4 ms·

Always impressive to me. And I know that people will say "Yeah, basically the only thing 'new' here is the engine" but there are also a bunch of other things th

Always impressive to me. And I know that people will say "Yeah, basically the only thing 'new' here is the engine" but there are also a bunch of other things that struck me; It did the hop 'off balance' (the final version expects to have 3 raptor engines working together) so the engine out scenario for landing still seems pretty safe. There is something like four more advanced vehicles in the warehouse section at various stages of completion. So scaling up making them seems to be working out. It looks "small" in the images but when you see people working on it you can tell its grain silo big. That is a heck of a thing to fly overhead. Rockets taking off and landing vertical has amazed me ever since I saw the DC-X do it once.

rbanffy 6y ago
The DC-X still manages to look modern next to it. Had it succeeded, it'd have done something not even SpaceX is doing, which is a fully reusable single-stage-to-orbit craft. I don't think we have the advanced materials for that.
- ecpottinger 6y ago
  I think the Delta-X could have done the job, what went wrong was letting NASA taking control of it. Remember these are also the people who went with segmented solid fuel boosters, these were the people who thought the VentureStar with three new techs that all had to work at the same time but rejected the designs that did not need as much new tech, these are the people who let the SLS design go forward. The Delta-X was an interesting design until NASA was involved.
  - mschuster91 6y ago
    The Wikipedia article on DC-X is interesting. > In a post-accident report, NASA's Brand Commission blamed the accident on a burnt-out field crew who had been operating under on-again/off-again funding and constant threats of outright cancellation. That is the reason why SpaceX is so much more efficient and revolutionary, compared to what Boeing/ULA on US side and EADS/Ariane on EU are doing - they are cutting politics out of the equation and with it, a whole boatload of issues.
    - cryptonector 6y ago
      Contractors like Boeing for SLS generally have sweetheart cost+ deals. They have zero incentives to cut costs -- nay, they have an incentive to increase costs because their profits are the "plus". SpaceX isn't interested in a sweetheart subsidy deal. They are competing. That's why their contracts with NASA are fixed price: it gives SpaceX every incentive to keep costs down so as to maximize profit. Surprise! SpaceX is doing better than the competition that gets sweetheart deals. It should really not be a surprise to anyone though, but it probably is to some.
- ChuckMcM 6y ago
  I agree. For a space craft that did it's 150m "hop" in 1992 it was even more impressive (especially considering how much the computers and IMU weighed in that thing!) I'm not convinced though that it ever really to achieve it's SSTO goals and still land it. With on orbit refueling perhaps (as could Starship in a similar scenario). It was also shooting for much lower mass to LEO.
  - rbanffy 6y ago
    Structural weight is mostly a function of the surface area and fuel capacity and payload are a function of the volume. If you make the rocket bigger, it's payload mass fraction increases.
    - ChuckMcM 6y ago
      > Structural weight is mostly a function of the surface area and fuel capacity and payload are a function of the volume. Agree with this. > If you make the rocket bigger, it's payload mass fraction increases. Don't agree with this. The way I see it, as a rocket gets bigger, and stays in one piece, its payload mass fraction decreases. The inability to jettison heavy engines and structural components means those things become part of the 'mass fraction' that ends up in orbit. And the bigger you make those things, more and more of your mass fraction is being committed to carrying stuff and less is available for non-rocket payload. Hence its a decreasing mass fraction in terms of amount of payload. Its fun to play around with this in Kerbal but its pretty much a hard limit. Things that can affect the mass fraction in a positive way are things like more ISP in the engines. When you look at the evolution of the Falcon 9, the increase in mass to LEO was a result of two things, one upgrading the efficiency of the Merlin 1D engine and two developing a way to put more propellant and oxidizer in the same volume by super chilling it.
      - rbanffy 6y ago
        If you look at it, chilling the fuel and oxydizer is kind of increasing the fuel capacity without adding structural weight. I need to check my math to be sure of how much you can scale that way, but that's one of the reasons Starship is such a BFR.
- bluthru 6y ago
  Here's a video on SSTO: https://www.youtube.com/watch?v=Sfc2Jg1gkKA https://www.youtube.com/watch?v=Sfc2Jg1gkKA Elon talking about SSTO: https://www.youtube.com/watch?v=cIQ36Kt7UVg https://www.youtube.com/watch?v=cIQ36Kt7UVg
- iso947 6y ago
  In theory starship will have the delta v to get to LEO and back in a single stage, but the payload would be so small it wouldn’t be worthwhile.
  - garmaine 6y ago
    Incorrect, it couldn’t get back. The landing fuel and reentry structures would make it weigh too much. But as a demo they have considered a one-way orbital SSTO trip that’ll burn up on reentry.
    - rbanffy 6y ago
      A suborbital cross globe flight would also be quite fun, but they'd need to build a landing/launching pad and refueling station.
- cryptonector 6y ago
  Single stage to orbit (from Earth) is not as efficient as two stages to orbit, and that's the reason it's not done. If SpaceX manages to deliver Starship and reuse it and its booster, that will be a huge improvement over any possible reusable SSTO. SSTO or otherwise, reentry and landing are difficult enough, but SSTO adds other difficult problems.

rbanffy 6y ago

The DC-X still manages to look modern next to it. Had it succeeded, it'd have done something not even SpaceX is doing, which is a fully reusable single-stage-to-orbit craft. I don't think we have the advanced materials for that.

ecpottinger 6y ago
I think the Delta-X could have done the job, what went wrong was letting NASA taking control of it. Remember these are also the people who went with segmented solid fuel boosters, these were the people who thought the VentureStar with three new techs that all had to work at the same time but rejected the designs that did not need as much new tech, these are the people who let the SLS design go forward. The Delta-X was an interesting design until NASA was involved.
- mschuster91 6y ago
  The Wikipedia article on DC-X is interesting. > In a post-accident report, NASA's Brand Commission blamed the accident on a burnt-out field crew who had been operating under on-again/off-again funding and constant threats of outright cancellation. That is the reason why SpaceX is so much more efficient and revolutionary, compared to what Boeing/ULA on US side and EADS/Ariane on EU are doing - they are cutting politics out of the equation and with it, a whole boatload of issues.
  - cryptonector 6y ago
    Contractors like Boeing for SLS generally have sweetheart cost+ deals. They have zero incentives to cut costs -- nay, they have an incentive to increase costs because their profits are the "plus". SpaceX isn't interested in a sweetheart subsidy deal. They are competing. That's why their contracts with NASA are fixed price: it gives SpaceX every incentive to keep costs down so as to maximize profit. Surprise! SpaceX is doing better than the competition that gets sweetheart deals. It should really not be a surprise to anyone though, but it probably is to some.
ChuckMcM 6y ago
I agree. For a space craft that did it's 150m "hop" in 1992 it was even more impressive (especially considering how much the computers and IMU weighed in that thing!) I'm not convinced though that it ever really to achieve it's SSTO goals and still land it. With on orbit refueling perhaps (as could Starship in a similar scenario). It was also shooting for much lower mass to LEO.
- rbanffy 6y ago
  Structural weight is mostly a function of the surface area and fuel capacity and payload are a function of the volume. If you make the rocket bigger, it's payload mass fraction increases.
  - ChuckMcM 6y ago
    > Structural weight is mostly a function of the surface area and fuel capacity and payload are a function of the volume. Agree with this. > If you make the rocket bigger, it's payload mass fraction increases. Don't agree with this. The way I see it, as a rocket gets bigger, and stays in one piece, its payload mass fraction decreases. The inability to jettison heavy engines and structural components means those things become part of the 'mass fraction' that ends up in orbit. And the bigger you make those things, more and more of your mass fraction is being committed to carrying stuff and less is available for non-rocket payload. Hence its a decreasing mass fraction in terms of amount of payload. Its fun to play around with this in Kerbal but its pretty much a hard limit. Things that can affect the mass fraction in a positive way are things like more ISP in the engines. When you look at the evolution of the Falcon 9, the increase in mass to LEO was a result of two things, one upgrading the efficiency of the Merlin 1D engine and two developing a way to put more propellant and oxidizer in the same volume by super chilling it.
    - rbanffy 6y ago
      If you look at it, chilling the fuel and oxydizer is kind of increasing the fuel capacity without adding structural weight. I need to check my math to be sure of how much you can scale that way, but that's one of the reasons Starship is such a BFR.
bluthru 6y ago
Here's a video on SSTO: https://www.youtube.com/watch?v=Sfc2Jg1gkKA https://www.youtube.com/watch?v=Sfc2Jg1gkKA Elon talking about SSTO: https://www.youtube.com/watch?v=cIQ36Kt7UVg https://www.youtube.com/watch?v=cIQ36Kt7UVg
iso947 6y ago
In theory starship will have the delta v to get to LEO and back in a single stage, but the payload would be so small it wouldn’t be worthwhile.
- garmaine 6y ago
  Incorrect, it couldn’t get back. The landing fuel and reentry structures would make it weigh too much. But as a demo they have considered a one-way orbital SSTO trip that’ll burn up on reentry.
  - rbanffy 6y ago
    A suborbital cross globe flight would also be quite fun, but they'd need to build a landing/launching pad and refueling station.
cryptonector 6y ago
Single stage to orbit (from Earth) is not as efficient as two stages to orbit, and that's the reason it's not done. If SpaceX manages to deliver Starship and reuse it and its booster, that will be a huge improvement over any possible reusable SSTO. SSTO or otherwise, reentry and landing are difficult enough, but SSTO adds other difficult problems.