3 ms·

For an apples to apples comparison, you need to include the BFS itself in the “mass to orbit” number. Or subtract the mass of Apollo from Saturn V’s.

maxerickson 8y ago
The payload is such an interesting comparison that there is a word for it. The wikipedia articles give 100,000 kg for the BFR and 140,000 kg for the Saturn V. For hundreds of missions, the BFR strategy of refueling to leave orbit probably makes sense, but it's pretty clear which rocket puts more payload in a 90 mile orbit, a very direct comparison of launch capability. And of course, BFR may exceed projections (or fail to meet them).
- mikeash 8y ago
  Wikipedia’s number for the BFR is payload other than the BFS itself. BFR puts up a gigantic spaceship, and a huge payload inside it. Saturn V did not do this. Apollo (or Skylab) was the payload.
  - computerex 8y ago
    The BFS is part of the whole stack, it is the second stage. It is unclear because of lack of technical specification from SpaceX but at the moment it seems unlikely that the BFB will fly without the BFS. So you can't look at the BFS as a separate thing as you are implying, it is a core part of the architecture. It'd be like saying that the Saturn V can haul x amount of payload in addition to its second stage.
    - mikeash 8y ago
      You can’t ignore it either. The BFS isn’t a useless hunk of metal once it’s in orbit, it’s still very useful. Consider a past example. The Space Shuttle’s payload to orbit was many times smaller than Saturn V’s. Yet the Shuttle could do missions over two weeks long with seven crew, far more than Apollo could. How is that possible? Because the orbiter didn’t count as part of the “payload”. BFR is going to send 8 people on a trip around the moon. Saturn V couldn’t do that, even though it could orbit more “payload.” It all depends on the mission. If you just want to put satellites in orbit, Saturn V is more capable (ignoring costs). If you want to send people somewhere, BFR is way more capable. BFR can put a lot more mass into orbit, it’s just that a lot of that mass is taken up by mandatory stuff. If that stuff is useful for you then it should count. If it’s not then it shouldn’t. And that brings us back to my original point, way up there, that BFR is major overkill for a satellite launcher, but makes perfect sense for a Mars mission.
      - maxerickson 8y ago
        The trip to the moon is great, but it's 2 launches.
        mikeash 8y ago
        Is it? The mission profile shown during the presentation makes no mention of that. It also shows only 30 minutes in orbit before the lunar injection burn, which wouldn’t be enough to refuel from a tanker.
      - computerex 8y ago
        Saturn V and Apollo were designed for a very specific purpose. And so the CSM could only sustain the crew for the trip to the moon. The 310k lbs payload did not include the CSM and LEM. In theory the Saturn V booster could haul up a BFS style ship if such a thing existed.
        mikeash 8y ago
        “The 310k lbs payload did not include the CSM and LEM.” Are you saying the Saturn V was able to lift 310k lbs plus the CSM and LEM? I’m pretty sure that not true. Saturn V was a general purpose rocket. It wasn’t tied to Apollo, as evidenced by Skylab. It just worked out that nobody found a cost-effective use for it beyond Apollo and Skylab.
        computerex 8y ago
        Sorry for the confusion, I meant that the Saturn V could haul 310k lbs and the payload didn't necessarily need be the CSM/LEM. So in theory they could attach a dragon/bfs type thing as payload.
        mikeash 8y ago
        I see. You’re right that it could. It wouldn’t be as good, though, since the BFR’s total mass to orbit is greater. That’s why I’m saying you need to take BFS into account and not just look at “payload” numbers.
- CydeWeys 8y ago
  And BFR will launch 100 Mg for a tiny fraction of the price of the 140 Mg that the Saturn V could do. Add to that the fact that the plan is for two BFRs to dock in LEO and shuttle across supplies and you end up with larger mission capacity, still at a fraction of the price. Reusability is the huge game-changer here. When you're reusable, the max payload per launch doesn't matter nearly as much since it's not a one-shot deal.
  - computerex 8y ago
    I have no stock in the proposed cost savings until it actually becomes a reality. What people don't realize is that reusability isn't as straightforward as SpaceX makes it seem. A used stage has to be taken apart, inspected and refurbished. It is unlikely that SpaceX saves any money on reusing their stages, they might even be losing money. https://spacenews.com/spacexs-reusable-falcon-9-what-are-the-real-cost-savings-for-customers/ https://spacenews.com/spacexs-reusable-falcon-9-what-are-the...
    - mikeash 8y ago
      They have stated that their very first reused booster cost less than half as much money to refurbish than it cost to build a new one. That was quite a while ago, with a much less advanced reusable design. The current version of the Falcon 9 incorporates lessons learned from tearing down and reflying the earlier units, so should be much cheaper. Even if you think there are no possible improvements, it can’t possibly get worse than a 50% savings. Unless you’re proposing that they’re lying out their asses?
    - greglindahl 8y ago
      The article you link is 2 years old. The price difference is now known: F9 to GTO is $50mm using a reused-and-recoverable booster, compared to the old list price of $62mm. The cost difference is fully known inside of SpaceX; their public statements disagree with your speculation.

maxerickson 8y ago

The payload is such an interesting comparison that there is a word for it. The wikipedia articles give 100,000 kg for the BFR and 140,000 kg for the Saturn V. For hundreds of missions, the BFR strategy of refueling to leave orbit probably makes sense, but it's pretty clear which rocket puts more payload in a 90 mile orbit, a very direct comparison of launch capability. And of course, BFR may exceed projections (or fail to meet them).

mikeash 8y ago
Wikipedia’s number for the BFR is payload other than the BFS itself. BFR puts up a gigantic spaceship, and a huge payload inside it. Saturn V did not do this. Apollo (or Skylab) was the payload.
- computerex 8y ago
  The BFS is part of the whole stack, it is the second stage. It is unclear because of lack of technical specification from SpaceX but at the moment it seems unlikely that the BFB will fly without the BFS. So you can't look at the BFS as a separate thing as you are implying, it is a core part of the architecture. It'd be like saying that the Saturn V can haul x amount of payload in addition to its second stage.
  - mikeash 8y ago
    You can’t ignore it either. The BFS isn’t a useless hunk of metal once it’s in orbit, it’s still very useful. Consider a past example. The Space Shuttle’s payload to orbit was many times smaller than Saturn V’s. Yet the Shuttle could do missions over two weeks long with seven crew, far more than Apollo could. How is that possible? Because the orbiter didn’t count as part of the “payload”. BFR is going to send 8 people on a trip around the moon. Saturn V couldn’t do that, even though it could orbit more “payload.” It all depends on the mission. If you just want to put satellites in orbit, Saturn V is more capable (ignoring costs). If you want to send people somewhere, BFR is way more capable. BFR can put a lot more mass into orbit, it’s just that a lot of that mass is taken up by mandatory stuff. If that stuff is useful for you then it should count. If it’s not then it shouldn’t. And that brings us back to my original point, way up there, that BFR is major overkill for a satellite launcher, but makes perfect sense for a Mars mission.
    - maxerickson 8y ago
      The trip to the moon is great, but it's 2 launches.
      - mikeash 8y ago
        Is it? The mission profile shown during the presentation makes no mention of that. It also shows only 30 minutes in orbit before the lunar injection burn, which wouldn’t be enough to refuel from a tanker.
    - computerex 8y ago
      Saturn V and Apollo were designed for a very specific purpose. And so the CSM could only sustain the crew for the trip to the moon. The 310k lbs payload did not include the CSM and LEM. In theory the Saturn V booster could haul up a BFS style ship if such a thing existed.
      - mikeash 8y ago
        “The 310k lbs payload did not include the CSM and LEM.” Are you saying the Saturn V was able to lift 310k lbs plus the CSM and LEM? I’m pretty sure that not true. Saturn V was a general purpose rocket. It wasn’t tied to Apollo, as evidenced by Skylab. It just worked out that nobody found a cost-effective use for it beyond Apollo and Skylab.
        computerex 8y ago
        Sorry for the confusion, I meant that the Saturn V could haul 310k lbs and the payload didn't necessarily need be the CSM/LEM. So in theory they could attach a dragon/bfs type thing as payload.
        mikeash 8y ago
        I see. You’re right that it could. It wouldn’t be as good, though, since the BFR’s total mass to orbit is greater. That’s why I’m saying you need to take BFS into account and not just look at “payload” numbers.
CydeWeys 8y ago
And BFR will launch 100 Mg for a tiny fraction of the price of the 140 Mg that the Saturn V could do. Add to that the fact that the plan is for two BFRs to dock in LEO and shuttle across supplies and you end up with larger mission capacity, still at a fraction of the price. Reusability is the huge game-changer here. When you're reusable, the max payload per launch doesn't matter nearly as much since it's not a one-shot deal.
- computerex 8y ago
  I have no stock in the proposed cost savings until it actually becomes a reality. What people don't realize is that reusability isn't as straightforward as SpaceX makes it seem. A used stage has to be taken apart, inspected and refurbished. It is unlikely that SpaceX saves any money on reusing their stages, they might even be losing money. https://spacenews.com/spacexs-reusable-falcon-9-what-are-the-real-cost-savings-for-customers/ https://spacenews.com/spacexs-reusable-falcon-9-what-are-the...
  - mikeash 8y ago
    They have stated that their very first reused booster cost less than half as much money to refurbish than it cost to build a new one. That was quite a while ago, with a much less advanced reusable design. The current version of the Falcon 9 incorporates lessons learned from tearing down and reflying the earlier units, so should be much cheaper. Even if you think there are no possible improvements, it can’t possibly get worse than a 50% savings. Unless you’re proposing that they’re lying out their asses?
  - greglindahl 8y ago
    The article you link is 2 years old. The price difference is now known: F9 to GTO is $50mm using a reused-and-recoverable booster, compared to the old list price of $62mm. The cost difference is fully known inside of SpaceX; their public statements disagree with your speculation.