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SpaceX SN9 Explodes on Landing

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Re: SpaceX SN9 Explodes on Landing

#121

Post by toss1 »

cmoscoe wrote: post #52
rglover wrote: post #28

Love seeing these tests for two reasons: 1.) Experiencing history in the making, especially knowing that the SpaceX team will eventually get it right. 2.) Realizing that even the best of the best have repeated failures and need to rely on iteration to get "there."

On the 'repeated failures' piece, that's somewhat new for aerospace. Traditionally, things would be over-engineered, and losing a test vessel would be considered a bad thing. SpaceX seems very content to blow up a bunch of rockets on their way towards not blowing up rockets. This seems to have caused at least part of their recent issues with the FAA, who seem to be less ok with explosions. It will be very interesting…

>> On the 'repeated failures' piece, that's somewhat new for aerospace

Unless you go back to the early pre-Mercury program days of NASA - they had lots of failures, and that was just trying to go up without re-usability, not land and reuse. There's all kinds of fun failure reels (e.g., [1]) and lists (e.g., [2])

[1] https://www.youtube.com/watch?v=g79K-R7xTFo [2] https://en.wikipedia.org/wiki/List_of_spaceflight-related_ac...

Re: SpaceX SN9 Explodes on Landing

#122

Post by avmich »

PeterisP wrote: post #22
mempko wrote: post #11

Earlier quoted context omitted.

It's funny because the Soviets did it right, in that they funded smart people and gave them control. The Nasa's approach was to have people create proposals and get approval for funds. We have forgotten that the "fund smart people and let them do what they want" is the best approach. Look at Xerox Parc, Bell Labs, etc. Nasa's modern approach with SpaceX and other companies seems to reflect these hard learned lessons.

"fund smart people and let them do what they want" - well, that's not exactly how it worked - for example, while Korolov was mostly able to get the resources he needed in the 1950s, in the early 1940s he did his engineering work on bomber design from a prison labor camp (which is a bit far from "let them do what they want" or "give them control") after losing most of his teeth from malnutrition during forced labor in…

Since Spring 1945, Korolev was much more able to control resources, getting to reconstructing V-2 manufacturing - Soviet version, of course, dubbed R-1 - then upgrades to R-2 and R-3, then even more powerful R-5 - all alcohol-based - and then, starting from 1953, working on R-7.

One interesting piece of history (Chertok wrote about it in his memoirs) - in Spring 1961, just before Gagarin's flight, which, of course, was priority number 1, Korolev managed to worry about upcoming R-9 testing, saying to his people "after Gagarin, they won't allow us to work on R-9 as easily".

Korolev did enjoy significant freedom in how he did things - the Council of Main Designers was created thanks to that freedom, and von Braun's decision to add fifth F-1 to Saturn just because he felt it will be needed - bypassing all bureaucracy - would be quite understood by Korolev and his team, they had similar things done themselves. It was often the case that Korolev went to Kremlin with some space-related offerings, and got green light, after the principal work was already done, and more scaled-up development was all what remained. You have to work your asses off this way of course, but you have full support of your political bosses and you're a hero for everybody.

Re: SpaceX SN9 Explodes on Landing

#123

Post by ehsankia »

rglover wrote: post #28

Love seeing these tests for two reasons: 1.) Experiencing history in the making, especially knowing that the SpaceX team will eventually get it right. 2.) Realizing that even the best of the best have repeated failures and need to rely on iteration to get "there."

SpaceX themselves made a failure montage for Falcon 9

https://www.youtube.com/watch?v=bvim4rsNHkQ

It's easy to forget how many failures that had, but look how far it has come, at this point I don't think they've had any major failures in 5+ years. Maybe a couple sea drone ship booster landing issues but zero mission failures in a very long time.

Re: SpaceX SN9 Explodes on Landing

#125

Post by GizmoSwan »

gridspy wrote: post #113
GizmoSwan wrote: post #102

Earlier quoted context omitted.

How so?

No orbital upper stage has been rapidly reusable. No existing rocket has tried to perform either the "belly flop" or the "Landing flip manouver" that SpaceX is trying to do. The failures are due to complex issues (fuel tanks, valves, engine reliability under complex forces) not simple control system issues (choosing wrong thrust, not able to orient using thrusters, etc)

I don't understand the term belly flop or rapidly reusable. Do You mean that it is becoming horizontal to reduce the falling speed rate to land on its belly?

shuttle was reused and landed on wheels parallel to its belly.

Re: SpaceX SN9 Explodes on Landing

#126

Post by avmich »

mempko wrote: post #11
the-dude wrote: post #10

Earlier quoted context omitted.

[flagged]

It's funny because the Soviets did it right, in that they funded smart people and gave them control. The Nasa's approach was to have people create proposals and get approval for funds. We have forgotten that the "fund smart people and let them do what they want" is the best approach. Look at Xerox Parc, Bell Labs, etc. Nasa's modern approach with SpaceX and other companies seems to reflect these hard learned lessons.

It's interesting to see that during Moon Race, in USSR there were 3 space design teams - Korolev's (later Mishin), Chelomey's and Yangel's - competing for resources, while NASA established centralized planning with everybody doing parts of the common project (with lots of money of course). It seems that "capitalistic" approach in USSR lost to more "communistic", central planning approach in USA.

Re: SpaceX SN9 Explodes on Landing

#127

Post by avmich »

GizmoSwan wrote: post #105
avmich wrote: post #101

Earlier quoted context omitted.

You can choose to develop rockets - especially of such size - this way instead of putting (much) more efforts in calculating how it would behave and prepare for all cases.

Nasa did the calculation with with ancient computers and these guys are speculating and not using proper technology to achieve success. It makes no sense in 2021. They should not be experimenting. Their simulations should be been solid before this stage. It is good way to burn cash.

Simulations of certain things are still a problem today, even though less than it was in 1960-s. For example, trans-sonic aerodynamics is still hard. I'd imagine a good simulation of Raptor's inner flow when Starship does active maneuring can be a problem, especially if you also need to take into account material properties under dynamic loads.

Re: SpaceX SN9 Explodes on Landing

#128

Post by MichaelMoser123 »

avmich wrote: post #103
valuearb wrote: post #35

Earlier quoted context omitted.

At least 126 technicians and cosmonauts were killed by accidents during the Soviet space program. It’s rumored that additional cosmonauts died on missions that the Soviets covered up.

That's likely to include the Nedelin catastrophe ( https://en.wikipedia.org/wiki/Nedelin_catastrophe ) - "The most recent estimated death toll, released by Roscosmos on the 50th anniversary of the accident and originating with agency engineer Boris Chertok, was that 126 people had died, but the agency qualified the number by saying that the actual number could be anywhere from 60 to 150 dead."

The Nedelin catastrophe was an ICBM test run of a rocket with hypergolic fuel that exploded on the launch pad; there was the 1980 launch pad explosion of a (military) sattelite launcher that killed 44 people and injured 43. The Russian version of the article says that hydrogen peroxide filters were produced with catalytic materials, this was later fixed after another launch almost failed in the same manner (it doesn't say how that blast was avoided), initially they suspected an action of the ground crew to have causes the blast in 1980. Both blasts were kept secret until Perestroika in 1989. both explosions were on rockets with hypergolic fuel.

The Russian wikipedia article also has a list of 'other failures' - these are fires in an ICBM silo in Russia in 1960 - eight dead; the US had a fire in a Titan II bunker in 1965 that killed 53 and another one in 1980 that killed one man; also Brazil had a fire of a liquid fueled rocket that killed 21, also on start preparations. (and another blast in Plesetsk in 1973 that killed seven http://www.plesetzk.ru/index.php?p=1973&d=doc/disaster - wikipedia doesn't list everything)

Rocket fuel can be very dangerous stuff! At least liquid methane/oxygen aren't hypergolic.

https://en.wikipedia.org/wiki/1980_Plesetsk_launch_pad_disas... https://ru.wikipedia.org/wiki/%D0%9A%D0%B0%D1%82%D0%B0%D1%81...

Re: SpaceX SN9 Explodes on Landing

#130

Post by GizmoSwan »

avmich wrote: post #127
GizmoSwan wrote: post #105

Earlier quoted context omitted.

Nasa did the calculation with with ancient computers and these guys are speculating and not using proper technology to achieve success. It makes no sense in 2021. They should not be experimenting. Their simulations should be been solid before this stage. It is good way to burn cash.

Simulations of certain things are still a problem today, even though less than it was in 1960-s. For example, trans-sonic aerodynamics is still hard. I'd imagine a good simulation of Raptor's inner flow when Starship does active maneuring can be a problem, especially if you also need to take into account material properties under dynamic loads.

Lets assume that is the case.

That is where they should spend their cash to produce something of real value that can be reused. Simulation close to perfection is the end game. Not sending something chunky into space.

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