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 Yeah, but Pournelle's Codominium universe was rigged: perfect black body forcefield, magic jump drive between points of equivalent spacetime curvature orbiting stars, and the Moties STILL couldn't invent hormonal contraceptives!
Show threadSteve BellovinMar 26, 2024
@cstross @KarlSchroeder @hendric @isaackuo @sudnadja @nyrath @FredKiesche That's why I said quasi-realistic… (Pournelle and NIven wrote that they started with a plastic model of an imaginary warship and used that as the prototype for the MacArthur (and what a name, but I guess it goes along with Lenin…).) The jump drive was designed, per another essay, to make interstellar travel difficult but expensive, to avoid other plot failure modes.
Show threadCharlie StrossMar 26, 2024
@SteveBellovin @KarlSchroeder @hendric @isaackuo @sudnadja @nyrath @FredKiesche I have a [long-delayed] space opera on the cutting room floor that explores different ideas, in the age of 3D printing and effectively infinite data storage. Maybe it'll come out in a couple of years?
Show threadCharlie StrossMar 26, 2024

@SteveBellovin @KarlSchroeder @hendric @isaackuo @sudnadja @nyrath @FredKiesche (We expect ships to carry reaction mass. Why not have them also carry feedstock and a printer, so that the core military tech you need is a big reactor, bigger radiators to dump waste heat, and a design library full of weapons and countermeasures?

(The term "energetic merchant cruiser" comes up: it's officially unarmed, stands up to customs inspector scrutiny, but you do *not* want to fuck with it …)

Show threadSteve BellovinMar 26, 2024
@cstross @KarlSchroeder @hendric @isaackuo @sudnadja @nyrath @FredKiesche I'm blanking on the name of the series and the author, but not all that many years ago there was a series where fleets did include manufacturing ships. It was notable for being one of the few space navy books to worry about orbital mechanics, relativity, and (especially) logistics. (The religion seemed to include the stars as containing or personifying their ancestors. Ring a bell?)
Show threadabs(in)theMar 26, 2024

@SteveBellovin @cstross @KarlSchroeder @hendric @isaackuo @sudnadja @nyrath @FredKiesche sounds like Jack Campbell's Lost fleet. I would say it got even better with the later Lost Stars/Tarnished Knight set.

My favourite Jack Campbell would be his "Lady be good" short story

(Apologies if this overlaps with someone else also answering :)

Show threadSteve BellovinMar 26, 2024
@abs0 @cstross @KarlSchroeder @hendric @isaackuo @sudnadja @nyrath @FredKiesche Only with my answer…
Show threadabs(in)the
@SteveBellovin @cstross @KarlSchroeder @hendric @isaackuo @sudnadja @nyrath @FredKiesche Meh, we're eventually consistent
Mar 26, 2024 at 8:58pmWeb