Sign in to follow this  
Followers 0
bogi_khaosa

Voidships vs. the Mighty Force of Gravity

23 posts in this topic

OK this is probably more an engineering question than a game one. :)

 

For a game I'm going to run --

 

If a largish Imperial ship were on a planet's surface (Earth gravity), would it support its own weight? Or would it collapse?

Share this post


Link to post
Share on other sites

Interesting question. it might depend on whether it was constructed within an artificial gravity (enclosed void dry dock) or in the open void. Astronomical phenomena such as gravity riptides put a lot of stresses on a vessel, and I'm sure they're built with the understanding that they may run afoul of them from time to time. I'd say anything larger than a cruiser would fold. I think BFG had rules for low-orbit planetary assaults, and there have been a few (fluff) instances of voidships entering and leaving atmosphere, with the only noteworthy occurrence being the havoc this causes on weather patterns.

 

What's the context of your query? 

Share this post


Link to post
Share on other sites

I can think of three examples of an Imperial ship on or near a planet's surface. In two of them, the ships crashed and later relaunched back into space. In the other, the ship floated near the surface of Mars. Granted, the ship in the last case was the Emperor's flagship during the Great Crusade, so you shouldn't assume current Imperial ships can do what that ship did. I would think that most of the major Imperial ships could be able to survive a crash landing though, including the ability to support it's own weight without collapsing.

Share this post


Link to post
Share on other sites

Battlefleet Gothic had transports and frigates capable of atmospheric entry - anything larger than that would crash / break apart.

 

However, that is just one source of fluff, and we have a lot of products with a different take on the subject (possibly even Rogue Trader? not sure) ... also, OP's query sounds more like something looking for real world physics rather than the various contradictory instances of 40k pseudoscience?

Share this post


Link to post
Share on other sites

If this came up in my campaign, I would probably rule that anything smaller than a cruiser can land/take off, and anything cruiser-sized or larger cannot.

Edited by Adeptus-B

Share this post


Link to post
Share on other sites

Kroot Warpsheres from Rogue Trader Battlefleet Koronus are battleship-sized and stated to be capable of landing/taking off planets.

Edited by LordBlades

Share this post


Link to post
Share on other sites

Interesting question. it might depend on whether it was constructed within an artificial gravity (enclosed void dry dock) or in the open void. Astronomical phenomena such as gravity riptides put a lot of stresses on a vessel, and I'm sure they're built with the understanding that they may run afoul of them from time to time. I'd say anything larger than a cruiser would fold. I think BFG had rules for low-orbit planetary assaults, and there have been a few (fluff) instances of voidships entering and leaving atmosphere, with the only noteworthy occurrence being the havoc this causes on weather patterns.

 

What's the context of your query? 

 

The characters are in a ruined ship (Hey guys don't read this!!!!), which has to drop out of the warp somewhere, and to make things easier I'm thinking of just having it materialize on a planet's surface.

 

I realize this may not be possible though, hmmm.

Share this post


Link to post
Share on other sites

Ships can survive landing.  It is just less likely the larger they are.  It depends on the surface they are on more than anything.  If a large ship is supported only at the ends, it will probably break up.  If it lands on a (relatively) soft surface that distributes its weight better, then it should be ok. 

Share this post


Link to post
Share on other sites

Rogue Trader has a ship background package that is essentially "this is an old ship that once crash-landed on a planet and was eventually recovered." Probably not under its own power. There are a lot of factors regarding if it could support its weight, in part the nature of the landing, whether void shields were active at the time, etc.

Share this post


Link to post
Share on other sites

Faith and Coin has a crashed ship that broke up upon landing, but the players are able to determine that the void shields were intact when it crashed by how intact the ship is (other than breaking up).  Planetbound of Millennia is probably my favorite ship background, and the players ship in my campaign actually started still on the planet.  Lifting it was part of their first Endeavor.

Radwraith and Kshatriya like this

Share this post


Link to post
Share on other sites

I kind of want the thing to start collapsing in on itself all around the players under its own weight, making them have to find some way off as quickly as possible.

Share this post


Link to post
Share on other sites

I don't think that larger vessels recovered from planetary surfaces were actually brought up in one piece. Maybe one piece at a time, then re-assembled in orbit.

 

Voidships are usually not meant to land. Lighter voidships, and by lighter I mean 6 million tons and less than 2km long, should be able to land. But a Light Cruiser or a Cruiser's roughly 20 to 30 megatons and about 5km long. This is why they have space stations after all.

Edited by Marwynn
Kshatriya likes this

Share this post


Link to post
Share on other sites

I kind of want the thing to start collapsing in on itself all around the players under its own weight, making them have to find some way off as quickly as possible.

 

Ah- in that case I would have the ship emerge from the warp too close to a planet, and the gravity starts tearing the ship apart, forcing the PCs to find Salvation Pods before it is completely destroyed. When the Pod lands on the surface, you can have a lot of fun with a fertile Imperial world being decimated by the wreckage (some it highly radioactive) raining from the sky, destroying settlements, causing a 'nuclear winter', etc. Somebody's got some 'splainin' to do...

Share this post


Link to post
Share on other sites

Lynata is correct. In BFG, Escorts and transports could land while larger ships could not. However, The Blood angels flagship (Which was ostensibly at least a battleship) crashed and relaunched after essentially performing minor repairs and damage control! Further, In the old 40k epic had cruisers descending into low orbit to deploy troops (Via grav cones). The basic rule that I've taken is that while most ships (gm's call) are capable of entering the atmosphere and remaining airborne landing requires specialized receiving facilities (Docks) unless the ship is specifically capable of a "dry landing". (Such as an assault transport)

 

Further: It is hardly a "Routine" operation to bring a full sized voidship down for a landing. I have a whole set of "Houserules" that deal with this subject. 

 

As to the engineering involved: I think most voidships, given their descriptions would survive being planetside and might even be able to be re-lifted if repaired. A planet's surface is a relatively stable field whereas gravity riptides and warp rifts are not!

A voidship's hull is designed to deal with almost inconceivable stresses (Many shipboard weapons hit as hard or harder than a nuke in RT!) so the stresses of atmospheric entry pale by comparison. Even crashing often does not compromise the hull unless the ship was heavily damaged before hand (Which of course, It usually is if it crashed in the first place!). 

 

Anyway; This article has my thoughts on this:  https://drive.google...dit?usp=sharing

Edited by Radwraith

Share this post


Link to post
Share on other sites

In the Salamander Tome of Fire story a Strike Cruiser crash lands and after repairs to its engines manages to lift off again. A Marine Malevolent Strike Cruiser also descends into the atmosphere, low enough to cast a shadow and provide close fire support.

Share this post


Link to post
Share on other sites

During the Badab War, the Star Phantoms landed their battle barge on a moon, but little information is given as to the moon's gravity, so it's hard to tell how impressive this feat really was.

This is actually a classic 40k FAQ: I've seen it asked in various ways in my years of lurking on 40k RPG forums...

My take on it is that warp-capable spacecraft are substantially over-engineered compared to equivalent sized planetary craft. The warp is a horrifically hostile environment, even with a Gellar field, so warp capable ships need to be able to withstand tremendous stresses. If a warp-capable vessel is an ocean liner, a system ship, no matter how large is, in terms of comparative robustness of construction, a rubber dinghy.

My view is that Imperial spacecraft are in many places almost solid blocks of metal, with superstructures consisting of tens of metres of tempered steel braced with adamantium. (In part this can be used to hand wave away any discrepancies in internal volume areas/ crew sizes that some of the cleverer forumites have pointed out, too.)

This super-robust construction means that some warp capable vessels are tough enough to survive entering a planet's gravity well, or even atmosphere, without disintegrating. They're rarely built for this, but they stand a chance or surviving it. Such a manoeuvre can never be entered into lightly, and it can never be taken for granted that ANY ship would survive trying it, but some of the better constructed warp capable craft, specifically Arks Mechanicus and Astartes vessels, would probably stand a better chance than most Naval or civilian vessels.

Anyway, that's my take on it. No real canon source for it, but it's an approach that explains ships both surviving and ships NOT surviving entering a planet's atmosphere...

Share this post


Link to post
Share on other sites

I am not an engineer or physicist by any stretch of the imagination but my rudimentary understanding was that there is a difference between the thrust needed to have something like a Gothic Class Cruiser take off and reach escape velocity and the maximum strain a structure can take before collapsing when on the surface of the planet.

 

That is to say a Gothic Cruiser is about what? 600 or 700m tall. Which is probably within the limits it could take within Earth's gravity.  

 

However the upward thrust needed to lift this behemoth of a star ship off the ground is probably too much, especially given where its engines are located. 

 

So to sum up I reckon an Imperial cruiser could land (just about) but probably not take off again.

 

Just my take on it but I'd love to see the explanation of an actual engineer.

Edited by Visitor Q

Share this post


Link to post
Share on other sites

I am not an engineer or physicist by any stretch of the imagination but my rudimentary understanding was that there is a difference between the thrust needed to have something like a Gothic Class Cruiser take off and reach escape velocity and the maximum strain a structure can take before collapsing when on the surface of the planet.

 

That is to say a Gothic Cruiser is about what? 600 or 700m tall. Which is probably within the limits it could take within Earth's gravity.  

 

However the upward thrust needed to lift this behemoth of a star ship off the ground is probably too much, especially given where its engines are located. 

 

So to sum up I reckon an Imperial cruiser could land (just about) but probably not take off again.

 

Just my take on it but I'd love to see the explanation of an actual engineer.

Actual engineering and 40k physics rarely mix that well!  :rolleyes: But as I pointed out earlier, there are plenty of Canonical sources that say that Warp capable vessels in 40k can enter an atmosphere and remain aloft! (I would assume through the use of antigrav technology similar to landspeeders.). If a vessel can fly then it can, at least theoretically land and take off again. My take on it has always been that Imperial vessels are rarely designed to land (As in have actual landing gear) but can "dock" at a planetside starport if available.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0