40K firepower analysis 1 (pdf)

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40K firepower analysis 1 (pdf)

Post by User15046 » Sun Nov 11, 2012 7:54 pm

Didn’t know to put this here or In the other websites, but for now ‘other analysis’ seems more appropriate.
Thanks for the warm welcome on the introductory page  I have moved away from the website idea for a little while, and decided to do my analysis in word documents first due to some heavy set backs on my site (disappearing paragraphs, needed something more robust). I might make the website more of a technical encyclopaedia based on the documents or something later.
Anyway, here is the first document, naval firepower!
I approach from several angles (kinetic energy, ramming, and case studies) to derive the magnitude I believe to be most plausible for 40K capital firepower. Rather than spanning several orders of magnitude or being completely ‘up in the air’ as some people like to keep it.

Doc can be found via the url:
https://www.dropbox.com/s/y4y8qttmp0lo4 ... 20Navy.pdf

I will update these documents as and when I can. This current document still needs more sources, such as fusion based warheads being used (cant find my edition of space hulk) or mentioned. I like each block of text to be followed by quotes.
Also gonna add torpedoes eventually, couldn’t find Connor’s page where he discusses possible masses for torpedoes, though it was thousands of tons iirc… and would need to be considering the heavy macro-shells.
Feedback and / or quotes more than welcome. It isn’t proof read, so any amendments there are also appreciated. Let me know what you think.

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Re: 40K firepower analysis 1 (pdf)

Post by User1350 » Mon Nov 12, 2012 4:23 am

You might want to change Rouge Trader to Rogue Trader in the PDF (twice that I noticed). Unless there is a 40K Slaneeshi dancing girl RPG.

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Re: 40K firepower analysis 1 (pdf)

Post by sonofccn » Tue Nov 13, 2012 2:57 am

Magos wrote:Feedback and / or quotes more than welcome. It isn’t proof read, so any amendments there are also appreciated. Let me know what you think.
Since you ask here are my initial thoughts. I hope they help inform and cultivate your work.

Issues I misunderstood/couldn't find source:

*Speed of macrocannons

* Shell size in relation to type of macrocannon

* Engagment ranges/ time to intercept

* 20th century nukes required 20 megatons to "destroy" a city

*Ramming speed

* Size of fleets in battlefleet gothic

General issues:

* One shouldn't construe being the size of something to weighing the same especially two radically differnt items designed for completely alternate tasks Ie a Macroshell and a tank/ Land Raider

* I'm not sure of the logic assuming "kilo-tonne" is its weight as opposed to its explosive yield. We afterall talk of nukes by their explosive payload not their total mass of reactant.

*Not to dwell on it but requiring 20 megatons to destroy a city seems over enthusastic. Hiroshima was quite effectively destroyed with 16 kilotons. As well as far as I know the Castle Bravo test was the US's most powerful nuclear detonation and it was A) typicaly estimated at 15 megatons and B) a complete and unexpected accident. Further launch delivery systems like the peacekeeper relied on numerous small yield warheads of maybe total count of 3 megatons.

* If macroshells have warheads it makes calculating mass and therefore kinetic energy problematic. A warhead is lighter than a corosponding solid block of the same dimensions obviously.

*I'm not sure of the logic of extrapolating from a troop transport to try and guess a warship's mass. They are two radically different vehicles which, at best, use the same base material. Further if canon masses exist they would have authority over any such speculation.

* I can not concur that this "The area between the two ships was saturated with energy as enough firepower to level a city was
unleashed across it. Execution Hour" is sufficent to estimate the passage of mere seconds. If further passages contain hard and fast details which can bookend the quote that would be something but as is the passage is quite vague.

*This "The weapons carried by some ships are powerful enough to reduce whole cities to plains of radioactive
glass. Battlefleet Gothic" I would argue is incongruent with your argument presented since it implies that only "some" ships are "powerful enough to reduce whole cities to plains of radioactive glass" with their weapons. Perhaps the full context of the quote makes it plainer it is talking about special weapons carried aboard some ships but as read seems to be a general statement on ship's firepower rather than a special class of "big guns".

* I feel I most note that in this"Running almost the complete length of the battleship, the starboard and port batteries were capable of
unleashing an incredible amount of firepower, easily enough to cripple even the largest warship with a
single barrage, or lay waste to entire continents if she entered the upper atmosphere of a rebellious
planet. Imperial Glory" the single barrage is attached to the largest warships not the "lay waste to entire continents" part. There is no reason one must assume a solitary barrage would "lay waste to entire continents".

* I would suggest this "We can infer that when no timeframe is given, and a ship is said to be capable of levelling
continents, we are talking about an extended ‚barrage‛, because of the gathered data and actual
case studies on planetary bombardment." much like your city destroying estimate is making too big an assumption on too limited a pool of evidence, in both cases one example, that is vague or open to interpetation.

* While this is rather straight forward "A mighty Repulsive-class Grand Cruiser with powerful reactors and heavy armour in sloping facets of
adamantine and ceramite scores of meters thick, the vessel carried a weight of armament and ordinance
that could reduce a continent to ruins with a single salvo. Black Crusade" "ruin" does not require or demand setting everything on fire across a continent. Indeed "ruin" could entail long term issues such as loss of infastructure to primary or secondary effects of this salvo. There is also the issue on if this salvo is all aimed squarely togather or if this hypothised salvo is spread out maximizing its destructive potential.

* This "It would be possible to manufacture a missile of any size: from a weapon a little larger than a normal
rocket shell, to one capable of wiping out a city, province, or continent. Rogue Trader" would qualify as a theoritcal possibility. One whose plausbility would have to be determined by the verse in question. By itself the quote does not mandate that such a weapon exists at all.

Additional firepower examples:

*"A plasma bomb is a large missile typically used by or against spacecraft. They are also used for planetary sieges. The missile energises at launch, converting into a mass of seething plasma - each missile becomes a ball of boiling energy sufficient to melt a city-block. As it converts to plasma, the missile divides into 6 fragments, this enables the plasma to spread out and saturate its target. A target under plasma attack becomes a blazing inferno which only the very fortunate survive." Rogue Trader

"A nova cannon is a huge weapon, normally
mounted in the prow of a ship so that the recoil it
generates can be compensated for by the vessel’s
engines. It fires a projectile at incredible velocity,
using graviometric impellers to accelerate it to
close to light speed. The projectile implodes at a
preset distance after firing, unleashing a force
more potent than a dozen plasma bombs." BFG rulebook

Implying a Nova Cannon shell has the rough equivilent firepower to melt 12 city-blocks.

"" The torpedo wave's target had been the two largest rok-fortresses in the enemy fron tline. The roks were massive, one of them easily over eight kilometres from tip to tip, and possibly as many as four kilometres across. Eight torpedoes s truck it, the remaining six finding the other one. Normally, it might have taken several dozen torpedo strikes to destroy targets this large. Not today, however. Today the Imperium warships were using new ordnance: so called "rock-buster torpedoes", specially designed for the task at hand.
" shadow point page 83

Simply put a 8 by 4 KM asteriod is not going to stand up to multi-gigaton abuse. Plugging it in here for a diameter of 8000 gives 2.4 gigatons for cratering energy assuming nickel-iron. Further :

"The Drachenfel's lance batteries gored into the sides of another rok, blasting away or vaporising hundreds of tonnes of soft, porous rock." Shadow point page 93

So 2.4 gigatons would be a very generous over estimate for dozens of torpedo strikes.

"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." Caves of ice page 166-167

Showing Cain believes a flotilla of battleships, however 40k defines such, are needed to level the continent rather than a solitary or lesser ships. Bracketing continent ruining firepower within the Imperial Navy.

" In the distance I can just about make out a sally port of Coritanorum. Two gatehouses flank a big armoured portal dug into an outcrop of rock from the mountain into which most of the citadel is dug. It's that mountain that makes it so easy to defend, rendering it impervious to all but the most sustained and concentrated orbital bombardment." Last Chancers 13th legion

"'Admiral Becks, your plan is totally unacceptable' the wisened warmaster said, smoothing the folds in his long black trench coat. 'It is impossible to reduce Coritanorum from orbit.'
'Nothing is impossible to destroy, Warmaster Menitus' the fleet admiral replied with a smug grin creasing the leathery skin of his hawk-like face. 'It may take a decade of bombardment, but we can annihilate that rebellious fortress and everyone in it.'
"Last Chancers 13th legion

An example of a very tough, dug in fortress and its resistence to orbital bombardment.

* Special thanks to as always to Mr. Oragahn for compiling examples in easy to locat segments

EDIT: Special hat tip to Mith for this gem:
Rogue Trader core rulesbook 2009 wrote:Macrobatteries from the main armament of most ships, filling the braodsides of vesseles with rank upon rank of gigantic weapons. Each require a crew of dozens, if not hundreds, to operate. Whether they fling kilo-tonne warheads across the void or roast their targets with high-intensity energy, macrobatteries fire in volley.
So it does appear to be talking of yield rather than total weight.

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Re: 40K firepower analysis 1 (pdf)

Post by User15046 » Tue Nov 13, 2012 5:47 pm

Cool feedback. It may be some time before i may amendments to the actual document however Ill reply quickly here to a couple of the points for now though.

Time to intercept:
Its pretty hard to get round high yields running only with shell masses and provided range. If a macrocannon has a effective range of 30,000 Km (30 cm in BFG, 1 Cm = ~1000Km in BFG) then the shell must reach the target in a reasonable timeframe. They do fire in pattern to lock targets in a maze of destruction however, so there is certainly at least some lag time between firing and striking the target. I personally don't imagine this lag time to be more than a minute though. Take the nova cannons 5000Kps, it has a flight time of 30 seconds to reach its target at range. It is the nova cannons great length and far high muzzle velocity that gives it such great range when compared to macro shells (the actual shells will be almost comparable in scale). So velocity determines range, and if a macrocannon can hit a target within 30,000Km within half a minute like the nova may strike a target at 150, then the shell would have to travel at 1000Km/s, one fifth the speed.

Kilo-tonne macro-shells
Given the numbers we might run into when discussing kinetic energy, blowing up cities, or laying waste to planetary surfaces in six days with a battlefleet (unknown size, usually not that massive), a kiloton TNT equvilent warhead seems very low. The use of thermal nuclear weapons would imply megatons at least, given multi ton shells. A "kilo-tonne" warhead could well mean a one thousand metric ton warhead, a testement to its massive size rather than yield. In Koronus we get another instance of kilotonne range shells... though these are not warheads like those fired from macrocannons, but rather solid lumps of metal fired from ork heavy guns. Because they are solid they will be several times more massive, more so if their also larger which they might be. They have about half the effective range, so perhaps half the velocity (orks have worse targeting, so id propose between >500Kps and 1000kps). At 500kps they would reach the target in half a minute.
Kinetic energy of a 3000 ton ork shell at proposed 500kps = 3.75e+17J
If we used 1000kps and put the shorter range more down to ill-accuracy, we would arrive at a far greater yield.
Koronus wrote:
Alongside more conventional macrocannons, the orks commonly employ short-ranged but extremely powerful guns. Firing dense slugs of scrap metal massing thousands of tonnes, as well as jury-rigged plasma bombs, these shells quickly become inaccurate over long range.
Given the mass of these shells, i would expect he heaviest macrocannon shells to mass hundreds of tons, to perhaps even a kilo-tonne. The word tonne is used in both instances.

20 MT nukes
kiloton range detonations neither completely level nor completely eradicate an entire city. It does require megatons for that - 20MT were listed as the "city killers". 'Devastate' or 'ruin' i could agree, we could only be looking at kilotons as a minimum.

Finally
I feel I most note that in this"Running almost the complete length of the battleship, the starboard and port batteries were capable of
unleashing an incredible amount of firepower, easily enough to cripple even the largest warship with a
single barrage, or lay waste to entire continents if she entered the upper atmosphere of a rebellious
planet. Imperial Glory" the single barrage is attached to the largest warships not the "lay waste to entire continents" part. There is no reason one must assume a solitary barrage would "lay waste to entire continents".
Yes barrage is in the first part talking about destroying even the largest warships, but it is also made clear that the ship has the capacity to lay waste to an entire continent from the upper atmosphere. I think this text leans more toward a single barrage doing the job rather than multiple barrages, which would rely on the ship running out of fuel or shells and having to restock several times before completing its task. Thus it seems to me the ship can lay waste to a continent with an 'extended barrage'.

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Re: 40K firepower analysis 1 (pdf)

Post by User15046 » Tue Nov 13, 2012 7:01 pm

Actual examples of what firepower failed to do are interesting. In the case of high firepower, they are hard to explain, short of tech that enhances roks or fortresses endurance by an order of magnitude, akin to the "power armour" or tensor force field enhanced hulls in SW.

Plasma bombs probably come in any size, ranging from grenades to nova cannons, the ones that melt six city blocks might be one of the hundreds of the smaller weapons mounted in broadside. Or else, even the nova bomb would be yielding kilotons.

Ramming is derived from the speed you can reach in rouge trader, which iirc is faster than is BFG. The speed of 200,000 km/h requires thirty minutes constant acceleration while pushing thrust further than its max. sustainable acceleration of 2.5G. ~10 gigatons kinetic derived from the ships mass provided in the same source. If conventional firepower falls short of a gigaton / salvo, then this much kinetic energy will obliterate any ship, which isn't all that inappropriate.

At this time, the only bombard that indicates gigatons / second was delivered by a battlefleet, and perhaps a repulsive depending on interpretation of ruining a continent.

Shell masses, probable/implied velocities, and use of fusion warheads would also point to single digit gigaton macroweapons, but may be ill-consistent or contradictory with observed effects and limitations.

I have heard flotilla in gothic means ~3. Thus three battleships carry enough macro shells to level a continent.
Such ships are larger than 7km grand cruisers, perhaps ~8. Lets say 500*500*100 cubic meters of each vessel is dedicated to storing macro shells. Macrocannons are actually comparable to novas in diameter, only they are stocky rather than long. So 50 meter wide 150 meter long shells may not be unreasonable, ~280,000^3 meters. The three ships could carry a maximum of almost 2700 shells under these parameters.
A continent treated as 200,000Km^2 would require each to level ~7400km^2.
if my math up to now is all correct, that means each warhead would have to level everything within a 50Km radius. A 6 gigaton nuke would create 20PSI over pressure within this radius, leveling even heavy concrete buildings.

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Re: 40K firepower analysis 1 (pdf)

Post by Mr. Oragahn » Thu Nov 15, 2012 7:54 pm

Ranges and speed weren't thought thoroughly:
Andy Chambers wrote: I'm not sure if I've talked about scale before but here goes anyway. BFG works around an approximate scale of 1cm=1000KM for the planets and other tabletop features. Obviously this means the ship models are massively out of scale, an Imperial cruiser is NOT 9000KM+ long! The scale is basically there as a rule of thumb and I didn't worry about it too much when it came down to setting weapon ranges, ship speeds and so on. These were all done to create the right impression of distance on the tabletop. For example 60cm 'feels' like a long way and 30cm doesn't, the weapon ranges aren't defined by some pseudo-science calaculation of the energy dissipation rate of lasers (fairly obviously ) but to create an interaction between the (massively out of scale) models on the tabletop.

The more interesting question is perhaps how long is a turn, and that one I don't know the answer too - I'd guess somewhere between 15 minutes and an hour (quite likely telescoping so that at long range a turn is an hour but by the time you're within 15 cm its 15 minutes). This would make an attack craft capable of moving 30cm per ordnance phase capable of doing approximately 30-120,000 km/h. I've got no idea if this is realistic for starfighter speeds, or unfeasibly fast, incredibly slow or what , perhaps someone on the list could enlighten us all on this front (don't just tell us what it says it the Star Wars technical manual though!).

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Re: 40K firepower analysis 1 (pdf)

Post by sonofccn » Fri Nov 16, 2012 1:17 am

Magos wrote:Its pretty hard to get round high yields running only with shell masses and provided range. If a macrocannon has a effective range of 30,000 Km (30 cm in BFG, 1 Cm = ~1000Km in BFG) then the shell must reach the target in a reasonable timeframe. They do fire in pattern to lock targets in a maze of destruction however, so there is certainly at least some lag time between firing and striking the target. I personally don't imagine this lag time to be more than a minute though. Take the nova cannons 5000Kps, it has a flight time of 30 seconds to reach its target at range. It is the nova cannons great length and far high muzzle velocity that gives it such great range when compared to macro shells (the actual shells will be almost comparable in scale). So velocity determines range, and if a macrocannon can hit a target within 30,000Km within half a minute like the nova may strike a target at 150, then the shell would have to travel at 1000Km/s, one fifth the speed.
Ultimatly through the mechanics of battlefleet gothic, like all games, is balanced for gameplay rather than a "realistic" protrayal. As well looking at the quote Mr. Oragahn provided refrences both scale issues within the game as well as a rather fluidic passage of time.
magos wrote:Given the numbers we might run into when discussing kinetic energy, blowing up cities, or laying waste to planetary surfaces in six days with a battlefleet (unknown size, usually not that massive), a kiloton TNT equvilent warhead seems very low.
That may or may not be but it is a fairly straightforward piece of fluff. One far more specific than flowerly language of the more vague examples.
Magos wrote:The use of thermal nuclear weapons would imply megatons at least, given multi ton shells.
Assuming mulit-ton shells are the ones carrying a warhead and that the Imperium posseses similar effiecency in their nuclear arms as Modern Earth.
Magos wrote:A "kilo-tonne" warhead could well mean a one thousand metric ton warhead, a testement to its massive size rather than yield.
No. I'm afraid that would be obfuscating to the point of nigh ommission. As I said we don't talk of our nuclear stockpile in weight of reactants, without knowing the reactants as well as the basic method of fission/fussion knowing the gross mass wouldn't be informative and its counter productive if describing the weapon to describe it in terms which require you to pull out a scratch piece of paper and a pencil in order to "decode".
Magos wrote:In Koronus we get another instance of kilotonne range shells... though these are not warheads like those fired from macrocannons, but rather solid lumps of metal fired from ork heavy guns.
Rogue Trader Battle fleet Koronous page 76 wrote:Alongside more conventional macrocannons, the orks commonly employ short-ranged but extremely powerful guns. Firing dense slugs of scrap metal massing thousands of tonnes, as well as jury-rigged plasma bombs, these shells quickly become inaccurate over long range.
That would be evidence the Ork fire shells in weight of thousands of tons. However these are 'eavy gunz, described as you quoted extremely powerful, which are heavier than gunz which are the most common macrobattery analogue. And we must note this one describes the "shell" as "massing thousands of tonnes" rather than talking about a warhead. Lastly due to the Ork ramshackle, cobbled togather technology and their prefrence for powerful, unstable technology making comparisons to the Imperial Navy difficult at best.
Magos wrote:kiloton range detonations neither completely level nor completely eradicate an entire city. It does require megatons for that - 20MT were listed as the "city killers".
Listed where? Some googling gets some hits on forums of 20 MT city killers but I don't see any calculations, can't find any explanation why 20 megatons.

here:
SS-18 Mod 1 - R-36M The SS-18 Mod 1 carried a single large reentry vehicle, with a warhead yield of 18 to 25 MT, a distance of about 6,000 nm. In January 1971 pop-up tests, began during which the mortar launch was perfected. The actual flight tests for the single-RV Mod-1 began on 21 February 1973, though some sources suggest that testing began in October 1972. The testing phase of the R-36M with various different types of warheads was finished in October 1975 and on 30 December 1975 deployment began [though some Western sources suggest that an initial operational capability was reached in early 1975]. A total of 56 were deployed by 1977, though all were replaced by Mod 3 or Mod 4 missiles by 1984. These high-yield weapons were assessed in the West as possibly developed to attack American Minuteman ICBM launch control center
mentions 18-25 megaton Soviet nuke suggesting it was used to take out "launch control center"s rather than "kill" cities.

here:
Best estimate here is that the B41 was produced in at least two versions, one of which had a yield of 25 mt--the highest yield weapon ever built by the U.S. It is likely that only a small fraction of the weapons built were the high yield version, and that these were the first ones retired (in the 1960s).
suggests the US did build a 25 megaton bomb, so I was mistaken, but relatively few and then retired them.

further down:
The Titan II carried the highest yield missile warhead ever deployed by the United States. This was the W53 warhead with a 9-megaton yield, which could be delivered by the Titan II to a range of 15,000 km.[18] About 60 W53 warheads were built from December 1962 to December 1963.[19]
Suggests the largest warhead we stuck on a ICBM was merely 9 megatons.
Magos wrote:Yes barrage is in the first part talking about destroying even the largest warships, but it is also made clear that the ship has the capacity to lay waste to an entire continent from the upper atmosphere. I think this text leans more toward a single barrage doing the job rather than multiple barrages, which would rely on the ship running out of fuel or shells and having to restock several times before completing its task. Thus it seems to me the ship can lay waste to a continent with an 'extended barrage'.
I do not see where the text leans anywhere. It is quite ambiguous as to the time frame it takes to lay waste. As well I do not understand why the ship would need a restock if it couldn't lay waste in a single barrage, surely it carries enough munitions to fire its guns more than once.
Magos wrote:Actual examples of what firepower failed to do are interesting. In the case of high firepower, they are hard to explain, short of tech that enhances roks or fortresses endurance by an order of magnitude, akin to the "power armour" or tensor force field enhanced hulls in SW.
Save one quote specificly cites the mountain as why the fortress was so durable as to the Roks there is no mention of forcefields or super tech holding the Roks togather. Further page 82 of the Koronous battlefleet states this concerning Roks:

"Dimensions: varied; up to 4 km in diameter

...

Roks are tough, as only a repurposed asteriod can be..." Reinforcing Roks are tough and its because of their composition rather than advanced super tech.
Magos wrote:Plasma bombs probably come in any size, ranging from grenades to nova cannons, the ones that melt six city blocks might be one of the hundreds of the smaller weapons mounted in broadside. Or else, even the nova bomb would be yielding kilotons.
Well I'd be more cautious due to its a couple of old quotes from two different rulebooks, the plasma bomb I think was from the original Rogue Trader back in the '80s, but Occam's razor keeps me from believing that they are talking of two completely different weapons systems that just happen to have the exact same name.
Magos wrote:I have heard flotilla in gothic means ~3. Thus three battleships carry enough macro shells to level a continent.
Source? Wouldn't that overlap with Squadrons, 2-6 vessels I thoguht,?

Googling the definition I got this:
flo·til·la (fl-tl)
n.
1.
a. A small fleet.
b. A fleet of small craft.
2.
a. A U.S. Navy organizational unit of two or more squadrons of small warships.
b. A similar unit in the navy of another country.
magos wrote:Thus three battleships carry enough macro shells to level a continent.
Why the assumption the battleships only would use macro shells? The only weapon mentioned in the quote was lances and presumbly Battleships carry a full compliment of death dealing weaponry.
Magos wrote:Macrocannons are actually comparable to novas in diameter, only they are stocky rather than long.
They are? Nova cannons are one of the most powerful and exotic weapons in the Imperial Navy's arsenal. The biggest I saw cited on your PDF was the size of a tank/ land raider and I thought Nova cannon shells were supposed to be building sized ie tens of meters in width.
Magos wrote:So 50 meter wide 150 meter long shells may not be unreasonable
Where are you getting the Nova cannon's dimensions if I may ask?

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Re: 40K firepower analysis 1 (pdf)

Post by Mr. Oragahn » Fri Nov 16, 2012 2:57 am

We have fluff that clearly describes torpedoes as not so impressive pieces of technology. As a matter of fact, the vast majority of them aren't even guided, even less capable of acquiring targets on their own.
Simply put, they're dumb projectiles fired in large quantities, in the hope that some may cross the path of the target.
Let's also notice that they're self propelled and to that logic, the vast bulk of their volume would be dedicated to fuel transport, especially for distances which can be measured in planetary diameters. We're a far cry from merely launching a shuttle some hundreds of km up the ground. I noticed how the ground-to-orbit propulsion of defense missiles wasn't so great in the 40k misc thread: while starships could only run an accurate bombardment by coming close to the planet (low orbit), they started to expose themselves to counter fire from missile silos.
And yes, those rockets that launch shuttles into space are quite "building sized".

http://www.youtube.com/watch?v=ju74P0Q7iso
Last edited by Mr. Oragahn on Mon Nov 19, 2012 12:39 am, edited 1 time in total.

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Re: 40K firepower analysis 1 (pdf)

Post by General Donner » Sun Nov 18, 2012 11:17 am

Good to hear from you again, Magus!


Some initial brief comments on your document and the ongoing discussion here:

*I personally don't think we should use the BFG game mechanics for determining weapons ranges. All game systems will by default be abstracted in order to promote playability, and here the units the game uses aren't even in-universe kilometers, but centimeters of tabletop.

*That said, weapons ranges in the thousands to tens of thousands of kilometers seem to be among the more commonly given in the novels, so I'm not necessarily opposed to using one in the 20,000-50,000 km or so range for a sample calculation. (For lower limits one might wish to knock a zero or two off those figures, I suppose.) And hitting at that range within a fairly brief time (certainly a few minutes at most is enough, reaching toward the upper end) seems reasonable, as well.

*I'm skeptical of macro-cannon shells massing thousands of tons being common, though. The "tank-sized" or "multi-ton" data are far more commonly mentioned in the books and fluff, and indeed the kiloton references are more easily taken as refering to yields. If there are weapons that fire shells of such great mass, they'd probably be rare superguns, not the standard macro-cannons of the broadsides.

*On city-destroying weapons, I think it should be noted that a timeframe is not usually specified. Nothing is said to indicate that only single shots are intended. Indeed, some books (such as Execution Hour) specifically say otherwise: there, it's mentioned that a cruiser's batteries can "raze whole cities with sustained orbital bombardments" (emphasis added). This would seem to indicate lower numbers than megatons or gigatons, as obviously even a single salvo of many such weapons would leave the city little more than a crater.

*On continent- and world-destroying weapons, likewise, no time is usually given. And sometimes there may be cause to suspect technobabblish weapons at work (for example, cyclonic warheads). We should probably keep the possibility of hyperbole in mind, as well. In some books (such as Nightbringer) weapons said to be able to destroy continents are actually shown to be quite less formidable by other examples.



Attempting a sample calculation of my own of what I might consider some lower limits for a macro-shell, given these data and various assumptions: If we assume a five-ton shell propelled at some 500 kilometers per second (a tenth of nova cannon muzzle velocity, sufficient to hit a 30,000 km distant target in one minute), we get a kinetic energy of about 5.6e13 joules, or some 13 kilotons. If we assume a tank-sized fifty-ton shell, we add an order of magnitude, of course.

If we assume, instead, that the typical effective range of the gun is closer to 3,000 kilometers (as some novels would have it*) and that they can cross this distance in the same timeframe, we drop one order of magnitude from the velocity estimate and two from the kinetic energy (which includes v^2), for some 130 tons or 1.3 kilotons of TNT equivalent, respectively.

Note that these are somewhat vague lower limits only. Actual figures may be higher. They fit reasonably well with a number of other data, though: Terawatt beam weapons in the broadsides of warships from the Rogue Trader RPG, the already quoted sustained-bombardment destruction of cities, single warship-grade plasma bombs destroying city-blocks (rather than whole cities), and so on.

One complication might be that macro shells are often stated or implied to use chemical high explosives** rather than nuclear or exotic warheads, which would suggest quite lower velocities (as otherwise the kinetic energy would far outstrip the usefulness of the explosives). I'm presently unsure what to make of that.



*For example, Death Or Glory or Wolf's Honour

**For example, Execution Hour or 13th Legion

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Re: 40K firepower analysis 1 (pdf)

Post by User15046 » Sun Nov 18, 2012 2:03 pm

Bit pressed for time so ot going to bother with quoting, ill just reply with relevant headers.

Ranges
While little technical thought was put into the original weapons ranges given to ships in BFG, and are inconsistent in the BL material, but often still gravitate around thousands of kilometres. Sometimes farther, sometimes much less, due to this inconsistency I appeal to the original material and the figures that seem to be the most accepted, tens of millions of meters.

Shell sizes
Yes. “multi-ton” would be pretty darn light for a “land raider sized” shell though, unless multi-ton equates to tens of tons. The largest shells are discharged from cannon muzzles over 50 meters in diameter, suggesting near enough shell diameter, I don’t imagine a tank sized projectile coming out a cannon that large. So yes the largest are far greater than tank sized, and because tank sized would seem a bit to large to merely be a “few tons”, that is why I listed them as the “middle-weight” shells. Even if they are not 6 megatons per ton, or even less than 1 megaton per ton, they will still be far greater in yield than a kiloton when fitted with a nuclear fusion warhead.
For comparison, a land raider is over ten meters long, so if this were a long fine shell 1 meter wide its volume might be slightly less than 7.5 cubic meters. If they were one third their length in diameter they would be <67.5m^3.
The shells fired from the larger visible capital macrocannons, should be closer to 50 meters in diameter, assuming their three times longer than their diameter their volume would be ~280,000m^3. That should put these shells at some 4000 times the volume of the “tank sized” shells mentioned. A cruiser can only mount eight of the heaviest macro-cannons, and sometimes they lack them all together in favour of more numerous weaker guns (seen in art).
1000 tons doesn’t seem unreasonable to me for a shell of such scale, it equates to only ~3.6 kilograms per cubic meter hundreds of times less dense than water! They would have to be mass-lightened to say the least. If you said the tank sized shells were the “multi-ton” ones, and scaled them up to the building sized ones here, we would arrive at thousands, tens of thousands of tons.

Eavy gunz
Anyway, if they travelled at the same proposed velocity as a macro-shell, their kinetic energy would be ~357 megatons. This is a many times greater than the proposed KE’s for even the largest macro-shells. Maybe sheer kinetic energy is more effective against warships than are significantly higher yield warheads, or I underestimated shell velocity and the actual KE here is >6 gigatons, or I overestimated the macro-fusion warhead yields, they are upper limits after all as they assume the max. yield/mass ratio for fusion.

Flortila of battleships with enough munitions to level a continent
A barrage is a continued bombardment, not a single salvo? If the ship has the capacity (and thus the supplies) required to lay waste to a continent, then it must do so a single barrage? If it couldn’t wipe out a continent in a barrage, then the limiting factor would have been supplies, thus the ship would have to go restock and come back to finish it of. Salvo is all guns firing once, barrage is extended bombardment.

Roks
Its worth mentioning that Ork roks can survive re-entry, and crashing into planets. Their integrity might be spiced up by the ork WAAGH.
Size of a flotilla
I admit, something I read on a forum (supposedly used to describe 2-3 ships in some 40k book). Two squads say 4 – 12 battleships. This is a monstrous force though.
Use of macro shells to level the continent
I figured lances would be deep crust penetrators, dealing with underground structures. And that it would be the firepower that could level to a continent. Torpedoes are fired from the front, they can’t fire torpedoes and macrocannons at the same target, but macro’s are more numerous. Torpedo numbers would seem more limited, especially if you go by the RT Koronus numbers.

Shell dimensions?
Length to diameter ratio? A guess. Though this ratio is consistent with the large shell we see fired in the DoW exterminatus. 30 – 50 meters are the figures I have seen for muzzle, with the projectile being slightly smaller in diameter. SO if anything, the largest macroshells will dwarf the smaller 30 meter nova shells… it must be the exotic warhead and muzzle velocity that makes the nova cannon special… not the size of the shell.


Several sources mention megaton range munitions now according to a SB (I would like to get the quotes) because really, it is in-consistent. I think the in-ability to destroy a mountain / kiloton range broadside salvos required to destroy cities over barrages are outliers personally, due to the sheer KE’s that I suspect should be involved and sources stating megatons/use of fusion weapons. That said, explicit bombardments demonstrating high firepower seem pretty scarce and vague. I listed several sources that mention city destroying firepower, and now apparently there a similar amount of ones that mention megaton range weapons. Combined, I think these might outnumber the kiloton or gigaton events. Because firepower is so up in the air inconsistent in the vast bulk of material, and there is so much to dig through to get to it yourself, I used KE calcs and an appeal to physics. Consensus here seems to be more akin to RT’s take on the subject, kilotons. I came here thinking something far higher, but thinking about it, there arnt any explicit bombardments that come to mind that require the firepower to be that high, and in some, far less. I personally don’t think firepower will be right down in the kiloton range, but I am starting to think megaton-range weapons will be a more supportable theory. My shell 15-30 second to reach target KE calcs, actual quotes regarding yield, and most quotes regarding city destroying firepower -save the one that says it takes extended bombardments- would support such a position. Two squadrons of battleships having enough firepower to level an entire continent in a single barrage and use of thermonuclear tech might also support the notion. Because 40K is inconsistent, somewhere down the line you are going to have to reject some examples because they don’t fit the hopefully logical and working hypothesis (in this case it would be the extended bombard required to destroy a city, for example), that takes into account a greater number of sources and context of the setting (like the upper limits determined by exterminatus). A ship wielding megatons shouldn’t struggle with a mountain for very long. RT suggests ship ramming tactics can get into the gigatons, for what its worth.
When I have the time, I may create three duplicates of my work, for low [KT] mid [MT] and high [GT] theories along with the relevant supportive quotes, and list explicitly contradictory ones at the end of each document, then see which gets the most fleshed out with supporting pieces and which ones get the most sources contradicting with them. Naturally this would require a larger poole of evidence though, larger than the one i have at the moment.

Anyone have the actual quotes mentioning these megatons? Or chemical based macro-warheads? I have seen “macro-nuclear” warheads and fusion bombs before.

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Re: 40K firepower analysis 1 (pdf)

Post by Mr. Oragahn » Mon Nov 19, 2012 12:54 am

I don't know enough yet about the Ork's Eavy Gunz, but considering their love for short range battles and their cunning use of stone launchers in space, I wouldn't be surprised that they threw them only at shorter ranges and thus at lower velocities.
Perhaps smaller systems could launch projectiles at faster speeds, assuming, perhaps, a cumulative effect in the latent psychic field that would allow the projectiles to be faster than what their mechanical parts would normally allow...

Let's also note that megaton firepower isn't impossible with kiloton weapons, as long as there are enough kiloton guns firing at once. It seems OK that the big macro cannons would fire megaton-level ordinance, while the smaller pieces, often numbering in the dozens on several racks, would be a couple tens of kilotons each, but managing to reach firepowers worth of several megatons on very large ships.

The immense amount of firepower quotes I found certainly don't site anywhere the gigaton range or high megaton one. Grossly distorted interpretations from certain enthusiast hammies tend to significantly skew the reality, to say the least. A guy like Connor would often claim yields six or nine orders of magnitude greater than needed, and claim no interpretation could be obtained for events which would, in fact, be rather easily gauged and would end pointing to firepower levels equally as low. Every single thread I started from his own observations proves this.
So many quotes simply don't even fit with the megaton mark and absolutely require moderate kilotonish firepower to work.
Even the superweapons used by Chaos forces that helped them gouge a larger crater in Shadow Point would be a completely mundane event with megaton level weapons.

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Re: 40K firepower analysis 1 (pdf)

Post by WhiteLion » Fri Aug 16, 2019 5:42 am

https://1d4chan.org/wiki/Autogun

Provided yields for these weapons can go from 42 exajoules (about 5.297 times more powerful than the most powerful earthquake ever recorded; a 42 exajoule earthquake would be approximately magnitude 9.98) right down to the measly 15 tetrajoules...*sigh* Games Workshop never fails to surprise us. Seriously believe us, we know that tetrajoules isn't an official unit of measurement, but since tetra is Latin for four this essentially gives us....4 joules of power....which is weaker then a human punch or a flashlight.... Don't believe us? We got that from Rogue Trader rpg: BattleFleet Koronus pg. 31 & 20 which is quote on quote:

"Look at her, son. Isn’t she a beauty? Over two hundred Vulcan mega-bolter defence turrets, fifteen tetrajoule Sunsear las-broadsides, prow plating ten metres thick, the finest auspex masts in the battlefleet… And the lines on her! Fluted prow, elegant statuary… those xenos scum won’t know what hit them!” – Bosun Phineas Jhule tempts fate at the embarkation of the Fire of Heaven
"The Avenger dates from an earlier period of fleet tactics, when, squadrons of grand cruisers were employed as “line-breakers.” Traditionally, they were thrown into the midst of massive fleet engagements, soaking up enemy fire while racing into the middle of enemy formations, then crushing their opponents at short range with tetrajoules of energy from their oversized broadsides."
Yeah...we in /tg/ aren't sure whether this was intentional or a gross example of a severe typo. So...um....FEAR THE 60 JOULE BROADSIDE BATTERIES!. A possible explanation for this stupidity GWs forgot that the term "quadrillion" is a thing and is using "tetrajoule" to mean 1 000 000 000 000 000 joules (as the word "billion" comes from the latin word for two, "trillion" for the latin word for three and so on.). This gives a result of 15 quadrillion joules in a broadside.

This specs are relesed by Rogue Trader Official, one Macrocannon at max power is 42 exajoule = 10 Gigaton , all weapon in Warhammer are adjustable, the macrocannons according to the energy with which they will be operated, Cyclonic torpedoes as we read in the novels have different powers, in a specific episode with a torpedo saver a planet was destroyed, literally destroyed, the word they used in the novel has been atomized. On that occasion two-stage cyclonic torpedoes were used, each of which is able to physically erase a planet like the black death in Star Wars. Even the Lances are adjustable in power. if you are interested I can give you the names of the novels, the stories are beautiful and above all what is in the novels is canon

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Re: 40K firepower analysis 1 (pdf)

Post by Khas » Fri Aug 16, 2019 8:30 pm

Welcome!

Admittedly, the only 40K novel I have is one of the Ciaphas Cain novels - "The Greater Good", to be precise - but I don't doubt you that most of the 40K novels are good. I say "most", because we all know how bad C.S. Goto's works are.... Then again, Games Workshop has said that just because a story in 40K is canon, doesn't mean that it's true - ie, it could be an in-universe work of propaganda.

The fact that variable yields are mentioned is interesting.... and something of a relief, all things considered.

Are you sure it was a cyclonic torpedo that was used? I thought those things did their work by setting fire to a planet's atmosphere.

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Re: 40K firepower analysis 1 (pdf)

Post by WhiteLion » Sun Aug 18, 2019 11:13 am

Thanks for the welcome. They have used a two-stage cyclonic torpedo, it is the most powerful variant, the first stage is a Melta warhead that penetrates the planet, the second warhead explodes the planet from the inside, are weapons designed for the Necron worlds and worlds that you have no interest in conquering or where there are too great threats that require extreme measures. As for the calculations they are useless to do for two reasons: 1) macrocannons and lances are of variable size and have adjustable power, the macrocannons of a dominator class have a size (50 meters in diameter x 150 meters in lenght), the macrocannons of a Glorian class (which is 26 km long ) have a diameter 3 times greater, the macrocannons and lances of the Abyss class are much larger because the Abyss class is as big as a continent, so we talk about macrocannons several hundred meters wide wanting to be modest in the estimates. The power of the weapons is then adjustable, in a book an example is given of how a heavy spear adjusted to the maximum can pierce and devastate a planet alone.
We cannot take video games into consideration because they are not canon, only books are canon.
when you say that some things that are said in the books can be said for propaganda is true but not when the words are followed by the facts, the planet Nostramo was in fact blown up completely, because attached with macrocannons set to the maximum power, in the book it is written , two-stage cyclonic torpedoes were not used. This is a fact and not propaganda.
All 40k weapons have three adjustments, the first involves naval damage, it is the most used one. The second is used for exterminatus by orbital bombardment with macrocannons and single-stage cyclonic spears or torpedoes. the third category is used for greater damage such as destroying an entire continent (in the books there are several practical examples, not propaganda in words, but only Battleship and cruisers have this typ of firepower). In last we have the weapons used for exterminatus extremis, that is when we need to detonate literally the planet with a blow, for example against opponents like in Necron against which the imperium has few possibilities.These weapons are the two-stage cyclonic torpedoes, the lances and the macrocannons of the Gloriana, Abyss and Ark Speranza classes set at maximum power, Let's talk about deciphered ships the size of a continent and armed with caanones and cruiser-sized lances able alone to annihilate entire armies and more fleets of cruisers.
Excuse me for my bad english but i no speak english very well

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Re: 40K firepower analysis 1 (pdf)

Post by Khas » Sun Aug 18, 2019 4:27 pm

Ah.

Granted, the Horus Heresy novels ARE the exception to that rule, being the definitive version of events in-universe.

Also, this is making me remember a hilarious curbstomp from another site, where Star Wars got pitted against a Triple Alliance of Star Trek, Halo, and Warhammer 40K. And yes, Trek, Halo, and 40K were allowed to share tech and resources. So.... the Borg, Flood, and Tyranids all merged into one, and well.... gg.

And don't sweat it. Your English is better than some native English speakers I know.

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