4 ms·

Proof of concept. It's a lot easier to do something, if you know it can be done.

by kurthr 1y ago

mempko 1y ago
I mean, SpaceX also knew it could be done since reusable rocket tests happened in the 90s.
- kurthr 1y ago
  Don't you mean the SpaceShuttle in the 80s? or Delta Clipper which didn't reach orbit? Really, what SpaceX did was radically different from the tests in the 90s from the rockets, to the controls, to the reusability goals. Otherwise they wouldn't have built Grasshopper. Now NewGlen is kinda a knockoff of Delta Clipper, but that's a different beast.
- mensetmanusman 1y ago
  And physics, nothing prevents the goal beyond execution.
- hwillis 1y ago
  The DC-X was 9.1 tonnes empty and 19 tonnes full- meaning landing thrust was ~half of takeoff thrust. The Falcon 9 was 400 tonnes full and 26 tonnes empty, so takeoff thrust was >20x higher than landing thrust. That's a huge engineering difference, roughly like the difference between a car and a helicopter. The Falcon 9 was also 4x taller, meaning 16x more force to correct a lean. A little burp would send the rocket right back up in the air.
benjiro 1y ago
Its more about money. If you know that something can be done, and there is a potential market for such a project, it then becomes easier to get the funding. Chicken or the egg... One thing we also need to point out, is that SpaceX uses like 80% of their yearly launches, for their own communication / sat service. This gave a incentive for that investment. Is the same reason why, despite SpaceX throwing those things up constantly, there really is a big lag of competitors with reusable rockets. Its not that they where / not able to quickly get the same tech going. They simply have less market, vs what SpaceX does non-stop. So the investments are less, what in time means less fast development. SpaceX is a bit of a strange company, partially because they used a lot of the public funds to just throw shit at the wall, and see what sticks. This resulted in them caring less if a few rockets blew up, as long as they got the data for the next one with less flaws. It becomes harder when there is more oversight of that money, or risk averse investors. Then you really want to be sure that thing goes up and come back down into one piece from the first go. A lot of projects funding are heavily based upon the first or second try of something, and then (sometimes unwisely) funding is pulled if it was not a perfect success story.
- kurthr 1y ago
  I agree, a lot is about money, but it's not like Honda is raising external funds. Getting management to agree to do anything pretty much requires guaranteed success in large organizations.
- PaulHoule 1y ago
  Even before SpaceX started launching their own satellites in huge numbers they had a business model where they were selling the launch, not the rocket, and selling it at a fixed price, so if some small refinement saved them 5% on launch costs it went to their pockets so they had an incentive to make those small refinements. Dragon 9 was based on conservative and boring technology but it was cost optimized before it was reusable, then reusability crushed the competition. For that matter, Starship is boring. "Throw at the wall and see what sticks" isn't "trying a bunch of crazy stuff" but trying a bunch of low and medium risk things. For instance, development of the Space Shuttle thermal tiles was outrageously expensive and resulted in a system that was outrageously expensive to maintain. They couldn't change it because lives were at stake. With Starship they can build a thermal protection system which is 90% adequate and make little changes that get it up to 100% adequate and then look at optimizing weight, speed of reuse and all that. If some of them burn up it is just money since there won't be astronauts riding it until it is perfected.
  - imtringued 1y ago
    Starship has exactly the opposite development strategy to what made the Falcon 9 so successful. Calling a complete change in process and philosophy "boring" appears to be hubris. Falcon 9 didn't have three versions of which two were obsolete. Falcon 9 didn't put optional goals on the critical path, which are now delaying and preventing commercial launches.
    - inemesitaffia 1y ago
      Falcon had multiple versions and upper stage reusability was planned too.
- 1y ago
PaulHoule 1y ago
Also psychology and politics kept people from following the easy path. The Space Shuttle was wrong in so many ways, not least that it was a "pickup truck" as opposed to a dedicated manned vehicle (with appropriate safety features) or a dedicated cargo vehicle. Because they couldn't do unmanned tests they were stuck with the barely reusable thermal tiles and couldn't replace them with something easier to reuse (or safer!) Attempts at second generation reusable vehicles failed because rather than "solving reuse" they were all about single-stage to orbit (SSTO) [2] and aerospike engines and exotic composite materials that burned up the money/complexity/risk/technology budgets. There was a report that came out towards the end of the SDI [3] phase that pointed out the path that SpaceX followed with Dragon 9 where you could make rather ordinary rockets and reuse the first stage but expend the second because the first stage is most of the expense. They thought psychology and politics would preclude that and that people would be seduced by SSTO, aerospikes, composites, etc. Funny though out of all the design studies NASA did for the Shuttle and for heavy lift vehicles inspired by the O'Neill colony idea, there was a sketch of a "fly back booster" based on the Saturn V that would have basically been "Super Heavy" that was considered in 1979 that, retrospectively, could have given us Starship by 1990 or so. But no, we were committed to the Space Shuttle because boy the Soviet Union was intimidated by our willingness and ability to spend on senseless boondoggles! [1] The first few times the shuttle went up they were afraid the tiles would get damaged and something like the Columbia accident would happen, they made some minor changes to get them to stick better and stopped worrying, at least in public. It took 100 launches for a failure mode than affects 1% of launches to actually happen. [2] https://en.wikipedia.org/wiki/Single-stage-to-orbit https://en.wikipedia.org/wiki/Single-stage-to-orbit [3] https://en.wikipedia.org/wiki/Strategic_Defense_Initiative https://en.wikipedia.org/wiki/Strategic_Defense_Initiative (which would have required much cheaper launch)
- EvanAnderson 1y ago
  > The Space Shuttle was wrong in so many ways, not least that it was a "pickup truck" as opposed to a dedicated manned vehicle (with appropriate safety features) or a dedicated cargo vehicle. I wonder what the STS system would have been like if the DoD's cross-range requirement hadn't been imposed.
bookofjoe 1y ago
See, for example: 4-minute mile
- LeifCarrotson 1y ago
  I don't know how relevant that is. That's something that can be done by an individual, training for something slightly slower than 4 minutes and pushing through to achieve a time that onlookers might not have expected. The real friction in building a reusable rocket isn't the engineering, it's setting "let's build a reusable rocket" as a design goal, and getting a whole bunch of engineers and a whole bunch of dollars to start on that goal. You have to start with a whiteboard sketch and board-room presentation that shows it's achievable, and then send the engineers out to refine the sketch into something worth funding, and then work for months or years to build a rocket that would be a disaster if it's not achievable.
  - bookofjoe 1y ago
    >Proof of concept. It's a lot easier to do something, if you know it can be done. This. What I wanted to emphasize was how, after Bannister finally broke through the 4-minute barrier, many others did it soon after: 3 more in 1954; 4 in 1955; 3 in 1956; 5 in 1957; 4 in 1958. List: https://imgur.com/a/UadE3xa https://imgur.com/a/UadE3xa

Proof of concept. It's a lot easier to do something, if you know it can be done.

by kurthr 1y ago

Proof of concept. It's a lot easier to do something, if you know it can be done.

mempko 1y ago

I mean, SpaceX also knew it could be done since reusable rocket tests happened in the 90s.

kurthr 1y ago
Don't you mean the SpaceShuttle in the 80s? or Delta Clipper which didn't reach orbit? Really, what SpaceX did was radically different from the tests in the 90s from the rockets, to the controls, to the reusability goals. Otherwise they wouldn't have built Grasshopper. Now NewGlen is kinda a knockoff of Delta Clipper, but that's a different beast.
mensetmanusman 1y ago
And physics, nothing prevents the goal beyond execution.
hwillis 1y ago
The DC-X was 9.1 tonnes empty and 19 tonnes full- meaning landing thrust was ~half of takeoff thrust. The Falcon 9 was 400 tonnes full and 26 tonnes empty, so takeoff thrust was >20x higher than landing thrust. That's a huge engineering difference, roughly like the difference between a car and a helicopter. The Falcon 9 was also 4x taller, meaning 16x more force to correct a lean. A little burp would send the rocket right back up in the air.

benjiro 1y ago

Its more about money. If you know that something can be done, and there is a potential market for such a project, it then becomes easier to get the funding. Chicken or the egg... One thing we also need to point out, is that SpaceX uses like 80% of their yearly launches, for their own communication / sat service. This gave a incentive for that investment. Is the same reason why, despite SpaceX throwing those things up constantly, there really is a big lag of competitors with reusable rockets. Its not that they where / not able to quickly get the same tech going. They simply have less market, vs what SpaceX does non-stop. So the investments are less, what in time means less fast development. SpaceX is a bit of a strange company, partially because they used a lot of the public funds to just throw shit at the wall, and see what sticks. This resulted in them caring less if a few rockets blew up, as long as they got the data for the next one with less flaws. It becomes harder when there is more oversight of that money, or risk averse investors. Then you really want to be sure that thing goes up and come back down into one piece from the first go. A lot of projects funding are heavily based upon the first or second try of something, and then (sometimes unwisely) funding is pulled if it was not a perfect success story.

kurthr 1y ago
I agree, a lot is about money, but it's not like Honda is raising external funds. Getting management to agree to do anything pretty much requires guaranteed success in large organizations.
PaulHoule 1y ago
Even before SpaceX started launching their own satellites in huge numbers they had a business model where they were selling the launch, not the rocket, and selling it at a fixed price, so if some small refinement saved them 5% on launch costs it went to their pockets so they had an incentive to make those small refinements. Dragon 9 was based on conservative and boring technology but it was cost optimized before it was reusable, then reusability crushed the competition. For that matter, Starship is boring. "Throw at the wall and see what sticks" isn't "trying a bunch of crazy stuff" but trying a bunch of low and medium risk things. For instance, development of the Space Shuttle thermal tiles was outrageously expensive and resulted in a system that was outrageously expensive to maintain. They couldn't change it because lives were at stake. With Starship they can build a thermal protection system which is 90% adequate and make little changes that get it up to 100% adequate and then look at optimizing weight, speed of reuse and all that. If some of them burn up it is just money since there won't be astronauts riding it until it is perfected.
- imtringued 1y ago
  Starship has exactly the opposite development strategy to what made the Falcon 9 so successful. Calling a complete change in process and philosophy "boring" appears to be hubris. Falcon 9 didn't have three versions of which two were obsolete. Falcon 9 didn't put optional goals on the critical path, which are now delaying and preventing commercial launches.
  - inemesitaffia 1y ago
    Falcon had multiple versions and upper stage reusability was planned too.
1y ago

PaulHoule 1y ago

Also psychology and politics kept people from following the easy path. The Space Shuttle was wrong in so many ways, not least that it was a "pickup truck" as opposed to a dedicated manned vehicle (with appropriate safety features) or a dedicated cargo vehicle. Because they couldn't do unmanned tests they were stuck with the barely reusable thermal tiles and couldn't replace them with something easier to reuse (or safer!) Attempts at second generation reusable vehicles failed because rather than "solving reuse" they were all about single-stage to orbit (SSTO) [2] and aerospike engines and exotic composite materials that burned up the money/complexity/risk/technology budgets. There was a report that came out towards the end of the SDI [3] phase that pointed out the path that SpaceX followed with Dragon 9 where you could make rather ordinary rockets and reuse the first stage but expend the second because the first stage is most of the expense. They thought psychology and politics would preclude that and that people would be seduced by SSTO, aerospikes, composites, etc. Funny though out of all the design studies NASA did for the Shuttle and for heavy lift vehicles inspired by the O'Neill colony idea, there was a sketch of a "fly back booster" based on the Saturn V that would have basically been "Super Heavy" that was considered in 1979 that, retrospectively, could have given us Starship by 1990 or so. But no, we were committed to the Space Shuttle because boy the Soviet Union was intimidated by our willingness and ability to spend on senseless boondoggles! [1] The first few times the shuttle went up they were afraid the tiles would get damaged and something like the Columbia accident would happen, they made some minor changes to get them to stick better and stopped worrying, at least in public. It took 100 launches for a failure mode than affects 1% of launches to actually happen. [2] https://en.wikipedia.org/wiki/Single-stage-to-orbit https://en.wikipedia.org/wiki/Single-stage-to-orbit [3] https://en.wikipedia.org/wiki/Strategic_Defense_Initiative https://en.wikipedia.org/wiki/Strategic_Defense_Initiative (which would have required much cheaper launch)

EvanAnderson 1y ago
> The Space Shuttle was wrong in so many ways, not least that it was a "pickup truck" as opposed to a dedicated manned vehicle (with appropriate safety features) or a dedicated cargo vehicle. I wonder what the STS system would have been like if the DoD's cross-range requirement hadn't been imposed.

bookofjoe 1y ago

See, for example: 4-minute mile

LeifCarrotson 1y ago
I don't know how relevant that is. That's something that can be done by an individual, training for something slightly slower than 4 minutes and pushing through to achieve a time that onlookers might not have expected. The real friction in building a reusable rocket isn't the engineering, it's setting "let's build a reusable rocket" as a design goal, and getting a whole bunch of engineers and a whole bunch of dollars to start on that goal. You have to start with a whiteboard sketch and board-room presentation that shows it's achievable, and then send the engineers out to refine the sketch into something worth funding, and then work for months or years to build a rocket that would be a disaster if it's not achievable.
- bookofjoe 1y ago
  >Proof of concept. It's a lot easier to do something, if you know it can be done. This. What I wanted to emphasize was how, after Bannister finally broke through the 4-minute barrier, many others did it soon after: 3 more in 1954; 4 in 1955; 3 in 1956; 5 in 1957; 4 in 1958. List: https://imgur.com/a/UadE3xa https://imgur.com/a/UadE3xa