such things can be measured in the setting) Imperial Fleet is precisely because they’d now be going up against Traitor Ships? Good debate to be had there.

The BFG rulebook gives a good sense of why the shift happened and it has more to do with technological decline than trying to tailor against traitor ships. The Imperium's shipbuilding technology is declining gradually over time. We can see this again in the Murder class vs. Tyrant class. The Murder was built between M33 and M37. The Tyrant dates from M39, but can reach the 45cm range with only 4 firepower whereas the Murder does 45cm with 10 firepower. The Murder is also faster and has 2 prow lances.

In short, the Imperium relied more and more on the school of design that settled for slapping on slabs of armor for an armored prow and using the lower tech torpedo weapon systems as it became harder to construct the older ships. The older ships were faster, had longer range weaponry in greater numbers, and had more high energy lance weaponry. Later Imperial designs can at best only partially match the performance.

The same can be seen in the battleships. The old Desolator battleship has 60cm lances in its broadside weapon mounts and is fast for a battleship. The Apocalypse also has lances but is slower and has an armored prow. Its lances are normally 30cm with the option to boost to 60cm at the cost of a critical hit to itself as power relays burn out under the strain.

I think this is generally the case, although a lot of the current classes used by the Imperial Navy were in use in the Great Crusade, suggesting they were still useful then (perhaps with better tech- I suspect Apocalypse battleships did not always have the power relay issues, but the Imperium has lost the ability to create/maintain the relays necessary for peak performance). The Emperor class in particular seems to maintain tech equivalent to older ships.

The Emperor class actually doesn't really as it was never high tech in the same way as the Desolator. The Emperor class is painfully slow, so it doesn't have high output battleship sized engines. Its guns are all weapon batteries rather than lances. Launch bays are not particularly high tech. The sensor studded prow may be argued to be high tech or it may simply be a matter of quantity of additional sensors.

The Emperor class and the Retribution are both part of the lower tech solidly reliable school of design, whereas many of the Chaos ships were of the school of design that favored speed and long range lance weapons. The higher tech school has fallen out of favor as the Imperium's technology has declined.

The Imperium cannot fully match these old designs, but can partially match. For example, Murder class cruisers have 60cm firepower 10 weapon batteries. The Imperium currently can get 60cm range weapon batteries only with battlecruisers and battleships, with cruisers limited to generally at best 45cm. The Overlord class battlecruiser getting the range but only firepower 8. The Imperium can get a few 60cm lances, again in battlecruiser or larger classes, but they are generally dorsal lances meaning overall there are fewer of them. In all of these examples, the Imperium has to give up some area of performance: range, total firepower/quantity of lances, or the ship size in which they can match performance.

Well, I was wrong about them being consistent. However, in my defense, at the time and in comparison to televised Sci Fi like SW, ST, B5 and SG1, they were very consistent if differing examples varied by only three or four orders of magnitude.

I tend to favor the higher numbers out of personal taste and the increasing scale of lethality that renders individuals not to be missed. Asking why they need exterminatus weapons when they can hard-exterminatus is similar to asking why the Empire needed a Death Star in the days of the (G?) canon Base Delta Zero—some targets are too well defended or need to be destroyed too quickly for more conventional weapons. And there’s a big difference between melting a few feet of exposed crust and completely annihilating a whole planet, especially if said planet has extensive subterranean structure.

The HH book A Thousand Sons has “conventional” firepower vaporizing much of Prsopero’s oceans, yet city shields and super-material buildings allowed an army to survive.

WRT modern Imperial ship technology I always got the sense from BFG that they were essentially following the lasgun doctrine.

I.e. prioritising cost, reliability and logistics over pure damage output so they can afford to equip a larger fleet and have it operate more autonomously.

The older ships used by Chaos seem to prioritise power and range, however the BFG lore (though not so much the rules) seems to stress they are unreliable in various ways and obviously the older ones date from the height of the Imperium’s power when cost and reliability was maybe less of an issue (look at the wacky stuff the Legions had vs now). This is perhaps somewhat dissonant with the rag tag nature Chaos fleets are described as being though - maybe they just keep them going with warp magic…

Lord Zarkov wrote:
WRT modern Imperial ship technology I always got the sense from BFG that they were essentially following the lasgun doctrine.

I.e. prioritising cost, reliability and logistics over pure damage output so they can afford to equip a larger fleet and have it operate more autonomously.

The older ships used by Chaos seem to prioritise power and range, however the BFG lore (though not so much the rules) seems to stress they are unreliable in various ways and obviously the older ones date from the height of the Imperium’s power when cost and reliability was maybe less of an issue (look at the wacky stuff the Legions had vs now). This is perhaps somewhat dissonant with the rag tag nature Chaos fleets are described as being though - maybe they just keep them going with warp magic…

I agree but I don't think the Imperium had a choice in the matter as their technology degraded. The Imperial ship designs with their torpedoes are reliant on regular resupply. The older designs are capable of more independent operations as lances draw on the ship's reactor and thus don't run out of ammo.

As for the maintenance issue, I think it more a matter of scale. Maintaining smaller numbers might be doable for the Dark Mechanicum, and for the Imperium too which still has some of these designs mothballed in reserve fleets, however over time the Imperium was no longer able to do so on a large scale if these designs were the mainstay of the fleet.

Iracundus wrote:
The Emperor class actually doesn't really as it was never high tech in the same way as the Desolator. The Emperor class is painfully slow, so it doesn't have high output battleship sized engines. Its guns are all weapon batteries rather than lances. Launch bays are not particularly high tech. The sensor studded prow may be argued to be high tech or it may simply be a matter of quantity of additional sensors.

The Emperor class and the Retribution are both part of the lower tech solidly reliable school of design, whereas many of the Chaos ships were of the school of design that favored speed and long range lance weapons. The higher tech school has fallen out of favor as the Imperium's technology has declined.

The Imperium cannot fully match these old designs, but can partially match. For example, Murder class cruisers have 60cm firepower 10 weapon batteries. The Imperium currently can get 60cm range weapon batteries only with battlecruisers and battleships, with cruisers limited to generally at best 45cm. The Overlord class battlecruiser getting the range but only firepower 8. The Imperium can get a few 60cm lances, again in battlecruiser or larger classes, but they are generally dorsal lances meaning overall there are fewer of them. In all of these examples, the Imperium has to give up some area of performance: range, total firepower/quantity of lances, or the ship size in which they can match performance.

I agree in general, but it is clear the Imperium has retained a lot of tech, but in a patchy way. Interestingly, looking at the Armageddon class and Apocalypse class, it appears power relays are a particular shortcoming. This, alongside engines, could be the chief areas the Imperium has lost knowledge in. The Apocalypse in particular appears to have been a vastly more capable design 10,000 years prior, before the power relays deteriorated and prevented sustained long-ranged lance fire.

I do think you are selling the Emperor a bit short. I'm not convinced weapon batteries are less advanced than lances just for being weapons batteries. Each have their advantages and disadvantages. The Emperor has a surprisingly heavy weight of very long-ranged weapons batteries, they appear to be very advanced designs that the Imperium has retained the capability of producing in the limited quantities needed for battleships. They have capabilities superior to the Murder class (which has 45cm range batteries) without sacrificing launch capacity. The ship is slow, so I suspect the trade-off is directing more power into guns rather than engines, with maneouvrability being less critical for carriers as attack craft are the longest ranged weapons system in 40k. In addition, the command and control capability needed for controlling squadrons across a solar system is going to require a lot of tech, Emperor's perform this well. On the other hand, the BFG rules are written with the two Emperor class ships in the Gothic fleet in mind, and those were both ancient vessels, one had been in service from the time Murder class ships were common, and the other was a salvaged pre-Imperial vessel. You could expect them to be more advanced.




Automatically Appended Next Post:

 BobtheInquisitor wrote:
Well, I was wrong about them being consistent. However, in my defense, at the time and in comparison to televised Sci Fi like SW, ST, B5 and SG1, they were very consistent if differing examples varied by only three or four orders of magnitude.

I tend to favor the higher numbers out of personal taste and the increasing scale of lethality that renders individuals not to be missed. Asking why they need exterminatus weapons when they can hard-exterminatus is similar to asking why the Empire needed a Death Star in the days of the (G?) canon Base Delta Zero—some targets are too well defended or need to be destroyed too quickly for more conventional weapons. And there’s a big difference between melting a few feet of exposed crust and completely annihilating a whole planet, especially if said planet has extensive subterranean structure.

The HH book A Thousand Sons has “conventional” firepower vaporizing much of Prsopero’s oceans, yet city shields and super-material buildings allowed an army to survive.

Exterminatus weapons are rarely immediately available though, and very few available to the Imperium can actually destroy the entire planet rather than just the biosphere. I am only aware of Cyclonic missiles being able to totally destroy a planet, and the full-power version capable of this is supposed to be an irreplaceable relic of the Dark Age of Technology, with the Imperium's stockpile dwindling.

Other Exterminatus weapons merely destroy the biosphere, but leave an intact celestial body (that can theoretically be set foot upon in the future, although with sufficient environmental protections). Virus bombs fall into this category, and we know these have limitations- hardened fortifications provide protection from virus bombing, as seen on Istvaan and Tallarn. Cyrene is a planet that can be deployed onto following Exterminatus (via unknown means). These weapons seem pointless to wait for if a handful of battleships can achieve the same thing before the Exterminatus even arrives in system.

You can read across directly (sort of) using the Rogue Trader RPG, which has a bit more detail on the specific weapons carried by imperial (and ex imperial) designs.

Specifically, the Hades-class Heavy Cruiser is described as using broadsides of Deathstrike missiles. Obviously it's firing a LOT of them, because it's over 5km long so its gun decks are the equivalent of a sizable guard artillery regiment, but the individual 'shots' are weapons that you can comprehend in 40k scale.

@Haighus. You make a strong argument. One last reservation I had was that I figured an inquisitor could more easily call in one fast ship with a special weapon than a whole flotilla, whereas a navy Admiral or crusade Warmaster might arrange a conventional bombardment more easily.

I also had the impression that, while cyclonic torpedoes were rare, virus bombs were much more ubiquitous, and cheaper to deploy than several volleys from a ship of the line.

The 610 gigaton torpedoes from Space Hulk are one of the few yields directly spelled out. I don’t know how many volleys of such torpedoes it would take to wreck a biome, but I assume not many. Wouldn’t one of those torpedoes be almost a thousand times more destructive than the entire nuclear armament of present day Earth? Is that consistent with the lower yields interpretation?

 BobtheInquisitor wrote:
@Haighus. You make a strong argument. One last reservation I had was that I figured an inquisitor could more easily call in one fast ship with a special weapon than a whole flotilla, whereas a navy Admiral or crusade Warmaster might arrange a conventional bombardment more easily.

I also had the impression that, while cyclonic torpedoes were rare, virus bombs were much more ubiquitous, and cheaper to deploy than several volleys from a ship of the line.

The 610 gigaton torpedoes from Space Hulk are one of the few yields directly spelled out. I don’t know how many volleys of such torpedoes it would take to wreck a biome, but I assume not many. Wouldn’t one of those torpedoes be almost a thousand times more destructive than the entire nuclear armament of present day Earth? Is that consistent with the lower yields interpretation?

well, the Chicxulub asteroid strike, that killed about 75% of all life on earth (including the dinosaurs), is estimated at about 100,000 Gigatons TNT equivalent. Yellowstone's last eruption Was about 800-900 Gigatons, and that happened about 640,000 years ago and is not associated with a mass extinction event, though most of the continental united states was likely buried in ash form it.

the current combined nuclear arsenal of every nuke on earth today is about 1.5 gigatons.


so a 600 gigaton event on the planets surface is biome devastating (at least in the short term up to maybe a century or two), but such an event, or even a spread of 5-6, would not be a long term gobal killer. actual biome destruction on the scale needed to render a planet uninhabitable (on the hundreds to low thousands of years scale) would either require dozens of such impacts or access to MUCH more powerful weaponry.

Ah, thanks. That is a perspective I was lacking.

xerxeskingofking wrote:

 BobtheInquisitor wrote:
@Haighus. You make a strong argument. One last reservation I had was that I figured an inquisitor could more easily call in one fast ship with a special weapon than a whole flotilla, whereas a navy Admiral or crusade Warmaster might arrange a conventional bombardment more easily.

I also had the impression that, while cyclonic torpedoes were rare, virus bombs were much more ubiquitous, and cheaper to deploy than several volleys from a ship of the line.

The 610 gigaton torpedoes from Space Hulk are one of the few yields directly spelled out. I don’t know how many volleys of such torpedoes it would take to wreck a biome, but I assume not many. Wouldn’t one of those torpedoes be almost a thousand times more destructive than the entire nuclear armament of present day Earth? Is that consistent with the lower yields interpretation?

well, the Chicxulub asteroid strike, that killed about 75% of all life on earth (including the dinosaurs), is estimated at about 100,000 Gigatons TNT equivalent. Yellowstone's last eruption Was about 800-900 Gigatons, and that happened about 640,000 years ago and is not associated with a mass extinction event, though most of the continental united states was likely buried in ash form it.

the current combined nuclear arsenal of every nuke on earth today is about 1.5 gigatons.


so a 600 gigaton event on the planets surface is biome devastating (at least in the short term up to maybe a century or two), but such an event, or even a spread of 5-6, would not be a long term gobal killer. actual biome destruction on the scale needed to render a planet uninhabitable (on the hundreds to low thousands of years scale) would either require dozens of such impacts or access to MUCH more powerful weaponry.

This seems about right. I think there is also the question of how dense the energy is deployed for the immediate devastation (although the total energy does matter for things like heating the planet). I think that with modern nuclear weapons, for example, the yield is deliberately reduced per warhead in order to achieve a greater coverage via MIRV and hit more targets. A single large warhead is not needed for most targets. I think the local effects are likely to be very different between 10 five-megaton warheads and 1 fifty megaton warhead (like the Tsar bomba), unless the former all landed very close together. This is likely to have an effect on the amount of debris distributed into the area and atmosphere (a nuclear winter is very unlikely with current nuclear weapons, I don't know if that holds at weapons with a thousand times the payload!).

The torpedo figure was, IIRC, 110 five-gigaton warheads in one torpedo. That is likely to respond differently to one big 550 gigaton torpedo in effect (other torpedos may be more unified though- the BFG rulebook suggests the plasma drive is a major component of the payload, which suggests most torpedos have one big drive, rather than splitting into MIRVs with many little drives).

I wonder if there is a calculator for this. Maybe a question for What if?

How a torpedo acts varies, as no doubt there are different designs and different sizes. Some do split into multiple MIRV-like warheads as described in the BFG rulebook, p. 78, with each torpedo splitting into 12 smaller warheads. Smaller torpedoes might act like a single warhead. The Cobra class destroyer model has 2 torpedo tubes on each side of its prow, but in game rules its torpedo weapon system is "2 torpedoes", suggesting that each of those small tubes is 1/2 a torpedo marker, whereas the Lunar cruiser sized torpedoes seem to correspond 1:1 to a torpedo marker each.

All this talk reminds me of the fact that rocks are not free.

https://wh40k.lexicanum.com/wiki/Rocks_Are_Not_Free!

It doesn’t go into details of how big an asteroid we want to push down a gravity well, but does let us know that you can get similar results from 5 manga-melta warheads.

That's an ace autocorrect

Iracundus wrote:
How a torpedo acts varies, as no doubt there are different designs and different sizes. Some do split into multiple MIRV-like warheads as described in the BFG rulebook, p. 78, with each torpedo splitting into 12 smaller warheads. Smaller torpedoes might act like a single warhead. The Cobra class destroyer model has 2 torpedo tubes on each side of its prow, but in game rules its torpedo weapon system is "2 torpedoes", suggesting that each of those small tubes is 1/2 a torpedo marker, whereas the Lunar cruiser sized torpedoes seem to correspond 1:1 to a torpedo marker each.

I've now read that quote on pg78. It describes an action from a squadron of destroyers (presumably Cobra class) destroying a Chaos cruiser, so the 12-split MIRV* torpedos are the smaller destoyer ones! Comparing the the 110 warhead torpedo (I need to track down the original source for this, something to do with Space Hulk), that would suggest that 24 Cobra warheads (splitting from two torpedos) is broadly equivalent to 110 five gigaton warheads from this other design, implying about 20 gigatons per warhead for a Cobra (obviously the warhead is unlikely to be nuclear based on common Imperial weapons).

*I suppose they should just be MIV, as there is no need for re-entry.

Currently re-reading Eisenhorn. The following occurs at the end of Chapter 12 of Xenos (I'm reading the ebook so won't bother with page numbers). Spoilered for those who have not read it.



So an escort is able to precisely destroy a large structure from a range in the ballpark of 30000km-40000km if in a true geosynchronous orbit (we don't know the gravity of the planet, but it seems to be similar to Earth). It may be closer, but using its engines to maintain a functionally geosynchronous orbit. Impossible to tell, but BFG suggests ships need to be fairly close to accurately target ground installations, so the Defence of Stalinvast may be operating closer and engaging its engines.

The wording suggests it took more than one shot. This may be multiple shots from each weapon, or may just mean several weapons fired once each at the same target (a battery needing more than one weapon to be a battery). I suspect the latter.

Lances are not common weapons for escorts, so I wonder if the "Light Intruder" class actually refers to a type of monitor, which are typically very heavily armed at the expense of warp drives and speed.

This seems to be incredibly precise firepower, and very contained- it was done in tactical support of a concurrent ground assault without noted risk to the elite units going in alongside the strike.

Lance strikes have always been the orbit-to-surface precision weapon of choice: for several editions the tabletop orbital strike that astartes get was explicitly a lance strike, and in epic 'pin-point strikes' that could hit superheavy tanks and titans without massive Collateral Damage were also lances (where conventional batteries use a 5" template on an epic scale board)

locarno24 wrote:
Lance strikes have always been the orbit-to-surface precision weapon of choice: for several editions the tabletop orbital strike that astartes get was explicitly a lance strike, and in epic 'pin-point strikes' that could hit superheavy tanks and titans without massive Collateral Damage were also lances (where conventional batteries use a 5" template on an epic scale board)

It is interesting in comparison to descriptions of lances being capable of destroying mountains in a couple of volleys, which could be plenty precise but would have wiped out the entire estate in the above example, and is pretty useless as a tactical support weapon.

 Haighus wrote:

locarno24 wrote:
Lance strikes have always been the orbit-to-surface precision weapon of choice: for several editions the tabletop orbital strike that astartes get was explicitly a lance strike, and in epic 'pin-point strikes' that could hit superheavy tanks and titans without massive Collateral Damage were also lances (where conventional batteries use a 5" template on an epic scale board)

It is interesting in comparison to descriptions of lances being capable of destroying mountains in a couple of volleys, which could be plenty precise but would have wiped out the entire estate in the above example, and is pretty useless as a tactical support weapon.

They might have different firing modes? A low powered tac support shot (which also might be useful when intercepting fighters or taking out light unshielded targets) and a sustained fire mode for leveling mountains/dropping void shields.

Much like in Rouge One where the Death Star fires the main gun on one reactor’s power, which is enough to level a small city, vs. in Ep. IV where it’s turning planets into asteroid fields.

Probably. If you look at a capital ship Lance turret in Batlefleet gothic, something that's a strength 1 battery in game is usually a multi barrel turret.

Firing a single barrel at low power through atmosphere is probably a 40k 'orbital strike' whilst firing the full turret would be the 40k rpg 'lance strike' - which was basically a lascannon with a 500m blast.....


Automatically Appended Next Post:

Firing only some barrels from a lance battery to adjust yield is a practical and logical strategy. However, there is quite a difference between a hangar block and a mountain in scale, so I don't think that bridges the entire gap.

Having read further into Eisenhorn, the Defense of Stalinvast is warp-capable and not a monitor. It is probably similar to a Firestorm class, which has a single lance barrel.

 Haighus wrote:

Iracundus wrote:
How a torpedo acts varies, as no doubt there are different designs and different sizes. Some do split into multiple MIRV-like warheads as described in the BFG rulebook, p. 78, with each torpedo splitting into 12 smaller warheads. Smaller torpedoes might act like a single warhead. The Cobra class destroyer model has 2 torpedo tubes on each side of its prow, but in game rules its torpedo weapon system is "2 torpedoes", suggesting that each of those small tubes is 1/2 a torpedo marker, whereas the Lunar cruiser sized torpedoes seem to correspond 1:1 to a torpedo marker each.

I've now read that quote on pg78. It describes an action from a squadron of destroyers (presumably Cobra class) destroying a Chaos cruiser, so the 12-split MIRV* torpedos are the smaller destoyer ones! Comparing the the 110 warhead torpedo (I need to track down the original source for this, something to do with Space Hulk), that would suggest that 24 Cobra warheads (splitting from two torpedos) is broadly equivalent to 110 five gigaton warheads from this other design, implying about 20 gigatons per warhead for a Cobra (obviously the warhead is unlikely to be nuclear based on common Imperial weapons).

*I suppose they should just be MIV, as there is no need for re-entry.

I've done some digging. As far as I can tell, the gigaton-yield torpedo refers to "hellfire missiles", of which over a hundred are carried by a single Gothic class battlecruiser. This is from the Sin of Damnation mission book for Space Hulk first edition, in 1989, actually two years before Space Fleet was released. I think the Gothic class was subtly retconned to battleship for Space Fleet. Gothic classes since BFG are a cruiser vessel that is quite different to the Space Fleet vessel. In addition, the Sin of Damnation background has been retconned, going from 3 Imperial Gothic class battlecruisers supporting the Blood Angels to being BA strike cruisers.

As such, the canonicity of the 112 five-gigaton warhead missiles in current 40k lore is somewhat dubious, and torpedo yields may be lower than that. 40k canon being what it is, either interpretation is open to being "correct".

Real life wise, it's almost comically easy to destroy all life on a planet for any species that has the intelligence and ability to casually do interstellar travel. Heck, a single large enough vessel going the right angle at the right speed to collect radioactive particles on its hull then stopping could irradiate an entire planet.

As for nuclear and other large yield weapons, assuming the planet is Earthlike in make up and atmospheric conditions, anything over 40 megatons or so is a waste, as the excess energy gets blasted into space. However, having larger yields would make sense in a setting where point defense is low range or inaccurate--having larger yields mean even near misses can generate appreciable damage.

From what I understand, BFG tries to be somewhat true to what actual space combat would be like in that ships aren't slugging it out in visual range but across vast distances and use weapons and tactics to dictate that. Ships can often be massive enough to keep fighting even after taking critical damage, and ships can often break away from unfavorable engagements, especially the larger ships.

As for fleet support, there's a few wrinkles with it comes to indiscriminate bombardment. First, space based weapons in 40k tend to do permanent damage to the planet, and the planet is the thing that whatever factions are fighting over (or at least something on the planet). Chaos on a slave raid don't want their potential captives to be wiped out, the Imperium doesn't want to render a planet useless and unable to tithe, etc.

Larger and more important worlds tend to have ground based defenses that can withstand bombardment or shoe off anything but capital ships, and no one really wants to risk a golden bee-bee taking out an expensive vessel.

Lastly, it's more than likely that in any 'real' scenario where you'd see the kind of forces players put on tabletop, those conflicts would include fleet elements which are most likely busy blasting each other in orbit.

Battlefleet Gothica Armada 1 and 2 are probably close to how Chaos and Imperium ships would interact, if the scale were expanded out.

 Haighus wrote:

Lances are not common weapons for escorts, so I wonder if the "Light Intruder" class actually refers to a type of monitor, which are typically very heavily armed at the expense of warp drives and speed.

Firestorm-class Frigate has a lance.