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SpaceX SN9 Explodes on Landing

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Re: SpaceX SN9 Explodes on Landing

#261

Post by ctdonath »

GizmoSwan wrote: post #102
ctdonath wrote: post #97

Earlier quoted context omitted.

SpaceX Starship is way outside established industry specifications.

How so?

Pedantic trolling noted; I’ll engage just to hone my thoughts.

Every production rocket is fully expendable. Launch, expect discard of 100%* of launch system. Starship is designed for 100% reusable, with same-day fly/land/refuel/repeat. That’s obviously a huge difference.

* - exceptions:

Space Shuttle discarded most of the launch system, acting as glider to return crew/cargo and some engines. Reuse turnaround was months, with extensive repairs expected. Boosters required prolonged recovery and refurbishing, with high likelihood of loss.

Falcon 9 is only one remotely viable for same day return to pad and reuse of first stage. Second stage is discarded.

SN# is a fast-reuse second stage. Landing involves leveraging the terminal velocity physics of a brick (not gentle glide of Shuttle), followed by effectively flipping a 16-story building ~90° in free fall with powered deceleration to 0m/s in less than 2km vertical.

Nothing in the industry resembles the fast launch/fall/relight/reorientate/decelerate/land/refuel/repeat sequence, of SN#. There is no established industry specifications addressing such operation. And as the history of rocketry shows, establishing such specifications practically involves lots of crashes. [cue How Not To Land A Booster]

Re: SpaceX SN9 Explodes on Landing

#262

Post by ericd »

simonh wrote: post #260
Cogito wrote: post #249

Earlier quoted context omitted.

I mostly agree with you, but I'm not sure on why you're focusing human passenger safety on this at this early development stage, as if it's somehow a reasonable thing to focus on. Launching these things IS the issue so far, by far the main objective of these tests. Landing them would be nice, but the primary objectives are to launch the whole thing (in particular including aero surfaces and multiple engines, as compa…

I suppose that’s fair, but I think public perception might be a bit different. The public aren’t used to watching prototype jet airliners crashing in flames on runways, so some people are going to be concerned about it.

Interesting point, the image of a bunch of these blowing up in testing might loom large in people's minds once it starts carrying people, even if they rationally know it's had a much better safety record since then.

Re: SpaceX SN9 Explodes on Landing

#263

Post by evgen »

sudosysgen wrote: post #259
evgen wrote: post #257

Earlier quoted context omitted.

It takes a profoundly ignorant view of historical facts to blame Stalin and Trotsky on foreign interference.

It takes a profoundly ignorant view of historical facts to ignore the immense pervasiveness of foreign interference in the Russian Civil War. The mere presence of the Bolsheviks as a dominant force was due to foreign interference, as the Germans installed him and his friends in an attempt to destabilize the Russian Empire. Trotsky's growth in authoritarianism, when he was previously a moderating force, started with t…

To claim all of this was based on foreign interference is revisionism without foundation, ignoring the agency of the Russian people and its tragically flawed and corrupt leadership/aristocracy. The Germans did not create or even influence the conditions that led to the Russian civil war or the various abortive revolutions prior to the one in 1917; beyond helping Lenin get back to Russia from Switzerland there is a shocking lack of evidence of any direct support (just in case you are trying to suggest the "Kaiser's gold" theory, there is no evidence of significant monetary support in either German or Russian records.) Considering the fact that Russia was a participant in WW1 at the time it is naive to assume they as disinterested or uninvolved, but the Germans did not create Lenin or any of the other committees and factions involved.

You cannot just sweep across decades of internal Russian conflict and paint it with such a broad and quite frankly misinformed brush. Every European nation was involved to some extent, but none had the influence you claim nor did any create any of the central characters in this story.

Re: SpaceX SN9 Explodes on Landing

#264

Post by sudosysgen »

evgen wrote: post #263
sudosysgen wrote: post #259

Earlier quoted context omitted.

It takes a profoundly ignorant view of historical facts to ignore the immense pervasiveness of foreign interference in the Russian Civil War. The mere presence of the Bolsheviks as a dominant force was due to foreign interference, as the Germans installed him and his friends in an attempt to destabilize the Russian Empire. Trotsky's growth in authoritarianism, when he was previously a moderating force, started with t…

To claim all of this was based on foreign interference is revisionism without foundation, ignoring the agency of the Russian people and its tragically flawed and corrupt leadership/aristocracy. The Germans did not create or even influence the conditions that led to the Russian civil war or the various abortive revolutions prior to the one in 1917; beyond helping Lenin get back to Russia from Switzerland there is a sh…

Is your position that the only possible result of the Russian Revolution was Stalin and the Holodomor?

The phenomena of revolutions turning authoritarian because of an outside enemy attempting to destabilize is in no way unique to the USSR. It's a pattern you see all across the world. It's what gets a movement that was opposed to even the concept of a standing army because of the centralization of power and the risk that brings to the largest standing army.

The Germans didn't create Lenin, but they fundamentally changed the course of the Rebellion against the Tsar by sending him back to Russia at that precise time. They had an intent in doing so that was realized.

Re: SpaceX SN9 Explodes on Landing

#265

Post by gridspy »

GizmoSwan wrote: post #226
gridspy wrote: post #224

Earlier quoted context omitted.

737-Max crashed because of the "lets analyse this rather than test it" thinking that you described earlier. That and an overly cosy relationship with the FCC and a culture of silencing cautious engineering voices. It's seemed cheaper to tack larger engines and new software onto the old air-frame than to redesign the aircraft to be mechanically stable and update the cockpit. Not surprising that the same company (Boein…

Nope. A purposely designed aircraft is simulated is not one that is elongated with flight control data being patched. Example of how it works: https://www.darcorp.com/advanced-aircraft-analysis-software/ The bureaucracy had nothing to do with it. They did not want to spend the money to create a new craft. The long bodies aircraft was not airworthy physically speaking and so the software was designed to limit its pitc…

Both you and I agree that aerospace companies should do large scale vehicle simulations, which they do.

In addition SpaceX does complex fluid dynamics simulations to design and test their engines. That's likely part of why they have successfully made the "holy grail" of Full-Flow staged combustion work in the Raptor. [0]

None of the failures so far could have been detected through simulation since they were complex integration issues. At some point the cost of simulation is vastly larger than the cost of just creating a test article.

Components like drogue chutes, explosive bolts, failsafe valves and abort systems are typically validated both analytically (by reviewing designs) and are often hard to fully validate by testing.

Since validating components is so expensive, it leads companies that rely on analyitical validation (like Boeing) to become overly attached to previously analysed and working components because analysis is so time consuming and expensive. You end up with modern rockets built with space-shuttle engines as components (SLS) and old jets with new engines tacked on (747 Max).

When you talk about explosive deconstruction of a test article after something new was learnt you fail to realise the learning (not the landing) was the goal. If SN9 had landed correctly, it is very likely they would have deconstructed it anyway. They just deconstructed SN12, 13 and 14 to make way for SN15 which has a very improved design.

0: https://www.youtube.com/watch?v=LbH1ZDImaI8 "Is SpaceX's Raptor engine the king of rocket engines?"

Re: SpaceX SN9 Explodes on Landing

#266

Post by cnlevy »

jjoonathan wrote: post #250
ricardobeat wrote: post #136

Earlier quoted context omitted.

Aren't solid boosters, like those used by the Shuttle, a simpler design than liquid engines? On top of that, the Raptor engines used in the Starship, which seem to be considered state-of-the-art, are based on a soviet design from the 60s.

Raptors are state of the art. They are based on a soviet design from the 60s in the same way that they are based on US designs from the 60s. It's weird that people seem so keen to talk up the soviet part and talk down the US part.

I think he is referring to the Soviet https://en.wikipedia.org/wiki/RD-270 full-flow staged combustion engine from the 60s. The Americans had not been able to preserve the high-pressure hot oxygen from eating the preburner.

Re: SpaceX SN9 Explodes on Landing

#267

Post by jjoonathan »

cnlevy wrote: post #266
jjoonathan wrote: post #250

Earlier quoted context omitted.

Raptors are state of the art. They are based on a soviet design from the 60s in the same way that they are based on US designs from the 60s. It's weird that people seem so keen to talk up the soviet part and talk down the US part.

I think he is referring to the Soviet https://en.wikipedia.org/wiki/RD-270 full-flow staged combustion engine from the 60s. The Americans had not been able to preserve the high-pressure hot oxygen from eating the preburner.

Yes, the soviets had great accomplishments with the oxygen-rich cycle, but they had coking problems in the fuel-rich cycle that the US overcame -- there's a reason why it took until the Raptor for FFSC to become commonplace.

I don't mind acknowledging the great soviet accomplishments, of which there are many, but the circlejerk tendency to inflate their accomplishments and shrink their shortcomings (while doing the opposite to Cold War US) is insanely strong. It makes me wonder if I'm speaking to bots!

Re: SpaceX SN9 Explodes on Landing

#268

Post by alentist »

sudosysgen wrote: post #248
alentist wrote: post #219

Earlier quoted context omitted.

> The USSR, had it not had to fight a cold war against the US, could very well have been a much better system not just for space flight, but for a way to structure and run society in general. What makes you think that? If they had such a wonderful "way to structure and run society in general", why did the USSR and its satellite states have to systematically mass murder people who wanted to leave this wonderful societ…

A significant reason why Stalin was able to successfully rise to power and why the Bolsheviks were able to secure total power is because of foreign violence and interference. When all major foreign powers say that they wish for the destruction of your country and would openly prefer you to go back to more suffering, support for monsters like Stalin increases. Equally, when the threat of invasion is as high as it was…

You completely dodged the question and tried to change the subject, so I'll ask it again: If they had such a wonderful society, why did they have to systematically mass murder people who wanted to leave this wonderful society?

Re: SpaceX SN9 Explodes on Landing

#269

Post by alentist »

Layke1123 wrote: post #238
alentist wrote: post #219

Earlier quoted context omitted.

> The USSR, had it not had to fight a cold war against the US, could very well have been a much better system not just for space flight, but for a way to structure and run society in general. What makes you think that? If they had such a wonderful "way to structure and run society in general", why did the USSR and its satellite states have to systematically mass murder people who wanted to leave this wonderful societ…

Well, why did the US actively try to harm the USSR? If it was such a bad way of doing things, why did the US actively go out of it's way to sabotage it rather than just ignore it and let it die?

You completely dodged the question and tried to change the subject, so I'll ask it again: If they had such a wonderful society, why did they have to systematically mass murder people who wanted to leave this wonderful society?

Your question, on the other hand, is silly. Substitute the USSR with Nazi Germany.

Re: SpaceX SN9 Explodes on Landing

#270

Post by AstralStorm »

CydeWeys wrote: post #193
DennisP wrote: post #70

Earlier quoted context omitted.

And SpaceX has blown up ten Falcons on landing attempts.

After accomplishing their primary mission, which is a key distinction. If you blow up on landing that just means you lose your reuse discount on a future flight.

That's no good for Starship, which is meant to land with passengers and hardware on board.
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