Grand 40K Quantification Thread

[Lost Soal]

Necropolis, pg 20

Sondar Gate opened with a great shriek of hydraulic compressors and the armoured column poured out

Leaving in the direction of the enemy.

Necropolis, pg 43

Kowle's column had reached the rear of the queue of refugees tailing back from Sondar Gate

Returning from the battle. Demonstrates the direction of the enemy and incoming fire.

Necropolis, pg 24-27

Out of nowhere, just before nightfall, about a half hour after the klaxons had stopped yelping, the first shells fell, unexpected hurled by long range guns beyond the horizon.
Two fell short on the southern outer habs....

A gigantin salvo hit the railhead at Vayver Gate...

Another scatter pounded the Northern habs along the river...

In mid-stream, Follicks overladen ferry was showered with burning debris... Two more dropped beyond the Magnificat...

A staggered salvo ripped through the mining district...

Vollys of shels and long range missiles pounded into the southern face of the Main Spine.

Using the map at the beginning of the book, and on the GW website, we can gauge how far from the curtain the shells land.

Using the mid point between Hass West gate and Sondar gate;
The southern face of main spine is upwards of 8km.
Northern habs are 10km+

The Magnificat is 15km from Hass West
The Mining district if 15km From Sondar Gate

The Artillary is beyond the horizon.
Necropolis, pg 31

wailing plaintively up at the soldiers two hundred meters above them on the wall top

At 200m the Horizon is over 55.5km away. Couples with the targets, this give artillery ranges in excess of 70km. Although I admit it is possible that this is not from Earthshaker cannons.

On tank ranges.
Necropolis, pg 85

'You can see the flashes of tank cannons as they fire. four, five kilometers out'

Zoican tanks have a range of ~4-5km

[Falkenhayn]

So bolters are freakshly powerful, only we don't know how much?

Could they turn something in Stormy armor into scrambled eggs between momentum and KE?

If we're talking the "tossing around half a ton of person around like a rag doll" estimates than it might. Even if it doesn't penetrate, it probably would knock out if not kill the stormy in question (headshots would almost definitely kill). (of course, this is equivlaent to pounding said Stormy with a 30mm Avenger cannon/tank round, too, so that's not really a limitation.)

Though something more plausible for your average bolter (No, I don't consider that a normal example, unless you want to argue all bolters use reactionless propulsion, can hit their targets from miles away, and take out a modern MBT in a single shot..)

This is the tricky bit. The Bolt Pistol that Eisenhorn uses was gifted to him by a Deathwatch Librarian. As far as I know, he is in an unaugmented state at the time of the citation. Eisenhorn appears to use it with the same dexterity as the Scipio Pattern Naval Pistol that it replaced, meaning that SM weapons aren't scaled up, or Eisenhorn is somehow passively boosting his natural abilities through Delta Level psykics.

Also, the maximum range listed for a Grey Knight's gauntlet mounted Storm Bolter is 25 meters. However, given the method of employment and the MO of the Grey Knights (ie: diving headfirst into Abrahmic Hell with psykic melee weapons), it makes sense that their weapons would be fixed for maximum firepower and RoF as a space clearing measure.

[Falkenhayn]

They can also use Something (I can't remember it's name) else for bombardment, basically something made by divinely inspired Adeptus Mechanicus thats much larger than even a Titan- Some sort of gargantuan artillery , with each being unique.

Ordinatus is what they are called.

Have a copy of Iron Hands for some earthquake inspiring, mantle tickling Ordinatus Gehenna action?

[Dark Hellion]

Actually, IIRC (I'll check tomorrow if someone doesn't get there bfore me) Eisenhorn specifically mentions that the Space Marines Bolt Pistol nearly requires two hands for him to use.

[Connor MacLeod]

Unfortunately, Earthshakers really don't fire 3 ton shells

I'm aware of the 38 kg Earthshaker shell as well. I presume that "Earthshaker" is a name for a category of weapons. (As I understand it, some Earthshakes could be both powered and unpowered.) In this case we don't know which might be used (both may very well be used.) (Besides the kinds of recoil we are tossing about are going to invariably neccesistate higher-mass shells.. I'm not sure you can realistically expect chemical propellant to provide the sorts of velocities a lighter round would imply...)

And according to this (yes, THAT) thread Orsai notes the refrence as "First and Only", and given his record, I'm inclined to believe he's truthful.

While we're on the topic of tossing out Imperial Armor tidbits:

"Each massive cannon shell holds enough explosive to flatten a building with a single shot."
...
"The Stormsword siege gun fires huge rocket-propelled siege shells, each weighing in excess of 180 kgs.

Here we have a shell massing 180 kg. FAr more massive than 38kg Earthshaker round.

"Most missions use high explosive ro unds, but other more specailized rounds are issued to Basilisks, such as smoke shells, incendiary shells, and illumination shells for lighting up a battlefield at night. The Earthshaker is a 132mm calibre weapon, capable of firing a shell over 15 kms at a velocity of 814 mps.

...

"Such is the power of the Earthshaker cannon that its shells are easily capable of destorying enemy vehicles, strongpoints, or buildings."

The quote above. Note however, that 814 mps is actually quite high for a mere 15 km range.. this would correspond to a rough elevation of only 10 degrees or so. With a 45 degree elevation and the stated muzzle velocity, you could expect a potential range of 60-70 km, easily. (though such targeting would require spotter and targeting data relayed to the gunners for any real accuracy.

Each Manticore missile is divided into five parts: fuse, control and guidance equipment, electricla unit, explosive warhead, and propellant container. Each is poweed by a two part solid-fuel rocket, consisting of a starrting rocket and a main in-flight rocket motor. This generates speeds of up to 300 meters per second once airborne.

Guided missiles. In-flight speed is 300 m/s. We might infer similar performance for "rocket propelled" artillery shells like mentioned above. (meaning that such shells could have a velocity in excess of 1000+ m/s)

Using its standard 5 powder charges, the Earthshaker can reach out to approximately 16 km with a 38 kg shell. Earthshakres mounted on platforms are sometimes issued with charges 6 and 7, in an attempt to increase this range. This induces considerable strain and eventually leads to erosion of the firing chamber so that correctly seeling the breach before firing becomes impossible. Firing of charges 6 and 7 is occasionally allowed, but must be authorized by higher command, and is only used with good reason.

As noted above, the "38 kg" Earthshaker projectile. At a 59 degree max elevation (noted on page 185) , the muzzle velocity required to reach out to 16 km would be something like only ~400-500 m/s or so, which is alot less powerful than implied above. (Then again, the implication is that this weapon is alot smaller and less effective. 38 kg shells, if composed entirely of high explosive, would barely come out to half a ton of TNT, even assuming an order of magnitude greater efficieny than most modern explosives. You could just *barely* get a 15 meter diameter crater from that, if you were generous. Odds are you'd need closer to 500-1000 kg or so of explosive to get that sort of cratering, and that disregards melting or vaporization..)

[Connor MacLeod]

This is the tricky bit. The Bolt Pistol that Eisenhorn uses was gifted to him by a Deathwatch Librarian. As far as I know, he is in an unaugmented state at the time of the citation. Eisenhorn appears to use it with the same dexterity as the Scipio Pattern Naval Pistol that it replaced, meaning that SM weapons aren't scaled up, or Eisenhorn is somehow passively boosting his natural abilities through Delta Level psykics.

Telekinetic recoil damping might be possible (Though bracing his arm and anchoring himself like that is going to hamper his mobility, I should point out) but if it comes down to it, the "gravitic motors" Necronlord mentions would work better (there's not really much point for the motor if your bolter can fling said proejctile at mach 20)

I'm more concerned with the massive KE transfer, the implied overpenetration risk (remember that we're talking about something that is for all intents and purposes either a tank round/Avenger cannon round in terms of momentum and KE) and the multi-mile ranges.

Also, the maximum range listed for a Grey Knight's gauntlet mounted Storm Bolter is 25 meters. However, given the method of employment and the MO of the Grey Knights (ie: diving headfirst into Abrahmic Hell with psykic melee weapons), it makes sense that their weapons would be fixed for maximum firepower and RoF as a space clearing measure.

Just for reference, we're talking about a round that for all intents and purposes that exceeds the Earth's escape velocity. This round is goign to have a nearly flat trajectory over a mile, and is going to pulverize most living things it DOES hit (probably while penetrating without delivering all its momentum/energy into the target. Having the weapon on automatic is only going to make the recoil problem worse.

As I said, if we DO attribute this to the impact of the weapon and not its explosive effect, its likely that this IS a non-standard round. (unless you want to tell me its possible for a bolter to carry about one-tenth the effective impact firepower of the aforementioned fixed-emplacement Earthshaker cannon routinely.)

[Connor MacLeod]

They can also use Something (I can't remember it's name) else for bombardment, basically something made by divinely inspired Adeptus Mechanicus thats much larger than even a Titan- Some sort of gargantuan artillery , with each being unique.

Ordinatus is what they are called.

The Adeptus Mechanicus keep the largest and most potent engines of war for themselves. The Titans remain firmly under the command of the Adeptus Titanicus, the Adeptus Mechanicus' military division, which includes the Titan legions and the Skitarii regiments. Other more exotic war machines are kept under their own control, especially those using very advanced or alien weaponry. These machines are rarely seen, such as the Ordinatus. Ordinatus are huge rumbling war machiens towing large arrays of exotic weaponry, such as sonic weapons, Vorrtex missiles or massive Nova cannons.

Frankly, the idea of a ground-based nova cannon scares me extremely.

[Imperial Overlord]

Frankly, the idea of a ground-based nova cannon scares me extremely.

We discussed this in an earlier thread. They are two different weapons sharing the same name. The Ordinatus nova cannon is 'merely' a gigantic plasma weapon capable of obscene destruction and not the teraton rated ship killer.

Rules for it in the Specialist Games PDF Ordinatus

As for bolter overpenetration with Eisenhorn's extra special bolt pistol, if he's using the standard mass reactive ammunition it will explode inside the target and somewhat limit that danger.

[Connor MacLeod]

[quote="Ghostmaker, pg. 260"
At another place, in a dry creek bed, fourteen Basilisk self-propelled guns, their long barrels raised to the sky ready for bombardment, became lightning conductors. Electrocuted, the gun-crews danced and jerked, or melted onto the white-hot hulls for ten seconds before the combined munitions blew a square kilometer of jungle into the sky in a column of superheated energy and debris.[/quote]

According to Imperial Armour, volume 1, page 160, a basilisk masses some 40 tons apiece, and a crew of 4 (Driver, commander, gunner, and loader.)

14 of them comes out to 560 tons and a crew of 56 (42 in the gun crew, including the commanders.)

"melting" implies incineration level energies. Assuming 42 70 kg males, the minimum energy would 5 GJ to "vaporize" the water in the human body (this is probably a bit generous, since they don't seem to be exploding into vapor.) Cremation level energy is probably more around the order of 3 GJ or so. This is also generous because not all of them are evidently "melting" (And some of the melting/burnign could be attributed to hull proximity.)

Turning the hulls "white" implies temperatures approaching 1500K. Assuming iron-like propeties (which is probably conservative, since if it were white hot it would probably be melting by now) implies between 630 kj and 900 kj per kg of mass. Which comes out to a total energy of between 350-500 GJ over 10 seconds or so. This is probably a more reliable estimate than based on the individuals, for obvious reasons.

The detonation of the ammo is a bit harder to work out. Since we don't know if it blew out a crater or not, or how deep, we can't estimate calcs in that way. The implied "square kilometer of superheated" material implies a fireball radius of several tens of meters, which might suggest firepower in the tens or hundreds of tons range combined. Assuming a 30 meter diameter crater on the asteroid destruction calculator we come out to between 5 and 27 tons as a guesstimate.

A more accurate low-end estimate will be the idea that the explosion vpaorized all 14 tanks (and their crews) Vaporizing 560 tons of iron at 1500k temp requires the additional injection of around 3.7e12 joules of energy (Cremation of the crews is a relatively "insiginfiicant" 13 GJ or so.)
which should work as a rough order of magnitude estimate (it IS possible it took less energy since not all the tanks may have been vaporized, but odds are that it probably was given the already-existing state of things.)

According to the Imperial armour entry, a Basilisk carries no more than
20 rounds on average. With 14 tanks this comes out to around 280 rounds total (disregarding for a moment secondary ammo, which comes out to aroudn 4200 heavy bolter rounds) Going with the 3.7e12 joule figure (884 tons), we come out with an estimate of around 3.15 tons of explosive power per round. If we assume the heavy bolter rounds contributed around 5% of the total explosive force, each heavy bolter shell would be worth about 10 kilos of TNT.

[Connor MacLeod]

As for bolter overpenetration with Eisenhorn's extra special bolt pistol, if he's using the standard mass reactive ammunition it will explode inside the target and somewhat limit that danger.

The problem is that as I noted, the round's sheer KE/momentum is going to be immense, enough to kill a target WITHOUT the shell exploding. Indeed, even if overpenetration isn't an issue (whether or not it is is going to depend on timing - does the shell pass through the target before the detonator goes off - that depends on how quickly the fuse goes off, which I don't remember offhand if it was stated anywhere. Even if the shell doesn't pass out of the target before going off, it could penetrate fairly deeply enough to waste some of the explosive effect.)

A bolter (at least according to 3rd edition rules I could find) is supposed to be able to destroy an armored vehicle with its explosive warhead, but not (to my memory) the impact of the round.

In any case, I can simply make a case for these rounds being non-standard simply by pointing to the "Gravitic motor." Most rounds are stated to be rocket-propelled, which at these levels would be harmful to anyone firing the gun (we're talking about a hypervelocity plume of superheated gas ejected towards the guy firing...)

[Connor MacLeod]

More random quoting:

Using the orbital batteries of Jhanna to melt the planet's ice caps, drowning nearly four billion people in the resultant floods.

This decay and rediscovery makes for very eclectic technology. THere is no uniform technology level across the Imperium. Some technology is very advanced, others very primitive. Many vehicles might incorporate both extremes. This creates vehicils that might include sophisticated targeting systems or mind-impulse links, whilst being driven by a steam-powered turbine! Imperial starships are a good example of this fusion, whilst capable of sophisticated astro nagivation and warp jumps, many other onboard tasks have to be accomplished by manpower alone, such as men hauling upon chains to position guns.

Forge Worlds are the industrial heart of the Imperium. Ruled and maintained by teh Adeptus Mechanicus, they are planet-sized factories, producing the raw materials of war. Each world has billions upon billions of servitor slaves working in manufactorums that never cease production.

"There are thousands of Forge Worlds dotted across the enitre Galaxy"

"The Imperial Guard is the largest fighting force in the galaxy, and the largest militaer y organisation in the long history of Mankind. It his huhge, billions upon billions of men at arms and mllions of tanks and artillery guns stand ready to fight for the Emperor.
...
Many units are formed as infantry regiments, with tens of thousands of men."

[Imperial Overlord]

The problem is that as I noted, the round's sheer KE/momentum is going to be immense, enough to kill a target WITHOUT the shell exploding. Indeed, even if overpenetration isn't an issue (whether or not it is is going to depend on timing - does the shell pass through the target before the detonator goes off - that depends on how quickly the fuse goes off, which I don't remember offhand if it was stated anywhere. Even if the shell doesn't pass out of the target before going off, it could penetrate fairly deeply enough to waste some of the explosive effect.)

..........

In any case, I can simply make a case for these rounds being non-standard simply by pointing to the "Gravitic motor." Most rounds are stated to be rocket-propelled, which at these levels would be harmful to anyone firing the gun (we're talking about a hypervelocity plume of superheated gas ejected towards the guy firing...)

The gravitic motor is probably the best solution to it (I must confess the hellish transfer of momentum of that scene and what that implies has always bugged me). The mass reactive explosion does explain why he doesn't get ridiculous over penetration in his shots. Hyper velocity bolter rounds don't zip out of his targets or through the Witch Hunter's power armour. The shells still explode inside their targets.

[Black Admiral]

The Ordinatus Gehenna:

Revealed before their eyes was a monstrous cannon mounted on a carriage formed from three traction units. The weapon seemed huge against the backdrop of the jagged Argentum peaks until Gdolkin realised that the specks crawling around the base of the tracked units and over the holed hull itself were in fact human-sized figures - Death Guard, Imperial soldiers, traitor PDF troops and the tech-guard of the Adeptus Mechanicus.

The ordinatus engine rose up before them, a colossal construction of Mechanicus might, all monstrous traction units, defence cannons, augur arrays and command spires.

The ancient war machine was dominated by an enourmous barrel, larger even than one of the giant warrior-gods of the Titan Legions, that rose from the centre of the largest of three traction units. It was a leviathan creation of a gun dating from even before the birth of the glorious Imperium. Surrounding the monstrous cannon were all manner of archeotech devices, such as building-wide tesla coils to help focus and maintain the devastating, mountain-levelling beam the gargantuan gun produced.

The mouth of the barrel opened like a volcanic crater. At least half of the city-sized war machine was made up of the generarium units needed to produce the incredible amount of power necessary to fire the apocalypse cannon.

A pulse of crimson light erupted from the mouth of the enourmous cannon, wreathed in coruscating beams of barbed orange lightning, waves of power evaporating to heat and melting the fog of war from above the battlefield accompanied by a hurricane force wind.

In the distance, still some kilometers away, amidst the stripped bare bedrock of the Argentum Mountains, lay the focus around which the Plague God's forces had gathered like flies around a corpse.

The apocalypse beam cut through the roiling clouds circling above the ragged peaks, burning away the unnatural night that claimed dominion over the mountains in a searing blaze of light that was indeed like the light of apocalyptic oblivion.

The cannon's beam hit the mountainside with all the force of a crashing meteor. The mountain exploded, shards of rock the size of hive towers splintering away from the face of the target. The foothills of the Argentum range were buried by a tumultous landslide, sheets of rock pummeling down the mountainsides. Cataclysmic booms shook the spine of of the mountain range.

The beam continued to bore its way through the bedrock, into the planet, like a Mechanicus mining machine, the land for a radius of twenty kilometers suffering seismic disturbances violent enough to topple tall buildings. The very ground beneath the great Gehenna shook, so that barely a man was left standing on board that monumental vessel. It felt as if the recoil forces unleashed by the firing of the cannon were going to shake the wounded ordinatus apart.

A great gout of broiling lava vomited skywards as the apocalypse cannon's beam finally punctured a magma vent deep beneath the earth. Whatever lay beneath the mountains that was of such importance to the Death Guard and the other heretics was buried, destroyed in the volcanic heat of the gushing lava flow. Thousands of ravening cultists and their Nurgle Marine overseers dissolved in the fiery flood that erupted from beneath the planet, as if Fornax Orbis Majoris was at last being avenged upon its pillagers.

But if the violent seismic activity caused by the apocalypse cannon's blast had seemed terrible, it was as nothing compared to the devastation that came in its wake.

It was as if all sound had been sucked into the crater that had been created by Gehenna's cannon, for the breifest moment, only to be replaced seconds later by a subsonic whomph that passed through everyone and everything in a ten kilometre radius. And this was only the atmospheric pressuing precursor to the shockwave that was coming.

[DocHorror]

On the subject of Eisenhorns pistol, it could be fitted with suspensors to lighten its weight or aim him in weilding it.

[Lost Soal]

As a purely kinetic force, the shot from Eisenhorn is completely out of proportion to any other example I've read of bolters. It really needs to be rationalised better.
I honestly believe that the major cause would be the explosive, rather than the kinetic impact. And considering she was walking on a spider chassis it wouldn't take huge amounts to send her flying back by virtue of her stumbling back, then falling. The damage mentioned when she seen walking away could conceivably have been enough to momentarily lose control upon impact.

[Connor MacLeod]

The mass reactive explosion does explain why he doesn't get ridiculous over penetration in his shots. Hyper velocity bolter rounds don't zip out of his targets or through the Witch Hunter's power armour. The shells still explode inside their targets.

Only up to a point. If the bolter shell has alot of momentum in it, it could still "over-penetrate" the target even if the shell explodes. But instead of a single bolt punching through, you'd have a bunch of high-momentum shrapnel bursting out of the back of the target. (and as I said, unless you're sniping at this target from miles away, there's no real need to build up that sort of velocity or KE in most engagements where bolters are used. In fact, its potentially wasteful since the explosion is going to fragment the round anyhow)

[Connor MacLeod]

As a purely kinetic force, the shot from Eisenhorn is completely out of proportion to any other example I've read of bolters. It really needs to be rationalised better.

The gravitic motors explains the lack of recoil (this is perhaps a case where the Bolter's design assists in explaining the evident inconsistency - the power of the round to knock targets back like this can be independent of the type of weapon used.

As for the extraordinary effects, thats why I suggested that as a speciliazed Inquistor round, this ammo is specifically designed to take on powerful enemies (or very big ones) like Daemons. Most ordinary targets are probably going to be pulverized by the impact of the round (possibly even before the explosive goes off) which is extraordinarily wasteful. Since IIRc one of the duties of an Inquisitor is to tangle with powerful enemies like Daemons, it makes sense that they would make use of exceptionallry strong weaposn when the situation demands it.

I honestly believe that the major cause would be the explosive, rather than the kinetic impact. And considering she was walking on a spider chassis it wouldn't take huge amounts to send her flying back by virtue of her stumbling back, then falling. The damage mentioned when she seen walking away could conceivably have been enough to momentarily lose control upon impact.

Ideally yes, but after I suggested this I also realized there is a small problem with this as well: the explosion might very well strike Eisenhorn as well, unless its a shaped charge (which it could be.)

[Connor MacLeod]

Regarding the Gehenna ordinatus:

There are three mechanisms that i can see that might be quantifiable:

1.) Ability to "level" a mountain (both claimed and "observed.")

Assuming a 2 km diameter sphere (somewhat generous, since a mountain is not a sphere).. probably around 2-8 megatons for shattering a mountain. (using SD.net asteroid destruction calculator.)

2.) the seismic effects craeted by the beam's impact.

comparing the effects and the implied destructive radius to Richter scale magnitude effects here I'd guess that the quake effects were somewhere between magnitude 6 and 7. This would correspond to an energy equivalence of between one and 32 megatons

3.) The evident "blast wave" effect created by the energy release.

Using the "nuclear explosion effects" calculator, the effects are probably ccomparable to a roughly 10-12 megaton nuclear explosion's air blast (widespread destruction.). A 10-20 megaton asteroid impact would be, I believe, ,roughly comparable.

Thus I believe it probably can be safely said that the Ordinatus in question has a sustained output in the single or double-digit megaton range.

[Connor MacLeod]

This is going to be a series of big-ass posts...

A useful collection of Battlefleet gothic tidbits

There's actually a buttload of stuff here, so I'm just going to post what I think is relevant and let Necronlord take what else he thinks is worthwhile from the link:

Stellar empires cannot really be reckoned in terms of the spatial areas they occupy, but only in terms of the star systems under their control. The Imperium is the largest such empire in the galaxy. The million or more worlds that lie under its dominion are spread throughout the entire galaxy with the exception of the Eastern Fringe. It extends to the limits of the Astronomican, the beacon which its fleets rely on for navigation. Of course the Imperium does not control all of the star systems within this vast area, nor even the majority of the inhabited systems within its borders. The galaxy also contains many alien races ruling smaller empires of their own.

This quote seems to suggest that the planets controlled that matters more than the volume of space patrolled. (which after a fashion, makes a great deal of sense. Empty space IS, after all, empty space. Which means that basing fleet calcs solely on "Sector volume" alone may be questionable.

Each planet is responsible for its own defence. Imperial Commanders are obliged to build ground-based defences, spaceports, and what defence fleets that can. The number of weapons and ships in any individual system will vary, depending on the enthusiasm of its governor as much as the possible danger. In addition to ships under the control of the Imperial Commander, planets lying in vulnerable positions or having a history of trouble may also have an Imperial Fleet base. Although Fleet ships are independent of those of the Imperial Commander, both would be ready to meet an emergency. Fleet ships may also be stationed in one system so that thcy can patrol a number of nearby star systems.

Description of in-system defenses. I think its worth noting that the Imperium seems to favor a greater emphasis on "fixed defenses" in terms of numbers (especially for vital areas like Cadia or Terra) rather than on large numbers of mobile assets. This probably makes sense, given the age and time needed for construction of Warp-capable starships. (I'm betting hte in-system defense ships are cheaper to manufacture, and ton-for-ton, probably far more effective than a warp-capable ship of equal size due to their specialized natures. Same with battlestations or orbital weapons platforms.)

Journeys are undertaken in short jumps of up to 4 or 5 light years. Longer jumps are unpredictable and dangerous. The tides of warpspace move in complex and inconsistent patterns and ships attempting longer hops often end up wildly off course.

The idea presented here seems to be that the shorter the warp jump, the more accurate it is. This might also suggest the possibility that tactical war-jumps are possible under certain conditions (although limits mentioned later on might suggest difficulties in doing this while in-system.)

Light Years Minimum Warp Time Maximum Warp Time Minimum Real Time Maximum Real Time
1 2 mins 6 mins 43 mins 4.5 hrs
5 7 mins 30 mins 3.5 hrs 1 day
10 14 mins 1 hr 7 hrs 2 days
50 1.25 hrs 4.75 hrs 1.5 days 9 days
100 2.5 hrs 9.5 hrs 3 days 3 weeks
500 12 hrs 2 days 2 weeks 3 months
1000 1 day 4 days 1 month 6 months
5000 5 days 3 weeks 5 months 3 years
So, for example, a 100 light year jump will seem to take from 2.5 to 9.5 hours to a spaceship's crew, but between 3 days and 3 weeks will have passed in real space. These times do not include journey times out to and from jump points on the edge of the star systems. It takes from days to weeks of travel at sub-light speeds to reach a drop from the spaceship's starting planet, and a similar time to re-enter the destination system.
The Imperium is approximately 75 thousand light years from edge to edge. A journey of this length would take between 75 and 300 days in warp time, and between 6 years and 40 years real time.

The FTL velocities implied by the above vary from a few thousand c to some 12,000c, though I am well aware this should not be taken s a fast and hard limit (other examples suggest higher.) It may be that these reflect either a certain period in time, or only regional limitations

Once within warpspace a ship may move by means of its main warp drives, following powerful eddies and currents in the warp, eventually reaching a point in the warp corresponding to a destination in real space. The most difficult aspect of warp travel is that it is impossible to detect the movement of warpspace once a ship is in the warp. The ship can only blindly carry on, its crew trusting that it is going in the right direction. The longer a ship remains in warpspace the greater the chances of encountering some unexpected current that can turn it unknowingly off-course.
Navigation of warpspace can be achieved in two ways: the calculated jump and the piloted jump.
All warp-drives incorporate navigational mechanisms. When the ship is in real space, these monitor the ever shifting movements of the part of the warp corresponding to the ship's current position. By observing these movements in the warp it is possible to calculate a course, corrective manoeuvres, and approximate journey time to a proposed destination. Calculation relies on the assumption that the warp-currents observed from real space don't change significantly during flight. This method is known as a calculated jump. It is not safe to make a calculated jump of more than four or five light years at one go. The longer the jump, the greater the chances of a significant change in warp current movement.
The second, and more efficient, form of warp-navigation is the piloted jump. This method relies upon two factors: the human mutants known as Navigators and the psychic beacon called the Astronomican. The Astronomican is centred on Earth and is not only controlled by, but is directed by, the psychic power of the Emperor himself. The Astronomican is a beacon that, because it is psychic, penetrates into warpspace. A Navigator on hoard a ship in the warp is able to pick up these signals and can steer a spaceship through warpspace, compensating for current changes as he does so. A piloted jump can safely cover a far greater distance than a calculated jump. 5,000 light years would he the normal maximum jump, but longer jumps have been made.

Describes two methods of navigating in Warp: the most effective is via the psychic Navigators. The second example (usable only for short ranges in the Imperium universe warp) are via navigational devices

The Imperium is divided into five fleet zones known as the Segmentae Majoris. Although intended for purposes of fleet administration and shipping controls, the Segmentae have evolved into administrative divisions of the Adeptus Terra.
All shipping is supervised within the jurisdiction of one of the five Segmentae. Each Segmentum has an orbital headquarters called a Segmentum Fortress which forms the base of fleet operations within the Segmentum. The Segmentum Fortress is controlled directly by a high-ranking official of the Administratum known as the Master of the Segmentum.

There are five major fleets in the Empire. This fact becomes relevant later on.

Each Segmentum is divided into sectors. The size of a Sector varies according to local demands and stellar density. A typical sector might encompass 7 million cubic light years, equivalent to a cube with sides
almost 200 light years long.

Sector volume. Roughly matches up with what is stated in other sources. (particularily considering its basically na average.)

Sectors are divided into sub-sectors, usually comprising between 2 and 8 star systems within a 10 light year radius (some may encompass more systems - others only 1). This size is governed by the practical patrol ranges of spaceships. Because sub-sectors are divisions of worlds (rather than volumes of space) there are vast numbers of star systems within each sector which do not fall with in a sub-sector. These are referred to as inter sectors - and are commonly known as wilderness zones, forbidden zones, empty space and frontier space. Inter-sectors may contain gas or dust nebulae, inaccessible areas, alien systems, unexplored systems, uninhabited systems and uninhabitable worlds.

distribution and makeup of a sub-sector. Note that this quote also seems to suggest that much of the volume inside the Imperium, while "in" the Imperium's territory, may not be controlled or otherwise inhabited by it. The implication seems to be that there is a great deal of space that they claim but do not actually have the resourcese to control (as of yet, at least.)

A more accurate means of scaling may be achieved by the number of worlds in a sector or sub-sector (I believe estimates on both exist.)

The Imperium's interstellar ships comprise merchant vessels, warships, civil craft and several other specialised types. These are organised into specific fleets: merchant fleets, warfleets, and civil fleets. Each of the Segmentae Majoris has its own merchant, civil and warfleets. So for example, the Warfleet Solar is the warfleet of the Segmentum Solar, the Merchant Pacificus is the merchant fleet of the Segmentum Pacificus, the Civilus Tempestus is the civil fleet of the Segmentum Tempestus and so on.

Commentary on how the fleets of the Imperium are organized, and the categories. with roughly 3 fleets per Segmentum, that's 15 fleets total (5 War fleets, 5 civil, and 5 merchant fleets.)

The combined merchant fleets comprise almost 90% of all interstellar spacecraft in the Imperium. Each fleet is based in one of the five Segmentae Majoris. and its administrative staff operate from the Segmcntum Fortress. For example, the Solar fleet is based on Mars, while the fleet of the northern zone - the Segmentum Obscurus - is based on Cypra Mundi. Although these fleet bases are huge ports equipped with docks, shipyards and repair facilities, their main function is to administrate the fleets operating within their area. Only a small proportion of ships ever travel to the Segmentum Fortress where they are theoretically based.

Commentary on the distribution of spaceships in the Millenium and the organization of the Segmentum Fortresses. Note that this also establishes a bare minimum of five major shipyards for the Imperium.
Given Lost Soal's earlier quotes regarding the "fabric of the Imperium" and its millions of freighters, we can assume that the other 10% of the fleet is made up of Naval warships and private vessels, which gives an idea of their numbers (hundreds of thousands, likely.)
Note that this is "inter-stellar" spacecraft, ,not "sub-stellar" - that is, the warp capable vessels. Other calcs may be inclusive of warp-capable and "non-warp" capable craft.

Although the vast majority of interstellar spacecraft are part of the merchant fleets, there are several thousand ships registered to individuals, families or trading cartels. All privately-owned interstellar craft operate along routes licensed to them by the fleet authorities responsible for shipping within that Segementum. These route licences must be bought, and must be renewed after a fixed time, usually a hundred years. This means few privately-owned ships like to risk the effects of time dilation on long journeys. A licence may run out before the ship has completed its journey!

Civil fleets vary in size from a single vessel to several dozen. One of the largest is that of the Navigator family Redondo, numbering 47 registered interstellar ships. Most ship owners have only a single vessel.

This quote suggests that Civil fleets make up a very negligible precentage of the remaining 10% of the Imperium's fleets that are not Merchant vessels. (less than 1%.) This suggests that 10% of the Imperium's fleets are warp-capable warships of varying classes.

Each of the five warfleets serves within one of the Segmentae Majoris and is responsible for protecting shipping within it.
Most space battles take place around installations or planets, most of which can be defended efficiently by means of sub-stellar craft and planet-based defences. Even so, it is impossible to provide total defence for every Imperial world. The warships of the Imperial Fleet are highly mobile and extremely potent weapons, able to gather to meet large threats where necessary.
Warship captains are Imperial servants like their merchant brethren. However, all warship captains are appointed by the administrative officers of the Segmentum, and have no rights of ownership regarding their vessels. The organisation of the fleets is far more rigid than that of the merchant fleet, with a hierarchy similar to that of the land-based armed forces of the Imperium.

This implies (as Necronlord has pointed out, I believe) that the total strength of hte Imperial Navy cannot be such that it could adequately garrison every planet (whatever 'total defense" means.) suggesting that many millions of ships is unlikely. (This may be in reference to interstellar vessels only, however. As I noted, sub-stellar ships may be a different story.)

[Connor MacLeod]

Continued...

Imperial space is so vast, with so many star systems and areas of Wilderness Space to be patrolled, that even the many thousands of spaceships in the warfleets must be spread thin, with individual ships and squadrons set out on their own assignments. The Imperium cannot maintain permanent fleets ready to respond to invasion or rebellion. Nor would it make sense to do so - it would take so long for a fleet to get from its base to the war zone that the enemy would surely have moved on by the time it arrived.

Instead, temporary battlefleets are gathered together whenever they are needed. Warships within a relatively small area are summoned to join the battlefleet. It is rare for ships more than 50 light years from the battle zone to be included in the fleet and more commonly only those within 10 or 20 light years are summoned. Even with ships this close to the battle, it will take at least days and more often weeks for them to arrive.
Only during the very largest of wars, lasting for many decades, does the lmperium bring battleflects together and dispatch them en masse to a warzone. Such a war is currently underway in the galaxy's south-eastern spiral arm. Here the Tyranid Hive Fleet Kraken is inexorably advancing, conquering and consuming the planets in its path. A massive campaign involving millions of men, thousands of ships and whole chapters of Space Marines is being fought against the Tyranid invasion. Fleets are being mustered in all the Segmentae to begin the long journey to the warzone. The journey will take decades in some cases and many of the crew will never see the battles they are heading towards - but the Imperium knows all too well that in mere decades the Tyranid threat will be as strong as ever.

Several points of note:
- low end of "many thousands" of ships per war fleets. (this places an absolute low limit of around 10,000-15,000 "interstellar" vessels in the Navy, but as noted, other sources probably suggest much higher. "many thousands" suggests that even taken literally, the cacls are probably on the higher end of the thousands range.. 30,000-50,000 interstellar ships minimum.)

- reiterates that fleet sizes are small enough relative to the terirtory that the Naval assets are "spread thin", placing some constraints on total fleet size. (Same with the inability to maintain "permanant" fleets.)

It is also not unknown for squadron or fleet commanders to rebel and turn against the Imperium, using the awesome power they command to carve out their own petty empires on the fringes of Imperial space. The most infamous rebellion in the Imperium's long history is that of Warmaster Horus when fully half of the Imperial forces turned against the Emperor and mankind was divided in a terrible civil war. Only the death of Horus himself and the banishment of the rebels to the Eye of Terror brought peace to the Imperium. Even now, a constant vigil is kept around the Eye of Terror where the Chaos fleets remain, often launching small raids and occasionally major incursions into Imperial space.

"Half the Imperial forces" seems to imply naval ships as well as non-naval forces. This might give indications about Imperium Naval Strength or about Chaos strength if either number is known.

Most spaceships are old - open space, the most hostile environment to man, preserves the plastics and metals that spacecraft are made from. Space gives them with the power to endure through generations of men. The Imperial fleets number many thousands of ships, the majority of which are at least a thousand years old. Some are as old as the Imperium itself, a full ten thousand years. A very few claim a pre-Imperial origin. It is difficult for those born under the claustrophobic sky of a planet to appreciate the great dignity which is inherent in all old spacecraft.

Age is indirectly suggestive of their extreme durability, I think. I'll have to check more on this, but seems likely, given what is described below.

The spaceships of the Imperium are vast constructions that take many decades to build. Each craft represents a huge investment of time and resources. But once completed, fitted out, armed and commissioned, a spaceship continues in service for centuries, even millennia. After that, it may be refitted, modernised, reconstructed and live on practically indefinitely. Barring a major accident or destruction in battle, a ship is immortal like a great city, its population and fabric existing in a constant state of decay and renewal.

Starship construction implied in the "decades". Unknown whether this applies to escorts, cruisers, or battleships.

Throughout this time there is a constant process of rebuilding and renewal. Hulls are damaged by battles, asteroid storms and the ravages of the warp. Mechanical parts inevitably wear down. Electrical components fuse. Engine housings crack or melt under the immense pressure and heat created by plasma and warp drives. To combat this constant process of decay, every interstellar spaceship has a maintenance crew of hundreds or thousands of dedicated craftsmen, continuously striving to repair and refit the ship. Inside a large Imperial warship there are factories and workshops, huge forges and plasma furnaces, even small refineries and ore smelting plants to provide raw materials for the work of reconstruction.

Imperial warships are self-sufficient in terms of self-repair. Given access to resources and time, they can presumably repair some or most forms of damage the ship could encounter, which is consistent with their long-range operational capabilities.

Lower limit of thousands of crew.

Interstellar spaceships are powered by plasma and warp drives. Plasma drives are used to move through star systems at sub-light speeds. They burn with the fierce energy of a star, converting their fuel into a super-heated gas plasma to create the immense thrust needed to propel these gargantuan craft through space. As a large interstellar spaceship moves out of orbit towards the edge of a star system ready to jump into the warp, the fiery arc it traces across the night sky can clearly be seen from the planet it's leaving. It appears to be a great comet streaking through the heavens - on many worlds, the arrival or departure of' a spaceship is read as an omen, a divine harbinger of joy or doom.

Plasma drives described as basically a reaction drive ( meaning that if mass and acceleration are known, powerplant figures can be estimated.)
- implied stellar scale output "They burn with the fierce energy of a star" Unknown what ship this applies to.

Warp drives are altogether more esoteric and terrifying, understood by few even among a spaceship's crew. When the spaceship reaches the jump point at the edge of the star system it's leaving. its plasma drives are turned off and its warp drives engaged. These hurl the spaceship out of real space and into warpspace, propelling it through the warp to a destination light years away. If a spaceship's warp drives were switched on while it was still within a star system. the huge rent in the very fabric of space that they create would be catastrophic for the population and planets of the system. The spaceship itself would be torn apart as the massive pull of the star's gravity reacted unpredictably with the energies released by the warp drives.

Description of warp drives. Note that the implication is that gravity DOES affect the ability to utilize warp drives (Stellar-scale gravity wells can pose a significant danger while in-system.) suggesting possible means of interdiction. Also note that the activation of warp-drives in a star system is suggested to be extremely destructive (although the mechanism isn't precisely defined), suggesting it might make an effective weapon of mass destruction.

Fully one-third of a spaceship can be taken up by its engines with their huge thruster ports, cavernous combustion chambers, generators surrounded by massive protective cladding and the miles of pipes, tunnels, corridors and ducts needed for the control mechanisms, fuel supply and access by service crews.

"miles of pipes" is suggestive of multi-km lengths for starships (especially given the indication that 1/3 of a spaceship can be taken up by engines alone!)

The living areas of a spaceship contain the thousands, often tens of thousands, of men that serve aboard. These areas are often built up from the ship's hull into huge domes and spires that rise hundreds of metres into space. On some ships, they seem like the heart of a mighty city, immense towers rising to touch the stars, their sides glittering with lights, bridges spanning the void between them. On others they resemble a gigantic cathedral, the towers colonnaded and sculpted. Vast carved figures of legendary heroes recede into the darkness of space - huge homed gargoyles leap and leer from the highest pinnacles in mockery of the terrors of warpspace - golden domes blaze with the light of stars.

- Crew sizes specified into the thousands or tens of thousands, minimum.
- "living areas" implied to be domes/spires that rise "hundreds of meters" into space. Since the implication is that the living areas are not substantial sections of the ship, this further reinforces the implied scale above. (It also might serve as a useful scaling marker in determining starship dimensions.)

On freighters and merchant vessels, the rest of the ship is taken up by holds containing the ship's precious cargo. On warships this space is filled by the colossal power generators that drive their weapon systems. These towering structures hum and crackle with the monstrous energies bounded inside. They are housed within deep shafts which disappear from view into a darkness that is broken only by the crackling blue arcs of lightning which leap from the generators. When a laser battery is fired with a titanic unleashing of energy, its power well is filled with a furious roar. In battle, a warship echoes with the thunder of its weapons. its decks shuddering with the recoil of their furious discharges.

Weapons recoil (at least in most weapons) is implied to be enough to shake the decks, but presumably not enough to either knock people down or shove the ship physically aside. (But that is merely an implication. For some weapons, like Nova Cannon, this is clearly not true.)

LASER BATTERIES
Ranked batteries of powerful laser cannon are the most common armament on the spaceships of the Imperium. Mounted in huge turrets, the lasers are powered by immense generators deep within the spaceships. They release their energy in deadly bolts of light with the power to punch through the massive hulls of spaceships. They are brought to bear in a single broadside that rakes a line of devastation across an enemy spaceship.

This probably contradicts some of Battlefleet gothic given the change over to "lances" and "weapons batteries", but not neccesarily so (lances, or some of them at least, are implied to be lasers.)

FUSION CANNON
The fusion cannon is powered by the awesome energy released as atoms are brought together in a nuclear furnace and fused into new matter. At short range, the effects of a fusion cannon are devastating but they drop off quickly at longer ranges.

"Fusion cannon" description seems to differ from "fusion guns/meltas" in effect slightly. Implies the weapon is pwoered by a fusion reactor (which would be kind of inconsistent with the implied power generation figures they possess.) Maybe this applies to light weapons or point defense guns only.

PROW LASER
The prow laser is a single bank of laser cannon firing from the front of the spaceship. Although not as powerful as a laser broadside, it's forward position gives it a good arc of fire to attack incoming ships. It is often used to soften up the enemy as the spaceship prepares to ram.

Mention of prow and broadside-mounted lasers (lances?) as well as turreted weapons.

VORTEX TORPEDO
A vortex torpedo creates a vast vortex held when it explodes. The vortex field disrupts the very fabric of the universe as the raw energy of the warp is pulled through into real space with terrifyingly destructive effects, even to something as large as a spaceship.

Implication seems to be that a vortex torpedo relies on tapping the enerrgy of the warp and releasing it into normal space to inflict damage (though some sort of spatail distortion might also be a weapons mechanism.) Sort of like gridfire. (presumably other weapons such as the warp cannons on the Blackstone Fortresses operate in a similar fashion.)

PLASMA TORPEDO
The plasma torpedo explodes in a burst of super-heated energy that literally burns its way through a spaceship's hull as the craft is engulfed in a ball of white-hot flame thousands of metres across.

Curious that plasma torpedo diameters suggest they are "multi-kilometer" in diameter. Presumably this means the plasma is "contained" in the torpedo prior to detonation, then released as a ball of superheated matter kilometers across (This would be consistent with the apparent mechansim of plasma grenades and plasma missiles in other sources). Again also serves as indirect suggestion of multi-km lengths

[Connor MacLeod]

Last bits for now...

GOTHIC BATTLESHIP
The Gothic is the mainstay of the Imperial Fleet and Gothic squadrons form the core of most Imperial battlefleets. Gothic battleships bring both the protection and the authority of the Imperium to the star systems they visit. They operate in squadrons or singly, for the presence of even one of these vast warships is enough to bring a rebellious planetary governor into line or disperse raiding pirates to other more lucrative and less well-defended systems. Some Gothic squadrons are more or less permanently stationed in one star system. In the Segmentum Obscurus, for example, they form part of the fleet stationed around the Eye of Terror, defending the Imperium from attack by Chaos fleets and raiding Chaos Renegades. Other squadrons move from star system to star system, staying for a few months or years to complete their mission, refuel and resupply before making the jump to their next destination. During the squadron's assignment to a system, a large flotilla of sub-stellar craft constantly surround the battleships, moving to and from the system's planets and moons. They supply the ships with food, fuel, ore, raw materials, personnel and all the other necessary supplies that these huge spaceships, each the size of a large city, require for their upkeep. In battle, the long range of a Gothic battleship's vortex torpedoes make it a dangerous opponent, often able to launch one or more attacks before an enemy ship can get within range to return fire. When it does close with the enemy, the Gothic battleships powerful laser batteries are fully capable of destroying an opponent with just a few broadsides while its own strong shield defences protect it from enemy attacks.

- Gothic class battleship "the size of a large city" suggestive of a length of many miles

- range of torpedoes is implied to be substntailly longer than range of direct-fire weapons (lasers, no less..) Ie implied multi-light-second ranges.

- Gothic-class battleship is implied to be more powerful on its own than all the defensive installiations and sub-stellar craft that most Governers or raiders can amass. Its broadside lasers can destroy a target in a few salvos (possible benchmark for Gothic's offense or targets defensive capabilities if target is known.)

FIRESTORM CRUISER
Firestorm Cruisers are often used on long-range incursions and patrols and as the first line of defence against alien attack. In the inhabited parts of human space, they jump from system to system, maintaining regular contact and reaffirming the ever-watchful presence of the Imperium. Even with frequent patrols, the sheer size of the galaxy and the number of inhabited planets may mean decades pass before a system is revisited. Whole generations live and die between patrols and many of the Imperium's citizens never experience the passionate excitement of the arrival of a squadron of these mighty warships. In the less-densely populated parts of the galaxy, the Firestorm squadrons patrol the vast areas of Wilderness Space, hunting down pirates and rebels, watching for signs of invasion by Ork or Tyranid fleets, and fighting innumerable small battles at the fringes of Imperial space. Similar in design to the Gothic battleship, the Firestorm cruiser is a much faster spaceship. Although its weapons have neither the range nor the power of the Gothic battleship, the Firestorm makes up for this by its ability to close quickly with the enemy, allowing it to respond to unexpected enemy manoeuvres or move to exploit weakness in the enemy line.

- Firestorm's weaponry is implied to be simialr to, but less powerful and shorter ranged, than a Gothic battleship. This may imply that firepower and range are related (for energy weapons at least. Projectiles such as torpedoes one may assume are related to size of the projectile.)

IRONCLAD BATTLESHIP
The Ironclad battleship hails hack to a time before the Imperium and these ships are millennia old. They were built when mankind's shield technology was too primitive for the defence of spaceships. Instead their hulls are massively armoured, covered with layer upon layer of thick plates arranged to deflect and minimise the impact of torpedoes and laser fire. Over the many centuries of its service, every Ironclad has fought in countless space battles, and each ship's surface is pitted and rutted with the sears of combat, a glorious history of its long defence of the Imperium. In times of peace, the Ironclad and the Gothic battleships share many of the same roles. In battle, the Ironclad plays a very different part. The Ironclad's main weapon is the fusion cannon, a weapon of awesome power capable of destroying an enemy spaceship in a single shot, Its energy, however, falls off at longer ranges and the Ironclad needs to close with enemy to be most effective. Where the Gothic battleship can stand off at range and use its greater mobility to outmanoeuvre the enemy, the Ironclad must surge forward to deliver its attack at close quarters, braving the enemy fire and trusting to the protection of its massively-armoured hull.

- Imperium's armor technology is implied to be reflective/dispersive in nature, as opposed to other mechanisms (IE ablative.)

- Ironclad's firepower implied to be several times greater than a Gothic's, but its range much shoter.

COBRA DESTROYER
Cobra Destroyers usually act in support of battleship squadrons. When a Gothic battleship, for example, arrives in a system, its supporting Cobra squadrons are deployed to patrol the individual planets and moons. Their speed and mobility make them ideal craft to pursue and engage the sub-stellar spaceships of pirates, smugglers and rebels. For although they are small in comparison to the mighty battleships they accompany, Cobra Destroyers still vastly overawe and outgun all but the very largest of sub-stellar spaceships. Cobra Destroyers are among the fastest warships in the Imperial Fleet. In battle, they operate in large squadrons, moving in tight formation into close contact with the enemy before firing their lasers or their destructive vortex torpedoes. Even in large formations, Cobra squadrons can make tight turns, allowing them to sweep around an enemy's flank or move directly through his fleet, turn and launch a second wave of attacks from the rear. If the enemy turns to face the Cobras, he runs the very real risk of leaving himself open to attack from the rest of the battlefleet.

- Destroyer is implied to be more powerful than all but the "largest" sub-stellar spaceships. This probably places an upper limit on the size/firepower of such vessels.

CASTELLAN SHIELD SHIP
The Castellan is a battlefleet support ship. Its role is to provide other warships with the vital defence they need to be able to close with the enemy and bring their weapons to bear. The Castellan shield ship is built around a single huge shield generator. Most warships have a number of shield generators each projecting a short-range field in one direction. The Castellan shield emanates from the ship in every direction and is powerful enough to extend its protection to any spaceship close to the Castellan. When the Castellan shield is hit by enemy attacks, the shield generator absorbs the energy of the attacks, preventing them from damaging their targets. This causes a gradual build-up of power in the shield generator and only the close attention of its Adeptus Mechanicus custodians prevents it from exploding. Eventually, however, the power build-up becomes so great that unless the generator is shut down it overloads and ruptures in an almighty explosion that literally rips the Castellan apart from the inside. This sends out a vast fireball which engulfs the area that was under the shield's protection and can destroy the spaceships which were accompanying the Castellan for its protection. In battle, the Castellan's Captain must constantly assess the dangers of leaving the shield running or shutting it down to dissipate the energy build-up. If he shuts the shield down too often, he fails to benefit the other ships around him with the Castellan's protection. If he waits too long, he jeopardises those very ships he's meant to he defending.

- Imperium shield technology is implied to be "Sectional" and limited in area of protect, rather than "all encompassing" bubble shields. Presumablyh they use overlapping shield networks to provide total protection.

- Shields are, as noted, absorption and retransmission devices. They store absorbed energy and then radiate it away at a steady rate. However, it is implied that the radiation rate may be slow, or that the energy can only be "bled off" when the shields are down (perhaps the "bleed off" is blocked/absorbed by shields..) Alternately, it may be that the dissipation rate is far smaller relative to the sustained firepower a typical ship can deliver.

EMPEROR CAPITAL SHIP
Emperor capital ships are designed exclusively for war. Their role is not to patrol the Imperium's many star systems or to combat small fleets of rebels and pirates, but to fight in huge space battles as part of great battlefleets. Emperor Captains are chosen from the most experienced and revered of commanders - men whose judgment and outstanding tactical sense has been proved time and again in the heat of battle. It is traditional for the most senior Emperor Captain to be appointed as a battlefleet's commander - his ship becomes the flagship and the beacon to which the other squadrons rally as the fleet gathers for war. The firepower of these vast ships is terrifying indeed. From orbit a single broadside can incinerate a whole city or reduce a mountain range to rubble - moons can be atomised - enemy spaceships seared with pious fire. The huge Emperor ship can only manoeuvre at slow speeds, turning majestically to bring its broadsides to bear. But by driving its engines to their very limit it can surge forward at ramming speed. At the front of an Emperor ship is a massive energy ram ablaze with leaping bolts of raw power. When the ship rams at full speed it is near-invincible, smashing through even the most heavily-armoured hull and leaving its shattered enemy as a cloud of drifting debris in its wake. On board an Emperor capital ship there are docks for the fleet of smaller sub-stellar craft that the ship carries with it. These are used for supply and communication both with planets and with other ships in the battlefleet. The great echoing chambers contain freighters, maintenance craft, scout ships and shuttles. They also house the Emperor's own fleet of fighter craft. These are small warships without warp drives and incapable of interstellar travel which are transported within purpose-built carrier craft or huge capital ships like the Emperors. They are launched during a battle to augment their mother ship's own firepower and move in to make close range attacks against the enemy's ships.

1.) Emperor-class firepower is implied to be capable of "incinerate a whole city" or "reduce a mountain range to rubble" or "atomise a moon"

- Incinerating a city implies multi-km fireball diameters, which is suggestive low end of multi-megaton to multi-GT firepower, depending on diameter.

- Mountain range to rubble. Assuming for conservatism's sake that an individual peak was hemispherical, and an average radius of about 1-2 km yields a fragmentation energy of around 8-64 megatons per "mountain". Now a mountain "range" can extend for hundreds or even thousands of kilometers, so you could arguably inflate the figure by two or three magnitudes to arrive at a firepower estimate. If the mountains are particularily large (3-4 km radius) you might expect hundreds of megatons.

Of course, its possible that each "blast" might make much more massive craters. 40 lasers divided by, say... 100 km "range" yields a crater diameter of 2.5 km - at least 15 megatons per "mounain" a 25 km crater would require 15.6 gigatons.

On the other hand, if you assumed that the broadside created a crater hundreds or thousands of kiloemters in diameter, you're going to get into the millions or billions of megaton-broadside range.

- "moons can be atomized" - Depends on the size of the moon really as well as how you define "atomize". Logically moons could be as small (or smaller) as Deimos (the smallest moon in our Solar system) at about 12 km in diameter and bout 1e15kg in mass - or large as the Earth's moon (or larger) - at 3500 km diameter and 7.4e22 kilograms in mass. As for the definition, "atomize" can refer to something as simple as fragmentation (By britannica's definitions) to vaporization or even to "reducing it to atoms' (encarta).

Fragmenting Deimos can require around 300 megatons to 8 gigatons at least. Vaporizing Deimos totally could require 660-1300 gigatons. Fragmenting the "moon" could require 4e7 gigatons, while vaporization could require firepower in the e11 gigaton range. Its possible I'm underestimating the energy though - it could be well into the e29 joule range (if we're talking "scattering the mass" of the planet.)

2.) An Emperor-class is durable enough to survive ramming another target with little or no damage to itself (implied structural and forcefield protection.)

3.) Emperor class ships carry their own small craft, including freighters, maintenance craft, scouts, fighters, and shuttles. This implies they are "substantially" larger than most battleships, unless we're talking very small or light freighters.

ELDAR WRAITHSHIP
Unlike the spaceships of the Imperium, powered by plasma engines and warp drives, the Eldar Wraithship with its vast sails is powered by starlight itself. Every star radiates a gale of photons, known as the solar wind, which the Wraithship catches in its sails. The Eldar are masters of sailing the solar winds and their ships race forward, sails billowing out as they run before the wind. With the same case, they can turn their great ships into the wind and tack against it, heading directly towards a star.

Note that its unlikely Eldar craft actually use real "solar sails" - photon pressure is simply not strong enough to provide any real acceleration (compared to what an Imperium of man ship can do) - so they obviously rely on some other exotic form of propulsion (probably psychic-based, given how highly tied into the warp their other technologies are.)

[Imperial Overlord]

A lot of that starship technical details has been retconned.

Gothic class vessels are now classified as cruisers. (Battle Fleet Gothic p111). Game stats and point cost are much higher than that of a systems defence ships and monitors, confirming capabilities.

Build time of an easy to construct Lunar Class Cruiser above a feral world(extent of space building facilities unknown, but much [if not all] of the materials were gathered by primitives on the planet and then lifted into orbit: 11 years. (BFG p110)

Fusion Guns are classed as weapon batteries.

Each battery consists of rank upon rank of weapons: plasma projectors, laser cannons, missle launchers, rail guns, fusion beamers, and graviton pulsars.

Some lances are laser weapons.

However, this arrangement allowed the Overlord's dorsal lance turrets to be upgraded, giving them a range comparable to the vessel's other long-range laser batteries.

Torpedoes

A typical anti-ship torpedo is over 200 feet long and powered by a plasma reactor, which also acts as a sizeable portion of its warhead, turning it into a devastating plasma bomb . . . . .

Once a torpedo is launched, the plasma drive propels the torpedo forward at high speed, whilst beginning an energy build-up which will culminate in its detonation.

Firestorms are now classed as frigates based around combined weapon battery and lance arnament. Further comfirmation that some lance batteries are laser weapons. (BFG p 113)

Shields. Game mechanics indicate shields are deflection, energy absorbtion and retransmition devices (BFG p9). As shield networks on most ships continue to protect in every direction until the network as a whole is overloaded, absorbed energy is probably spread over the whole shield network. Variable armour levels on some ships (which apply when shields are up) imply that some shield generators are better able to deflect incoming firepower although powerful weapons such as lances or bombardment cannons overcome such capacities. The overload explosion of a Castellan Shield Ship is not reflected in BFG game mechanics or fluff and is probably best rationalized as a consequence of the ship storing far more energy than any other ship its size in its shield network.

[Connor MacLeod]

A lot of that starship technical details has been retconned.

Its still valid unless directly cxontradicted. Edit: In fact I checked with NecronLord before I started plunging through this, and he was okay with it for the most part.

Gothic class vessels are now classified as cruisers. (Battle Fleet Gothic p111). Game stats and point cost are much higher than that of a systems defence ships and monitors, confirming capabilities.

I've also seen "Gothic class battlecruisers" referenced in Space Hulk. Historically there's not neccesarily an inconsistency: The "Battlecruiser" distinction changed and shifted as the gap between cruisers and battleships closed (some historical cruisers were either very fast battleships or very powerful cruisers.)

Besides, I was actually ignoring most of the game stats and going with just the fluff-related stuff.

Build time of an easy to construct Lunar Class Cruiser above a feral world(extent of space building facilities unknown, but much [if not all] of the materials were gathered by primitives on the planet and then lifted into orbit: 11 years. (BFG p110)

But the cruiser range is pretty diverse, as is the battleship range. Moreover if you wanted to be a little pedantic, anything over 10 years could be considered "decades"

Fusion Guns are classed as weapon batteries.

They're part of weapons batteries, but there's alot of weapons in weapons batteries (including laser cannons and even in some cases plasma torpedoes IIRC.)

Moreover, I do recall references to fusion "lances" as well as plasma "lances".

Frankly that wouldn't neccearily preclude some vessels mounting "batteries" of all of one type rather than a mixed type. Its not as if Imperium tech is always consistent (IE I doubt ALL guns automatically require slaves to haul them around for targeting purposes..)

Each battery consists of rank upon rank of weapons: plasma projectors, laser cannons, missle launchers, rail guns, fusion beamers, and graviton pulsars.

Some lances are laser weapons.

See above.

However, this arrangement allowed the Overlord's dorsal lance turrets to be upgraded, giving them a range comparable to the vessel's other long-range laser batteries.

Again, see above. I'm aware of these references, and I'm also aware there are references to plasma and fusion lances as well (I dont remember which BFG resourcecs though.)

Torpedoes

A typical anti-ship torpedo is over 200 feet long and powered by a plasma reactor, which also acts as a sizeable portion of its warhead, turning it into a devastating plasma bomb . . . . .

Once a torpedo is launched, the plasma drive propels the torpedo forward at high speed, whilst beginning an energy build-up which will culminate in its detonation.

Again, I'm aware of this quote.

Firestorms are now classed as frigates based around combined weapon battery and lance arnament. Further comfirmation that some lance batteries are laser weapons. (BFG p 113)

frigate and cruiser distinctions have blurred historically as well (around the 70's a frigate was smaller than a cruiser, but carried a cruiser's armament.) THat's not necceesarily an inconsistency neccesarily as a reclassification/redesign.

Shields. Game mechanics indicate shields are deflection, energy absorbtion and retransmition devices (BFG p9). As shield networks on most ships continue to protect in every direction until the network as a whole is overloaded, absorbed energy is probably spread over the whole shield network. Variable armour levels on some ships (which apply when shields are up) imply that some shield generators are better able to deflect incoming firepower although powerful weapons such as lances or bombardment cannons overcome such capacities.

Again, I'm aware of this. The only difference seems to be that the BFG references imply a faster dissipation rate than before, which can easily be explained as a refinement of shield technolgoies on some or all vessels.

(There's actually two ways to interpret that. One is that the dissipation rate is alot higher, but they can't dump excess energy until shields are lowered. This might make some sense, if the radiation mechanism would be obscured by shielding.

Alternately, the dissipation rate is (stlill) alot lower than the absorption rate.,) but quick enough that the shields are only down temporarily during battle (although the actual timeframe isn't easily derived.)

The overload explosion of a Castellan Shield Ship is not reflected in BFG game mechanics or fluff and is probably best rationalized as a consequence of the ship storing far more energy than any other ship its size in its shield network.

If the shielding mechanism fails and the ship blows up, any energy it DOES store is going to be released in some manner (probably vaporizing the entire ship.) Since energy doesn't disappear into thin air. If the ship can't dump it into space and the heat sinks are overloaded, then it'll probably vaporize the ship (rather violently.)

[Lost Soal]

The Castellan Ship, to me anyway, appears to have a different type of shield than the Void Shields of others. In those, enough energy directed into them will knock down the shields, the captain doesn't decide to drop them. The Castellan on the other hand suggests that the shields can't actually be knocked down, the energy just builds up until critical.

I'm trying to decide if they are two different shield types, or if the standard issue shield has somethiing akin to a fuse which automatically drops the shields at a set point, while the Castellans have had it removed and the captain is trusted to decide how much risk he wants to take.

[andrewgpaul]

Just for reference, the 'gothic class battleship' referred to by Connor is this:

Catalogue page

Note some variants (ie, the plastic version) had an additional structure at the prow.

How elegantly those human battleships drifted, pulsing out their seething balls of plasma. Those were vertical cities, spiry and crenellated, ghostly in the light from distant Lacrima Dolorosa-cities bonded to spear-blade decks that jutted out for a full four kilometres with underslung warp-keels far to the forrard.

It's not impossible that different Segmentum fleets use the same name for different ship classes. After all, in BFG, there's the Retribution-class battleship, as well as a Lunar-class called Retribution. I imagine a name like Gothic is fairly common in the Imperium

Starship Dimensions reckons an Emperor battleship is 7500m long. dunno where he got that from.