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I'm writing a space scifi story involving an alternate history timeline, so I'm writing it around an In System war between Space Nato and Space Comintern.
Now I'm consulting my local astrophysics undergrads about the various technical details but theres one question on my mind, now Battlefield 2142 had "Titans" warships that hovered a few hundred meters above the ground and basically as overland aircraft carriers.
Now I'm wondering about the plausibility of an in system warship designed for war in space but designed to be able to enter the atmosphere and "convert" into basically a titan and "hovers" in its theatre and is basically a strategic/tactical weapons platform.
Now so basically whats a plausible way for some sort of propulsion system to keep probably over a million tonnes of steel and other materials afloat?
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magnetics. Using powerful electro-magnetic sheild technology, the Titan pushes against the planets iron core.
Posts: 1941 | Registered: Feb 2003
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And inertial dampeners. They fix EVERYTHING!
Any big ship entering the atmosphere is going to be a bad experience anyway; it'll be almost no different than a meteor entering the atmosphere. The only possible way around that would be to enter slowly, but not only will that makes it pretty much useless from a military standpoint but can you imagine what it would take to prevent it from falling like an anvil?
BSG got it right in this sense: jump in to the atmosphere, begin falling like a three thousand foot long flaming anvil, launch vipers like bullets through the flames, and jump out before you make a crater the size of Wyoming.
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posted
Just change the gravitational constant of the universe, thus changing the mass of the planet and reducing its gravity.
Posts: 7593 | Registered: Sep 2006
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Blayne Bradley
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Ummm no. I am aiming for 99% realism.
So no shields, I am told thats there virtually no scientific justification for them and even if they did exist would be invulnerable and difficult to represent in any interesting way.
So its several meters of some sort of Titanium alloy with Active Reactive Armor and heat sinks, primary offensive weaponry is coilguns and nuclear tipped warheads.
The point of a ship capable of entering the lower atmosphere is this, the ABM systems of the respective sides makes launching ICBMs at each other useless, a victory in space would be required before a full strike could be launched and by the time the above suggested weapon is available the Warsaw Pact has finally after 27 years of fighting took Europe and has already brought the war to the continental United States, the point of the weapon is to "end" the war via shock and awe, possessing a nuclear arsenal capable of being used in theater both tactically and strategically and as a mobile forward base for resupplying and servicing aircraft such as gunships.
If you've played BF2142 they'ld serve as something very similar to how Titans are used in that game, I am just wondering if there ANYTHING plausible in actual science to allow or account for a propulsion system capable of keep a battleship suspended in air.
So please, actual answers no retarded snarks.
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1) Any force capable of slowing reentry of a craft the size you imagine, and then keeping it suspended a few feet off the ground would make a far more dangerous weapon than the fighting forces you would have aboard that ship.
2) Why must it float? Keeping a ship of that mass suspended above the earth is a waste of energy that any tactician would use for other purposes--say directed at targets elsewhere. If you wish to make it mobile, wheels work fine.
3) ABM are stopping small multi-war-headed missiles from reaching the enemy, so your decision is to send down a titanic chunk of weaponry. Won't those same ABMs just blast away at the Titan as it enters the atmosphere?
Posts: 1941 | Registered: Feb 2003
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posted
Just use magnets.
Posts: 1287 | Registered: Apr 2006
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Blayne Bradley
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1) Dunno. I like the idea of plausibly describing how a BF2142 Titan could work.
2) The idea of floating is to keep it mobile, wheels dont work well in say... a ruined city.
3) Stopping a lightly protected ICBM is a whole level of magnitude easier then a heavily armoured space craft designed to sustain direct nuclear hits on its broadside. So while a missile wont go through, a massive blob of metal should have no problem, in fact my inspiration for this comes from when a renegade KGB agent starts the war by kamikazing a cruiser into the continental United States killing 20,000,000.
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Not that there's anything wrong with this type of fiction, but it doesn't sound like hard science fiction to me.
Posts: 16551 | Registered: Feb 2003
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quote:Originally posted by mr_porteiro_head: Not that there's anything wrong with this type of fiction, but it doesn't sound like hard science fiction to me.
Yeah, I know of no plausible mechanism for this to work. If you really want to use these vehicles and still make it somewhat in the direction of hard scifi, then I'd suggest just making them run on handwavium and trying to model everything else as accurately as possible.
One good place to start would be Darth Mauve's third point
quote:ABM are stopping small multi-war-headed missiles from reaching the enemy, so your decision is to send down a titanic chunk of weaponry. Won't those same ABMs just blast away at the Titan as it enters the atmosphere?
posted
One would assume that if he has that level of technology, the Titan would have to have SOME type of point defense capability. If they have the level of technology necessary to do what he wants it to do propulsion wise, I'd find it almost impossible to believe that they don't have lasers capable of shooting down ABMs, though they'd have to solve a pretty major blooming issue if they want to shoot through or in an atmosphere.
Still, it doesn't sound like a really efficient use of high technology. You basically want repulsorlift technology from Star Wars. In other words, you want to control gravity. There's nothing even close to being on the books for how such a technology would operate.
Posts: 21898 | Registered: Nov 2004
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Blayne Bradley
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The above question is only 1 relatively minor possible weapon system in use that sounded cool enough to explore before dismissing it, Ild rather not handwave the tech for it, I want everything to seem plausible "hmm, could we have this 80 years from now?"
I already answered the other point, the space born ABM system isn't a system per se as it is a command network of orbital manned defence craft, satellites, and interceptor craft to intercept with ease ICBMs, it can't stop dedicated warships which makes a large part of the war strategic maneuvering for the "final" battle where one side annihilates the other's fleet and thus their ABM system within short order.
If the idea of some sort of practical theoretical propulsion system to keep it suspended hovering midair isn't scientifically feasible Ill drop it and find some other trump card that one side can use to win.
So far the only atomic warheads that CAN be used in theory are those tactical artillery and shoulder launched warheads which practicallity would dictate would have short half lifes and thus only a few days worth of fallout. SO their long term use as "another bomb" is minor.
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I was thinking of something along the lines of hydrogen-powered thrust in a configuration similar to a Harrier jump jet. Mind you, if we're talking about keeping a million tons of matter airborne, that's a lot of thrust. The Space Shuttle apparently carries more than two million pounds of fuel, and that's just to get into Earth orbit and back.
I don't have the physics off the top of my head for how much thrust it would take to allow a million tons of mass to overcome Earth's gravity. I'm pretty sure it's beyond current technological capabilities; I don't know about hypothetical ones. It may well be that the amount of fuel needed (and associated weight) grows faster than the amount of thrust required to overcome that weight at those levels.
Alternately, as has been suggested, perhaps using a similar reactor to power an electromagnet- though I have to wonder how stable such an arrangement would be. I suspect most of our magnetically-lifted technologies, existant (bullet train) and hypothetical (space elevator), run on rails on a predictable course for a reason.
Posts: 3826 | Registered: May 2005
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Blayne Bradley
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quote:Originally posted by Lyrhawn: One would assume that if he has that level of technology, the Titan would have to have SOME type of point defense capability. If they have the level of technology necessary to do what he wants it to do propulsion wise, I'd find it almost impossible to believe that they don't have lasers capable of shooting down ABMs, though they'd have to solve a pretty major blooming issue if they want to shoot through or in an atmosphere.
Still, it doesn't sound like a really efficient use of high technology. You basically want repulsorlift technology from Star Wars. In other words, you want to control gravity. There's nothing even close to being on the books for how such a technology would operate.
The events of my books will be 2087ish AD. So everything I want to write about I want for us, to possibly be feasible for then if tech maybe progressed a tad faster and if alot of money was thrown at it.
the answer to point defence is AEGIS, since the primary weapons used is almost entirely missile based with coilguns added a bit afterwards.
Now what makes a better anti warship weapon? Coilguns or railguns? Assume Fusion Reactor technology has been made practical for warships in terms of size, containment, and output.
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In the grand old days of the republic, we simply used orbital bombardment with mass drivers. That and canes to keep the kids off our lawns.
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Blayne Bradley
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The practical challenges of using mass drivers (originally used for lifting of material payloads for construction) wont be overcome in my books for a few years of fighting, although they DO start off as stationary platforms to defend strategic points such as shipyards.
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quote:Originally posted by Mucus: In the grand old days of the republic, we simply used orbital bombardment with mass drivers. That and canes to keep the kids off our lawns.
posted
I would agree that the only way anyone would want to suspend this way is if it involved expending very little fuel and reaction mass.
Alastair Reynolds has written a lot of stuff about propulsion and manipulation of spacetime that you could imitate. None of it was really based on or extrapolated from real technology, though. It was just intelligent sounding BS. (I think he tried to respect conservation of energy, at least, but it required some contortions.)
Posts: 4287 | Registered: Mar 2005
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quote:Originally posted by Mucus: Just change the gravitational constant of the universe, thus changing the mass of the planet and reducing its gravity.
Were you channeling Star Trek's Q? Posts: 4519 | Registered: Sep 2003
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Maybe I'm missing the point, but I still don't understand the purpose of such a weapon from a military standpoint.
I've never played BF2142, but according to this link the Titan doesn't like an aircraft carrier but rather a sort of offensive craft, such as a destroyer.
It still seems rather impractical. I don't see anything about it that can't be done with modern day methods. For example, if you're looking for a mobile aircraft carrier solution why not design something capable of actual flight; in essense, an absurdly large aircraft that can deploy vehicles in the same manner modern day craft deploy crews - by drop shipping them. Fly in, unload everything, fly out. of course, it would have to deal with the same heat issues the modern day Space Shuttle does, only at a much grander scale.
And can you imagine how much "...several meters of some sort of Titanium alloy with Active Reactive Armor and heat sinks..." would WEIGH?
And, generally, one of the cardinal rules of any big, semi-stationary military asset is "don't paint a big red bullseye on it."
Posts: 3486 | Registered: Sep 2002
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You're not going to get this to work with 'feasible' technology.
Either humans find some sort of propulsion/antigrav system that makes these work, or they don't work.
Posts: 15421 | Registered: Aug 2005
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Blayne Bradley
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quote:Originally posted by Nighthawk: Maybe I'm missing the point, but I still don't understand the purpose of such a weapon from a military standpoint.
I've never played BF2142, but according to this link the Titan doesn't like an aircraft carrier but rather a sort of offensive craft, such as a destroyer.
It still seems rather impractical. I don't see anything about it that can't be done with modern day methods. For example, if you're looking for a mobile aircraft carrier solution why not design something capable of actual flight; in essense, an absurdly large aircraft that can deploy vehicles in the same manner modern day craft deploy crews - by drop shipping them. Fly in, unload everything, fly out. of course, it would have to deal with the same heat issues the modern day Space Shuttle does, only at a much grander scale.
And can you imagine how much "...several meters of some sort of Titanium alloy with Active Reactive Armor and heat sinks..." would WEIGH?
And, generally, one of the cardinal rules of any big, semi-stationary military asset is "don't paint a big red bullseye on it."
Stealthiness is a virtual impossibility in space combat if you want something that can from a practical standpoint, project force, thus I completely chuck the concept of it, forget about trying to avoid a fight, Bring it on! with thick hull and layers of defencive systems.
The thrusters of the space shuttle can be seen from Jupiter for example.
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Blayne Bradley
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quote:Originally posted by Samprimary: You're not going to get this to work with 'feasible' technology.
Either humans find some sort of propulsion/antigrav system that makes these work, or they don't work.
Which is why I will probably drop it. I am not an astrophysics student, so thus is why I consult with people. Either the undergrad I kidnapped when I run into him or the interwebs at large.
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Corwin: Heh. I sometimes wonder if anyone gets some of my more random references. Thanks for restoring some of my faith Posts: 7593 | Registered: Sep 2006
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my 2 cents as an aerospace propulsion engineer:
Conventional rocket motors (including nuclear-augmented systems) - not possible. While the current technology is not perfect it's at something like ~75% of the theoretical capabilities, and to lift something for a couple minutes that thing tends to be about 80-95% propellant. If you're talking about the thrust required to keep something big aloft for an extended period of time, it's just not feasible (your warship structure would be almost entirely propulsion apparatus and then the rest of the vehicle would be a huge, highly vulnerable hydrogen/oxygen tank system that would make it a giant floating bomb.
Ion propulsion - not possible. Similar to above on current level of technology vs theoretical limit (well sorta). The bigger issue here is that ion propulsion is really really efficient, and might be usable to move a giant Ark ship on a long-term mission, the thrust produced is tiny... an ion engine the size of a coffee can can produce the thrust to lift a piece of paper... definitely not feasible in a gravity environment.
"Commonly accepted" technologies that don't really exist, or at least are maybe more feasible (though if you got the right experts in the room they'd probably come up with similar problems to what I've already mentioned)
Magnetic Systems - I'm sure there would be immense side-effects, but assuming you had a really good power system, you might be able to create a really powerful magnetic field that would keep you off the ground... it might even be semi-directional, so as long as you don't think too hard it could work.
Reactionless Thrusters - completely against physics, but super convenient.
Antimatter thrusters - could get rid of some of the 'giant explosive tank' issues of the conventional propulsion above. Still would likely make the thrusters a big portion of the vehicle, and would be destroying everything beneath the vehicle... other technological issues abound but might be feasible.
General assessment: fun sci-fi propulsion is pretty much all impossible with anything approaching currently understood technology. That being said, there's not too much opposition to suspension of disbelief on this front.
I think as long as you're consistent about what the limitations and impact of the technology are, people aren't going to get super caught up in how exactly it works.
i.e. I am a big fan of how they dealt with propulsion in BSG, not because it was possible, but because it was far more plausible and well thought out than most other places, and they were pretty consistent with it. Basically BSG uses something like conventional/nuclear propulsion but toning down the engine size and ignoring the giant propellant tanks.
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Blayne Bradley
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Yes but Ild like my gimmick however to be "Hmm, that sounds really plausible" I know that if I wanted to as long as technology was displayed consistently it wouldnt matter if it was Phletonium, but my preference is that I shouldn't have to.
No big deal as the suggested weapon is not plot important and wouldve if it did appear in the final book.
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quote:Originally posted by TheGrimace: an ion engine the size of a coffee can can produce the thrust to lift a piece of paper... definitely not feasible in a gravity environment.
quote:Originally posted by Mucus: Corwin: Heh. I sometimes wonder if anyone gets some of my more random references. Thanks for restoring some of my faith
posted
"I think we all forgot to mention buoyancy. Just make the thing lighter than air."
I usually just use a 50/50 mix of matter and negative matter. Using hydrogen or helium takes up too much darn space. Note that negative matter is not antimatter: matter + antimatter = Energy matter + negative matter = Nothing
Inre negative pressure: ...strange things happen if w falls below -1 (an isolated lump of such material could appear to have negative mass, which is just what one might need to prop open a wormhole)
Also good for keeping north and south monopoles separate -- to prevent them from mutually annihilating each other in a burst of (newly created) highly energetic nucleons, gamma rays, and neutrinos -- if you are interested in creating a tough monopolium hull which can easily survive high-energy lasers and near-miss nuclear explosions while keeping it lightweight.
"And then, the Earth being small, mankind will migrate into space, and will cross the airless Saharas which separate planet from planet and sun from sun. The Earth will become a Holy Land which will be visited by pilgrims from all the quarters of the Universe. Finally, men will master the forces of Nature; they will become themselves architects of systems, manufacturers of worlds." -- Winwood Reade, The Martyrdom of Man, 1872
posted
Perhaps a better question: how do you keep the two apart, given contact between the two will apparently annihilate both? Given that negative matter will accelerate towards an applied force, magnetic containment might be a tricky fish to fry.
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