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 threadJohn LuskMar 26, 2024

@KarlSchroeder @isaackuo @cstross @sudnadja @nyrath @FredKiesche

I think Stuhlinger (or somebody) proposed this for a Mars mission, except tripartite, not bipartite.

Show threadWinchell Chung ⚛🚀Mar 26, 2024

@tarheel @KarlSchroeder @isaackuo @cstross @sudnadja @FredKiesche

Krafft Ehricke designed these. I'm still looking for the tripartite one you mentioned.

Show threadJohn LuskMar 27, 2024

@nyrath @KarlSchroeder @isaackuo @cstross @sudnadja @FredKiesche

He described it to me in person (he was a good friend of my grandfather, Wilhelm Angele, so we spent some time together when I was a kid). Maybe I misunderstood or his proposal never saw the light of day.

Show threadWinchell Chung ⚛🚀

@tarheel @KarlSchroeder @isaackuo @cstross @sudnadja @FredKiesche

I'm sure the design exists.

All I am saying is I have yet to be fortunate enough to stumble over an old scientific paper that was blessed with an artist conception. Which is a disappointment that happens regularly to me.

Mar 27, 2024 at 11:27amWeb
Show threadJohn LuskMar 27, 2024

@nyrath @KarlSchroeder @isaackuo @cstross @sudnadja @FredKiesche

Could a been a coffee-machine proposal. 🙂

I think he also had a plan for crews in each of the nodes to visit each other, like three houses close together being on good terms with each other. Kind of an emotional/social health aspect.

No idea what the mechanics of that would have been. Elevator on the cables?

Show threadWinchell Chung ⚛🚀Mar 27, 2024

@tarheel @KarlSchroeder @isaackuo @cstross @sudnadja @FredKiesche

The closest image I've managed to find was this.
And it is more about orientation effect on floor geometry than it was tripart spin habs.

Grey lines are floor contours.