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I just leafed through Dark Adeptus the other day and I recalled the Chaos Grand Cruiser that entered the atmosphere of a planet. It was mentioned that modern Imperial warships could not do that feat because they didn't have the technology - given the fact the ship was still firing thrusters, it probably was using suspensors or antigrav tech of some kind (think of a starship with a really powerful grav chute on it )

As others noted starships have probably entered the atmosphere briefly for one reason or another (I think it might have happened in the first Salamanders novel too, bu tI havent read that in awhile.) whereas in other cases ships entering the atmosphere usually crash (Lords of the Night, Emperor's Mercy, etc.)

Besides, starships tend to be large, heavy things, and they would take lots of energy to keep aloft or move around in an atmosphere (such as landing and taking off). To put it in perspective, a Thunderhawk in Angels of Darkness using landing thrusters reduced humans in and around it to ash when it was trying to land. A Starship is, for the most part, thousands if not millions of times LARGER than a thunderhawk, and would probably do alot more damage trying to lift off or land. Nevermind the effects of supporting that mass.

So if you want your starship to lift off or land I suspect you use suspensor-like technologies. Or maybe that weird "mass reducing" stuff from the Eye of Terror novel (although I suspect that it is all rare technology, so have a good reason why they have that.)

Kanluwen wrote:Just as a point, the Acclamator (I and II) class of Assault Ships that we saw landed within Episode II of the Star Wars prequels were 752 meters long. It was also explicitly designed with this in mind as they were made to unload all the troops and equipment and then act as a command center during the invasion proper.

The smallest Star Destroyer class, the Victory is 900 meters long. It can't enter atmosphere without having something like a 90% chance of breaking to bits.

I can't find any good reference material right now, but aren't the smallest ships in 40k a kilometer at least?
I can't see it going too well unless something has been designed for it.

Many Imperial ships have expressely been said as having the ability to enter a planets atmosphere. its also explained that this technology is only present on the oldest ship types, newer classes of ships don't have it.

So Chaos ships and the older Imperial varients such as Battlebarges, Strike Cruisers, Grand Cruisers...etc will indeed be able to enter a planets atmosphere and suffer no ill effects.

newer classes can't for obvious reasons.

I dunno if it helps, but I've been reading the latest Gaunt's Ghosts novel, and the Imperial frigate they board begins in atmo. Dunno if they'd do that with a battle barge though.

I imagine most space-to-surface transfers take place in drop pods, thawks, and the like.

They can but a ship entering that low would lose maneuverability and open itself up to all kinds of nasty ground fire.

Randomonioum wrote:Unless the ship is specially treated to resist the high levels of heat, gak is going to go down, no matter whether it can stay moving in orbit or what have you. Its a massive object, moving at high speeds, suddenly coming into contact with friction. Fire EVERYWHERE.

Yeah, because the fact that they are designed to withstand lance batteries that fire at the heat of the sun won't protect them at all...

According to The Chapters Due (a book that almost made me like the Ultramarines as a chapter!) Strike cruisers (which are basically just light cruisers, remember, and merely around what? 2.75 km long?) can enter the upper atmosphere but it err... Isn't a recommended maneuver, shall we say.

Realize that the ships in that instance came into the atmosphere HEAD ON and not in a controlled descent ala a space shuttle, etc.

I can't find any good reference material right now, but aren't the smallest ships in 40k a kilometer at least?
I can't see it going too well unless something has been designed for it.

Yeah, because applying Star Wars physics to 40k physics is a valid form of comparison.

It was mentioned that modern Imperial warships could not do that feat because they didn't have the technology - given the fact the ship was still firing thrusters, it probably was using suspensors or antigrav tech of some kind (think of a starship with a really powerful grav chute on it )

I don't recall them mentioning that a modern imperial cruiser couldn't achieve the same feat, but I don't have access to my book for another 3 months, can you source a quote please?

in dark adeptus ( second book in the grey knights series by ben counter)
it says about a chaos cruiser holding a steady level above some titans in love atmo, around 1 km altitude if i remember correctly. It also mentions the ability to maintain this levitation was only available to old ships like the chaos cruiser because the mechanicus lost the technology in the 10000 years after the heresy.

edit: k i havent seen connors post before writing this. really should check if there is a second page before posting.

chaos0xomega wrote:Yeah, because the fact that they are designed to withstand lance batteries that fire at the heat of the sun won't protect them at all...

Well for one thing it depends on what you mean by "heat' - temperature or energy. Temperature isn't very useful, since materials can have different temps and still have the same energy. Second, it will depend on how the lance works - lances don't need to operate like heat rays, and if they focus it on a very small area they can be highly penetrative - since many lances are Piercing/raking/slicing weapons as well they don't really need to damage large surface areas to be nasty, either. It can also depend greatly on the parameters of the reentry - velocity, ship mass and shape, atmospheric density (esp since air gets thinner the higher the altitude is), etc. I'm also pretty sure atmospheric reentries at high speeds involve some fairly significant stresses on the ship frame, both because of gravity and because of the passge through the air (and if you move fast enough, air will behave like a solid object for all intents and purposes.)

It also depends on what you mean by "withstand", I suppose. Is the armor unharmed, or does it take some harm but remains mostly intact, etc. Hell, even if the hull remains fine, why does that mean that anything inside it remains untouched?

I don't recall them mentioning that a modern imperial cruiser couldn't achieve the same feat, but I don't have access to my book for another 3 months, can you source a quote please?

Dark Adeptus", page 379 wrote:
The Titan works spread out below the belly of the Hellforger. The ship's enormous shadow turned Chaeroneia's
permanent twilight into the black of night as the grand cruiser descended through the last few layers of pollutant
cloud and into the relatively clear lower atmosphere. The navigation daemon kept the cruiser's battery of thrusters
firing constantly keeping the Hellforger hanging impossibly over the titan works. Few newer ships could have
managed it - most were not even designed for the possibility of atmospheric flight. But the Hellforger was old
indeed and it knew a few tricks the Imperial Navy had long forgotten.

I was slightly wrong. some ships might be able to do it, but the majority evidently cannot. I suppose that will depend on whether or not you believe a CSM is an authoritative source on Imperial military capabilities.

Alright, finally found something in the Battlefleet Gothic books:

"A ship within a planet's gravity well may elect to enter high or low orbit. [...]
In certain scenarios, ships can enter low orbit to attack a planet. Achieving low orbit is essential to any such attack, since a drop ship's range is very limited and any attempt to bombard ground forces from a greater distance is purely up to chance. [...]
To represent interference from the planet's gravity well and the outermost edge of its atmosphere, all firepower shooting in low orbit suffers one column shift to the right, lances and nova cannons require a 4+ roll to fire and torpedoes may not be fired by ships at all. [...]
Ships which move within 45cm of the planet edge will be gripped in the heart of the gravity well and must use their engines to keep station if they don't wish to crash. [...]
Escorts and transports which voluntarily move off the planet edge are said to have landed and are removed from play. Capital ships cannot land."

Of course the above only represents GW's perspective and the authors of licensed products may prefer their own interpretation. OP would be fine with that Astartes Strike Cruiser in low orbit, though - seems pretty much like the standard to unload troops, though "low orbit" only refers to the edge of the atmosphere.

Lynata wrote:Alright, finally found something in the Battlefleet Gothic books:

"A ship within a planet's gravity well may elect to enter high or low orbit. [...]
In certain scenarios, ships can enter low orbit to attack a planet. Achieving low orbit is essential to any such attack, since a drop ship's range is very limited and any attempt to bombard ground forces from a greater distance is purely up to chance. [...]
To represent interference from the planet's gravity well and the outermost edge of its atmosphere, all firepower shooting in low orbit suffers one column shift to the right, lances and nova cannons require a 4+ roll to fire and torpedoes may not be fired by ships at all. [...]
Ships which move within 45cm of the planet edge will be gripped in the heart of the gravity well and must use their engines to keep station if they don't wish to crash. [...]
Escorts and transports which voluntarily move off the planet edge are said to have landed and are removed from play. Capital ships cannot land."

Of course the above only represents GW's perspective and the authors of licensed products may prefer their own interpretation. OP would be fine with that Astartes Strike Cruiser in low orbit, though - seems pretty much like the standard to unload troops, though "low orbit" only refers to the edge of the atmosphere.

I plan on using a battle barge, but the point still stands. I can claim it is low orbit for troop deployment.

KilroyKiljoy wrote:

They had to be built on some planet, right? Which means they'd have to be able to leave said planet once it was done being constructed. Also, they need to land somewhere eventually.

Just to mention this, starships are built in docks outside a planet's atmosphere, like the Ring of Iron that orbits Mars. It's one of the reason's that present-day humanity is trying to figure out how to build a space elevator - it's damned expensive trying to fly all those satellites and spaceships into high orbit.

I don't see a problem with ships entering atmosphere but, I don't think the larger vessels would actually "land". When Titans are deployed its done so in gigantic drop pods. Then the pods are reconstructed after the war and are hooked up to cables on low orbiting ships. Then they simply drag the pod back up. I don't think entering atmosphere above the battleground would be wise as the ships create massive weather desturbances.

infinite_array wrote:

KilroyKiljoy wrote:

They had to be built on some planet, right? Which means they'd have to be able to leave said planet once it was done being constructed. Also, they need to land somewhere eventually.

Just to mention this, starships are built in docks outside a planet's atmosphere, like the Ring of Iron that orbits Mars. It's one of the reason's that present-day humanity is trying to figure out how to build a space elevator - it's damned expensive trying to fly all those satellites and spaceships into high orbit.

They already exist in 40K. They're called Tsiolkowski towers and Mars alone has three.

While it is true that most shipyards and dry-docks for spaceships are in... well in space. There are several mentions in the fluff of land-based naval construction silos. I guess those silos are only manufacturing ship parts or escort vessels.

Beginning of Mechanicum, whatever big ship the Emperor is in lands on Mars, and in Salamander, their Strike Cruiser 'lands' on a planet. Takes off again too.

They probably can fly in the atmosphere of the planet...but why would they when they can blast their enemies from tens of thousands of km up in the sky...

daveNYC wrote:Beginning of Mechanicum, whatever big ship the Emperor is in lands on Mars.

That was the Bucephalus. One of the largest and most powerful warships the IoM ever built. And guess what? It wasn't even built by the Mechanicum but was built on Terra, before the Unification with Mars. When the tech-adepts saw it coming down the Martian sky, they wondered what marvelous technologies could prevent such a gargantuan vessel from crashing on the ground.

Would that mean the Mechanicum didn't have the technology required to keep large spaceships aloft during an atmospheric flight before the Union with Terra? Probably. Remember, to build their ships for their exploratory fleets during the Age of Strife, the AdMech built the Ring of Iron, gigantic spaceyards around the red planet. So they built their largest ships in space, and apparently didn't know how to make them enter the atmosphere of a planet without having them crashing into the ground.

chaos0xomega wrote:Yeah, because the fact that they are designed to withstand lance batteries that fire at the heat of the sun won't protect them at all..

Probably not, really. A lance is a lot of energy, focused into one spot, in a brief window of time. Unless lances fire perpetually for a minute, I doubt they are going to come close to delivering the same quantity of energy. Also, the heat is spread over the entire hull. Theres nowhere for the heat to disperse to, and its going to start eating up at the insides. And the sudden pressure of the atmosphere after no pressure from the vacuum is only going to complicate matters. The ship might be able to go down, but its going to take some serious damage, hull or components wise.

Randomonioum wrote: And the sudden pressure of the atmosphere after no pressure from the vacuum is only going to complicate matters. The ship might be able to go down, but its going to take some serious damage, hull or components wise.

Professor Hubert Farnsworth: Good Lord! That's over 5000 atmospheres of pressure!
Fry: How many atmospheres can the ship withstand?
Professor Hubert Farnsworth: Well, it was built for space travel, so anywhere between zero and one.

Look to melta based weapons for things hulls are designed to defend against which are very heat based.

Except that most ship hulls, or hulls of anything else, really, don't withstand melta weapons very well.

Melta is a bad example as the heat is focused on a single area, entering an atmosphere will exude less heat for the area then a Melta weapon would.


Besides, we have canon sources of ships entering atmospheres. and these same sources also state that not all ships can do this.