Negatory on that. GP#2 is a wasp-waisted 300 ft cylinder with tapered ends.
Unless there’s another General Products?
Great to see Red Dwarf in there.
There are quite a few fictional ships in sci-fi novels I’d love to see in there but of course the designs and specs are all just descriptions on a page.
I feel if they went to TTGL movie size it would take a full hour of zooming out to get there.
Seeing some of these ships to scale, I kind of feel like a lot of them are just ridiculously large for no apparent reason.
Ships around a mile or so long like an Imperial Star Destroyer, Battlestar or SDF-1 from Robotec, fine. They are basically a giant self contained battleship / troop carrier / aircraft carrier designed to fly around a planet and unleash an entire army / air wing for sustained operations. You could probably house a million people comfortably in one of those ships.
And the ship from District-9 or Independence Day have to be large enough on screen to loom ominously over a city.
But why does the Lexx or the Event Horizon have to be so big for their crew of six?
Pretty sure an army of the dead will awaken.
IIRC, the Lexx is designed to blow up planets Death Star-style, and the Event Horizon contains a black hole. Anyway, you are right that it is seldom explained how big fictional prime movers and other technology are supposed to be, and in anything but “hard science fiction” it would be foolish to attempt to. Still, there should be some diegetic or symbolic reason for a ship to be the size of a city.
The Dillon-Wagoner Graviton Polarity Generator , known colloquially as the spindizzy , is a fictitious anti-gravity device imagined by James Blish for his series Cities in Flight . This device grows more efficient with the amount of mass being lifted, which was used as the hook for the stories—it was more effective to lift an entire city than it was to lift something smaller, such as a classic spaceship.
Especially with the lesser-known ships, it seems like a case of one-upmanship. “Oh, you think your super duper star destroyer is big? Well, mine’s bigger!”
Still, I once “created” a spaceship that was one light year long. So there!
Not going to go through all the calculations, but I’m pretty sure if that spaceship was anything more than a thin sheet of paper, its Schwarzschild Radius would exceed its length and it would immediately collapse into a black hole. And even if it didn’t, its mass would still have enough gravity to crush it into a spherical shape.
Details!
Just don’t ask where the material comers from. First, we find 2 million Dyson spheres and cannibalize them…
So long as your cross-section is reasonable, you could have a ship of any length without risk of it being a black hole. I’m not sure why you’d want to, but you could.
Bragging rights. 
The Ringworld was eventually equipped with a Quantum II hyperdrive, so it counts as a really big starship.
Stay in your lane…
Does anyone else remember that fan image of a “Ultra Star Destroyer” that was literally something like 100 kilometers long, and then someone else came up with a hilarious “after action report” of it’s first flight and how people in different sections of the ship rebelled and now there’s 8 different 100,000 man armies occupying different parts of the ship?
Where’s HMS Camden Lock?
But where do you go, when your vehicle is already 90% of the destinations in the Galaxy?
It would take a minimum of six months to coordinate operations at both ends of a ship 1 ly long, assuming the command center is at the center. Unless, of course, the intraship communications are subspace.