The latest iteration of the Freehauler Alcione, incorporating the theme of negative mass propulsion, which better fits the story setting and the trope of the tramp space freighter than the harder science Daedalus drive.
At 300 meters, and a dry mass of around 80,000 tons, this is a respectable sized vessel, the size of modern day nuclear powered aircraft carrier or unladen oil tanker.
But when you take away all the space dedicated to reactionless drive, reactor, thermal radiators, FTL zone-transit, manoeuvering rockets, fuel, container haulage, hanger, storage, water and volatiles, biospherics, defensive lasers, radiation and armour shielding, etc etc, there isn’t much space left.
Which of course makes for fun writing. I want to keep the sense of claustrophobia. Space may be vast, infinite even, but the ships that traverse it aren’t necessarily large. Sure, some can be, like the classic starliners and kilometers long corporate bulk and container haulers and giant mining vessels, the huge worldships and hab ships and the dreadnoughts and carriers. But I expect most ships would be small and cramped, the equivalent of a WW II sub. Add jerry-rigged construction and a mishmash of parts and modules from other ships, or matter printed on the fly, and the FHSS Alcione may not be the shiniest ship in the spacedock. But she’s still home for those who sail her across the infinite ocean of space.
The only two really spectacular piece of tech on this vessel is the reactionless drive, with negmass stored in hyperspace and constantly transferred back and forth to balance the changing positive mass of the ship (as the two have to be equal at all times, though I suppose there would be some margin of error or the system would probably be unworkable), and the ortho-rotational FTL unit which enables the ship to shift from real space to superluminal zones and back.
From whence comes such miraculous pieces of clarketech (technology so advanced as to be indistinguishable from magic)? Luckily, being a scifi writer I can cheat (if I was rigorously hard science I probably couldn’t!) and say they were gifted to humanity and other lesser races by technologically more advanced aliens (and more than one race. The race that has the reactionless drive isn’t the same as the FTL race).
This is actually an old trope. Arkady and Boris Strugatsky’s Roadside Picnic has hyper-advanced aliens visiting Earth, and leaving extraordinary tech with their refuse, after they depart. Alastair Reynolds Revelation Space universe uses the classic &gifting& trope, but replaces aliens with a posthuman clade called &conjoiners&. It really doesn’t matter what literary or worldbuilding device you use. Aliens, posthumans, and the gods of mythology are all equally symbols and metaphors of the transcendent.
But why would these aliens do this, if being so advanced they could take whatever they want by force?
Well, any number of reasons. They may need humans as cannon fodder to fight their futile and monstrous wars. They may be scavengers who stole it from some other race, and in turn trade it for whatever (but whatever they trade it for, the price is horrendous). They may be engaged in some vast strategic game of which we cannot even glimpse (and if we do, any glimpse we have is totally wrong). Or they may just be nice and generous people.
The freehaulers who just break even keeping their horrendously expensive ships running on whatever profits they make from cargo haulage to grey market profiteering to honest freight transport to on the side smuggling, don’t really care. They love their austere lifestyle and libertarian-anarchist freedoms and wanderlust, travelling from world to world and space station to space station, beholden to no-one but themselves and their fellow merchanteers and freehaulers.
And like everyone else, they never stop to think of the terrible cost humankind paid (or didn’t pay, does anyone really know or care?) for the stardrive. They just want to keep doing what they’re doing.