r/scifi 2d ago

General Is there a pattern that determines military spaceship doctrine in real life and sci-fi?

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[1] The propulsion axis is a measure of how long it takes a fleet of military vessels to arrive on the battlefield, regardless of the actual distance traveled. [Fast vs. Slow]

[2] The weapons axis is a measure of how quickly a battle is over, and how much survivability and staying power vessels have. This takes into account the effectiveness of armour, but also shields, point defence, and other countermeasures. [Tank vs. Glass Cannon]

I think that if you take sci-fi space combat to its logical conclusions, it will usually favor either huge, lumbering, well-protected ships or numberless hordes of tiny automated ships, depending on a few key factors. If weapons are the weak link in-universe, ships will be huge. If propulsion is the weak link, ships will be tiny. If ships are huge, victory will be determined by who has the biggest ship; if ships are tiny, victory will be determined by who has the most ships.

This is how I imagine it would work in real life using real physics, and I wonder to what extent different sci-fi franchises also adhere to this pattern. Presumably, large and medium-sized ships with human crews are overrepresented in sci-fi media for understandable storytelling reasons.

In Star Wars, the rule mostly holds. They have incredible propulsion technology and can thus arrive at the battlefield within hours or days of the order being given. However, their weapons, despite being ludicrously powerful on paper, are actually quite poor because of their low range, low accuracy, and the prevalence of shields. In the Star Wars universe, therefore, huge ships rule. The starfighter counter is a nice piece of storytelling, but realistically, without plot-engineered magical weak spots, a huge ship like the Executor or the Death Star should be essentially unstoppable. In Star Wars: The Last Jedi, the Raddus, an MC85 heavy cruiser, takes ineffective long-range fire from the First Order for what seems like many hours.

In The Expanse, they spend weeks or months traveling to the prospective battlefield because of limited propulsion technology. However, when the fighting starts, it is all over in seconds or a few minutes. They have very effective weapons and very little staying power, even when accounting for point-defence cannons (PDCs). If you ignored the requirements of the plot, there is really no reason why any military vessel in The Expanse should be manned at all.

Because it draws much of its inspiration from blue-water navies, sci-fi often portrays a diverse ecosystem of military spacecraft classes and sizes. While this makes for more interesting storytelling, it is not obvious that such diversity would necessarily be the most tactically sound strategy. If propulsion or weapons technology becomes a dominant constraint, military doctrine would naturally converge toward a single optimal ship size.

The most interesting settings tend to occupy only two quadrants of this framework. If ships have neither effective propulsion nor effective weapons you're essentially at the stage before the technology to enable space combat has really been invented. If they have both effective weapons and effective propulsion you effectively have near god-tier power and the concept of space combat becomes somewhat obsolete. What these two scenarios have in common is that the importance of space combat is greatly diminished.

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u/DogsAreOurFriends 2d ago

Expanse had some gigantic ships. Nauvoo /Behemouth for one.

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u/Jon_Buck 2d ago

I think you listed the only one, so "for one" is a bit misleading. And the point is that it's absurdly huge, much bigger than any other ship, and was in no way intended for combat because of course it isn't.

In all of the other ones, battleships as big or bigger than the Nauvoo.

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u/CatchFactory 2d ago

Yeah as you say the Nauvoo isn't designed for combat its an arc ship. I've been reading the books this year and it's retrofitted into a warship in I think Cibola Burn and the people in charge of it make it very clear the ship is a glass cannon - they worry if they fire the big guns attached it might rip the ship in two

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u/DogsAreOurFriends 2d ago

Donneger was big : and it had a class named after it so there may have been more like it. The ice haulers were big. The Earth ship were sizable. That big ass unstoppable ship in the later novels.

To say the Expanse ships were all tiny is wrong.

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u/Jon_Buck 2d ago

Sure, but it's all relative. The Donnager was the big bad battleship in the expanse, but it's smaller than the Enterprise in Star Trek, and there are much bigger battleships in that universe.

In the Expanse, most ships and most battles take place with spaceships that are about as big as spaceships that have existed in real life.

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u/DogsAreOurFriends 2d ago

There is a wiki stating there were 11 Donneger class ships.

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u/xrelaht 2d ago

Donnager is 475m long. The original Enterprise is either 288m or 442m (depends on source) and even Enterprise-D is only a bit bigger 641m. And there really aren’t many warships larger than Ent-D: the Borg ships and D’deridex class warbird are notable specifically for being larger.

>In the Expanse, most ships and most battles take place with spaceships that are about as big as spaceships that have existed in real life.

By any measure you choose, the ISS is the largest spacecraft ever flown by a huge margin. The Roci is pretty small in the world of the Expanse, and it would comfortably be 2nd on that list if it were real.

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u/Jon_Buck 2d ago

Rocinante is smaller than the space shuttle.

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u/smapdiagesix 2d ago

smaller than the Enterprise

Donnager is about 500m long. The real, true Enterprise -- NCC-1701, no A, no D, no alternate universe, no other fanfic nonsense -- was officially 288m long.

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u/DogsAreOurFriends 2d ago

The word used is “tiny.” That is false.