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The Space Shuttle is an enormously complicated system. The Orbiter itself is a marriage of a crew transfer spacecraft, a space station, a cargo tug, a cargo car

The Space Shuttle is an enormously complicated system. The Orbiter itself is a marriage of a crew transfer spacecraft, a space station, a cargo tug, a cargo carrier, and a goddamned airplane. Worse yet, it used one of the most finicky propellants around, LOX/LH2. Then you shoehorn that beast into a weirdly designed partially expendable heavy lift launcher with SRBs and a drop tank and it's no wonder you end up with a system that is difficult to operate inexpensively. Meanwhile, the Falcon 9 stage is primarily just engines, tanks, and frame, with a sprinkling of avionics and RCS plus landing legs for the reusable version. The idea that a system so monstrously simple in comparison to the Shuttle could possibly have the same levels of difficulty of reusability is either extraordinarily naive or propaganda.

acqq 13y ago
No, it's not propaganda, if you'd care to search you'd find enough material yourself. They first planned to reuse the booster engines and just produce new tanks. They discovered that the engines weren't reusable as much as they hoped only once they made actual launches. The rocket engines function a bit differently than the jet engines, all the problems are bigger by the order of magnitude. The engines have to sustain immense temperature extremes, which in turn change the characteristics of the parts. What's usable on the first launch can be just a trash the next time. Until you have enough launches, you just don't know how reusable equipment you have.
- dba7dba 13y ago
  True. But falcon 9 is far less complicated than shuttle so the chance of having more reusable equipment should be higher.
  - acqq 13y ago
    I'm giving the example not of the whole Shuttle (complex) but just the booster engines for Shuttle (also simple). Designed to be very reusable, discovered not to be only after the real launches. That's how it works. Before you have the actual launch statistics, you can appear much smarter than you are actually. Everything is easy as long as it's just a theory. To compare, let's see what SpaceX is actually doing: The last, second attempt to recover a booster of Falcon 9 was: http://aviationweek.com/space/spacex-plans-multiple-reusable-booster-tests http://aviationweek.com/space/spacex-plans-multiple-reusable... "While SpaceX remains coy about the exact fate of the modified Falcon 9 first stage, the overall results appear to be encouraging despite the apparent breakup of the booster after it landed in heavy seas." Previous attempt: "The latest flight test follows an unsuccessful recovery attempt on Sept. 29, 2013, when the first upgraded Falcon 9 v1.1 was launched from Vandenberg AFB, Calif. Although three of its nine Merlin 1D engines fired to slow the initial descent ahead of a single engine firing for final braking, the vehicle’s spinning motion could not be controlled. As a result of aerodynamic torque, the fuel centrifuged inside the tank, flaming out the engine and sending the stage crashing into the sea."
    - InclinedPlane 13y ago
      You do realize that SpaceX is only running tests of the flight profile when they are "landing" the F9 first stage in the ocean, right? They aren't actually trying to recover the boosters so they can reuse them, they would just like to get more data. Actual reuse will involve returning the first stage to land, where it will make a controlled, powered landing.
      - acqq 13y ago
        Of course. All of which doesn't refute my point: until there are enough reuses in real launches these are just unsupported claims of being better in reuse than the NASA. SpaceX have the goals and that's OK but some people here behave like SpaceX already achieved them. In fact it's harder than most can comprehend. The political aspects of Space Shuttle can be ignored, the technical aspects are enough. Reuse is harder than it appears.
- InclinedPlane 13y ago
  The SSMEs were bleeding edge engines when they were built. Moreover, they were strapped to the Shuttle orbiter so every time they were used they were on for an entire flight from sea level through the entirety of the atmosphere up through vacuum. Then they spent a week or two in cold soak on orbit. Then they experienced a mach 25 re-entry and the jostling of an unpowered horizontal landing at a few hundred kph. Oh, also, I should mention how difficult it is to optimize an engine for vacuum as well as sea level operation. In a vacuum you want a high expansion ratio nozzle because that maximizes Isp, but it also lowers pressure. That doesn't work if you have to fight against 1 atm of sea level pressure. That alone is actually a big reason why rockets have multiple stages, because the Isp boost of the high-expansion ratio nozzle on the upper stage is an enormous performance win. One way around the problem is to boost the exhaust pressure, enabling a higher expansion ratio nozzle which can still operate at sea level, but that makes the engine even more complex and difficult to manufacture, let alone reuse. So you have the SSME which is a high pressure staged combustion regeneratively cooled LOX/LH2 engine optimized for both sea level and vacuum operation. It's a wonder they were reusable to any degree whatsoever within the first several flights. Even so it took until the mid 1990s for the engine design to fully mature and enter a truly operational phase (vs. prototype phase). Meanwhile, let's look at what SpaceX has on their plate. They have a low pressure (1/3 the psi of the SSME) gas-generator cycle (non-staged combustion) LOX/Kerosene pintle injector engine which uses two different nozzles for sea level and vacuum operation. It's a design with heritage back to an era before color television. It's such a tried-and-true design with so much history that the patents on it expired decades ago. Additionally, in contrast to all the rigmarole an SSME has to go through for each flight the Merlin-1D merely accelerates to a fraction of orbital speed, never leaves the atmosphere, and, in a reuse scenario, is back at the launch site within minutes. No hypersonic atmospheric flight. No re-entry. No bumpy landing. No cold soak. No transition from atmospheric to vacuum operation. It's a vastly simpler engine which is exposed to vastly less strenuous conditions. Again, if you think that the Merlin-1D will face anything approaching the problems of the SSME in reusability then you are either extraordinarily ill-informed or you are peddling propaganda.
  - acqq 13y ago
    I was talking about boosters all the time (supposed to be simpler), not the engines on the Shuttle. See also the current state of the reuse of the boosters by SpaceX.

acqq 13y ago

No, it's not propaganda, if you'd care to search you'd find enough material yourself. They first planned to reuse the booster engines and just produce new tanks. They discovered that the engines weren't reusable as much as they hoped only once they made actual launches. The rocket engines function a bit differently than the jet engines, all the problems are bigger by the order of magnitude. The engines have to sustain immense temperature extremes, which in turn change the characteristics of the parts. What's usable on the first launch can be just a trash the next time. Until you have enough launches, you just don't know how reusable equipment you have.

dba7dba 13y ago
True. But falcon 9 is far less complicated than shuttle so the chance of having more reusable equipment should be higher.
- acqq 13y ago
  I'm giving the example not of the whole Shuttle (complex) but just the booster engines for Shuttle (also simple). Designed to be very reusable, discovered not to be only after the real launches. That's how it works. Before you have the actual launch statistics, you can appear much smarter than you are actually. Everything is easy as long as it's just a theory. To compare, let's see what SpaceX is actually doing: The last, second attempt to recover a booster of Falcon 9 was: http://aviationweek.com/space/spacex-plans-multiple-reusable-booster-tests http://aviationweek.com/space/spacex-plans-multiple-reusable... "While SpaceX remains coy about the exact fate of the modified Falcon 9 first stage, the overall results appear to be encouraging despite the apparent breakup of the booster after it landed in heavy seas." Previous attempt: "The latest flight test follows an unsuccessful recovery attempt on Sept. 29, 2013, when the first upgraded Falcon 9 v1.1 was launched from Vandenberg AFB, Calif. Although three of its nine Merlin 1D engines fired to slow the initial descent ahead of a single engine firing for final braking, the vehicle’s spinning motion could not be controlled. As a result of aerodynamic torque, the fuel centrifuged inside the tank, flaming out the engine and sending the stage crashing into the sea."
  - InclinedPlane 13y ago
    You do realize that SpaceX is only running tests of the flight profile when they are "landing" the F9 first stage in the ocean, right? They aren't actually trying to recover the boosters so they can reuse them, they would just like to get more data. Actual reuse will involve returning the first stage to land, where it will make a controlled, powered landing.
    - acqq 13y ago
      Of course. All of which doesn't refute my point: until there are enough reuses in real launches these are just unsupported claims of being better in reuse than the NASA. SpaceX have the goals and that's OK but some people here behave like SpaceX already achieved them. In fact it's harder than most can comprehend. The political aspects of Space Shuttle can be ignored, the technical aspects are enough. Reuse is harder than it appears.
InclinedPlane 13y ago
The SSMEs were bleeding edge engines when they were built. Moreover, they were strapped to the Shuttle orbiter so every time they were used they were on for an entire flight from sea level through the entirety of the atmosphere up through vacuum. Then they spent a week or two in cold soak on orbit. Then they experienced a mach 25 re-entry and the jostling of an unpowered horizontal landing at a few hundred kph. Oh, also, I should mention how difficult it is to optimize an engine for vacuum as well as sea level operation. In a vacuum you want a high expansion ratio nozzle because that maximizes Isp, but it also lowers pressure. That doesn't work if you have to fight against 1 atm of sea level pressure. That alone is actually a big reason why rockets have multiple stages, because the Isp boost of the high-expansion ratio nozzle on the upper stage is an enormous performance win. One way around the problem is to boost the exhaust pressure, enabling a higher expansion ratio nozzle which can still operate at sea level, but that makes the engine even more complex and difficult to manufacture, let alone reuse. So you have the SSME which is a high pressure staged combustion regeneratively cooled LOX/LH2 engine optimized for both sea level and vacuum operation. It's a wonder they were reusable to any degree whatsoever within the first several flights. Even so it took until the mid 1990s for the engine design to fully mature and enter a truly operational phase (vs. prototype phase). Meanwhile, let's look at what SpaceX has on their plate. They have a low pressure (1/3 the psi of the SSME) gas-generator cycle (non-staged combustion) LOX/Kerosene pintle injector engine which uses two different nozzles for sea level and vacuum operation. It's a design with heritage back to an era before color television. It's such a tried-and-true design with so much history that the patents on it expired decades ago. Additionally, in contrast to all the rigmarole an SSME has to go through for each flight the Merlin-1D merely accelerates to a fraction of orbital speed, never leaves the atmosphere, and, in a reuse scenario, is back at the launch site within minutes. No hypersonic atmospheric flight. No re-entry. No bumpy landing. No cold soak. No transition from atmospheric to vacuum operation. It's a vastly simpler engine which is exposed to vastly less strenuous conditions. Again, if you think that the Merlin-1D will face anything approaching the problems of the SSME in reusability then you are either extraordinarily ill-informed or you are peddling propaganda.
- acqq 13y ago
  I was talking about boosters all the time (supposed to be simpler), not the engines on the Shuttle. See also the current state of the reuse of the boosters by SpaceX.