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.