Yeah scrubbydubbed.
iām no rocket scientist, but all this tanking and detanking, the tanks must be getting a bit brittle, especially with the extremely low temps.
any time they fill the tanks, and dump them, they are putting stress on the material due to the cold/heat causing retraction/expansion. if i understand correctly, it would be like bending a paperclip back and forth, the metal will become brittle and weak, and potentially fail. or do we still have a long way to go before that material gets to that point?
https://twitter.com/elonmusk/status/704102461766676481[quote=āKindred, post:365, topic:445, full:trueā]
iām no rocket scientist, but all this tanking and detanking, the tanks must be getting a bit brittle, especially with the extremely low temps.
any time they fill the tanks, and dump them, they are putting stress on the material due to the cold/heat causing retraction/expansion. if i understand correctly, it would be like bending a paperclip back and forth, the metal will become brittle and weak, and potentially fail. or do we still have a long way to go before that material gets to that point?
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You are correct that this happens, but Iām willing to bet that the one rocket to date(besides the shuttle) that has been built for reuse has been designed around temp cycling of materials. It would be an extremely obvious thing to overlook and I canāt imagine that happeningā¦not to mention that the merlin engines have been tested to run fine for at least 40 cycles(on/off).
i was insinuating that its a shitty situation to not even have a launch and the tanks are most likely potentially already brittle, is all.
I was attempting to answer your question here, unless I misunderstand what youāre asking. It sucks that itās a scrub but hey itās better than a RUD.
Forgot to post it! Yes, tomorrow! Hurray!
ā¦and there was much rejoicing. You can find the stream at the same placeā¦Iāll see you dirty animals there!
Edit: Nice to see it confirmed by SpaceX
I thought the same myself so I did a little investigation into it. The Falcon 9 tanks are made of an Aluminium-Lithium alloy, originally developed for airframes in commercial airliners because itās lighter and stronger than aluminium.
Iām no material scientist, but after a lot of googling and reading wikipedia it seems like brittleness isnāt going to be a problem. For three reasons:
-
Falcon 9 is designed to be reusable so itās meant to be re-tanked many many times as well as to re-enter at hypersonic speeds. Seems like theyād design it to be pretty tolerant of thermal cycling!
-
Al-Li alloys are one of the best alloys for cryogenic storage (although it seems like they suffer in high heat). To quote TotalMateria.com (emphasis mine):
Commercial aluminum-lithium alloys are targeted as advanced materials for aerospace technology primarily because of their low density, high specific modulus, and excellent fatigue and cryogenic toughness properties.
- It seems like metal stress and fatigue are actually quite predictable things, especially with detailed inspections. To take your paperclip example bending back and forth would break it, but a material scientist would be able to inspect the paperclip and tell you how many more times you can bend it before it breaks. SpaceX have had 24+ hours to inspect the rocket and make this determination (likely backed up with quite a bit of datasheet info+testing of their alloy of choice).
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Thatāll be about an hour before the Soyuz undocks.
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Launch pushed to Friday because of very high shear winds. 
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after googling and a bit of asking around, i came to the same conclusion.
thank you so much for an informative and thorough post! and the citation to help me read more about it. i figured that it would handle that much stress given its re-usability yet t i was not entirely sure how or what they used. thanks so much for giving me the right direction!
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Itās lalalalalaunch day!! 1 hour 15 minutes until liftoff! You know the drillā¦
Upper level winds are still being watched so thereās a chance of scrub. Otherwise, weather is 90% go.
Unfortunately I have to watch from mobile this time but Iāll be there!
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Fool me 4th, shame on you. Fool me 5thā¦
( In other words: Launch the bloody thing please. 
)
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There is a none zero chance of scrub because of those damn windsā¦if so backup date is tomorrow!
ā¦ anyone seen LucasFIN? No? Then itās looking good so far. 
EDIT: lol at the like XD
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Maybe the curse will be broken today 
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They are going ahead with fuelingā¦this means they donāt think upper level winds will be a problem and Iām hopeful we will see liftoff!
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Well. Now we have to hope the rocket doesnāt blow up.
Donāt you dare jinx it.
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Gotta love the drone shipās name