WH40K - 40K misc numbers... (SDN)

[Mr. Oragahn]

Mmm... surely some don't add up. That said, missile sized aren't always that consistent, but building sized ones recur.
I'm not sure how the width will change anything much, unless the missile becomes ridiculously small.

Now, the Nova Cannon firing a shell at 5000 km/s, that's odd. Any idea of how heavy the slug was? Perhaps they didn't wait for the capacitors to be fully charged? Perhaps something was damaged. In Shadow Point (see my other thread), it was fired at near c, although it only fragmented a large asteroid while hitting dead center. As I said here, the asteroid itself, a Rok, is not a solid piece of rock, far from it.

Something of interest, quoted from here:

As far as I am concerned, the 600 GT number is not "official", or at the very least is not representative of Gothic-scale torpedoes or firepower. It appears that the original reference is from the "Mission" book for the 1st Edition of Space Hulk. It mentioned that the Gothic Cruisers were carrying hundreds of Hellfire missiles that each contained 122 5 GT Warheads. This was from the 1st edition version, which explains why I didn't find it. The 2nd Edition version of the same mission mentions the same three ships, but the reference to their missiles was replaced with "fusion bombed down to a fine powder". So it is pretty much retconned by omission anyway.

This makes a hell of a difference, and probably also solves the problem posed by the 1st edition quote as it required impossibly huge nuclear missiles.

[Mith]

Mmm... surely some don't add up. That said, missile sized aren't always that consistent, but building sized ones recur.
I'm not sure how the width will change anything much, unless the missile becomes ridiculously small.

Now, the Nova Cannon firing a shell at 5000 km/s, that's odd.

Is it? Aside from the game manuel, which supports near-light speed aside from hyperbole?

Any idea of how heavy the slug was?

Nope. But given that the door was fifty meters wide, it's probably closer to twenty or thirty meters.

Perhaps they didn't wait for the capacitors to be fully charged?

Doubtful. They were firing into a Tyranid Hive fleet and hadn't even recieved any form of damage yet. There is absolutely no reason to believe that they'd be weaker than usual.

Perhaps something was damaged. In Shadow Point (see my other thread), it was fired at near c, although it only fragmented a large asteroid while hitting dead center.

You mean it was used like a cannon shell? I find that strange. It's a bomb. The entire speed of it is almost entirely irrelevent.

As I said here, the asteroid itself, a Rok, is not a solid piece of rock, far from it.

Ouch, that pretty much kills any chance of uber level firepower.

Something of interest, quoted from here:

As far as I am concerned, the 600 GT number is not "official", or at the very least is not representative of Gothic-scale torpedoes or firepower. It appears that the original reference is from the "Mission" book for the 1st Edition of Space Hulk. It mentioned that the Gothic Cruisers were carrying hundreds of Hellfire missiles that each contained 122 5 GT Warheads. This was from the 1st edition version, which explains why I didn't find it. The 2nd Edition version of the same mission mentions the same three ships, but the reference to their missiles was replaced with "fusion bombed down to a fine powder". So it is pretty much retconned by omission anyway.

This makes a hell of a difference, and probably also solves the problem posed by the 1st edition quote as it required impossibly huge nuclear missiles.

Ah! Now that is interesting. So in other words, they're retconned out. Wow, that's...that's pretty shitty of these guys.

[Mr. Oragahn]

I just realized that I was lucky you could decipher anything of what I typed. Booze, bad. :)

[Mith]

I just realized that I was lucky you could decipher anything of what I typed. Booze, bad. :)

I've debated with Point45, that looked crystal clear in comparison. =p

But what would you say if I found a site that is full of 40kers and at least two or three of them agree that 40k has kt-mt yields?

[Khas]

I'd say "WOO-HOOO!"

Link, please?

[Mith]

I'd say "WOO-HOOO!"

Link, please?

Enjoy.=)

http://www.warseer.com/forums/showthread.php?t=225665

[Mr. Oragahn]

It seems that the most recent BFG rulebook doesn't peg the Nova Cannon's slug at near c.
But both Cadian Blood and Shadow Point, along the BFG rulebook I used, do say it's that fast.
Notice, though, that there are not standards in IoM tech. One's Nova Canon might be different from another's, which could explain the discrepancy in shell size (it seems to be between 30 and 60 m wide), and then you have to add the ship itself, which even if belonged to a given class, could come with some differences.

[Jedi Master Spock]

http://www.warseer.com/forums/showthread.php?t=225665

What I was going to bring up next was recoil, which is the point at which we start talking about how [un]massive the NC shell needs to be to avoid putting the three hundred meter barrel back through the rest of the ship.

That's better analysis of WH40k than I've ever seen on SDN or SB.

Now, here's a question: Why is everybody using solid steel as a benchmark, rather than looking at actual shells or bombs? The NC shell is a giant plasma fusion bomb. Shouldn't it be something more like a giant lithium deuteride pellet than a chunk of iron?

If we took the Tsar Bomba and scaled it up by a factor of 64 - making it 32m long, a tenth of the length of the barrel from Warriors of Ultramar - it would weigh in at 1700 tons. Its bulk density was barely more than that of water. If the NC shell was a thin adamantium shell surrounding a liquid deuterium core, and a 30m diameter sphere, it would weigh in at 2300 tons. 2000 tons might look like a reasonable guess based on the size of the gun itself - that would give about 6 gigatons of kinetic energy.

This still presents a serious recoil problem - 2x10^6 kg at 5x10^6 m/s (= 10 trillion kg m/s) would slam a solid steel cannon 300m long x 50m wide, with a 25m interior bore, back at 2.8 kilometers per second. Mach 8.4. That's going to need a lot of bracing, in other words.

For something that's being loaded by muscle power, and fired out of a cannon several hundred meters long, we really want to have the NC shell not more than a couple hundred tons (comparable in mass to a medium-small building), with sub-gigaton kinetic energies, but it's not bad to consider the generous case - there could be some in-universe explanation for the recoil not being as much a problem as it seems.

Just bear in mind, the "generous" case actually paying attention to the information is for KE six orders of magnitude less than Connor has claimed (which claim, I'll add, is repeated ad nauseum on SB and SDN with minimal justification).

This is still a pretty good thing for WH40k, all things considered, especially since the NC does its damage via its warhead, not impact.

[Mr. Oragahn]

There's also the point that the acceleration applied at once over all the shell, regardless of how many accelerating sections there are in the tube, would rip said shell apart.
Remember the adamantium strength figure you derived from the Land Raider case, something like 5 times better than conventional steel or something similar I believe.
There's just no way the material could withstand such stress, unless it were as tough as God's skin. Now, with inertial dampeners, it might be able to solve the entire problem.

There are many other problems with the projectile's nature. Sometimes it's said to implode, but it's supposed to have the force of a dozen plasma bombs and still deal damage over at least a 1000 km radius or more. It's even possible that one of the BFG editions says that the projectile deals damage when it implodes. Now, I also pointed out the capabilities of plasma bombs, and at best a cluster missile of 6 of them can melt a city block. That alone doesn't even evoke any explosion but more like dousing a fraction of a city in some kind of very very hot napalm.

[Mr. Oragahn]

Another funny one:

Development team in WD320:
"The background should be like Schrödinger's Cat - Nothing is defined until the players look into the box by playing games and determining the outcome for themselves. Backgrounds should be full of possibilities to be exploited and expanded by players, not answers that limit the potential of the game and its setting."

And Marc Gascoigne wrote:
"Keep in mind Warhammer and Warhammer 40,000 are worlds where half truths, lies, propaganda, politics, legends and myths exist. The absolute truth which is implied when you talk about 'canonical background' will never be known because of this. Everything we know about these worlds is from the viewpoints of people in them which are as a result incomplete and even sometimes incorrect. The truth is mutable, debatable and lost as the victors write the history..."
...
"Now, ask us some specifics, eg can Black Templars spit acid and we can answer that one, and many others. But again note thet answer may well be 'sometimes' or 'it varies' or 'depends'."
...
"To attempt answer the initial question: What is GW's definition of canon? Perhaps we don't have one. Sometimes and maybe. Or perhaps we do and I'm not telling you."

In the end, it's all "fanfic" as with no clear cut answer to everything, people are forced to make up their own damn minds on what to believe and what not to believe. I mean, many people are ready to dismiss anything by Goto as utter nonsense. But that's ignoring the background and making up your own version of it. Where do you draw the line with sources? Ones that you don't like? Ones that don't hold up to others? What?

Apparently some explanation from BL (Black Library?) to explain inconsistencies or something.

[Mith]

http://www.warseer.com/forums/showthread.php?t=225665

What I was going to bring up next was recoil, which is the point at which we start talking about how [un]massive the NC shell needs to be to avoid putting the three hundred meter barrel back through the rest of the ship.[/

And out the back engine.

That's better analysis of WH40k than I've ever seen on SDN or SB.

Honestly, it's one of the most civil debates from two sides that I've seen in some time from anywhere, save for maybe here. It was actually really nice to read and didn't revolve around people putting their egos on the line.

Now, here's a question: Why is everybody using solid steel as a benchmark, rather than looking at actual shells or bombs? The NC shell is a giant plasma fusion bomb. Shouldn't it be something more like a giant lithium deuteride pellet than a chunk of iron?

Well, the OPer seemed to be treating it like a gun and from that perspective it makes sense. However, given that everyone else pointed out that it's not a gun, it's a missile, any sort of KE is rather pointless. It's like trying to calculate the KE of a photon torpedo.

If we took the Tsar Bomba and scaled it up by a factor of 64 - making it 32m long, a tenth of the length of the barrel from Warriors of Ultramar - it would weigh in at 1700 tons. Its bulk density was barely more than that of water. If the NC shell was a thin adamantium shell surrounding a liquid deuterium core, and a 30m diameter sphere, it would weigh in at 2300 tons. 2000 tons might look like a reasonable guess based on the size of the gun itself - that would give about 6 gigatons of kinetic energy.

This still presents a serious recoil problem - 2x10^6 kg at 5x10^6 m/s (= 10 trillion kg m/s) would slam a solid steel cannon 300m long x 50m wide, with a 25m interior bore, back at 2.8 kilometers per second. Mach 8.4. That's going to need a lot of bracing, in other words.

Funny enough, they suggested anti-gravity/mass lightning technology, same as Oraghan, and given that they're clearly more familiar with the setting than we are, is rather interesting. Then again, the fact that the Eldar have F*ing hovercraft should have made this desperately obvious--actually, so does the Imperium! Their speeders are hovercraft! God, I'm so stupid, why didn't I just point to that?

Ah well, live and learn.

For something that's being loaded by muscle power, and fired out of a cannon several hundred meters long, we really want to have the NC shell not more than a couple hundred tons (comparable in mass to a medium-small building), with sub-gigaton kinetic energies, but it's not bad to consider the generous case - there could be some in-universe explanation for the recoil not being as much a problem as it seems.

Um, was it loaded by hand? I know the coil was, but then again I'm not familiar with railguns/coilguns, so maybe that's how they load it?

Just bear in mind, the "generous" case actually paying attention to the information is for KE six orders of magnitude less than Connor has claimed (which claim, I'll add, is repeated ad nauseum on SB and SDN with minimal justification).

Oh God, watching Hat screaming about the petatons was just laughable. It made even the 800tt for SW almost seem respectful in comparison.

This is still a pretty good thing for WH40k, all things considered, especially since the NC does its damage via its warhead, not impact.

Indeed it is, but it shows us a few things as well.

1) Nova Cannons, despite their power, are not planet bombardment worthy
2) It takes a massive, and I do mean massive, amount of space, power, and time to use this weapon.
3) Nova Cannons are no more than 12x more powerful than a melta bomb, so I guess that means it can melt away about 72 blocks of a city?=P

[Jedi Master Spock]

To explain a little further: One reason why nova cannon KE/momentum/recoil is relevant is that WH40k ships use smaller direct-impact cannons and mass drivers as part of their weapons batteries. The fact that the nova cannon is the most overwhelming weapon the IoM can construct means that we expect everything else to be less overwhelming in every way.

If a nova cannon fires at 5,000 km/s, the macro cannon won't be firing faster than 5,000 kps. A 3 ton macro cannon shell (the default guess for "several tons") going at 5,000 kps (as fast as a Nova Cannon shell) would have a kinetic energy of ~9 megatons. That's a generous case - Macro Cannons being high-powered kinetic weapons.

We've established normal WH40k "explosive shell" yields at ~2 gigajoules per 38 kg shell (Earthshaker cannon) which puts the potential explosive yield of a macro cannon shell at ~40 kt. (Unlike the nova cannon, the macro cannon is quite conventional.) So from the fact that we know how fast a nova cannon fires, we can provide much better bracketing on the yield of a macro cannon - less than 2.5 orders of magnitude, whereas before, it was essentially a total unknown, roughly bracketed by vague notions of how much they "ought" to do.

Now, to put the nova cannon in perspective, here's a wattage calculation. 2.5e19 joules on a 30 minute firing cycle is a time-averaged output of 3.3 megatons of KE per second. As it's a fusion device, we would expect conventional explosive effects of a similar order of magnitude - the nova cannon's time averaged total yield output could be estimated at 10 megatons total yield per second, for example.

I'd like to take this moment to underline what differentiates WH40k from other franchises. Few ST or SW weapons approach multi-gigaton yields - however, they may be fired much more quickly than the once every half hour of the nova cannon. Even the massive slow-moving turbolasers of a Star Destroyer may be swiveled more quickly than a spine-mounted nova cannon.

There is little question in my mind that getting hit amidships by a nova cannon would be quite harmful to, say, a GCS. There is also little question in my mind that a Lunar class cruiser is highly unlikely to be able to hit a GCS with a nova cannon.

Back when I actually believed the 610 GT nonsense that was being constantly spouted about WH40k torpedoes, that firing cycle problem meant that a GCS on the high end could average a similar output to a WH40k escort. Using more realistic yields means that something like the nova cannon, which represents a significant fraction of a cruiser's firepower, puts out a time average of, say, a 100 MT photon torpedo every 10 seconds.

The actual shot is still quite impressive (unless you're a Borg cube that can sometimes soak up 100+ gigatons of energy without blinking), but everything surrounding that shot is not, and the overall firepower of a WH40k ship, in terms of an averaged rate over time, is not necessarily any greater than that of a UFP ship.

[Mr. Oragahn]

@ Mith

The NC is worth a dozen plasma bomb, not melta bombs. That said, the behaviour of the PB is weird enough that I would indeed say it's close to the behaviour displayed by melta weapons: lots of heat that melts materials, but little blast.

Also, I didn't notice that some people at Warseer suggested mass lightening tech. You're sure of that?It's not like warseer has any superior authority on such matters, but it's intriguing.
Would you remember where you read that exactly?

@ JMS

I'm not going to bring up any discussion about Trek because this is not the place for it, but here are some facts about the IoM space warfare weapons.

The Nova Cannon in Shadow Point is fired at near lightspeed and can probably be gauged at some gigatons (it fragments a 8 x 4 km Rok, and those Rok are far from being solid lumps either - more info here). Its effects still largely remain limited, and it seems to cause more damage to the smaller units which get caught in the indirect omnidirectional blast.

As for the macro cannon, the cannon itself is lifted by people, the preparation of a solution seems to take some time as well as a shell has to be shoved into the cannon iirc, and the crews have to leave the firing chamber before the shot.

An example of firing rate for a warship's lances exists in Execution Hour. "Less than a minute".

[The Dude]

I think the mass lightening thing might be in the Rogue Trader RPG rulebook. I have to flip through it again to be sure but I remember folks complaining about how the densities and mass where off when it came out.

[Jedi Master Spock]

I'm not going to bring up any discussion about Trek because this is not the place for it, but here are some facts about the IoM space warfare weapons.

Well, the point about Trek is really just pointing out that almost every other major franchise - ST, SW, etc - the firing cycles are much faster.

The Nova Cannon in Shadow Point is fired at near lightspeed and can probably be gauged at some gigatons (it fragments a 8 x 4 km Rok, and those Rok are far from being solid lumps either - more info here). Its effects still largely remain limited, and it seems to cause more damage to the smaller units which get caught in the indirect omnidirectional blast.

IMO, the folks on the WH40k board have it right - for the purposes of casual discussion, 5,000 kps is "near lightspeed" enough. The precision of the 5,000 kps figure is desired over any number pulled out of a hat.

Fragmenting an 8 km Rok with one shot on impact is gigaton-appropriate - that puts it precisely on the level of energy I'm talking about. A NC shell being, say, 200-2000 tons and 5,000 kps means 2.5-25 exajoules of KE, which is in the right range for shattering a Rok without significant vaporization.

As for the macro cannon, the cannon itself is lifted by people, the preparation of a solution seems to take some time as well as a shell has to be shoved into the cannon iirc, and the crews have to leave the firing chamber before the shot.

We're probably talking on the order of a one minute firing cycle for the macro cannon. Maybe as little as thirty seconds, maybe as much as several minutes.

But while it fires more quickly, it's also much less powerful. A one minute firing cycle for a macro cannon means a time-averaged output of 160 kilotons/second for the high-end estimate I offered. Overall, the fact that the NC shell is likely hundreds of times as massive as a macro cannon shell and packs an enormous blast that likely exceeds its KE means that I expect a NC to have time-averaged firepower similar to dozens of macro cannons in spite of the firing rate difference.

An example of firing rate for a warship's lances exists in Execution Hour. "Less than a minute".

Not surprised, but they're also individually less powerful than a nova cannon, IIRC.

The targeting and tracking problem is a serious one. Certainly I expect lances - being beam weapons with a relatively quick firing cycle - to be one of the most useful weapons in the WH40k arsenal in space battle scenarios against more nimble opponents; certainly I also expect that accuracy against targets smaller and nimbler than ISDs will not be great, even for lances.

The only thing that I can think of exhibiting similar firing rates in SW or ST to WH40k are "superweapon" style attacks. Almost everything can be fired on a cycle of < 30 seconds except for superlasers, thalaron radiation weapons, et cetera.