Advice Thread OOC Future Tech Only

[The 44th Indp Legion]

This has been bugging me for a while now - but what if your ships/fighters had a propulsion method that didn't require fuel in the ordinary sense?

Given the size and sheer mass of most of my ships ICly (I don't usually bring anything but the 'small' ones out for RPs for obvious reasons, but w/e), the main sublight propulsion is, in principle, an alcubierre drive - in other words, a spatial distortion drive that will accelerate irrespective of mass. A bonus feature is being able to deflect stuff (including lasers, funnily enough) with it at certain angles. However, the fighters and missiles both use a different propulsion system from that and another. The fighters use a 'gravatic' drive, the same technology as on my hovertanks, to propel them efficiently whilst relatively near a great mass, usually a planet, but ships fine too. Missiles on the other hand use a more traditional rocket-like propellant, which enables them to traverse inter-ship distances autonomously, but is less efficient because you have to drag a mass in fuel around. Obviously my tech base takes a few liberties, but could similar principles be applied more realisticly? Furthermore, I'd like to add that 'strike craft' (by which I mean actual ship-sized stuff) rather than 'fighters' can work well in an FT setting, if noly because if you put them in a big mothership/carrier-thing, you don't have to fit them with (an often bulky, heavy and in combat unnecary) intergalactic FTL drive, right? That could be a lot of weight saved, right? Or am I just talking fantasies and nonsense?

[SquareDisc City]

a single paper that is not openly available without paying up and that doesn't seem to be matched by other, freely-available scientific documentation

You do realise that this is relatively often the case. It's annoying, but we can't do a lot about it.

I suppose the FT version of a hybrid would be the aforementioned combination of fusion reactor, antimatter generator, and antimatter reactor. Again this is only worthwhile if you're of the view, whether OOC or IC, that antimatter is dangerous so you don't want to be carrying loads of the stuff around.

Regarding scaling, the assumption seems to be that the engines always achieve the same specific impulse. This may not be the case. Let's consider the somewhat unlikely but perfectly functional example of using a mass driver to propel your ship. Now our 4-unit-ship will look like follows.

XXXO=
XXXO=
XXXO=
XXXO=

In this case I'm using O to represent the physical bulk of the mass drivers, and X to represent other stuff.

Now when we scale up to an 8-unit ship, we've got a lot more available volume, so can use bigger mass drivers.

XXXXXXOO=
XXXXXXOO=
XXXXXXOO=
XXXXXXOO=
XXXXXXOO=
XXXXXXOO=
XXXXXXOO=
XXXXXXOO=

Being bigger, these mass drivers will get their projectiles up to a higher speed, sending them off with more momentum, and thus giving greater thrust and greater specific impulse. Thus, the scaling issue are mitigated.
(Note that specific impulse only counts propellent shot out of the back, not fuel burned up in the reactors. Our volume available for reactors scales the same as our ship mass, so I don't think this is an issue.)

I don't think it's unreasonable for this to apply generally - that with more "depth" to work with, a rocket engine can deliver greater specific impulse.

44th, you're indeed correct that reactionless drives will have totally different considerations. There's a lot of latitude for making up one's own physics with such though, so it's not really possible to discuss in a general manner.

[Fata (Ancient)]

Jeesh Arthropoda could have been a little more gentle when you completely slammed me into the hypothetical dirt.

And when I think Capital ship, I think Capital, like that of a city, or a country. I'm thinking like flagships. I had no idea you guys had other definitions for capital ship. I also don't see why you got to be so completely blunt, and somewhat rude. When I said "you guys" I was referring to a general nation with uber ships. I wasn't targeting anyone specific. But apparently everyone one is allowed to have an opinion except me, cause this always seems to happen. I say something or write a small rant compared to the normal rant on nations states and it seem there is always someone jumping down my throat and slapping me with my own words. I'm not very good at writing and describing with words, so there is no way for me to put my point across accurately.

Just wait and see, ill probably be attacked verbally again on the basis on being "a cry baby" or what ever. Probably have my intelligence insulted multiple times too.

[Our Most Resplendent Goddess Sen]

Fighters are great from a literary standpoint since they allow the Rugged Space Hero to engage in Manly Single Combat with the Evil Aliens in the rings of Planet ZK-5.

From a technical standpoint, not so much, unless your tech has been specifically tailored to make them viable.

Meanwhile, this article on HowStuffWorks indicates that the complete opposite is true in real-life hybrid vehicles - that smaller engines are more efficient. So your mileage may vary.

The most efficient gas engines are combined-cycle gas turbines in the several-hundred megawatt range, with thermal efficiencies as high as 60%. Most efficient engine that's actually used in a vehicle? Probably one of Warsila's ludicrously huge diesel engines; a quick check of their web page shows several container-ship diesels with efficiencies over 50% (anything with a BSFC of 176 g/kwh or less, since bunker fuel has a heat of combustion of 41 mj/kg), and these are engines so large that if you fall into one of the cylinders you need a ladder to get out.

Car engines are substantially lower (~30% range IIRC) even though they use higher-quality fuel. They're small, so they don't have the weight or room needed to have every efficiency-improving gadget in the history of mankind tacked on.

Very good points, I suppose. However, it still doesn't answer one fundamental issue that I have with big ships vs. small ships: the square-cube law. What's being discussed is true for the reactor itself, but if the main engines still only provide thrust over one face of a rectangular prism, and the prism as a whole has a volume - and therefore mass (assuming equal density in the entire volume) - growing faster than the area of thrust, then wouldn't that be an increasingly-restrictive bottleneck as the size grows?

Since when has engine thrust been related to area? I mean, maybe your logic holds if you plaster a million fighter-grade engines to the ass of a capital ship, but it really doesn't if you're using properly-sized engines for the vehicle in question. To use a real example, the F-1 rocket engine has a diameter of 3.76 meters (~11m²) and produces 6,770 kilonewtons of thrust, so it produces 605 kilonewtons per square meter the engine occupies. The much smaller Merlin 1C uses the same propellant at similar chamber pressures; wiki sez it has a diameter of 1.25 meters (~1.23m²) and produces 400 kilonewtons, or about 325 newtons per square meter the engine occupies.

Big ships have big mass, which means more propulsive force is necessary to move with a given acceleration than a small ship with a small mass. More force equates to more fuel consumed per unit of acceleration.

Which has exactly zip to do with whether or not they use more fuel per unit mass.

[IshCong]

This has been bugging me for a while now - but what if your ships/fighters had a propulsion method that didn't require fuel in the ordinary sense?

Given the size and sheer mass of most of my ships ICly (I don't usually bring anything but the 'small' ones out for RPs for obvious reasons, but w/e), the main sublight propulsion is, in principle, an alcubierre drive - in other words, a spatial distortion drive that will accelerate irrespective of mass. A bonus feature is being able to deflect stuff (including lasers, funnily enough) with it at certain angles. However, the fighters and missiles both use a different propulsion system from that and another. The fighters use a 'gravatic' drive, the same technology as on my hovertanks, to propel them efficiently whilst relatively near a great mass, usually a planet, but ships fine too.

Maybe I just don't understand the full implications of your gravitic drive, but it doesn't seem like a great plan. I mean, hover-tech could* be useful on a planet's surface because it can help lessen friction from the ground, but that's not a factor in space. And it's not like gravity is a very strong force, the entire mass of Earth manages not even 10m/s at the surface and unless your ships are of moon/planet scale they probably won't create any appreciable gravitational pull.
So...I guess I'm wondering how this drive is supposed to work.

Missiles on the other hand use a more traditional rocket-like propellant, which enables them to traverse inter-ship distances autonomously, but is less efficient because you have to drag a mass in fuel around.

Is there any inherent reason why the missiles cannot use the same gravitic drive your fighters do?

Obviously my tech base takes a few liberties, but could similar principles be applied more realisticly? Furthermore, I'd like to add that 'strike craft' (by which I mean actual ship-sized stuff) rather than 'fighters' can work well in an FT setting, if noly because if you put them in a big mothership/carrier-thing, you don't have to fit them with (an often bulky, heavy and in combat unnecary) intergalactic FTL drive, right? That could be a lot of weight saved, right? Or am I just talking fantasies and nonsense?

I'm inclined to say that while that is a possibility, the value saved by not equipping one's ships with FTL drives is rather difficult to measure as I know of no uniform size or cost associated with them.

Of course, not having FTL drives on all ships means you are going to have to gather them up before departure or leave them behind, which could make rapid advances or withdrawals more problematic. And if you lose that/those motherships/carriers...every other ship is functionally lost because they can no longer go anywhere. Unless you have spare carriers lying around to pick up strays, but then these are the largest ships you're producing, so having tons of spares lying around...

[Yes Im Biop]

For Christ's sake can we PLEASE talk about something else besides fighters?

Space ant's.

[Old Sarthal]

For Christ's sake can we PLEASE talk about something else besides fighters?

Space ant's.

While space ants are possible, space bees would obviously be more effective, as space ants must carry fuel for the return trip, while space bees die after stinging anyway, not to mention that space bees are far more intimidating, especially if crossbred with space sharks.

[Yes Im Biop]

Space ant's.

While space ants are possible, space bees would obviously be more effective, as space ants must carry fuel for the return trip, while space bees die after stinging anyway, not to mention that space bees are far more intimidating, especially if crossbred with space sharks.

...Space Spider Hawks.

[Rethan]

Space ant's.

While space ants are possible, space bees would obviously be more effective, as space ants must carry fuel for the return trip, while space bees die after stinging anyway, not to mention that space bees are far more intimidating, especially if crossbred with space sharks.

You.

I like you.

[Old Sarthal]

While space ants are possible, space bees would obviously be more effective, as space ants must carry fuel for the return trip, while space bees die after stinging anyway, not to mention that space bees are far more intimidating, especially if crossbred with space sharks.

...Space Spider Hawks.

The existence of Space Spider Hawks implies the existence of Space Spiders .

[Yes Im Biop]

...Space Spider Hawks.

The existence of Space Spider Hawks implies the existence of Space Spiders .

Implications... terrifying

[Rethan]

The existence of Space Spider Hawks implies the existence of Space Spiders .

Implications... terrifying

Totalius.

The most terrifying thing to have ever graced FT barring the Mekantans imo.

[G-Tech Corporation]

The existence of Space Spider Hawks implies the existence of Space Spiders .

Implications... terrifying

I surmise they spin webs of dark matter in the void between stars to capture the unwary spacefarer, then cocoon him in stranglets and siphon off his matter and thermal energy to warm their bellies in the frigid blackness whence they make their homes.

[Escalan Corps-Star Island]

Implications... terrifying

I surmise they spin webs of dark matter in the void between stars to capture the unwary spacefarer, then cocoon him in stranglets and siphon off his matter and thermal energy to warm their bellies in the frigid blackness whence they make their homes.

Yum.

[Balrogga]

Implications... terrifying

I surmise they spin webs of dark matter in the void between stars to capture the unwary spacefarer, then cocoon him in stranglets and siphon off his matter and thermal energy to warm their bellies in the frigid blackness whence they make their homes.

You know, that gives me some ideas I can use with my Kythons. Thanks

[Escalan Corps-Star Island]

I'm scared now.

[G-Tech Corporation]

I surmise they spin webs of dark matter in the void between stars to capture the unwary spacefarer, then cocoon him in stranglets and siphon off his matter and thermal energy to warm their bellies in the frigid blackness whence they make their homes.

You know, that gives me some ideas I can use with my Kythons. Thanks

My pleasure.

[Yes Im Biop]

I'm scared now.

The hell have i done...

[YellowApple]

I'm scared now.

The hell have i done...

A wonderful thing.

That brings up an interesting question, though; what considerations would need to be taken to establish the feasibility of an organism that lives in the vacuum of space as its natural habitat? Based on things like space activity suits in real life, as well as the amount of radiation in space, I imagine an exoskeletal organism would have a better chance of survival, but that's just wild speculation.

[G-Tech Corporation]

The hell have i done...

A wonderful thing.

That brings up an interesting question, though; what considerations would need to be taken to establish the feasibility of an organism that lives in the vacuum of space as its natural habitat? Based on things like space activity suits in real life, as well as the amount of radiation in space, I imagine an exoskeletal organism would have a better chance of survival, but that's just wild speculation.

Hence, Space Spiders. Their genomes would have to be excessively mutation resistant, their exoskeletons would need a tensile strength near that of FT composites, and they might even need multiple membranes through which foodstuffs would pass to prevent explosive decompression of their innards.

[Arthropoda Ingens]

A wonderful thing.

That brings up an interesting question, though; what considerations would need to be taken to establish the feasibility of an organism that lives in the vacuum of space as its natural habitat? Based on things like space activity suits in real life, as well as the amount of radiation in space, I imagine an exoskeletal organism would have a better chance of survival, but that's just wild speculation.

Hence, Space Spiders. Their genomes would have to be excessively mutation resistant, their exoskeletons would need a tensile strength near that of FT composites, and they might even need multiple membranes through which foodstuffs would pass to prevent explosive decompression of their innards.

You're assuming that space lifeforms would still be carbon- and DNA based.

As opposed to consisting of weird spacetime bullshit, Xeelee-like.

[G-Tech Corporation]

Hence, Space Spiders. Their genomes would have to be excessively mutation resistant, their exoskeletons would need a tensile strength near that of FT composites, and they might even need multiple membranes through which foodstuffs would pass to prevent explosive decompression of their innards.

You're assuming that space lifeforms would still be carbon- and DNA based.

As opposed to consisting of weird spacetime bullshit, Xeelee-like.

Well, yes. I suppose they could be dark matter shadow creatures, or sentient bundles of stranglets, or cosmic ray entities.

But then we can't theorize about them, and that, as we all know, is absolutely no fun at all.

[SquareDisc City]

The hell have i done...

A wonderful thing.

That brings up an interesting question, though; what considerations would need to be taken to establish the feasibility of an organism that lives in the vacuum of space as its natural habitat? Based on things like space activity suits in real life, as well as the amount of radiation in space, I imagine an exoskeletal organism would have a better chance of survival, but that's just wild speculation.

Toss away your science and run on rule of cool. Survival in space purely on solar power might be possible, but to grow an organism needs to take in matter, and space is known for its lack of such.

Now an atmosphere-less planet is another mater. Provided there's a suitable solvent life could exist. In a vacuum any liquid will tend to either freeze or boil, but it could be replenished from geological sources. The organism's skin and general physiology might well be designed to minimise fluid losses; perhaps it could be waxy like certain plants. If warm-blooded it would not need as fast a metabolism as life on Earth since there'd be no air to cool it. And of course it can't breathe, it would have to take in everything it needs from either solid or liquid substances.

[Strykla]

A wonderful thing.

That brings up an interesting question, though; what considerations would need to be taken to establish the feasibility of an organism that lives in the vacuum of space as its natural habitat? Based on things like space activity suits in real life, as well as the amount of radiation in space, I imagine an exoskeletal organism would have a better chance of survival, but that's just wild speculation.

Toss away your science and run on rule of cool. Survival in space purely on solar power might be possible, but to grow an organism needs to take in matter, and space is known for its lack of such.

Now an atmosphere-less planet is another mater. Provided there's a suitable solvent life could exist. In a vacuum any liquid will tend to either freeze or boil, but it could be replenished from geological sources. The organism's skin and general physiology might well be designed to minimise fluid losses; perhaps it could be waxy like certain plants. If warm-blooded it would not need as fast a metabolism as life on Earth since there'd be no air to cool it. And of course it can't breathe, it would have to take in everything it needs from either solid or liquid substances.

Who says life is constrained by earthly rules? In the book Blindsight, you had aliens that ate magnetic fields.

Well, ran off them.

[Yes Im Biop]

A wonderful thing.

That brings up an interesting question, though; what considerations would need to be taken to establish the feasibility of an organism that lives in the vacuum of space as its natural habitat? Based on things like space activity suits in real life, as well as the amount of radiation in space, I imagine an exoskeletal organism would have a better chance of survival, but that's just wild speculation.

Toss away your science and run on rule of cool. Survival in space purely on solar power might be possible, but to grow an organism needs to take in matter, and space is known for its lack of such.

Suck in enough energy and it could force its self to mutate
Now an atmosphere-less planet is another mater. Provided there's a suitable solvent life could exist. In a vacuum any liquid will tend to either freeze or boil, but it could be replenished from geological sources. The organism's skin and general physiology might well be designed to minimise fluid losses; perhaps it could be waxy like certain plants. If warm-blooded it would not need as fast a metabolism as life on Earth since there'd be no air to cool it. And of course it can't breathe, it would have to take in everything it needs from either solid or liquid substances.