5 ms·
I didn't really get that. I don't think it matters where along the orbit the second stage lands. It needs enough delta-V to decelerate enough not to burn up reg
by sgtnoodle 4y ago
I didn't really get that. I don't think it matters where along the orbit the second stage lands. It needs enough delta-V to decelerate enough not to burn up regardless.
- avmich 4y agoIf the second stage lands on the landing pad, that's fine. If, however, Earth rotates so that the landing pad isn't under the orbital pad at the moment of landing, the hopping was the idea for how to get where needed. But hopping has its own drawbacks.
- Gravityloss 4y agoYeah, earth moves a few hundred km while the second stage goes around earth. The cross range will be abysmal when landing so it can't land on the pad that easily with one orbit. But it can land westward of the pad, then refuel and fly the few hundred kilometers to the pad.
- sgtnoodle 4y agoA few hundred kilometers doesn't sound like a big deal to compensate for during the de-orbit burn. Also, couldn't it just orbit multiple times until an optimal alignment comes along?
- Gravityloss 4y agoIf you're going 8 km/s in one direction (like you do when orbiting earth), changing direction even a bit is a big deal. That's why the space shuttle had those humongous wings and fragile thermal protection and why its payload ratio was lousy. To be able to go around once and land to the same spot it needed cross range and very good aerodynamics. It doesn't make sense to bring those wings to orbit just for that.
- Gravityloss 4y agoI calculated and changing plane at the pole enough to cause a 200 km shift at the equator would be about 250 m/s delta vee. So not actually impossible.
- Gravityloss 4y agoThe cross range would need to be around 1000 km for Kennedy Space Center... so a real problem.