On: The tyranny of the rocket equation (2012)

[suoduandao2]

Why isn't there more interest in the dirigible launch/landing platform idea? Heck of an engineering feat to construct one of course, but nothing obviously defying the laws of physics and it would get us out of the thicker part of the atmosphere pretty effectively. And a self-landing rocket wouldn't need as much fuel for the return trip because the buoyancy of the landing platform would absorb some of the shock.

[ultra_nick → suoduandao2]

Keeping a floating platform up would be expensive. Gravity is the main force they're fighting.

They have used planes in a similar way though: https://en.m.wikipedia.org/wiki/SpaceShipTwo

[thrtythreeforty → suoduandao2]

To paraphrase xkcd, space isn't about going up. It's about going sideways fast enough that you miss the ground.

[effie → thrtythreeforty]

It's much easier to go sideways fast at height of 10km. That's why rockets start vertically (go up), and only later in height they tilt to "go sideways".

[themerone → suoduandao2]

Atmospheric drag is relatively insignificant compared to gravity.

[aaronblohowiak → themerone]

Right but you can you bouyancy rather than ejection mass.