4 ms·

This is an early manufacturing path-finding test article and test, not a test article and test designed to validate that the system is safe. The procedures, des

by gpm 7y ago

This is an early manufacturing path-finding test article and test, not a test article and test designed to validate that the system is safe. The procedures, design, manufacturing techniques, and everything else are still being developed and certainly haven't been validated yet. Failures are expected. It is a good thing that there is nothing inherently wrong with the design, just because that would mean more re-design work for SpaceX. A procedural issue (possibly this failure), a manufacturing defect (MK1 failure), a failure due to a temporary hack (SN1 failure), etc are all understandable errors and easily fixable at this point in time. Starship isn't really being driven by the "boots on the moon by 2024" push by the government. Starship is a private venture being developed on their own schedule (and with their own money).

deleted 7y ago
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bumby 7y ago
> Starship isn't really being driven by the "boots on the moon by 2024" push by the government. You’re right, bad choice of phrasing on my part to boil it down to a turn-of-phrase. What I’m really poking at is how schedule pressure affects decision making. SpaceX is well known to have very ambitious timelines. I am wondering how much that pressure affects process checks like configuration control
londons_explore 7y ago
I worry that the people who ran this test either didn't know what they were doing, or were too tired or didn't care. The top tank was covered in ice, indicating it was nearly full, while the bottom tank had no ice. That leaves three possibilities: * The intention is the bottom tank was pressurized with gas:. There is no way that much gas at ~4 bar is safe. It would destroy all nearby buildings if it failed. That's a serious safety failing. * The intention is the bottom tank was filled with LN2. Whoever was running the test didn't notice the tank didn't turn white, and didn't have any kind of level gauge or flow meter? * The intention is the tank was unpressurized. The design could never withstand the top tank filled and the bottom tank unpressurized and empty. Whoever designed and ran the test didn't understand the basics of the design. All of those 3 possible explanations point to more than a simple oversight, and IMO suggest the team working at 3am might possibly not really understand what they were doing.
- gpm 7y ago
  > There is no way that much gas at ~4 bar is safe. It would destroy all nearby buildings if it failed. Wat? This is a launchpad, the safety assumption at play here is that this vehicle (and in fact a much larger vehicle with this vehicle as a second stage) can be filled with liquid methane and liquid oxygen, explode (with the energy of a small nuclear bomb, a few kilotons), and no one will get hurt. The area around the launchpad is kept clear during testing by local law enforcement for this very reason. Hours before the test that failed, in a different test, the same test article was pressurized with room temperature nitrogen, likely up to ~7 bar (based on previous tests for which we were given figures). For comparison, this is the same location that the following test was performed at, all the additional structures you see have been added recently by SpaceX as ground support equipment and they are undoubtedly perfectly aware and ok with the idea that they might be damaged in the case of a failure https://www.youtube.com/watch?v=bYb3bfA6_sQ https://www.youtube.com/watch?v=bYb3bfA6_sQ As for the rest of your post, yes, if you assume the people running the tests were incompetent then they would be incompetent. We can't fully rule out the idea of course, but it's far from the only option. Most likely the failure was not nearly so simple as "we forgot to pressurize a tank" - particularly considering that the bottom tank was clearly pressurized as it was venting. The most reasonable suggestion for a proximate cause I've seen, for instance, is that the pressure release valve on the lower tank iced over and leaked until the pressure was no longer enough to support the above mass and it failed. This is supported by the evidence that we know they were having valve issues related to cryogenic liquids earlier in the day, and that the bottom tank was inexplicably venting for roughly 13 straight minutes before the failure. It doesn't quite line up with Elon's suggestion that this was possibly a test configuration error.

by gpm 7y ago

deleted 7y ago

[deleted]

bumby 7y ago

> Starship isn't really being driven by the "boots on the moon by 2024" push by the government. You’re right, bad choice of phrasing on my part to boil it down to a turn-of-phrase. What I’m really poking at is how schedule pressure affects decision making. SpaceX is well known to have very ambitious timelines. I am wondering how much that pressure affects process checks like configuration control

londons_explore 7y ago

I worry that the people who ran this test either didn't know what they were doing, or were too tired or didn't care. The top tank was covered in ice, indicating it was nearly full, while the bottom tank had no ice. That leaves three possibilities: * The intention is the bottom tank was pressurized with gas:. There is no way that much gas at ~4 bar is safe. It would destroy all nearby buildings if it failed. That's a serious safety failing. * The intention is the bottom tank was filled with LN2. Whoever was running the test didn't notice the tank didn't turn white, and didn't have any kind of level gauge or flow meter? * The intention is the tank was unpressurized. The design could never withstand the top tank filled and the bottom tank unpressurized and empty. Whoever designed and ran the test didn't understand the basics of the design. All of those 3 possible explanations point to more than a simple oversight, and IMO suggest the team working at 3am might possibly not really understand what they were doing.

gpm 7y ago
> There is no way that much gas at ~4 bar is safe. It would destroy all nearby buildings if it failed. Wat? This is a launchpad, the safety assumption at play here is that this vehicle (and in fact a much larger vehicle with this vehicle as a second stage) can be filled with liquid methane and liquid oxygen, explode (with the energy of a small nuclear bomb, a few kilotons), and no one will get hurt. The area around the launchpad is kept clear during testing by local law enforcement for this very reason. Hours before the test that failed, in a different test, the same test article was pressurized with room temperature nitrogen, likely up to ~7 bar (based on previous tests for which we were given figures). For comparison, this is the same location that the following test was performed at, all the additional structures you see have been added recently by SpaceX as ground support equipment and they are undoubtedly perfectly aware and ok with the idea that they might be damaged in the case of a failure https://www.youtube.com/watch?v=bYb3bfA6_sQ https://www.youtube.com/watch?v=bYb3bfA6_sQ As for the rest of your post, yes, if you assume the people running the tests were incompetent then they would be incompetent. We can't fully rule out the idea of course, but it's far from the only option. Most likely the failure was not nearly so simple as "we forgot to pressurize a tank" - particularly considering that the bottom tank was clearly pressurized as it was venting. The most reasonable suggestion for a proximate cause I've seen, for instance, is that the pressure release valve on the lower tank iced over and leaked until the pressure was no longer enough to support the above mass and it failed. This is supported by the evidence that we know they were having valve issues related to cryogenic liquids earlier in the day, and that the bottom tank was inexplicably venting for roughly 13 straight minutes before the failure. It doesn't quite line up with Elon's suggestion that this was possibly a test configuration error.