3 ms·

Perhaps they use a diamond frame filled in with graphene instead. Still seems pretty unlikely though. And probably too easy to puncture, ruining the vacuum. Or

by db48x 2y ago

Perhaps they use a diamond frame filled in with graphene instead. Still seems pretty unlikely though. And probably too easy to puncture, ruining the vacuum. Or perhaps they just build surfaces out of more complicated things than carbon. Hydrocarbons could be as easily assembled as diamond with similar techniques, and are a lot lighter than pure carbon. Plus they would want to put electronic advertising on the surface of the ball anyway, so it’s got to have a bit more going on to form LEDs and whatnot.

Terr_ 2y ago
I was thinking about smaller bubbles and aerogels, but when the volume changes by a factor of 0.10, the thickness-budget only changes by a factor of ~0.46. So while many smaller spheres--or pockets sharing walls--might be easier to engineer, the square-cube law [0] eats away at your lifting-power as everything becomes mostly-diamond with very little air-displacing vacuum. [0] https://en.wikipedia.org/wiki/Square%E2%80%93cube_law https://en.wikipedia.org/wiki/Square%E2%80%93cube_law
- db48x 2y ago
  Yup, the scaling works the wrong way for small objects. A vacuum–zeppelin makes a lot more sense than a beach ball.
  - IgorPartola 2y ago
    Exactly. That’s why a cubic meter of air is probably not the right range to look at. Something several magnitudes larger might do better.
    - Terr_ 2y ago
      Likely, but even a cubic meter is already a large step up from the scales in the book, ex: > Each aerostat in the dog pod grid was a mirror-surfaced, aerodynamic teardrop just wide enough, at its widest part, to have contained a pingpong ball. It doesn't say they aren't relying on some kind of down-thrust, but at that point I'd wager it's much easier to skip the whole marginal buoyancy part entirely. Use those conductive diamonds for an ionic thruster or something.

3 ms·

Perhaps they use a diamond frame filled in with graphene instead. Still seems pretty unlikely though. And probably too easy to puncture, ruining the vacuum. Or

by db48x 2y ago

Terr_ 2y ago
I was thinking about smaller bubbles and aerogels, but when the volume changes by a factor of 0.10, the thickness-budget only changes by a factor of ~0.46. So while many smaller spheres--or pockets sharing walls--might be easier to engineer, the square-cube law [0] eats away at your lifting-power as everything becomes mostly-diamond with very little air-displacing vacuum. [0] https://en.wikipedia.org/wiki/Square%E2%80%93cube_law https://en.wikipedia.org/wiki/Square%E2%80%93cube_law
- db48x 2y ago
  Yup, the scaling works the wrong way for small objects. A vacuum–zeppelin makes a lot more sense than a beach ball.
  - IgorPartola 2y ago
    Exactly. That’s why a cubic meter of air is probably not the right range to look at. Something several magnitudes larger might do better.
    - Terr_ 2y ago
      Likely, but even a cubic meter is already a large step up from the scales in the book, ex: > Each aerostat in the dog pod grid was a mirror-surfaced, aerodynamic teardrop just wide enough, at its widest part, to have contained a pingpong ball. It doesn't say they aren't relying on some kind of down-thrust, but at that point I'd wager it's much easier to skip the whole marginal buoyancy part entirely. Use those conductive diamonds for an ionic thruster or something.