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After the success of the Falcon Heavy a couple days ago, I'm actually surprised there weren't more hiccups in SpaceX activity. They are pushing the limits of sp

After the success of the Falcon Heavy a couple days ago, I'm actually surprised there weren't more hiccups in SpaceX activity. They are pushing the limits of spaceflight technology, there are _bound_ to be setbacks like this. A roadmap with no errors like this is highly improbable. Amen for rigorous testing.

mabbo 8y ago
There's a line from Bezo's annual shareholder letter a few weeks ago that this brings to mind: "As a company grows, everything needs to scale, including the size of your failed experiments. If the size of your failures isn't growing, you're not going to be inventing at a size that can actually move the needle." https://www.cnbc.com/2019/04/11/jeff-bezos-annual-shareholder-letter.html https://www.cnbc.com/2019/04/11/jeff-bezos-annual-shareholde...
rayiner 8y ago
I think SpaceX is great. But how are they “pushing the limits of spaceflight technology?” The SpaceX Merlin engine uses the same basic RP-1/LOX cycle as the Saturn V’s first stage engine, which is more than half a century old now. Rocketdyne’s engine produced about 7-8 times as much thrust (which is why SpaceX needs 27 engines on three boosters for a Falcon 9 Heavy, versus 5 for a Saturn V.) (Here is the computing equivalent of what SpaceX is doing: creating a PDP-11 with modern technology, that’s maybe 75% as fast, but at a fifth to a tenth of the cost.) A more accurate summary is SpaceX is retreading well-worm ground that was trod before many of us reading this article were born, bringing modern materials and manufacturing capabilities to bear improving the same basic designs. That’s cool. But that’s not pushing the boundaries of space flight technology.
- dsfyu404ed 8y ago
  Doing things at a Harbor Freight price point that have never been done at that price point before basically always winds up being uncharted engineering territory. Anyone can build something that works when you don't care about cost.
  - rayiner 8y ago
    No doubt SpaceX is solving lots of cool engineering problems. But portraying those cost-optimization efforts as “pushing the limits of spaceflight technology” is a triumph of marketing. And it obscures how little real progress has been made in aerospace over the last half century.[1] (Also, your last sentence is obviously not true. The physical sciences are a harsh mistress. Lots of things never work.) [1] Even with computer aided design, composites, laser sintering, etc., the thrust-to-weight ratio of a Merlin engine is a factor of two better than an RP-1/LOX engine from half a century ago. That’s about the same factor improvement as we achieved in subsonic jet engine performance over that time period. Aerospace technology moves very slowly, there is no reason to be hopeful and optimistic.
    - dsfyu404ed 8y ago
      Pushing the cost floor lower certainly falls within the scope of "pushing the limits" to me.
      - rayiner 8y ago
        Then you’re really cut out for a happy life as an industrial engineer!
- krisoft 8y ago
  You are asking: how are they “pushing the limits of spaceflight technology?” Let's not go futher, just concentrating at the incident in question. The anomalous test happened on a location named "Landing Zone 1". That's not a thing any other rocket company has. Why? Because they don't land their rockets. It happened with a space capsule fished out of the brine. No other company reuses their space capsules in such a way. The detonation very likely will be found to have something to do with the SuperDraco system. Which they originally designed there to enable propulsive landing on dry land. The russians have their kick engines, sure, but that's not really same as hover landing, isn't it? Why did they plan that? For rapid reusability. So yes, if you ignore all the things they did for reusability, then they indeed are not pushing the limits of spaceflight technology.
  - rayiner 8y ago
    > Let's not go futher, just concentrating at the incident in question. The anomalous test happened on a location named "Landing Zone 1". That's not a thing any other rocket company has. Why? Because they don't land their rockets. Parachute landing a crew pod into the ocean is something we first did the year my dad was born. > Which they originally designed there to enable propulsive landing on dry land. We landed an entire orbiter like an airliner three years before I was born.
    - gliptic 8y ago
      Landing an orbiter like an airliner is not what SpaceX is doing.
    - grecy 8y ago
      > Parachute landing a crew pod into the ocean is something we first did the year my dad was born You're getting confused between the tiny pod that people sit in - which basically does nothing, and the actual rocket, with all the flames and gasses and actually make the pod go somewhere. Nobody has ever landed and reused the rocket before SpaceX > landed an entire orbiter like an airliner three years before I was born Yes, a thing with wings landed using lift from the wings. It did not use rockets for propulsive landing like SpaceX have designed.
- jessriedel 8y ago
  > The SpaceX Merlin engine uses the same basic RP-1/LOX cycle as the Saturn V’s first stage engine, which is more than half a century old now. If I build an electric car with the same rubber technology as cars have used for a century, this would not mean I hadn't pushed the limits of technology. > Rocketdyne’s engine produced about 7-8 times as much thrust (which is why SpaceX needs 27 engines on three boosters for a Falcon 9 Heavy, versus 5 for a Saturn V.) "Thrust per engine" is a bad metric since, for larger payloads, it can be better to add more engines than make them bigger, and that metric immediately disqualifies that strategy. (For instance, more full independent engines means more redundancy. Which strategy is better is going to depend on the details.) We wouldn't say that 18-wheelers are worse technology than 4-wheeled earth movers because the latter have more weight per wheel. Ultimately, the thing we care about is most mass to highest orbit at lowest risk. But if you want to concentrate on raw engine performance, you probably should look at metrics like ISP (which SpaceX is indeed not pushing the limits). > A more accurate summary is SpaceX is retreading well-worm ground that was trod before many of us reading this article were born, bringing modern materials and manufacturing capabilities to bear improving the same basic designs. That’s cool. But that’s not pushing the boundaries of space flight technology. Surely re-useable first stages is the biggest advance by far in spaceflight technology in decades? It sounds like by "space flight technology" you just mean engines, but chemical rockets are within about a factor of 2 of the maximum efficiency allowed by the laws of physics. So within that paradigm, you're just not going to get revolutionary (multiple-orders-of-magnitude) improvements in the things we care about (mass to orbit) by improving engines as opposed to things like re-usability. So I think by your definition, the only thing that would be really be an improvement would be nuclear rockets, or something else even more extreme.
  - rayiner 8y ago
    > If I build an electric car with the same rubber technology as cars have used for a century, this would not mean I hadn't pushed the limits of technology. That's a misleading comparison, because we're not talking about some ancillary aspect of the design (like rubber tires). This is more like designing a car with the same basic engine technology as a 1969 Impala, except you're using an aluminium engine block and modern crumple zones. > "Thrust per engine" is a bad metric since, for larger payloads, it can be better to add more engines than make them bigger. More engines can also mean more chances for failure. (You can make the design resistant to engine-out conditions, but some engine-out conditions are less recoverable than others.) Regardless, the Falcon 9 Heavy also has substantially lower maximum thrust than the Saturn V. > Surely re-useable first stages is the biggest advance is spaceflight technology in decades? It sounds like by "space flight technology" you just mean engines, but chemical rockets are within about a factor of 2 of the maximum efficiency allowed by the laws of physics. So within that paradigm, you're just not going to get revolutionary (multiple-orders-of-magnitude) improvements in the things we care about (mass to orbit) by improving engines as opposed to things like re-usability. So I think by your definition, the only thing that would be really be an improvement would be nuclear rockets, or something else even more extreme. I don't even really disagree with that point. Unless there is some groundbreaking advance in rocket engines, you're not going to be "pushing the boundaries of spaceflight technology." It's just like how we don't say Intel is "pushing the boundaries of CPU technology" every time they widen the vector units on the same basic Core architecture they've been using for almost two decades. It's a mature field where revolutionary improvements aren't possible with foreseeable technology. But that doesn't mean you get to relabel incremental improvements as revolutionary.
- gliptic 8y ago
  Merlin is also the highest thrust-to-weight engine ever, by a large margin. F-1 could produce a lot of thrust because it was huge, not because it was efficient. But that's stuff they've already accomplished. You're ignoring what they have in development. The Raptor engine is among the most advanced engines ever made, pushing combustion/metallurgy technology literally to the limits, certainly not well-worn ground. Not to mention Starship/Super Heavy, which is pushing reusability further. They might not accomplish everything they set out to do, but that's why it's "pushing" rather than "pushed".
  - rayiner 8y ago
    > Merlin is also the highest thrust-to-weight engine ever, by a large margin. F-1 could produce a lot of thrust because it was huge, not because it was efficient. It's about twice the thrust-to-weight ratio of an F-1, which was designed in 1969. With all the advances in materials science since 1969 (composites, etc.), that tells you a lot about the glacial pace of advancement in the field. It's also not clear to me why that even matters--a Saturn V has about 90,000 pounds of engines; a Falcon 9 Heavy has about 27,000 pounds. Both need millions of pounds of fuel. (As to your comment about "pushing" versus "pushed"--that interpretation of OP's comment doesn't match the fact that he's talking about a setback involving SpaceX's current generation of vehicles.)
    - ddalex 8y ago
      Mate, not everything in the world moves as fast as the Javascript ecosystem. There are some hard laws at hand, called physics, that limit what you can lit under a rocket and get propulsion. Oxygen needs to be there. A combustible needs to be there as well. This is known since the 19th century. It just turns out that RP-1 is a good choice. Given the same chemical reaction, improving the engine efficiency state-of-art by 50% in 50 years is astounding. With Raptor they are actually getting close to the theoretical limits. What other expectations do you have for advancements? New chemicals are hard to get by. Nuclear is beyond contemplation. You can't invent new physics. What do you expect?
      - 8y ago
Kiro 8y ago
You're defending a very dangerous enterprise. SpaceX will cause a lot of death and destruction.
- abledon 8y ago
  can you elaborate?

mabbo 8y ago

There's a line from Bezo's annual shareholder letter a few weeks ago that this brings to mind: "As a company grows, everything needs to scale, including the size of your failed experiments. If the size of your failures isn't growing, you're not going to be inventing at a size that can actually move the needle." https://www.cnbc.com/2019/04/11/jeff-bezos-annual-shareholder-letter.html https://www.cnbc.com/2019/04/11/jeff-bezos-annual-shareholde...

rayiner 8y ago

I think SpaceX is great. But how are they “pushing the limits of spaceflight technology?” The SpaceX Merlin engine uses the same basic RP-1/LOX cycle as the Saturn V’s first stage engine, which is more than half a century old now. Rocketdyne’s engine produced about 7-8 times as much thrust (which is why SpaceX needs 27 engines on three boosters for a Falcon 9 Heavy, versus 5 for a Saturn V.) (Here is the computing equivalent of what SpaceX is doing: creating a PDP-11 with modern technology, that’s maybe 75% as fast, but at a fifth to a tenth of the cost.) A more accurate summary is SpaceX is retreading well-worm ground that was trod before many of us reading this article were born, bringing modern materials and manufacturing capabilities to bear improving the same basic designs. That’s cool. But that’s not pushing the boundaries of space flight technology.

dsfyu404ed 8y ago
Doing things at a Harbor Freight price point that have never been done at that price point before basically always winds up being uncharted engineering territory. Anyone can build something that works when you don't care about cost.
- rayiner 8y ago
  No doubt SpaceX is solving lots of cool engineering problems. But portraying those cost-optimization efforts as “pushing the limits of spaceflight technology” is a triumph of marketing. And it obscures how little real progress has been made in aerospace over the last half century.[1] (Also, your last sentence is obviously not true. The physical sciences are a harsh mistress. Lots of things never work.) [1] Even with computer aided design, composites, laser sintering, etc., the thrust-to-weight ratio of a Merlin engine is a factor of two better than an RP-1/LOX engine from half a century ago. That’s about the same factor improvement as we achieved in subsonic jet engine performance over that time period. Aerospace technology moves very slowly, there is no reason to be hopeful and optimistic.
  - dsfyu404ed 8y ago
    Pushing the cost floor lower certainly falls within the scope of "pushing the limits" to me.
    - rayiner 8y ago
      Then you’re really cut out for a happy life as an industrial engineer!
krisoft 8y ago
You are asking: how are they “pushing the limits of spaceflight technology?” Let's not go futher, just concentrating at the incident in question. The anomalous test happened on a location named "Landing Zone 1". That's not a thing any other rocket company has. Why? Because they don't land their rockets. It happened with a space capsule fished out of the brine. No other company reuses their space capsules in such a way. The detonation very likely will be found to have something to do with the SuperDraco system. Which they originally designed there to enable propulsive landing on dry land. The russians have their kick engines, sure, but that's not really same as hover landing, isn't it? Why did they plan that? For rapid reusability. So yes, if you ignore all the things they did for reusability, then they indeed are not pushing the limits of spaceflight technology.
- rayiner 8y ago
  > Let's not go futher, just concentrating at the incident in question. The anomalous test happened on a location named "Landing Zone 1". That's not a thing any other rocket company has. Why? Because they don't land their rockets. Parachute landing a crew pod into the ocean is something we first did the year my dad was born. > Which they originally designed there to enable propulsive landing on dry land. We landed an entire orbiter like an airliner three years before I was born.
  - gliptic 8y ago
    Landing an orbiter like an airliner is not what SpaceX is doing.
  - grecy 8y ago
    > Parachute landing a crew pod into the ocean is something we first did the year my dad was born You're getting confused between the tiny pod that people sit in - which basically does nothing, and the actual rocket, with all the flames and gasses and actually make the pod go somewhere. Nobody has ever landed and reused the rocket before SpaceX > landed an entire orbiter like an airliner three years before I was born Yes, a thing with wings landed using lift from the wings. It did not use rockets for propulsive landing like SpaceX have designed.
jessriedel 8y ago
> The SpaceX Merlin engine uses the same basic RP-1/LOX cycle as the Saturn V’s first stage engine, which is more than half a century old now. If I build an electric car with the same rubber technology as cars have used for a century, this would not mean I hadn't pushed the limits of technology. > Rocketdyne’s engine produced about 7-8 times as much thrust (which is why SpaceX needs 27 engines on three boosters for a Falcon 9 Heavy, versus 5 for a Saturn V.) "Thrust per engine" is a bad metric since, for larger payloads, it can be better to add more engines than make them bigger, and that metric immediately disqualifies that strategy. (For instance, more full independent engines means more redundancy. Which strategy is better is going to depend on the details.) We wouldn't say that 18-wheelers are worse technology than 4-wheeled earth movers because the latter have more weight per wheel. Ultimately, the thing we care about is most mass to highest orbit at lowest risk. But if you want to concentrate on raw engine performance, you probably should look at metrics like ISP (which SpaceX is indeed not pushing the limits). > A more accurate summary is SpaceX is retreading well-worm ground that was trod before many of us reading this article were born, bringing modern materials and manufacturing capabilities to bear improving the same basic designs. That’s cool. But that’s not pushing the boundaries of space flight technology. Surely re-useable first stages is the biggest advance by far in spaceflight technology in decades? It sounds like by "space flight technology" you just mean engines, but chemical rockets are within about a factor of 2 of the maximum efficiency allowed by the laws of physics. So within that paradigm, you're just not going to get revolutionary (multiple-orders-of-magnitude) improvements in the things we care about (mass to orbit) by improving engines as opposed to things like re-usability. So I think by your definition, the only thing that would be really be an improvement would be nuclear rockets, or something else even more extreme.
- rayiner 8y ago
  > If I build an electric car with the same rubber technology as cars have used for a century, this would not mean I hadn't pushed the limits of technology. That's a misleading comparison, because we're not talking about some ancillary aspect of the design (like rubber tires). This is more like designing a car with the same basic engine technology as a 1969 Impala, except you're using an aluminium engine block and modern crumple zones. > "Thrust per engine" is a bad metric since, for larger payloads, it can be better to add more engines than make them bigger. More engines can also mean more chances for failure. (You can make the design resistant to engine-out conditions, but some engine-out conditions are less recoverable than others.) Regardless, the Falcon 9 Heavy also has substantially lower maximum thrust than the Saturn V. > Surely re-useable first stages is the biggest advance is spaceflight technology in decades? It sounds like by "space flight technology" you just mean engines, but chemical rockets are within about a factor of 2 of the maximum efficiency allowed by the laws of physics. So within that paradigm, you're just not going to get revolutionary (multiple-orders-of-magnitude) improvements in the things we care about (mass to orbit) by improving engines as opposed to things like re-usability. So I think by your definition, the only thing that would be really be an improvement would be nuclear rockets, or something else even more extreme. I don't even really disagree with that point. Unless there is some groundbreaking advance in rocket engines, you're not going to be "pushing the boundaries of spaceflight technology." It's just like how we don't say Intel is "pushing the boundaries of CPU technology" every time they widen the vector units on the same basic Core architecture they've been using for almost two decades. It's a mature field where revolutionary improvements aren't possible with foreseeable technology. But that doesn't mean you get to relabel incremental improvements as revolutionary.
gliptic 8y ago
Merlin is also the highest thrust-to-weight engine ever, by a large margin. F-1 could produce a lot of thrust because it was huge, not because it was efficient. But that's stuff they've already accomplished. You're ignoring what they have in development. The Raptor engine is among the most advanced engines ever made, pushing combustion/metallurgy technology literally to the limits, certainly not well-worn ground. Not to mention Starship/Super Heavy, which is pushing reusability further. They might not accomplish everything they set out to do, but that's why it's "pushing" rather than "pushed".
- rayiner 8y ago
  > Merlin is also the highest thrust-to-weight engine ever, by a large margin. F-1 could produce a lot of thrust because it was huge, not because it was efficient. It's about twice the thrust-to-weight ratio of an F-1, which was designed in 1969. With all the advances in materials science since 1969 (composites, etc.), that tells you a lot about the glacial pace of advancement in the field. It's also not clear to me why that even matters--a Saturn V has about 90,000 pounds of engines; a Falcon 9 Heavy has about 27,000 pounds. Both need millions of pounds of fuel. (As to your comment about "pushing" versus "pushed"--that interpretation of OP's comment doesn't match the fact that he's talking about a setback involving SpaceX's current generation of vehicles.)
  - ddalex 8y ago
    Mate, not everything in the world moves as fast as the Javascript ecosystem. There are some hard laws at hand, called physics, that limit what you can lit under a rocket and get propulsion. Oxygen needs to be there. A combustible needs to be there as well. This is known since the 19th century. It just turns out that RP-1 is a good choice. Given the same chemical reaction, improving the engine efficiency state-of-art by 50% in 50 years is astounding. With Raptor they are actually getting close to the theoretical limits. What other expectations do you have for advancements? New chemicals are hard to get by. Nuclear is beyond contemplation. You can't invent new physics. What do you expect?
    - 8y ago

Kiro 8y ago

You're defending a very dangerous enterprise. SpaceX will cause a lot of death and destruction.

abledon 8y ago
can you elaborate?