Isaac Ji KuoMar 24, 2024

@[email protected] @nyrath @FredKiesche

What sort of vehicle should accelerate at 1 g or so, though? You get the benefits of the Oberth effect at much lower accelerations, and designing for lower accelerations provides a lot of benefits. You get reduced structural mass - especially for solar arrays and radiators, lower thruster/engine mass, and usefully better specific impulse.

Show threadCharlie StrossMar 25, 2024
@isaackuo @sudnadja @nyrath @FredKiesche If you've got a magic reaction drive (unlimited thrust, no waste heat, no fuel mass problem), then you might as well thrust at whatever acceleration is best for the cargo. If that's humans, it would be the *lowest* acceleration to keep the adverse medical effects of microgravity at bay (probably a lot less than 1g but more than 0.1g).
Show threadIsaac Ji KuoMar 25, 2024

@cstross @[email protected] @nyrath @FredKiesche

Depending on your definition of "unlimited thrust", you could squint and say artificial spin gravity qualifies. It obviously has no waste heat or fuel mass problem.

If your spacecraft spins, the most intuitively obvious thrust axis is parallel to the spin axis, but it's not a no-brainer. For example, with solar electric you probably want the spin axis pointed to the Sun, but you usually want thrust perpendicular to the Sun.

Show threadKarl SchroederMar 25, 2024
@isaackuo
Once you stop accelerating, you split the ship in two and let out a line. Then you spin the bolo. Simple! People think of spacecraft like boats, as necessarily unitary. Baw. Split 'em up into however many pieces you need and spin the parts separately if you need to. It's not like the other sections are going anywhere unless they're pushed.
@cstross @[email protected] @nyrath @FredKiesche
Show threadRichard HendricksMar 25, 2024
@KarlSchroeder @isaackuo @cstross @sudnadja @nyrath @FredKiesche Rotating warships a la B5 are just a bad idea (no matter how cool they look). Rotating is enormous momentum and makes it hard to do dynamic motions. And damage to the section would rapidly cascade into a disaster. Expanse's "everyone strap in for high G" is the only sensible way to fight.
Show threadKarl SchroederMar 26, 2024
@hendric
Realistic space warships aren't single entities except when under power; they're dispersed constellations (swarms) and typically will engage in battle from millions of kilometers away. Incoming ordnance will be stealthed and traveling at tens of kilometers per second. Possible fleet trajectories will be known ahead of time. The concept of 'maneuvering' simply doesn't apply.
@isaackuo @cstross @[email protected] @nyrath @FredKiesche
Show threadSteve BellovinMar 26, 2024
@KarlSchroeder @hendric @isaackuo @cstross @sudnadja @nyrath @FredKiesche “Mote in God's Eye” was (quasi-)realistic in that sense. Warships were powered by a fusion-powered reaction drive, with decks perpendicular to the thrust axis. When coasting and not in combat, they'd rotate about the long axis to provide “gravity”. Flywheels were used to spin the ship up and down.
Show threadCharlie StrossMar 26, 2024
@SteveBellovin @KarlSchroeder @hendric @isaackuo @sudnadja @nyrath @FredKiesche I have a soft spot for Iain M. Banks's Culture novels where the tech is 100% rigged for plot purposes BUT the space battles are epic (especially in "Surface Detail" and "Excession").
Show threadPhilippa Cowderoy
@cstross @SteveBellovin @KarlSchroeder @hendric @isaackuo @sudnadja @nyrath @FredKiesche I appreciated Excession's exposition actively telling us that it's rigged on every count (including post-scarcity). Honesty about where the actual speculation starts is a good thing if that's what you're doing.
Mar 26, 2024 at 9:08pmWeb