Design a hard sci-fi-warship (RAR).

SF: discuss futuristic sci-fi series, ideas, and crossovers.

Moderator: NecronLord

Patroklos
Jedi Council Member
Posts: 2020
Joined: 2009-04-14 11:00am

Re: Design a hard sci-fi-warship (RAR).

Postby Patroklos » 2017-02-21 10:31am

Simon_Jester wrote:I'm going to be honest, sheer frustration at the quote spaghetti is strangling my ability to even start writing a reply to this right now. The discussion has gotten so fragmented and the context so broken up that I know you've lost track of some elements of my point, Patroklos, and I wouldn't be the least bit surprised if I've lost track of some of yours.

Would you be open to rebooting our discussion a bit and having a moratorium on writing more than, say, five paragraphs at a time? It might hypothetically make the discussion take longer total because we'd have to go in series and not in parallel, but at least we wouldn't have to worry so much about stuff getting fragmented.

If you have a whole list of separate points to make, or if I do, we could maybe have actual numbered lists at the bottom of our posts.

How does that sound?


That's a great idea, it took me over an hour to reply last and I am sure you could tell I was rushing at the end.

So to backtrack a bit I wanted to restart the thread based on Shroom's ship idea. One of the primary characteristics was the sphere shape and I wanted to explore the utility of using it.. I think the result of our back and fourth yielded the following.

1.) Spheres have superior maneuvering characteristics. This is due to the different moment of inertia requirements for spheres and other shapes of the same uniform mass/volume. Technically the sphere over performs in pitch maneuvers and underperforms in rolling maneuvers, but due pitching being far more relevant the edge still goes to the sphere.

2.) Spheres have no optimal cross section presentation. This can be a major downside depending on the character of combat. Specifically, besides presenting a bigger target over some possible enemy presentations, if armor is a thing and selected partial protection arcs are the norm a sphere will always have to present a thinner layer for the same mass/density of armor. At the same time it doesn't have an outsized cross section to present either.

3.) A sphere has the smallest surface area to volume ration. This means if all around armor protection is required a sphere will have a smaller armor mass penalty that other shapes for the same protection. This also comes with the drawback that if you need a lot of surface area for any number of possible systems the sphere is at a disadvantage.

4.) A sphere's alpha arcs will probably be smaller than other shapes, and they will not be as usefully located.

5.) Thrust loading is more difficult for a sphere as the ship's mass is probably not stacked directly on top of the main engine as much as a cylinder or other long skinny shape meaning more mass dedicated to structure (or the equator will sag during thrust).

Maybe we can try and agree on those for the most part before moving on? Or hash those out further before moving on at least.

The next major characteristic of Shroom's amoeba ship is the hull/armor medium/inner hull concept. There is a lot to be said about the effectiveness of the armor in that setup.

Sky Captain
Jedi Master
Posts: 1032
Joined: 2008-11-14 12:47pm
Location: Latvia

Re: Design a hard sci-fi-warship (RAR).

Postby Sky Captain » 2017-02-21 11:47am

Thinking of armor. Every combat ship will need radiation protection or it will get soft killed by nearby nuclear explosions that othervise would do little if any damage. Particle beam weapons also would demand anti radiation armor. Armoring against radiation require lot of mass so if you are commited to lugging that mass around anyway may as well make radiation shielding from materials that are also good against high speed shrapnel. It would not help against nuke going off few meters away, but against flak warheads or simple shrapnel from missiles and shells destroyed by point defense it would prowide some benefit.

Maneuvering with main engine. If ship is designed similar to V 22 Osprey with 2 gimbaled main engine pods then it is easy to apply full acceleration forward, backward, up and down. Sideways acceleration would be available after a quick 90 degree roll by pointing one engine up, one down. Pitch and yaw by pointing one engine backwards one forward. Such arrangement would add some complexities especially if engines are radioactive, but if maneuvering is very important it may be worth it.

Patroklos
Jedi Council Member
Posts: 2020
Joined: 2009-04-14 11:00am

Re: Design a hard sci-fi-warship (RAR).

Postby Patroklos » 2017-02-21 01:20pm

Sky Captain wrote:Thinking of armor. Every combat ship will need radiation protection or it will get soft killed by nearby nuclear explosions that othervise would do little if any damage. Particle beam weapons also would demand anti radiation armor. Armoring against radiation require lot of mass so if you are commited to lugging that mass around anyway may as well make radiation shielding from materials that are also good against high speed shrapnel. It would not help against nuke going off few meters away, but against flak warheads or simple shrapnel from missiles and shells destroyed by point defense it would prowide some benefit.


The materials used for armor, and more importantly how you layer them, becomes very tricky if we are talking about the full spectrum of space weaponry being viable concurrently (nukes/particle bean/kinetic/laser).

For instance you mentioned radiation armor. That's going to look very different depending on whether we are talking about particle radiation (you want armor with lots of hydrogen like paraffin or even water tanks) or electromagnetic radiation (you want something dense like lead or tungsten). If particle beam weapons are a thing the layering is dictated for you, particle radiation armor has to go first. The reason for this is particle radiation that encounters normal metallic X-ray/Gamma ray armor turns into X-rays BEHIND that X-ray armor. That being said, from what I can tell materials good at stopping particle radiation appear to be rather fragile, which makes them poor laser or kinetic weapons armor.

So you may end up with attacks similar to WWII where they would send in fighter bombers to strafe battleships to kill AA crews (in this case send ships with lasers and railguns to scrape off/punch holes in the particle beam armor layer) and then follow up with torpedo bombers to get good drops on the now defenseless capital ship (in this case bring in a particle beam armed ship to bath the enemy in charged particles that hopefully now hit the naked Gamma-ray armor, frying the enemy crew behind it).

Shroom mentioned aerogels which piqued my interest. This is great because one form of them is made using carbon. Carbon can be decent against charged particle beams and gamma rays (though not great at either) and could be effective against kinetic weapons.

Maneuvering with main engine. If ship is designed similar to V 22 Osprey with 2 gimbaled main engine pods then it is easy to apply full acceleration forward, backward, up and down. Sideways acceleration would be available after a quick 90 degree roll by pointing one engine up, one down. Pitch and yaw by pointing one engine backwards one forward. Such arrangement would add some complexities especially if engines are radioactive, but if maneuvering is very important it may be worth it.


This is basically what Sea Skimmer was saying with the azipod suggestion. I think its a great idea of civilian ships or even glass cannons where any hit is a death sentence anyway. The idea seems at odds to the minimal cross section effort however, so there has to be some math done on the increase to your chances of taking a hit due to increased cross section over the increase in maneuverability. It may be a good trade.

User avatar
Shroom Man 777
FUCKING DICK-STABBER!
Posts: 20910
Joined: 2003-05-11 08:39am
Location: Bleeding breasts and stabbing dicks since 2003
Contact:

Re: Design a hard sci-fi-warship (RAR).

Postby Shroom Man 777 » 2017-02-21 02:35pm

The "wingtip-mounted" engines could not only have thrust-vectoring, but the appendages they're on could also be "variable-geometry" so it's like a V-22 or Babylon 5 starfighter but if their wings are F-14-like :D

Sure that's mechanically super-complex but screw it.
Image Image Image
shroom is a lovely boy and i wont hear a bad word against him - LUSY-CHAN!
Shit! Man, I didn't think of that! It took Shroom to properly interpret the screams of dying people :D - PeZook
Shroom, I read out the stuff you write about us. You are an endless supply of morale down here. :p - an OWS street medic
Pink Sugar Heart Attack!

User avatar
Sea Skimmer
Yankee Capitalist Air Pirate
Posts: 37032
Joined: 2002-07-03 11:49pm
Location: Passchendaele City, HAB
Contact:

Re: Design a hard sci-fi-warship (RAR).

Postby Sea Skimmer » 2017-02-21 11:37pm

As far as the sphere idea goes, unless the ship is very large a sphere will lead to very inefficient use of interior space, and incredibly bad maintenance access. This is a big problem for a hard sci fi ship, because you can't operate like a plane or a sub where you spend the majority of your time inactive in a base undergoing maintenance. For hard sci fi war your probably going to do 100% of this in the field with repair ship support, and frankly probably not even plan for your warships to ever go home, because propellent is expensive to ship out and travel times very long. One way ticket to conquest, you can ship the cancer riddled crews back on much higher speed transport vessels. I could even imagine warships being boosted home, but left to basically drift the passage on autopilot for years, in situations where the combat crew can go home in a few months for example.

The other big problem with a sphere is again unless its very large your going to have an incredibly hard time configuring the interior. LIke your nuclear reactors are going to be right up against 100% of your crew quarters. This is not going to lead to amazing ship design if your trying to save weight. Meanwhile the bigger a conventional linear hull design gets the stronger it gets too, because its a bigger girder, which tends to cancel out your bending problems. That eventually fails, but we'd be talking million ton vessels at that point. Also more stiffness is something composite materials are good at. I can't see rigidity being any real boon to a sphere ship, not if armor mass is in play, which also contributes to the 'packing' problem. A spherical ship needs spherical armor packages, that is not helpful at all, literally no matter what you plan to make the armor out that will be harder, if it will work at all. Realistically you'll just end up with stacks of boxes of whatever, under the sphere.

Sphere makes more sense for civilian purposes where you plan to make everything out of a triple layer of aluminum foil and could thus have a very large sphere with its strength governed only by the need to hold pressure. Then inefficent packing isn't a big concern because you have a huge amount of space in the first place.

Also people should remember that nothing says a single warship has to be effective...some pretty long periods of naval history on earth were basically dominated by ship to ship action being incredibly indecisive, and dependent on multiple ships overwhelming specific opponents.
"This cult of special forces is as sensible as to form a Royal Corps of Tree Climbers and say that no soldier who does not wear its green hat with a bunch of oak leaves stuck in it should be expected to climb a tree"
— Field Marshal William Slim 1956

Patroklos
Jedi Council Member
Posts: 2020
Joined: 2009-04-14 11:00am

Re: Design a hard sci-fi-warship (RAR).

Postby Patroklos » 2017-02-22 01:12pm

Sea Skimmer wrote:As far as the sphere idea goes, unless the ship is very large a sphere will lead to very inefficient use of interior space, and incredibly bad maintenance access.


This is a common criticism, but it rings hollow to me. This idea is predicated on laying out the ENTIRE sphere with decks layer cake style perpendicular to the thrust axis. This is extremely simplistic because 1.) It assumes the entire ship will be optimized for operating in gravity (either landed on a planet or under thrust) 2.) It assumes the entire ship is designed to be crew accessible in gravity.

If you insist on putting your decks up against the curved hull, this will only be a problem at the bow and stern where the inward curving hull will make headroom tough for normal human occupancy. At and near the equator it will barely be noticeable, and even about halfway up you can still conveniently place equipment that some engineer insisted must be shaped to optimally conform to humans under gravity comfort requirements. The good thing about this, however, is the worst spaces to occupy as a human in gravity (the extreme forward and aft sections) are also the optimal places to put either engines and propellant tanks or sensors and weapons. None of these need to be designed to conform to conventional gravity bound environments. Here is an example.

Image

I would note that a cylinder has the same problem regarding curves. Granted the deformations are in two dimensions instead of three. But for any given volume the severity of the curve will be more pronounced on a cylinder.

I am not following you on the maintenance access. Either there is a door through the hull or interior pressure bulkhead or there isn’t.

This is a big problem for a hard sci fi ship, because you can't operate like a plane or a sub where you spend the majority of your time inactive in a base undergoing maintenance. For hard sci fi war your probably going to do 100% of this in the field with repair ship support, and frankly probably not even plan for your warships to ever go home, because propellent is expensive to ship out and travel times very long. One way ticket to conquest, you can ship the cancer riddled crews back on much higher speed transport vessels. I could even imagine warships being boosted home, but left to basically drift the passage on autopilot for years, in situations where the combat crew can go home in a few months for example.


I have to disagree with you here. Not on the expendability of warship hulls, but on the idea if you do major maintenance it will be on the fly in situ. We are already at the point with real world warships where the components are so advanced little to no effort is put into repairing them in place besides just swapping out assemblies with spares. For anything electronic the stuff is just too complex or literally too small to work on. 2M (microminiature) repair shops are barely used and ships workshops are essentially unmanned as few ships have MRs and HTs onboard anymore. Long gone is are the days of the ET swapping out transistors on circuit boards or an MR lathing you a valve or some sort. And unlike on a sea going warship, hauling around a significant amount of spares is a significant mass penalty.

I agree tenders will exist for this very reason. I at the same time think even they will be unable to house the expertise and resources to accomplish major repairs and will be there to largely act as a spare part reserve. Depot level maintenance will still be a thing or we will build ships to be discarded after major damage.

The other big problem with a sphere is again unless its very large your going to have an incredibly hard time configuring the interior. LIke your nuclear reactors are going to be right up against 100% of your crew quarters. This is not going to lead to amazing ship design if your trying to save weight.


If you are planning on having our engine interior to the hull sure. There are reasons to do that, mass penalty for shadow shielding be damned. You can, however, put your engine on the end of a lattice spline on a sphere just as easy as you can do it with a cylinder. There are tactical limits to this though. The longer your ship gets, and if you are relying on a very small forward cross section and/or armor shadow for survivability, the longer you are means the less distance an enemy ship has to move to expose your ass. This is a big problem if there are multiple enemy ships.

I used solid shapes, sphere and cylinder, above to make the math easier.

Meanwhile the bigger a conventional linear hull design gets the stronger it gets too, because its a bigger girder, which tends to cancel out your bending problems. That eventually fails, but we'd be talking million ton vessels at that point. Also more stiffness is something composite materials are good at. I can't see rigidity being any real boon to a sphere ship, not if armor mass is in play, which also contributes to the 'packing' problem. A spherical ship needs spherical armor packages, that is not helpful at all, literally no matter what you plan to make the armor out that will be harder, if it will work at all. Realistically you'll just end up with stacks of boxes of whatever, under the sphere.


Probably, though any plesiohedron would work if you want regular stacking spaces though.

Equatorial sagging under thrust is definitely a drawback to a sphere.

Also people should remember that nothing says a single warship has to be effective...some pretty long periods of naval history on earth were basically dominated by ship to ship action being incredibly indecisive, and dependent on multiple ships overwhelming specific opponents.


If warships are using anything less than 100% all around armor then there will always be an incentive to force an opponent to expose a less than optimal profile. This means having more ships will be a major advantage as they can flank, forcing you to chose a threat axis to orient to when there is more than one to worry about.

And to clarify I don't mean armor has to be the same effectiveness on every point on the hull, just that there can't be any glaringly obvious weak points that mean the slightest mistake gets you hulled. Well, at least the ships on your own flanks can't have that weak spot. It may be that you have weapons optimized/protection minimized to forward arc ships in the center of your formation protected by all around defense oriented escorts on your flanks to make sure no enemy can't get into their baffles for the one shot kill.

Sky Captain
Jedi Master
Posts: 1032
Joined: 2008-11-14 12:47pm
Location: Latvia

Re: Design a hard sci-fi-warship (RAR).

Postby Sky Captain » 2017-02-24 05:20pm

Patroklos wrote:The materials used for armor, and more importantly how you layer them, becomes very tricky if we are talking about the full spectrum of space weaponry being viable concurrently (nukes/particle bean/kinetic/laser).

For instance you mentioned radiation armor. That's going to look very different depending on whether we are talking about particle radiation (you want armor with lots of hydrogen like paraffin or even water tanks) or electromagnetic radiation (you want something dense like lead or tungsten). If particle beam weapons are a thing the layering is dictated for you, particle radiation armor has to go first. The reason for this is particle radiation that encounters normal metallic X-ray/Gamma ray armor turns into X-rays BEHIND that X-ray armor. That being said, from what I can tell materials good at stopping particle radiation appear to be rather fragile, which makes them poor laser or kinetic weapons armor.


It probably would mean that you armor only against stuff that can't be intercepted like lasers, particle beams and minor shrapnel. Anything fast with significant mass or a nuke has to be stopped/deflected by point defense, fooled by ECM or ship is wrecked. It is the same like modern air combat where weapons are so powerful that only viable defense is to not get hit in the first place.

Patroklos wrote:This is basically what Sea Skimmer was saying with the azipod suggestion. I think its a great idea of civilian ships or even glass cannons where any hit is a death sentence anyway. The idea seems at odds to the minimal cross section effort however, so there has to be some math done on the increase to your chances of taking a hit due to increased cross section over the increase in maneuverability. It may be a good trade.


Such highly maneuverable designs would be especially attractive in a setting where torchships exist. If delta v is cheap then spending few dozen km/s on combat maneuvering would barely register on a fuel gauge. Given how devastating even a few kg railgun bullet would be if relative velocity between opposing ships can be several hundred km/s or more there would be huge incentive to design for maximum possible maneuvering to avoid cheap long range kills by dumb ballistic weapons

User avatar
Sea Skimmer
Yankee Capitalist Air Pirate
Posts: 37032
Joined: 2002-07-03 11:49pm
Location: Passchendaele City, HAB
Contact:

Re: Design a hard sci-fi-warship (RAR).

Postby Sea Skimmer » 2017-02-25 12:30am

Patroklos wrote:This is a common criticism, but it rings hollow to me. This idea is predicated on laying out the ENTIRE sphere with decks layer cake style perpendicular to the thrust axis. This is extremely simplistic because 1.) It assumes the entire ship will be optimized for operating in gravity (either landed on a planet or under thrust) 2.) It assumes the entire ship is designed to be crew accessible in gravity.


I really have no idea where you get this from. No, its predicated in geometry and real life, and how real things are produced and organized. Your making a wide range of assumptions here that are entirely your own.


If you insist on putting your decks up against the curved hull, this will only be a problem at the bow and stern where the inward curving hull will make headroom tough for normal human occupancy.


See this is where your just coming out of left field assuming were even on the same wavelength. What decks? Of even height? Decks on real ships have specific structural and occupational functions. Those aren't the same in a hard sci-fi warship. Precisely because we don't have gravity the key point of a deck operationally no longer matters and we can employ a much more flexible and thus optimal designs approaches. The structural bracing they provide real ships meanwhile can be replaced by other forms of structure; just what you would do comes down to very specific design details, as some ship concepts will need far more bracing then others.

I don't expect to have any much at all like a normal, whatever the axis, deck structure at all if you want to talk about a real future hard sci fi warship. I don't think a single damn thing I've ever seen argued before, or presented by sci fi authors really matches up much at all to what we would build even given more or less today's technology, if trillions of dollars for full out space warfare were to appear.

It's not that my ideas are so good or anything of the sort either; rather its that too much of the built up inertia of science fiction dates to a period were people couldn't really think about anything but metal for structure, as a basic issue. Now we have things like the 777X wing and King Stallion fuselage as realities for wholely composite structures, and all kinds of plausible embedded technology to look forward too. Like I'd like to see the composite beams holding the engines into a space ship also be the capacitors for its laser weapons. That's not imaginary stuff, people are trying to build vehicles like that as we speak.


At and near the equator it will barely be noticeable, and even about halfway up you can still conveniently place equipment that some engineer insisted must be shaped to optimally conform to humans under gravity comfort requirements. The good thing about this, however, is the worst spaces to occupy as a human in gravity (the extreme forward and aft sections) are also the optimal places to put either engines and propellant tanks or sensors and weapons. None of these need to be designed to conform to conventional gravity bound environments. Here is an example.

[img]http://i.imgur.com/vms1EeZ.png[img]


The example is in fact entirely comic book level.You show hydrogen storage with no tankage or plumbing concept, and no consideration for use of that enormous mass as protection, but it's that kind of issue that's at stake!


I would note that a cylinder has the same problem regarding curves. Granted the deformations are in two dimensions instead of three. But for any given volume the severity of the curve will be more pronounced on a cylinder.


Yeah but then you can put cylindrical tanks into the cylinder, and subdivide them if need be. A sphere randomly full of much smaller spheres will suck, you'd have to use saddle tanks, which gets us back into the wonderous world of please don't at this kind of pressure and COLD, which makes many desirable structural materials brittle to the point they can't be used.


I am not following you on the maintenance access. Either there is a door through the hull or interior pressure bulkhead or there isn’t.


Dude, life is not that simple. Have you ever been on say a submarine? Just because you can't get into a compartment doesn't mean you can get any useful work done on what is inside of it. The intricacy and interconnectedness of a space warship would be absolutely staggering. Jet fighter level or worse, except you don't get to spend literally half your time tearing it apart for routine checks.

I have to disagree with you here. Not on the expendability of warship hulls, but on the idea if you do major maintenance it will be on the fly in situ. We are already at the point with real world warships where the components are so advanced little to no effort is put into repairing them in place besides just swapping out assemblies with spares.


You realize that swapping out full assemblies requires more, and not less maintenance access right? And it certainly does encourage field repairs, it was what makes it possible.


If you are planning on having our engine interior to the hull sure. There are reasons to do that, mass penalty for shadow shielding be damned.


Yeah, reasons like counting as a warship. Also this is where you need to use more innovative solutions then sci fi is prone too frankly. Such as we can use a propellent tank as our shadow shield, and drain it last, and just not run the reactor at anywhere near full power as we limp home.


You can, however, put your engine on the end of a lattice spline on a sphere just as easy as you can do it with a cylinder. There are tactical limits to this though. The longer your ship gets, and if you are relying on a very small forward cross section and/or armor shadow for survivability, the longer you are means the less distance an enemy ship has to move to expose your ass. This is a big problem if there are multiple enemy ships.


I'm not a fan of a exposedstructure like that on something you intend to engineer as a warship. An armed merchant or science ship, sure. We can put missiles on anything. Also I will point out the very idea of a lattice is one of those things that seemed like the only plausible future in say 1980 when everyone 'knew' the future space materials of choice would be something like titanium or magnesium alloy. But you know here in the actual 21st century it looks to me like you'd end up building something like that as a carbon fiber or graphene tube if it was the year 2050 even, let alone past that. Again I cannot see any useful point to a sphere unless the highest mass structural requirement is retaining pressure, and that's just not going to be the case if you want even token armoring.

As far as exposing your ass goes, grazing angle applies to the value of your protection too. A very large surface exposed at a very sharp angle can get away with very thin protection. In contrast if you use a sphere you [i]always[i] present a non grazing angle target to the enemy no matter how you turn, which is one of the reasons why I judge it pointless complexity.
"This cult of special forces is as sensible as to form a Royal Corps of Tree Climbers and say that no soldier who does not wear its green hat with a bunch of oak leaves stuck in it should be expected to climb a tree"
— Field Marshal William Slim 1956

Patroklos
Jedi Council Member
Posts: 2020
Joined: 2009-04-14 11:00am

Re: Design a hard sci-fi-warship (RAR).

Postby Patroklos » 2017-02-25 03:34pm

Sea Skimmer wrote:I really have no idea where you get this from. No, its predicated in geometry and real life, and how real things are produced and organized. Your making a wide range of assumptions here that are entirely your own.


I am actually just forced to interpret an extremely vague comment by you for which you provided no examples to support. I don't think it is at all unreasonable to assume the problem you are talking about is linked to what most people why think hard about the subject consider the likely flaw you are concerned with.

If that's NOT what you are concerned with please let us know in a bit more detail, because there is nothing about "geometry and real life" that inherently make a sphere harder to organize. You have a point about producing it if its a proper sphere instead of some geodesic panel construction approximation.


See this is where your just coming out of left field assuming were even on the same wavelength. What decks? Of even height? Decks on real ships have specific structural and occupational functions. Those aren't the same in a hard sci-fi warship. Precisely because we don't have gravity the key point of a deck operationally no longer matters and we can employ a much more flexible and thus optimal designs approaches. The structural bracing they provide real ships meanwhile can be replaced by other forms of structure; just what you would do comes down to very specific design details, as some ship concepts will need far more bracing then others.


1.) Unless you at talking about very low tech levels where including artificial gravity arrangements is just not feasible (we are probably already past those tech levels now) or tech levels so high that mission lengths are such that microgravity health/moral issues are not a concern you WILL have to include it in any hard scifi warship design. It may not involve thrust perpendicular permanent decks relying on the engines to provide it (centrifuges or tumbling pigeon arrangements would look far different for instance), but you will have occupational spaces designed to function with gravity. My point was that however you do it, only a fraction of the ship will be arranged thus and the rest can be designed for zero g with due thought given to engine forces.

2.) Decks on we navy ships are not the way they are for structural reasons. You have a better argument for bulkheads, but only slightly. If there was no care to the realities of humans having to work in in occupationally functional (as you say) gravity constricted environments the internal supports of an Arleigh Burke would look drastically different than they due. Those decks have to exist the way they are for obvious reasons, and since they have to be there we integrate structural functions where we can, but compromises are made between optimal layouts for both to achieve a functional result.

It should go without saying that a spaceship doesn't have to worry about gravity nor can it rely on displacement pressure to support a keel (the keel being through the center or the ship, not along a nonexistent bottom). The only real analogous force is the thrust bearings of the shafts or other propulsion and any APUs if they exist (minus the water resistance).

I don't expect to have any much at all like a normal, whatever the axis, deck structure at all if you want to talk about a real future hard sci fi warship. I don't think a single damn thing I've ever seen argued before, or presented by sci fi authors really matches up much at all to what we would build even given more or less today's technology, if trillions of dollars for full out space warfare were to appear.


Please elaborate, I have no doubt you have interesting ideas about this.

It's not that my ideas are so good or anything of the sort either; rather its that too much of the built up inertia of science fiction dates to a period were people couldn't really think about anything but metal for structure, as a basic issue. Now we have things like the 777X wing and King Stallion fuselage as realities for wholely composite structures, and all kinds of plausible embedded technology to look forward too. Like I'd like to see the composite beams holding the engines into a space ship also be the capacitors for its laser weapons. That's not imaginary stuff, people are trying to build vehicles like that as we speak.


An excellent idea regarding the use of materials for duel purposes.

For Shroom's ship idea I intended to use the large aerogel armor layer as a super capacitor. I was imagining that this would also mean that instead of using aerogel as just a passive kinetic defense, this could maybe also turn it into a giant electric reactive (maybe more passive, I have to investigate more) armor system. The more I research aerogels the more I find them wanting in defending against anything above 10km/s. This means I means that a robust whipple layer would still be needed which may mean mass intensive outer hull plating. This could be largely skipped if the aerogel can indeed double as electric armor.


The example is in fact entirely comic book level.You show hydrogen storage with no tankage or plumbing concept, and no consideration for use of that enormous mass as protection, but it's that kind of issue that's at stake!


Its a back of napkin general diagram SS. Its pretty obvious the bulk of the tankage is the hull itself in that second doodle, and since the engine is attacked directly to that part of the hull the piping is sort of obvious...

And that enormous mass of LH2 is where it is to act as the engine's shadow shield, which you mention yourself further below.


Yeah but then you can put cylindrical tanks into the cylinder, and subdivide them if need be. A sphere randomly full of much smaller spheres will suck, you'd have to use saddle tanks, which gets us back into the wonderous world of please don't at this kind of pressure and COLD, which makes many desirable structural materials brittle to the point they can't be used.


Why would spheres inside of spheres suck?. Quite the contrarily, you can make some pretty effective structural arrangements with spheres stacked inside as sphere that negate some of the structural problems with a spherical outer hull (think a pyramid of for small spheres inside a large one, the apex butted up to the engine and the four corners of the base butted up against the forward hemisphere). Its not as completely out there as you think.

As for you cylinders fitting into cylinders, so what? If you are worried about the odd shaped spaces created by a smaller sphere butted up against the inside or bigger sphere the cylinder the nested cylinders have the same problem on they curved sides (again, granted its a 2D deformation vs a 3D). Sure, if they hey have flat ends they will stack nicely there. But if those cylinders are under pressure those flat ends will require a lot more structure. The spheres would not.

I would also point out spheres fit into cylinders, and cylinders fit into spheres. I see no reason why either shape would automatically prompt saddle tanks. I image ships of BOTH shapes would use discardable saddle tanks for the for their pre combat maneuvers simple to avoid having to protect empty tankage in a fight.


Dude, life is not that simple. Have you ever been on say a submarine? Just because you can't get into a compartment doesn't mean you can get any useful work done on what is inside of it. The intricacy and interconnectedness of a space warship would be absolutely staggering. Jet fighter level or worse, except you don't get to spend literally half your time tearing it apart for routine checks.


I am a career Navy man, and I just finished a tour at the Norfoly Naval Shipyard a year ago. I know all about ship maintenance, especially the logistics of said maintenance (my job there). We did work on subs. The maintenance on them is not harder on them over a surface ship due to any interconnectedness. Its because its a pressure hull you can't make access cuts on readily and it deoesn't come with large ready made hatches through the hull. Its because 90% of it is underwater even peirside which means you have to take it into drydock for what would be routine things on a surface ship. It has a nuclear reactor, so obviously difficulties there. But most fundamentally because its a pressure hull volume is expensive, which prompts it to be crammed solid with equipment. There isn't room to do maintenance readily.

The only one of those that translates readily to spacecraft is the nuclear part.

You realize that swapping out full assemblies requires more, and not less maintenance access right? And it certainly does encourage field repairs, it was what makes it possible.


We are talking primarily about circuit boards here, so not a lot of space required. I can count on two hands the number of parts maintained on a DDG that are larger than 2'x2'. One of those was the spare toilet. The sort of maintenance that goes beyond that is simply not done underway to any meaningful degree. If its not something as simple as swapping a card it doesn't get fixed.

The old engineering adage that accompanies this sort of repair is "you can't tow another ship behind you to pull parts off of." And assembly replacement means lots of spare parts which means lots of extra mass.

On this vein, however, I am still not seeing where you support a sphere would be worse for maintenance than other shapes. If you imagine physical space is the problem a sphere is better as increasing volume is cheaper. If you are worried about the crammed nature of a starship resembling a submarine, well, I can cram any shape to that degree.


Yeah, reasons like counting as a warship. Also this is where you need to use more innovative solutions then sci fi is prone too frankly. Such as we can use a propellent tank as our shadow shield, and drain it last, and just not run the reactor at anywhere near full power as we limp home.


A lot of the previous discussion revolved around how much you can afford to armor. A 100% protection solution is great, but the tyranny of mass vs engine performance vs weapons power is going to make different eras of ships be able to afford wildly different defense schemes. Sometimes it will be cowering behind the smallest armor crossection you can. Sometimes it will be drapping yourself in boron laser armore all around. If its the first, you have the concerns I highlighted regarding covering your ass. I will also not that in real life things using armor don't apply it evenly, such as tanks. For this reason the put a lot of time and thought into threat axis presentation. For a long time ships had to worry about being racked up the stern for several reasons.

I setup a configuration that used propellant as a shadow shield. You poopooed it. :(


I'm not a fan of a exposedstructure like that on something you intend to engineer as a warship. An armed merchant or science ship, sure. We can put missiles on anything. Also I will point out the very idea of a lattice is one of those things that seemed like the only plausible future in say 1980 when everyone 'knew' the future space materials of choice would be something like titanium or magnesium alloy. But you know here in the actual 21st century it looks to me like you'd end up building something like that as a carbon fiber or graphene tube if it was the year 2050 even, let alone past that. Again I cannot see any useful point to a sphere unless the highest mass structural requirement is retaining pressure, and that's just not going to be the case if you want even token armoring.


Those are great materials to use, but unless you have a really good reason to enclose that volume between your main hull and the engine you wouldn't use the tube as you describe. That tube construction is a strong structure using titanium too. The reason you use the lattice is that it requires less material for the same structural strength (its probably also made out of tubes). So you might use a carbon fiber tube over a titanium lattice, but then the question would be by don't you use a carbon fiber lattice for half the carbon fiber?

I think we have been pretty liberal thus far regarding material selections where we have gotten specific. Simon was talking about Kevlar filaments to provide rigidity to armor mediums. I mentioned aerogels made from carbon (silica is more common) as well as foamed metals. Boron for laser armor. We went through the gambit of radiation armor options. I have no doubt that future material science will render a lot of what we say here obsolete but given the spirit of the OP I am trying to link it to real life science however tenuously. If not we might as well just be talking about transparsteel/transparent aluminum aka mithril/Valaryian steel ake science fantasy.

I believe the original intent of Shroom's sphere shape selection was that he was relying on a very thick layer of very low density armor medium (aerogel) and was assuming he wanted even protection all over. The easiest way to get that is a sphere or at least an ellipsoid.

As far as exposing your ass goes, grazing angle applies to the value of your protection too. A very large surface exposed at a very sharp angle can get away with very thin protection. In contrast if you use a sphere you [i]always[i] present a non grazing angle target to the enemy no matter how you turn, which is one of the reasons why I judge it pointless complexity.


sloped armor is certainly a powerful tool even in space warfare, but it has its limits. Firstly this is a 3D environment, so unlike tank warfare you can't predict the likely angle of attack of a projectile as readily. Sure, a lot of time and effort is going to be put into presenting the optimal hull aspect to the enemy, especially if armor is so expensive mass wise that you only put it on certain aspects. But the reality is optimistically any angle forward of your beam is a likely enemy attack vector especially if they have a numbers advantage. But go for, it pick a face you consider the most vulnerable and slope the hell out of it. Some points though:

- As I have stated many times a sphere has no optimal presentation aspect but that also means it has not suboptimal one either (except one shared by all ships, its engine). There will always be a portion of its hull perpendicular against the enemy, but MOST of the hull presented will actually be at grazing angles very conducive to the protection you talk about. Given our maneuver discussions previously unless you are talking about lasers its not at all likely you hit that sphere direct on the nose where the armor is perpendicular to you.

- If you have optimized your ship for a particular aspect, say forward, to utilize maximum slope protection with say a pyramidal or cone shape some things are also true A.) For an equal mass equal density ship you drastically extended the length of your ship making you very unmanuverable, B.) In the case of a pyramid or other flat facing shape you present a perpendicular surface around your hull in ways far more vulnerable than any face of a sphere C.) If you use a cone you have the same vulnerability of a sphere, the weak spot is just a thin line instead of a small circle with the same increasing slope protection as you move away from the weak spot, the same goes for spheres and D.) B means maintaining optimal facing to the enemy will be a challenge and if you lose it you will have a hell of a time getting it back. Especially if your opponent is a sphere.

User avatar
LaCroix
Sith Marauder
Posts: 4100
Joined: 2004-12-21 12:14pm
Location: Vienna, Austria, Europe, Terra

Re: Design a hard sci-fi-warship (RAR).

Postby LaCroix » 2017-02-27 08:32am

Patroklos wrote:sloped armor is certainly a powerful tool even in space warfare, but it has its limits. Firstly this is a 3D environment, so unlike tank warfare you can't predict the likely angle of attack of a projectile as readily.


Actually, you can, even more than in planetary warfare, because of distances and speeds involved.

The enemy will approach you from a large distance, and at high speed. Therefore, he is pretty much locked into an angle of attack. There is no mechanism he could quickly change his vector in order to pass us by, slow down/match our speed and then engage us from a different angle. It would be a huge cost of dV, and take a lot of time. And it would mean offering us a shot at a vulnerable part of him, or mean he needs to armor a lot more of his ship, making the cost even higher.

The only way he could realistically endanger multiple vectors is if he had forward and broadside armament, which once more, increases weight, and reduces the amount of firepower he can bring to bear at any time of the engagement, while we only have to turn towards him as he passes by and use all our weaponry at the same time.

Same for missiles. To be capable of attacking from a flanking position, they would need to first approach us at a high speed, then turn around and approach us from the new vector, which means they also need to match our speed which was 180° opposite to their original vector. That's a LOT of dV to put into the missiles. And a lot of time to shoot them down (very beneficial to us, for this approach removes the danger of shrapnel hits after interception).

It's actually more likely to predict the angle of attack in a space battle than in a tank or naval battle, or any battle involving aircraft.
A minute's thought suggests that the very idea of this is stupid. A more detailed examination raises the possibility that it might be an answer to the question "how could the Germans win the war after the US gets involved?" - Captain Seafort, in a thread proposing a 1942 'D-Day' in Quiberon Bay

I do archery skeet. With a Trebuchet.

Patroklos
Jedi Council Member
Posts: 2020
Joined: 2009-04-14 11:00am

Re: Design a hard sci-fi-warship (RAR).

Postby Patroklos » 2017-02-27 10:05am

Everything you say about armor is true. IF we are talking about 1 on one duels. AND assuming one side dies during the initial closing.

As soon as you add another ship (or any weapons platform inside weapons range) your above situation no longer applies.

What you say about missiles isn't quite true. I can shoot out a missile with a rail gun launcher at a slight angle from our charging coding vector refrigerated to whatever low temp it's sytems will handle and you won't know it's there until it accelerates at you from your flank.

User avatar
LaCroix
Sith Marauder
Posts: 4100
Joined: 2004-12-21 12:14pm
Location: Vienna, Austria, Europe, Terra

Re: Design a hard sci-fi-warship (RAR).

Postby LaCroix » 2017-02-27 12:36pm

IT applies to all scenarios.

The ships are coming to our system from the same system. They have to stay in communication range to make a simultaneous attack possible. I can see them at very long range.
I deploy my ships to intercept them in the best manner possible. If there are 2 groups advancing, then I deploy in a way that I have the bigger group behind the smaller, and not between them.

The attacker can't avoid that, since there is no maneuvering besides slight corrections to the main vector at the speeds that an aproach would be made. So splitting his forces would only allow the defender to flank him, simply by moving to one side.

Missile refrigeration is nice. But I doubt it would work - whatever comes out of a railgun will be hot as hell. And there is still radar and stuff. Still, it would need a very impressive burn to make it hit a ship passing by at several (10+) km/s relative speed.
A minute's thought suggests that the very idea of this is stupid. A more detailed examination raises the possibility that it might be an answer to the question "how could the Germans win the war after the US gets involved?" - Captain Seafort, in a thread proposing a 1942 'D-Day' in Quiberon Bay

I do archery skeet. With a Trebuchet.

Patroklos
Jedi Council Member
Posts: 2020
Joined: 2009-04-14 11:00am

Re: Design a hard sci-fi-warship (RAR).

Postby Patroklos » 2017-02-27 01:09pm

LaCroix wrote:
The ships are coming to our system from the same system. They have to stay in communication range to make a simultaneous attack possible. I can see them at very long range.


Sure, but not necessarily zero lag communications range. Whatever that range is, its going to be MANY times any plausible weapons range. Hundreds of times more at least, but probably thousands. More than enough space and time to coordinate maneuvers even with minutes of lag time.

Remember that real navies, while inside eyeball and weapons range, used to coordinate complex maneuvers of sometimes hundreds of units with flags and later lights and later manually decoded radio. All of these took minutes, sometimes double digit, to see/verify/translate/decode/report.

I deploy my ships to intercept them in the best manner possible. If there are 2 groups advancing, then I deploy in a way that I have the bigger group behind the smaller, and not between them.


To be blunt, there are only very specific circumstances where geometry supports this and they all also assume no attempt to avoid it by the enemy. Also, good luck trying that against THREE enemy ships...

The attacker can't avoid that, since there is no maneuvering besides slight corrections to the main vector at the speeds that an aproach would be made. So splitting his forces would only allow the defender to flank him, simply by moving to one side.


That's not how maneuvering in vacuum works. Go reread the discussion between Simon and I regarding this. There are no restrictions on maneuvering through your center of gravity for the forward hemisphere of options. The magnitude of this movement is limited only by the power of your maneuvering thrusters.For the other hemisphere you have to break your original thrust vector more and more the closer to reversing you get but you will still get lateral movement if you are even the slightest degree off the reciprocal. This paragraph is describing using manuevering thusters only.

If you are talking about pitching to maneuver with your main engine things are closer to what you describe. But since you are talking about long range maneuvering ships have the time to to do so. In either case, the enemy is more thank likely to have the dV to avoid being kept directly on a threat axis. Its trivially easy to avoid this. The opposite however, of two enemy ships trying to shadow each other (say an unarmored missle bus behind and armored gunfighter), is accomplishable agains your one ship.

Missile refrigeration is nice. But I doubt it would work - whatever comes out of a railgun will be hot as hell. And there is still radar and stuff. Still, it would need a very impressive burn to make it hit a ship passing by at several (10+) km/s relative speed.


There are a couple ways to get around it, such as insulating the armatures from the round. You can turn on your actives sure, but that gives your enemy some awesome fire control solutions. Flank shots are harder than right towards the nose, but then you are probably showing a lot more cross section on your flank too.

User avatar
LaCroix
Sith Marauder
Posts: 4100
Joined: 2004-12-21 12:14pm
Location: Vienna, Austria, Europe, Terra

Re: Design a hard sci-fi-warship (RAR).

Postby LaCroix » 2017-02-27 01:50pm

The enemy had to come in at high relativistic speeds, in order to make it into my system in a plausible time. This means he had to make the last part of his jurney in reverse, trying to slow down, and is locked to a certain course cone. There is no way he can outmaneuver a defense formation lining up that can use their main thrusters to manouver. Especially that in hard sci-fy, he will know that they are coming, weeks and months in advance. Maybe even years, if someone contacted them using lightspeed tranmissions.

Even if they slow down further out, the defender can always advance and intercept them on his terms, or wait for them to come and deploy tactically with superior thrust.

And I can do the deployment trick against any number of enemy vessels. It's called "moving aside". As long as I keep my forces to one side of the approaching fleet, I will always have the option to fight them with local numerical superiority if they are trying to spread out. The defender has a lot of options that the attacker does not have, due to the fact that he is not slowing down from high fractions of c transit speeds.
A minute's thought suggests that the very idea of this is stupid. A more detailed examination raises the possibility that it might be an answer to the question "how could the Germans win the war after the US gets involved?" - Captain Seafort, in a thread proposing a 1942 'D-Day' in Quiberon Bay

I do archery skeet. With a Trebuchet.

Adam Reynolds
Jedi Council Member
Posts: 2147
Joined: 2004-03-27 04:51am

Re: Design a hard sci-fi-warship (RAR).

Postby Adam Reynolds » 2017-02-27 02:44pm

Interplanetary conflicts are reasonable as a means to secure resources, if you then have the problem that Earth almost certainly has military supremacy, but there is no value in fighting an interplanetary war unless you are merely concerned with self preservation. In that case, the attacking unit is likely not a fleet, it is instead more reasonable to use a relativistic kill vehicle of some sort. Which would be all but impossible for fleets based out of a solar system to stop before it hits.

Sky Captain
Jedi Master
Posts: 1032
Joined: 2008-11-14 12:47pm
Location: Latvia

Re: Design a hard sci-fi-warship (RAR).

Postby Sky Captain » 2017-03-04 05:30pm

Spherical ship would be difficult to maintain and fix if systems are intagrated inside the presuure hull like naval submarine. If ships are glass canons then modular strucrure could be better. Consider something like large girder with crew, engine, power, defense, sensor and weapon modules bolted on. It would be easy to replace obsolete systems , in case of minor combat damage swap damaged modules with new ones, if some ships are shot up too much canibalize them for spares.


Return to “Science Fiction”

Who is online

Users browsing this forum: Bing [Bot] and 9 guests