Imperial Flagships: How big are they?

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**DeathReaper**

Yak9UT wrote:Well it the asteroid was roughly 10KM so pretty close in size of a Imperial battleship. Thats why I thought a ship could do some serious damage to the planet and not to mention that reactor core could have a very serious outbreak of radiation.

In reality it could have a devastating effect on a planet. depending on the planets size, its relative rotation, the planets orbit and the tonnage of the ship. the Planet itself would survive. Most of the life on said planet would be destroyed.

Cornell University has an article about a similar situation. interesting read.

http://curious.astro.cornell.edu/question.php?number=146

**Grey Templar**

Yes, the planet would definitly survive.

Life might not be so lucky.

There is the actual impact of a 5-8 kilometer hunk of metal. Likely a crater in excess of 100 kilometers wide. Debris blown for hundreds of miles.

Radiation from reactor kills anything in the general vicinity that survives the Impact.

Dust cloud from impact blots out the sun for 1-5 years depending on Atmosphereic density(this happened when the Volcano krakatoa in Sumatra blew during the Roman empire and caused a worldwide famine) and plant life suffers causing food shortages(assuming planet doesn't import food.

Dust is also radioactive from the plasma reactor.

Then there is the Seismic Shifting that results. Tectonic plates become dislodged and massive earthquakes rock the planet(assuming a molten core) for years after.

**Yak9UT**

Well thats answered my questions

Now all the Imperium need to do is kamikaze thier ships into enemy planets and it would sort problems out

**The Imperator**

Kamikaze would just not be cost effective. It is much cheaper to use Exterminatus rather than plow your ancient and pricless ship that took decades to construct into the surface of ONE planet.

**Eyclonus**

Oh, did I mention the fun that void shields, anti-matter weapons and gravity system cause?

Shields: react with the atmospheric gases and cause ignition. Or it doesn't react to them but causes the ship to burrow through the crust and into the upper mantle of the planet... Considering the type of energy needed to produce and shape them, its more likely the constant feedback from impacting on the planet would cause them to burn out, explode from overload, or feedback into the reactor...

Anti-matter technology: some of the bigger things in 40k use this stuff, and its nasty, especially because the writers aren't really reading up on the science they tend to overload the quantity of the black stuff necessary. If the reactors go, the containment units will go, and hey presto more boom and doom...

Ship bound artificial Gravity: Considering that none of the ships seem to use inertia generated by spinning the hull it means the Imperium has gravity generating systems... which means they have the capacity to dick with one of the most fundamental forces of our universe. In terms of impacting a planet it means that once they enter the gravity well of the planet, the crew and structure of the ship is subjected to both its own gravity and that generated by the planet, assuming both are Earth standard (1G), then the crew of the ship will experience 2G, aka everything weighs twice as much... this will cause everyone, excluding space marines I'd guess, to be crushed by the weight of their own mass, lungs being unable to expand because the muscles aren't able to push against the resistance of the weight. Support structures on the ship will also suffer, literally experiencing twice the weight they were designed to carry, not mention the delicate aspects like circuitry, lights, etc... will just grind themselves down. Oh and lets not forget those darned reactors... either their safety systems go from the stress... their cores stop functioning because the energy imparted during the reaction can't beat the force of gravity, or they explode because the increased weight of the particles adds more force to the reaction then the system can safely handle...

On the outside, a ship with that kind of gravity effect is gonna weigh twice as much and thus, it will hit with more force then we have estimated, combined with the void shield issue and the entry speed, it could penetrate quite deep into the planet's surface... Not to mention if the gravity well extends far enough out of the ship, the surrounding environment will be subjected to a sudden doubling of weight, the shock of which will probably crush bones instantly as opposed to the slow death of the crew who have experienced a more gradual increase in gravity.

Automatically Appended Next Post:
Bonus Round:
Titans, ICBMs and Powerplants: Considering this is likely to happen on a world where major ongoing conflict is taking place, then there is a likelihood we get Titans stomping around, Titans don't get deployed on their own, it tends to be a few to quite a few. Titans pack their own portable reactors so they can deploy on campaign without needing to stop every hour to recharge, which means if the explode, they will explode really big, if a Titan or two is close to the blast, it will explode, thus making it just a little bit worse, same goes for power reactors and ICBM/Anti-Orbital missile silos, if enough are clustered together, we get a chainreaction that could extend outside of the primary blast radius and greatly amplify the effect on the planet. Not to mention that Titans tend to carry Vortex missiles etc... thats just more fuel on the fire here really.

Polar axis: Its obvious that we have the firepower to level our planet if we spread the bombs out and fired all at once, but you know... it takes less explosives to just knock us off our set orbit. If the USA & USSR HAD (don't jump with coldwar theory etc... this is just about the physics OK) fired nukes over the northpole and detonated them simultaneusly it would feth over our rotation, throw us off our orbit and that would greatly affect the population, shifts in gravity... shifts in solar radiation levels, temperatures... inertia compounding the effect of gravity... shockwaves resounding through out the entrire planet...

Now apply what I said previously and stick it on the north pole... On smaller planets, with wider orbits from their star, the planet would likely drop from a set orbit completely, and could go.... I have no idea, but it pretty much writes the planet off, and maybe a second if it hits another planet, replaying the event on a much grander scale... Or it experiences an unbalancing orbit, destabilizes the gravity of the planet with frequent shifts, causing the planet to break apart, or it just gets sucked into the star...

This is probably why the Imperium likes Exterminatus; because it doesn't potentially destroy an entire star system...

Does that answer your question Yak?

**chromedog**

Anyone remember Gorkamorka.

The planetary devastation was the result of a single ork killkroozer crashing into it.

A larger imperial vessel would have done about the same (safety standards for orks are not the same as for humans).

(OK, that it was also a necron tombworld might have had something else to do with it).

The impact scar was rather massive (it didn't spear the planet, it hit at a much shallower angle and skipped a few times).

**Eyclonus**

That game was awesome! Wish some of the rules in that became part of 40K, like jumping between transports or differences between T-Boning a vehicle to head-on collisions!

**Lord_Inquisitor**

Somewhere in the labyrinthine folders of my laptop, I have a picture that shows a bunch of different classes of Imperial ships, and their relative sizes.
I can't find the damn thing now, of course.
But! If I recall correctly, the largest one (a battleship I think) was listed at slightly over 4km long.

**Jihadnik**

Eyclonus wrote:
Ratbarf wrote:As to the destructability of a ship moving at speed, a 25 kg metal slug moving at 1.3% the speed of light impacts with a force greater than the bomb that landed on Hiroshima....

So a couple billion tons moving at a similiar rate should pretty much plow through the whole darn thing.

Isn't that how the Tau railguns are supposed to work?

Even if the ship was moving at slower pace there are number of things that can affect the whole planet. The meteor behind the Meteor Killed The Dinosaurs theory was smaller then sizes of some of those ships, not to mention it lacked plasma/fusion (could it be using the fusion process with plasma instead?) reactors, so therefore almost any large Imperial ship that plays chicken with a planet is bound to cause planet-wide disaster. If the reactor is like a nuclear reactor then you get a wide area saturated with radiation which will probably sterlize a good chunk of the planet's surface and make the atmosphere fairly toxic with radioactive dust. Not to mention if its close to C in speed, the friction of the ship against the atmosphere may just cause the oxygen to burn up...

I think TV tropes wiki has a page which discusses this class of event in detail, they call it a Colony Drop...

I thought Jesus killed the dinosaurs...?

**Eyclonus**

Jihadnik wrote:
Eyclonus wrote:
Ratbarf wrote:As to the destructability of a ship moving at speed, a 25 kg metal slug moving at 1.3% the speed of light impacts with a force greater than the bomb that landed on Hiroshima....

So a couple billion tons moving at a similiar rate should pretty much plow through the whole darn thing.

Isn't that how the Tau railguns are supposed to work?

Even if the ship was moving at slower pace there are number of things that can affect the whole planet. The meteor behind the Meteor Killed The Dinosaurs theory was smaller then sizes of some of those ships, not to mention it lacked plasma/fusion (could it be using the fusion process with plasma instead?) reactors, so therefore almost any large Imperial ship that plays chicken with a planet is bound to cause planet-wide disaster. If the reactor is like a nuclear reactor then you get a wide area saturated with radiation which will probably sterlize a good chunk of the planet's surface and make the atmosphere fairly toxic with radioactive dust. Not to mention if its close to C in speed, the friction of the ship against the atmosphere may just cause the oxygen to burn up...

I think TV tropes wiki has a page which discusses this class of event in detail, they call it a Colony Drop...

I thought Jesus killed the dinosaurs...?

There are people who say that... they tend to be quite angry and self-righteous... Like a Spess Mahreen!

**Grey Templar**

@Eyclonus: 2Gs won't kill anyone.

it takes about 50Gs for Death to be likely.

Astronoughts pull 3Gs exiting the atmosphere and that takes a bit of time.

A formula1 racing car does 5Gs when it breaks heavly.

2Gs for a long duration of time would cause health problems, but not in the time it takes a Ship to crash and, yes, then everyone will did.

**nosferatu1001**

GT - um, nope - at 9Gs you are, if upright, dead from lack of blood to the brain. This is of course sustained G, not instantaneous. Look up compression suits and what they do for pilots, and why astronauts lay on their backs for take off.

Plasma reactor == plain ol' fusion reactor. To the poster who assumes it must be better, why not simply assume BL suck at maths? It's far more likely.

**Asherian Command**

At least 2.5 kilometers. - fact
At least 90 stories tall. - believed

**Jaon**

Yeah I hear american fighter pilots experience 7gs. Thatd be enough to make your stomach drop....out of your skull...

**Asherian Command**

well lets see how many G's does it take to kill someone?
As you are going pretty bloody fast if it is going into a descent down to a planet. But probably they have stabilizers to ensure that does not happen.

**Eyclonus**

Actually looking at the Plasma Reactor issue, I'm assuming those things have a massive output, and the larger ships would be hauling a whole set of them.

I'm not good with energy and physics... but I'm going to assume the following: An Imperial battleship packs about 10 reactors, most of the time four of them are operating at minimum and six are performing at 50% capacity. Considering the ammount of energy required to sustain the various shields, the MASSSSSSSSIVE engines and etc, the reactors have to be capable of producing electricity on at least a level of tens of Pettawatts...

I'm not sure how one would convert 20 Pettawatts into joules or some metric for measuring explosive force, but I'm going out on a limb and calling a single reactor explosion bigger then the Tsar Bomba.

References:
Electricity
Energy

**Asherian Command**

dude its harnessing the power of the sun its going to be alot more powerful than that!

**Eyclonus**

Thats a metaphor dude, Hiroshima harnessed the power of the sun, and its considered piss-weak to most modern Nukes, I'm assuming that even with that big frowning on invention the Imperium has bigger and scarier nukes.

**Asherian Command**

Eyclonus wrote:Thats a metaphor dude, Hiroshima harnessed the power of the sun, and its considered piss-weak to most modern Nukes, I'm assuming that even with that big frowning on invention the Imperium has bigger and scarier nukes.

No no no.
The power of the sun. Like the energy inside the sun. NOVA- The most powerful unidentifiable element ever. Plasma is the sun's energy.

**Eyclonus**

Where would it sit on the orders of magnitude for energy?

**Asherian Command**

think of the city of new York.'s people but instead of being people they are energy x 1500.

**Eyclonus**

so 19,541,453 x 1500 joules = 29.3 Gigajoules or 6.35 tonnes (Metric) of TNT

Yeah... thats... scary.........

**Asherian Command**

Thats how much energy a flipping Regular generator in a Plasma gun holds -.-
Thats what is believed not really confirmed.

**nosferatu1001**

Have a look out for the ST vs 40k thread, that included some good calculations on "factual" weapon and shield output for various ships. The end result was that something that uses basic fusion, and was 0.12% the size of the earth, somehow was producing a power output many orders of magnitude greater than fusion reactions can account for.

The end result of that was: BL suck at maths. Even assuming they use AM/M reactions, which they DONT, it was still way off.

Plasma is a state of matter, it is not "the suns energy" (4th state, neutronium is the 5h (degenerate matter) and i think theres a 6th...possibly around 0K) - you can get "cold" plasma washes that disinfect your skin, about to go on trial in hospitals. Nova is the term for a sudden fusion reation explosion, normally caused by a whitedwarf-main sequence binary accreting matter

**Eyclonus**

I know BL suck at maths, I just want to see how many places after the decimal point.

**BearersOfSalvation**

nickmund wrote:Fusion reactors and plasma reactors are the same thing. In order to create a stable fusion reaction you need plasma. Thats how the sun works and thats how fusion reactors work today on Earth.

The fact that fusion reactors use plasma does not mean that what 40k calls 'plasma reactors' are fusion reactors - a modern car engine needs water to work, but no one calls it a water engine, a modern gasoline car engine needs electricity to work (spark plugs, battery, alternator), but a 'electric car engine' does not mean a standard gasoline-powered engine. 40k plasma reactors have far too much power output and use far too little fuel to be actual fusion reactors, even 100% effecient ones don't come close to matching what 40k plasma reactors do. If 40k plasma reactors used only fusion to power themselves, they would not be able to do what they're said to do in the background.

Eyclonus wrote:Anti-matter technology: some of the bigger things in 40k use this stuff, and its nasty, especially because the writers aren't really reading up on the science they tend to overload the quantity of the black stuff necessary. If the reactors go, the containment units will go, and hey presto more boom and doom...

40k Plasma reactors put out more energy from their fuel than perfectly effecient antimatter reactors would, they're really pretty impressive. A ship with antimatter engines would probably be much safer to crash on a planet than an Imperial Cruiser.

Ship bound artificial Gravity: Considering that none of the ships seem to use inertia generated by spinning the hull it means the Imperium has gravity generating systems... which means they have the capacity to dick with one of the most fundamental forces of our universe. In terms of impacting a planet it means that once they enter the gravity well of the planet, the crew and structure of the ship is subjected to both its own gravity and that generated by the planet, assuming both are Earth standard (1G), then the crew of the ship will experience 2G, aka everything weighs twice as much... this will cause everyone, excluding space marines I'd guess, to be crushed by the weight of their own mass, lungs being unable to expand because the muscles aren't able to push against the resistance of the weight.

The artificial gravity (or AG plus inertial dampeners) on ships has to protect the crew from accelerations of hundreds or thousands of Gs, I don't think that dealing with a nearby planet's gravity would strain them. Also, 2gs is not going to crush anyone. Fighter pilots endure accelerations of up to 10G or so for short times without squishing or suffocating. People can survive 2gs for an extended time pretty easily - it's tiring but you don't simply collapse into a puddle. At 4gs you can do things like break your spine from sitting down without lowering yourself, and people in bad condition will die, but it's not an instant crushing thing, and a human in good shape could survive.

[quoet]Polar axis: Its obvious that we have the firepower to level our planet if we spread the bombs out and fired all at once, but you know... it takes less explosives to just knock us off our set orbit. If the USA & USSR HAD (don't jump with coldwar theory etc... this is just about the physics OK) fired nukes over the northpole and detonated them simultaneusly it would feth over our rotation, throw us off our orbit and that would greatly affect the population, shifts in gravity... shifts in solar radiation levels, temperatures... inertia compounding the effect of gravity... shockwaves resounding through out the entrire planet...

**Asherian Command**

nosferatu1001 wrote:Have a look out for the ST vs 40k thread, that included some good calculations on "factual" weapon and shield output for various ships. The end result was that something that uses basic fusion, and was 0.12% the size of the earth, somehow was producing a power output many orders of magnitude greater than fusion reactions can account for.

The end result of that was: BL suck at maths. Even assuming they use AM/M reactions, which they DONT, it was still way off.

Plasma is a state of matter, it is not "the suns energy" (4th state, neutronium is the 5h (degenerate matter) and i think theres a 6th...possibly around 0K) - you can get "cold" plasma washes that disinfect your skin, about to go on trial in hospitals. Nova is the term for a sudden fusion reation explosion, normally caused by a whitedwarf-main sequence binary accreting matter

yep dark matter and the 7th is nova.
I wonder if the Eldar have been able to harness Dark Holes? If you think about it dark holes could be the most destructive natural force ever...

And i agree with the one above.
But our Military of todays world has reduced the amount of nuclear weapons. by at least half.

**Eyclonus**

Actually the comment on the Anti-matter was about their weapons, the mechanicus haven't looted an STC yet for anti-matter reactors.

With respect to the gravity issue, I just realized something I neglected to cover: Manual Labour. The whole navy uses manual labour with huge crews to move huge bulkheads, feed ammunition from the magazines. While I did have the whole 2G issue wrong, how would the ship function with the increased weight on the workload?

Also I don't think the Imperium has quite grasped what AG is or what it can do. I know gravity dampners are either very rarely mentioned or non-existent tech, but I don't think the technology is very advanced either way. If they were able to generate AG for keeping feet on the floor, couldn't they use that for other purposes? Like shielding against kinetic projectiles as well as energy weapons?

LOL We should petition GW to apply hard-science to 40k!

**Asherian Command**

I think some chapters have developed it or the Mechianicus hasn't released as they are a bunch of jerks.

**AndrewC**

BearersOfSalvation wrote:The fact that fusion reactors use plasma does not mean that what 40k calls 'plasma reactors' are fusion reactors

The BFG rule book does say that they are fusion reactors though.

Eyclonus wrote:Anti-matter technology: some of the bigger things in 40k use this stuff

BearersOfSalvation wrote:40k Plasma reactors put out more energy from their fuel than perfectly effecient antimatter reactors would

You're comparing one piece of science fiction to another, there is no baseline to compare the two.

I think that the answer as to how bad it would be if a ship crashed into a planet entire argument could be answered in the following statement;

Put your head between your legs and kiss your a**e goodbye.

Cheers

Andrew