5 ms·

Yes. And it also means the passengers don't have to wait around for the rocket to fuel up on the platform. I think that takes at least an hour or so?

Gravityloss 6y ago
The advantages are that you don't need to offboard and onboard, and you don't need personnel facilities at the refueling stop. Also fueling doesn't need to take an hour. The rocket consumes its fuel in minutes, fueling could be as fast.
- mulmen 6y ago
  The fuel pumps are literally powered by the rocket and use high pressure tanks to prevent vacuums from forming in the tanks. How do you plan on achieving that on the pad?
  - Gravityloss 6y ago
    It's just engineering. It's much easier than the turbopumps on the rocket. The rocket pumps have a much harder job than these refueling pumps, since the rocket's pumps have to raise the pressure to higher than the engine chamber pressure, so in Raptor that would be about three hundred bars (4500 psi). No such issue in tanking as the rocket tank pressure is low. You can also just use electrical pumps with no weight or size constraints, since it's not flight hardware. Large scale LNG pumping solutions at least are off the shelf items for LNG tanker ships. There also exist solutions for what to do with the gases in the LNG tank when it's filled. Oxygen tank contents you can of course just vent to the atmosphere. Falcon 9 first stage flight lasts 2 minutes and 34 seconds. Tanks go from full to empty. [1] You could design the refueling operation to be ten minutes if it provided some benefit to you. 1: https://spaceflightnow.com/2021/01/07/falcon-9-launch-timeline-with-turksat-5a/ https://spaceflightnow.com/2021/01/07/falcon-9-launch-timeli... There are other reasons though why flying a lot of people routinely won't be a thing.
    - mulmen 6y ago
      Yeah I’m sure it is solvable. It just doesn’t seem like the kind of thing worth doing. But if you told me 5 years ago a first stage booster could land and be reused I’d have laughed in your face. So yeah, maybe! Would be pretty funny if SpaceX could refuel a Starship faster than Tesla can recharge a Model S!

Gravityloss 6y ago

The advantages are that you don't need to offboard and onboard, and you don't need personnel facilities at the refueling stop. Also fueling doesn't need to take an hour. The rocket consumes its fuel in minutes, fueling could be as fast.

mulmen 6y ago
The fuel pumps are literally powered by the rocket and use high pressure tanks to prevent vacuums from forming in the tanks. How do you plan on achieving that on the pad?
- Gravityloss 6y ago
  It's just engineering. It's much easier than the turbopumps on the rocket. The rocket pumps have a much harder job than these refueling pumps, since the rocket's pumps have to raise the pressure to higher than the engine chamber pressure, so in Raptor that would be about three hundred bars (4500 psi). No such issue in tanking as the rocket tank pressure is low. You can also just use electrical pumps with no weight or size constraints, since it's not flight hardware. Large scale LNG pumping solutions at least are off the shelf items for LNG tanker ships. There also exist solutions for what to do with the gases in the LNG tank when it's filled. Oxygen tank contents you can of course just vent to the atmosphere. Falcon 9 first stage flight lasts 2 minutes and 34 seconds. Tanks go from full to empty. [1] You could design the refueling operation to be ten minutes if it provided some benefit to you. 1: https://spaceflightnow.com/2021/01/07/falcon-9-launch-timeline-with-turksat-5a/ https://spaceflightnow.com/2021/01/07/falcon-9-launch-timeli... There are other reasons though why flying a lot of people routinely won't be a thing.
  - mulmen 6y ago
    Yeah I’m sure it is solvable. It just doesn’t seem like the kind of thing worth doing. But if you told me 5 years ago a first stage booster could land and be reused I’d have laughed in your face. So yeah, maybe! Would be pretty funny if SpaceX could refuel a Starship faster than Tesla can recharge a Model S!