General > General Technical Chat
Spacex Starship IFT-2 launch today
coppice:
--- Quote from: wraper on November 20, 2023, 12:18:42 am ---
--- Quote from: coppice on November 20, 2023, 12:11:31 am ---
--- Quote from: Stray Electron on November 19, 2023, 05:56:45 pm ---
--- Quote from: Psi on November 19, 2023, 10:19:14 am ---Speculation is that the relight of the booster engines happened without stable acceleration to keep the fuel from floating/sloshing around in the tanks and many engines inhaled air and exploded. Resulting in an inability to continue the booster return and water landing mission, which triggered FTS.
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That shouldn't have been a problem. Ullage engines have been used for MANY years to provide a slight amount of acceleration so that the fuel and oxidizer are pushed to the bottom of the tanks so that they will be properly picked up for engine re-ignitions.
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The booster was twisting around at the time, which makes it pretty hard to get the fuel in the right part of the tanks. Most rockets which start twisting around quickly trigger their self destruct. This is not uncharted territory for Space X, though. This is an issue they also face with the Falcon, where they seem to have it sorted out very well. You might have expected them to have carried over what has proven reliable there, and nailed this on the first try.
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It's very different from Falcon though. Different fuel, very different engines with different ignition mechanism, autogenous pressurization instead of helium, pretty much uncharted territory in every corner.
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Sure, but they are much better positioned to get this right than anyone else. They are the only ones with experience. Sloshing is going to be the big issue, and that should be a fairly similar issue between the two designs.
CatalinaWOW:
Truly amazing how much failure analysis can be done with zero telemetry. Hopefully the guys with actual data can narrow it down. Could be lots of different things. But lots of good data.
Psi:
--- Quote from: wraper on November 19, 2023, 01:37:33 pm ---
--- Quote from: AndyBeez on November 19, 2023, 01:17:08 pm ---On a side note, I recently heard the Nasa versus SpaceX dynamic being described as, "it's rocket scientists versus space cowboys." Yee har...
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This year "space cowboys" put 4x more mass to the orbit (1000 tons) than the rest of the world combined. Also they are the only US launch provider that can currently deliver astronauts to ISS (for NASA you just mentioned).
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I more prefer the NASA vs SpaceX analogy of Scientists vs Engineers.
A scientist takes their time to do lots of theoretical testing and report writing until everything is proved to be perfect before building anything.
The engineer just tries shit until it works.
It's an over simplification, but is mostly accurate.
CatalinaWOW:
--- Quote from: Psi on November 20, 2023, 10:05:01 am ---
--- Quote from: wraper on November 19, 2023, 01:37:33 pm ---
--- Quote from: AndyBeez on November 19, 2023, 01:17:08 pm ---On a side note, I recently heard the Nasa versus SpaceX dynamic being described as, "it's rocket scientists versus space cowboys." Yee har...
--- End quote ---
This year "space cowboys" put 4x more mass to the orbit (1000 tons) than the rest of the world combined. Also they are the only US launch provider that can currently deliver astronauts to ISS (for NASA you just mentioned).
--- End quote ---
I more prefer the NASA vs SpaceX analogy of Scientists vs Engineers.
A scientist takes their time to do lots of theoretical testing and report writing until everything is proved to be perfect before building anything.
The engineer just tries shit until it works.
It's an over simplification, but is mostly accurate.
--- End quote ---
Neither end of that binary is optimum for most things. The real art is figuring out where in the middle of that spectrum best fits the job at hand. Close to the science extreme is appropriate for a deep space probe that will cost billions of dollars and take advantage of a once in a century planetary configuration. Close to the other end is appropriate for an RC toy that will be built in the millions and where consequences of failure are nil.
More interesting question is the best approach for problems like a WiFi light switch that will be built in huge volume but could kill many people if screwed up. What is novel about SpaceX is their vision that the application volume will be large enough to justify enormous spending on trial and error. It worked on Falcon9. The jury is still out on Starship, but from my point of view it looks like they might well end up making much more than they spend.
wraper:
--- Quote from: CatalinaWOW on November 20, 2023, 03:38:10 pm ---What is novel about SpaceX is their vision that the application volume will be large enough to justify enormous spending on trial and error. It worked on Falcon9. The jury is still out on Starship, but from my point of view it looks like they might well end up making much more than they spend.
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The thing is that SpaceX's trial and error is cheaper than current "traditional" rocket development which in the last decades was more like industry rotting from inside due to complacency and government bailouts. Look no further than obscene spending on SLS with all old tech, including 40 years old engines. https://www.space.com/nasa-sls-rocket-artemis-moon-plans-unaffordable-gao-report
--- Quote ---In late 2021, a report by NASA's Office of Inspector General showed that NASA will likely spend a total of $93 billion on the Artemis program between 2012 and 2025, and that each SLS launch will cost about $4.1 billion. A large chunk of the budget was attributed to hiring contractors in every U.S. state and more than 20 similar partners across Europe.
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