Sci-fi Weapons, Vehicles and Equipment

That is why the memory for spacecraft onboard computers are required to be redundant.

Radiation resistance comes in two flavors: either you try to make the circuitry immune to radiation, or you simply do everything extra redundant.

NASA has favored the former approach with special radiation-hardened circuitry. But e.g. the Ingenuity helicopter uses off-the-shelf components and is just fine. Modern computing has reached a state where you can just easily run the same program thrice and check for errors.

Scene idea: starship is about to leave port. Engineer reports that the reactor is warming up, at which point another crew member who isn't an engineer expresses bafflement over why a fusion reactor needs to warm up. The engineer explains that by "warming up", they really mean pre-heating the reactor vessel's walls prior to ignition because the sudden thermal shock of an emergency cold start puts serious mechanical strain on it (ie. it develops cracks from violent thermal expansion).

Would that be accurate?

For fusion warming up can also mean charging the capacitors for ignition....

Fusion takes a lot of energy to start up, like enough to power small cities.

If your just curious about believability though I would say yes, even though without actively cooling itself an object takes many years to cool down in space, after all there really isnt a better insulator in existance.

Edited by Imca on Feb 19th 2024 at 12:39:32 AM

The part about pre-heating seems accurate too - sudden temperature changes can cause internal stresses and cracking.

If the fusion reactor is a tokamak or stellarator type (or similar contained sustained fusion), then the plasma has to heat by about 150 million degrees before its even capable of fusion.

By contrast, a pulsed fusion reactor (ala National Ignition Facility) or other inertial confinement type generally doesn't need preheating since the laser does it in about a fraction of a second.

So yea, lots of fusion reactors need to warm up by quite a bit before they're capable of fusion.

EDIT:

By the way, a similar thing is true for regular fission reactors. Starting the reaction takes some time, so a fission reactor would have to "warm up" too before it is at operational power levels. You can't just pull out the rods completely and hope everything goes fine. It's how you get massive localized heat production, AKA explosions.

Edited by devak on Feb 18th 2024 at 5:18:56 PM

Funny alternate version of the prompt: The Engineer reports that the Magic Sci-Fi Powerplant™ is warming up, a non-engineer asks why it needs to be warm to work, and the Engineer has to explain that it's a figure of speech harkening back to an older time and he just means the hyperencabulators take a few moments to contraplane the antiprotons in the chamber array but "Warming Up" takes less time to say.

I can't help but imagine the Engineer would be a lot more snarky than that.

One of my favorite running jokes in the novel "Trading in Danger" is the protagonist, a newly-appointed merchant captain whose sum total of experience comes from spending most of four years in her planet's military academy, asking her crew how various pieces of specialized equipment (the FTL drive, the subspace communications gear, etc.) work, only for the trained specialist to either answer "it's way too complicated to explain, and you pay me to know how it works so you don't have to" or "it's way too complicated to explain, and it's also a trade secret so I'm not even allowed to open it up to fix it if it doesn't work, we just send it back and get it replaced under warranty" before sending the Captain away to do whatever it is she is getting paid to do instead of bugging her crew.

Incidentally, the fact that some of their stuff is powered by proprietary trade secrets that nobody understands becomes a plot point in that series of books.

Also buys time so you can get a cup of coffee or a sandwich before you have to do the real work.

Well, they do have a Magic Sci-fi Powerplant too. It's just that while the chief engineer knows how to operate and maintain it, she hasn't the faintest idea how it works because "damn it, captain, I'm a grease monkey, not a theoretical physicist!"

So that Space Elevator world I'm working on is largely based in real physics, except for one thing. The only form of Space Magic in setting is an FTL communications system known in setting as the Entanglenet, largely based on the idea of Quantum Entanglement etc etc for faster than light information trading. It's a black box technology kept majorly secret by its company of origin, and even if someone were to successfully reverse engineer, the system is already flooded and under control of the major corporate power.

It's used for everything from military communications among the major powers and colonies, to internet usage by the civilian population. And I started to think about the influence and power anyone who managed to make something so useful and vital would have on things. So I'm sort of having the company behind it be a big influence and sort of the enforcers of a major set of accords in setting.

After all, if you piss them off they cut off your access to their FTL network, and suddenly you are losing precious minutes of information that your enemies may take advantage of.

Don't think that company will be able to defeat espionage and reverse-engineering attempts forever.

They won't, but there are other methods of dealing with that, which is fun. From being able to control the network itself, to detecting when someone is working on a new ansible, etc. The setting is a little bit corporate dystopia.

This is still a bit early however, I'm working on the document, and it's largely through this and some M.A.D doctrine over asteroid chucking that the major powers now play by certain rules, with the idea of being able to pick up the pieces.

Edited by EchoingSilence on Feb 26th 2024 at 3:57:24 PM

@Belisaurius I'm reasonably certain that "encabulators" are an engineering in-joke about Techno Babble anyways.

Correct.

So, I've been thinking again.

If projectile velocity increases proportionally to how big an explosion gives it a shove, why not use the absolute biggest bomb we currently know of to fire a cannon?

Place a nuke inside a Containment Field with two open ends, and put a projectile at one end; pointed at say, a bad guy, or somewhere you need whatever makes up your projectile. Set off the nuke, and let half the plasma shove your projectile towards our hypothetical target, while the rest is vented out the back to control recoil, like with a rocket launcher (I had imagined mounting this abomination on a space ship as a weapon because nobody wants to be within the same postal code as a nuke in atmosphere, but they only have a blast radius of a mile in space).

I've heard of the Casaba Howitzer "concentrated nuke" that does something similar, but the idea is to hit the enemy with the plasma stream, but to my understanding, plasma dissapates pretty quickly, meaning you'd need to get it quite close to the enemy. It's also similar to the Orion Drive, which was the primary inspiration.

I've also heard of a manhole cover that got yeeted by a nuclear explosion back in the 50's, which should be passing Neptune about now if it survived passage through the atmosphere at all (Pascal B).

Using explosions to launch projectiles is the basis of all guns. So why not scale it up to the biggest explosion possible? It's brilliant!

In principle, you're right. However, there are limitations, and they come down to material science. There aren't many substances that can be used in the firing chamber and barrel for a nuke gun, at least not if you want to reuse it. Nor are there many materials that can survive the heat and acceleration to become projectiles.

Finally, you have air resistance to consider. The manhole cover you mentioned was probably vaporized as it slammed into the atmosphere. While fragments of it might have made it to space, they certainly wouldn't have been aimed accurately, nor done much damage.

A gun the size of a skyscraper, with immensely reinforced components, using a bus-sized projectile made out of the toughest material we have, operated in a vacuum — if you put all those together, the idea might work. Maybe. I wouldn't want to be the one ordered to design and build it. I would want even less to be the one ordered to fire it.

Radiation is a concern too: all nuclear devices we have today employ a fission primary, even if they have a fusion secondary. That fission primary leaves some nasty byproducts behind, and those would be deposited in the chamber and barrel and/or blown out the muzzle as fallout. I hope you don't like the people downwind of the gun much, because they certainly won't like you for long.

Not a "gun", but a proposed orbital defense weapon against ballistic missiles, is the x-ray laser satellite. It works by detonating a small nuclear warhead whose radiation gets focused into beams of x-ray photons, which would be aimed at a swarm of ballistic missiles. It's a very effective weapon concept, but it destroys itself on use.

It would also have severe side-effects: the Starfish Prime experiment in 1962 left a temporary belt of radiation in Earth orbit that damaged a number of satellites before it dissipated. Detonating a nuke in space today might damage or destroy hundreds or thousands of satellites, crippling our Earth-observation and telecommunications infrastructure.

Edited by Fighteer on Apr 14th 2024 at 3:16:29 PM

I'll file it under the "Mad Science" area of the tech tree, then.

"It will make warfare obsolete because you'd have to be insane to use it!" "Yes, you certainly would, but not for the reasons you're thinking of. I don't think it'll make warfare obsolete, either...!"

On one hand it’s entirely correct. Get a big enough bang behind something and the sky’s the limit with how fast you can accelerate something.

The biggest bangs however do not fling solid projectiles or anything resembling such or so says relativistic physics. Look at the eruptions from the Sun, solar flares and CME’s. The biggest bangs in our solar system. But nothing within one is solid even though components of them are traveling significant fractions of the speed of light. It’s all rendered into plasma or a (diffuse) particle beam.

Driving a projectile with explosions actualy has a speed limit...

That's one of the big reasons railguns are so attractive as a technology we are actualy reaching the upper limits of maximum projectile speed using conventional explosioves... there are some workarounds we can use like hydrogen guns and RAVEN guns... but even they run into the same problem just at higher speeds...

Basicly the problem is that while your right that in theroy biger boom = faster projectile... your caped at the speed the explosion actualy propagates... which depends on what kind of explosive you use.... but they all tend to be within the thousands of meters a second range, which is relitivly speaking a fairly low speed.

I know the propagation speed of a nuke is high among explosive types... but your still going to hit that cap and then be unable to use one to launch a projectile any faster no mater how much nuke you use behind it.

Railguns do not have this limit as electricity propagates pretty close to the speed of light.

The easiest way to picture the problem is to remember that when your launching a projectile the projectile is actually riding along something... and well like a surfer on a wave you cant go faster then the thing your trying to ride.

Edited by Imca on Apr 13th 2024 at 10:09:25 PM

You know, that actually makes me wonder... does electromagnetism have a finite propagation speed?

Because if so, even a railgun would have an upper speed limit.

It does, but its incredibly high, and edges the speed of light at which point "where are you getting all this energy" is going to hit you first.

Edited by Imca on Apr 14th 2024 at 8:11:32 PM

The limit is how fast the projectile can be accelerated, which comes down (again) to the material strengths of the projectile and barrel. Remember Newton's laws: you're generating an equal and opposite force in the gun.

Let's say you can accelerate a projectile at 10,000 g in a sustained manner. To get it to 99 percent of the speed of light would require approximately 3,000 seconds, during which it would travel a distance of 441 million km (reference).

Building a gun barrel 3 astronomical units long is an exercise for the student, but if you can do it you have an RKKV.

Again, I must note that the maximum speed of any projectile is a function not only of the weapon it's fired from but also the medium it travels through. In atmosphere, compression and friction will rapidly slow it down over time, so there is a practical limit.

Edited by Fighteer on Apr 14th 2024 at 8:50:43 AM

And the only thing that can step up and overcome this and still accelerate further without being an actual light speed weapon is gravity acceleration. Specifically like the conditions found right before you cross the event horizon of a black hole.

Relativistic jets ejected from a black hole are the fastest matter known to man. Literally 99 percent plus the speed of light.