The Original Warship - A Science Fiction Thread!

I like the idea of a "Space Bullet". It reminds me of 'Oumuamua.
How did you come up with the 12M tonnes for the compact warship?
My rough maths makes that about 3.5 tonnes per cubic metre. That seems like a lot to me.
But when I wonder about fantasy Starships I tend to go the more high energy route with lots of power for shields and engines...

 

To misquote someone from Jerry Maguire; You had me at "paw".
Any ship that has a paw will be cool....

 

Busts through nearest wall wielding a slide rule like a sword.

Did somebody say... SPACESHIP DESIGN!?

First of all, this website is one of the best resources for realistic spaceship design out there, so I'd highly recommend taking a look at it if you want to dive a bit deeper: Atomic Rockets - Atomic Rockets

Anyways, let's see what you've got here.

All right, so a long, thin, windowless tube. This mostly fine. Your ship is military, and hence will be utilitarian. There's generally very little practical need to actually look outside with your own two eyes when in space, since anything worth seeing is generally so far away as to be basically invisible. Instead, you would rely on an array of telescopes, cameras, and other sensors. However, I'd argue that it may still be worth having a few small windows somewhere on the ship, just in case something goes wrong with your sensors, or your crew wants to see Earth through something aside from a TV monitor. Remember, crew morale is important.

However, there is one issue with the overall appearance that a lot of authors neglect: heat dissipation. You mention that your power source is a nuclear fusion reactor. Even with hyper-efficient super-futuristic designs, your engines and generator are going to produce a lot of waste heat. In spite of what Hollywood would have you have you believe, the vacuum of space not cold. It's not really hot either, though. It's... a vacuum. Technically, it has no temperature since there is no material there to have a temperature. Thus, it basically behaves as a perfect insulator against convective and conductive heat dissipation, which are usually the main sources of heat dissipation of earth-based technology. When you hear "the temperature of space," what they're usually telling you is the temperature that an object will cool down too via thermal radiation if exposed to no other sources of heat except for starlight and background radiation.

Realistically, the ship should probably have enormous solar panel-like structures to radiate away excess heat. Heat could be transferred to the radiator panels either by simple conduction or by a more efficient active heat pump.

Yeah... Uh, don't do this. Think about how rough it is for two cars to collide on the highway. Now, imagine that scaled that up to orbital speeds and you'll have a general idea of why this would be very bad for the ship and crew's status as solid objects.

Just for reference, orbital velocity in low Earth orbit is roughly 7600 meters per second. By comparison, the highest speed limit on a US highway is 36 meters per second. Even a "slow" collision in space could be in the hundreds or thousands of meters per second. I have a hard time imagining a material so durable that it wouldn't be instantly vaporized by a collision at those speeds. But, even if the ship survives, what about the crew? That's an awfully big shock that they'll be going through. Even if they were strapped into acceleration couches, they'd likely be very... tenderized after such a collision.

Since, you've given a mass value for the ship, I can actually do some calculations here. For the sake of argument, let's say we have a collision at 500 m/s in which your ship completely penetrates its target, reducing your ship's velocity by 100 m/s in the process.

(0.5 * mv1 ^ 2) - (0.5 * mv2 ^ 2) = (0.5 * 10,886,216,880 kg * 500 m/s ^ 2) - (0.5 * 10,886,216,880 kg * 400 m/s ^ 2) = 490 Terajoules.

In other words, this collision is basically equivalent to setting off a nuclear bomb at the front of your ship. Which, now that I think about it, may not be quite as bad as it seems: Project Orion (nuclear propulsion) - Wikipedia Still, 490 Terajoules is an awfully lot of heat being transferred through your ship's nose. The ship itself may survive a few rammings like this, but without using some truly fantastical materials in its design it would hardly be undamaged after each one.

However, even if you solve all of the massive engineering hurdles associated with ramming, you're still left with the problem that there are simpler, less dangerous, more effective ways of damaging your enemies, even methods that use the same idea as your ramming technique: Kinetic bombardment - Wikipedia

So, yeah. Ramming should be usually be held out as a last-ditch suicide attack and not much else.

This is a clever idea for self-repair that I could see being implemented in real life. In fact, I think I may have heard of something like this being considered for a real spacecraft somewhere. Just to be clear, though, what do you mean when you say "repair the hull in combat." I assume that this means the liquid hardens when exposed to vacuum. I don't know that it needs to fill most of the interior of the spacecraft, though, especially considering how heavy you say it is. Normally I'd say that this honey-goop makes your ship needlessly heavy, but you seem to be operating in a future where producing enormous amounts of thrust via nuclear energy has become cheap and easy, so I'll give it a pass.

Ah! So you do know about Project Orion! Excellent! You're going to need to clarify a bit for me, though. What do you mean when you say "the nuclear blasts would take place inside of the vessel," because this seems like an extraordinarily bad idea. Are you setting it off in some sort of "combustion chamber" with a hole open to space? I believe that, when set off in a vacuum, most of a nuclear charge's energy is not released in heated plasma, but rather as x-rays. If your combustion chamber could survive the burst of plasma (which would still quite powerful) and the interior were perfectly reflective, then I'd imagine that this would be fairly efficient, since you're guaranteed that all of the light energy will be radiated backwards, thus generating thrust. However, if it's anything but perfectly reflective, a lot of that energy would end up being transferred to the hull, resulting in at best a large loss of efficiency and at worst a ship-shattering kaboom. Probably the latter.

Like I mentioned above, nuclear explosions that occur in a vacuum release most of their energy as x-rays, not plasma, so electromagnetic fields wouldn't be able to do much there. I'm not sure how you'd manage to realistically create a weapon like this. Lasers and railguns would probably be much more effective weapons, since you don't need to get terribly close to your target to do damage and the projectiles/light beams can't be effectively intercepted. Missiles would be useful, but they may be taken out with a well-targeted laser before they can hit their target.

Your idea to spit acid on enemy ships is an interesting one, but not one that I think will be terribly effective at anything but close range, and you'd want to stay at long range as much as possible, especially considering that effective long range weapons would probably be available in the form of railguns and lasers.

 

Actually, I did a bit of thinking today and realized that fully enclosing the engine's explosion would give no thrust advantage whatsoever. Basically, fully enclosing it wouldn't work because the half of the rays bouncing around the interior would cancel out their own thrust before they could escape. To get the most out of each nuclear charge, you'd want to detonate it at the center of a half-sphere of hyper-tough mirror material, with the other half being exposed to empty space. So, no setting off nuclear weapons inside of your own ship.

On the subject of particle beams vs lasers, there's upsides and downsides to both. Lasers are more focused (although they still suffer from diffraction at long distances), less affected by gravity, and always function at the speed of light. However, it may be possible to nullify the effect of a laser by simply covering your ship with high-quality futuristic mirrors. I've never heard of anyone proposing something like this, but I see no reason why it isn't possible, especially in a setting where materials tough enough to contain a nuclear blast exist. Of course, it would also be theoretically possible to simply shorten the laser's wavelength until it penetrated whatever armor the target was using, so it's your call on how well your fictional materials can reflect gamma lasers. Maybe you could even have an arms race going on, where everyone is trying to develop mirror armor faster than everyone else can develop high-energy gamma lasers.

Particle beams would not suffer from this potential weakness. The particles would collide with the hull and transfer heat. Not much they can do about it. Better yet, if they're charged particles, you can even ionize their hull and cause all sorts of nasty electrical failures. Although potentially at the risk of ionizing your own ship as well. Those charged particles have to come from somewhere. Charged particle beams would also require ammunition in the form of a particle source. This could be as simple as a tank of compressed hydrogen or as complicated as a magnetic jar full of electron-stripped protons. Also, a particle beam would probably struggle in an atmosphere for the same reason you would struggle to throw a handful of dust more than a foot or two. It would still create a lot of heat and radiation, so it may still be somewhat effective if used from orbit against a ground installation (and everything for twenty miles around it) if it had high enough energy. But, it wouldn't be nearly as effective as a laser.

Overall, I'd say go with some of both. That way your weaknesses are covered either way.

Also, have you ever heard of a whipple shield? Whipple shield - Wikipedia. It probably wouldn't do much against a nuclear-launched shell, but perhaps you could consider it as a lighter alternative to some of your heavy-duty super armor.

 

Armor penetration. As the wavelength gets shorter and shorter, it becomes harder and harder to find a material that can interact with the rays meaningfully enough to reflect them. Which does lead to a problem at the extreme end of the spectrum: Sure, your laser can pass straight through the target's armor as though it were glass, but the same is true for the rest of the ship, and as a result the weapon has little to no effect.

Conversely, as the wavelength shortens it becomes harder and harder to construct a laser that could generate the x-rays and gamma rays at the levels you desire. Just a note: there's no actual strictly-defined difference between x-rays and gamma rays. It's just generally held that x-rays are higher wavelength than gamma rays.

The fins would be thoroughly useless in space, except maybe for radiating heat, and a couple of tiny winglets probably won't do much in that regard. Any weapon you mount to the fins would probably be equally or more effectively mounted elsewhere on the hull, such as on a retractable arm. The only use I could think of is if you wanted to try an aerocapture maneuver:Aerocapture - Wikipedia, but from the sound of it your ship has more than enough thrust and delta-V (Which is to say, ability to change velocity) to not need such maneuvers.

I suppose that they could be useful if you ever decided to land the ship on the surface of an atmospheric planet, but I don't know why you would want to do that often enough to justify the design feature. You primary thruster is a barely-controlled nuclear blast. Not really ideal for trying to land anywhere. I suppose that the ship could have small "conventional" maneuvering thrusters that are safer to use in an atmosphere and powerful enough to levitate the ship. But again, why? Orbital repair and refueling stations would exist in this setting, so there wouldn't really be much planetside that couldn't be more effectively retrieved or dropped off by shuttle. Perhaps stealth? The Project Rho site is very adamant that stealth technology would not exist in space, so perhaps "stealth" could exist in your setting simply in the form of landing on a planet's surface and finding a way to camouflage your ship. Although that would still be very difficult it the ship is as large is you say. Or perhaps even hiding underwater... Ooh. Chance for your submarine-shaped design to become an actual submarine.

On making the jump from fusion to antimatter: You can do it if you want, but I don't really see a need to, especially not for a military application. Sure, it would be very high energy density, but fusion power is already pretty good in that regard. It's a pretty rare fuel source as well. Hydrogen for fusion would be available basically anywhere. Antimatter would not. Antimatter would need to be manufactured, which means that the energy would still need to be generated elsewhere by some other method. i.e. Antimatter is a battery, not a generator. Plus, it's more dangerous. If your magnetic containment fails, you suddenly have a city-killer level explosion on your hands. Or if the container receives too hard of a shock, the antimatter could bump up against the side of its container. Or if the container is damaged and the antimatter is released. Again, boom. For a military ship that is likely to encounter both of those issues, I don't know that I'd trust antimatter. Perhaps it would be good for a commercial space liner, but not something meant to see heavy combat.

On lasers: The first excerpt on the "conventional weapons" page of the Project Rho site describes lasers as being very bad at damaging armor because of the diffraction they experience at long range, and only really good for destroying exposed sensors and weapons. However, in your totally overpowered setting you could counteract this by simply upping the power.

Just a note: You seem to be designing from the top-down. You come up with an interesting drawing and then try to use science to justify it. This is fine, especially since you don't seem to be trying to write a truly hard science fiction setting, but just be aware that you're doing it the opposite way from how it would actually be done. A real design would start out with a list of requirements, then figure out what needs to be done to meet those requirements. The final shape would be the last thing the engineers are considering. Unless the final shape is part of the requirements, of course, but that would not usually be the case for a military application.

 

Well, there is no truly realistic option for fast interstellar flight. The closest you could get would be either a wormhole or Alcubierre drive: Alcubierre drive - Wikipedia. You seem to be familiar with wormholes, and an Alcubierre drive is basically just a Star Trek warp drive. Basically, it encases a ship in a bubble of separate spacetime in which space is contracting ahead of the ship and expanding behind the ship. Since the ship is technically not moving and only the space around it is moving, it would be able to exceed the speed of light.

However, both wormholes and Alcubierre drives are based hypothetical physics. As far as we know, there are no physical laws that say they can't exist, but that could change in the future. Wormholes are not known to exist naturally, and we only have the vaguest idea of how one might be manufactured, Plus, both would rely on exotic forms of matter with negative mass to stabilize them, and as far as we know these forms of matter are purely speculative. To my knowledge, the closest known phenomenon to negative mass is the negative energy density created by the Casimir effect: https://en.wikipedia.org/wiki/Casimir_effect.

On top of that, faster-than-light travel would in reality likely imply that time travel is possible and even easy. The reason for this is a bit complicated, requires a basic understanding of relativity, and is much better explained by the handy graphics on this site than by me: Sharp Blue: Relativity, FTL and causality - Richard Baker. Of course, most authors just ignore or handwave this particular inconvenience, since dealing with the ramifications is hard no matter which way you slice it.

So, yeah. Basically, you're going to have to make something up if you want fast interstellar flight.

Also, I've made another mistake regarding the propulsion system. I'd always assumed that an Orion drive was propelled by the raw burst of nuclear x-rays. However, I just did the calculation and discovered that pure photon thrust is several orders of magnitude too weak to be useful. I did some more reading and found out that the nuclear charges were actually designed to convert most of their energy into a plasma burst, which would strike the pusher plate and accelerate the spacecraft that way. So, yeah. Sorry. Putting a reflective coating on the pusher plate would have little to no effect.

As for how much you would be able to accelerate your ship on Orion propulsion alone... Well, I'm still a bit fuzzy on how the math for these things works, but luckily the Project Rho site has some convenient mass and delta-V tables: http://www.projectrho.com/public_html/rocket/enginelist.php#id--Pulse--Orion. You'll be looking at the one at the bottom, since it appears to be a fusion-based design in which everything has been pushed to its hypothetical science-fiction maximum. While there aren't any delta-V numbers for that particular design, it has 82 times the exhaust velocity of the previous design in the table (since it's plasma, not x-rays!), and thus 82 times the efficiency and delta-V. That puts you at 8200 km/s of delta-V. Still short of your 30000 km/s request, but 8200 km/s is still a HUGE amount of delta-V. By comparison, the earth moves around the sun at 30.5 km/s.