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yourlocalFSDO OP t1_ivtbw4e wrote

SLS is rated for 85mph sustained winds on the pad, looks like sustained wind peaked right around the number with gusts significantly higher. Will be interesting to see if there is any damage

Edit: it appears 85mph was actually the GUST limit. There was a 100mph gust recorded. I'm not optimistic for a November launch at this point

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kgm2s-2 t1_ivto3sk wrote

According to Ars Technica's quote from the SLS lead engineer, 85mph is actually the limit for gusts, which implies the sustained wind limit is lower than that. They've definitely exceeded designed loads (the question is how big the "engineering design margin" is...but wind loads go as square of wind speed, so 15mph over budget is significant).

Edit: Back-o'-the-napkin math says they'd have to have at least a 40% design margin to have not suffered any damage...the famous B777 wing load testing video has it making it to 154% of design load, I'd have to believe that Artemis' margins are not more than that.

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Mc00p t1_ivugg06 wrote

>the question is how big the "engineering design margin" is...but wind loads go as square of wind speed, so 15mph over budget is significant

NASAs human-rated rockets require a structural safety requirement of 40% with the stipulation that you can have lower margins after a lot of testing. I believe the external Shuttle tanks were 25% as I think the 1.4 margin is so difficult to achieve throughout the whole system.

Edit: The industry standard for non-human rated rockets is a margin of 1.25

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[deleted] t1_ivufb69 wrote

What drives this requirement? I’d assume ability to remain standing, which it still is so if my assumption is correct they lucked out

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yourlocalFSDO OP t1_ivul7rr wrote

Wind loading on the rocket is much different than the force it's designed to take in flight. It's possible to have structural damage to the rocket if the wind loading gets too high. It doesn't have to fall over for things to crack or yield

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[deleted] t1_ivunpjm wrote

Yeah I understand axial loads are going to be higher than radial during flight. Are you saying you don’t know what drives it or it is wind loading?

If it is wind loading I can’t imagine cracks forming as much as minor waviness of the skin panels that would produce significant disturbances during flight.

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zerbey t1_ivti5xr wrote

Whoever made the decision to leave Artemis on the launch pad is going to be answering some awkward questions later.

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5yleop1m t1_ivto816 wrote

I don't think they had a choice. They just got the thing back onto the pad, and it takes multiple days to prepare and move back. Further more moving it puts a lot of stress on the rocket too and they only have so many moves budgeted.

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alcoe19 t1_ivu1o3e wrote

Its also more dangerous to roll the rocket back during high winds. Their safest bet at that point was to just leave it there.

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a1danial t1_ivubeme wrote

I remember that additional roll outs would require further certification of certain components. I'd imagine the walker is rated for a number of roll outs.

If anything I have nothing but respect for the SLS team. We, the public, can never fully appreciate the consideration behind decision making, especially the case to roll back the SLS due to hurricane.

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sonoma95436 t1_ivwekoz wrote

I feel sorry for them. They didn't assemble this mess and I mean Bechtel's Mobile launch platform that's causing a lot of these issues. They need to shut down this program.

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chem-chef t1_ivwfi0u wrote

Why push it out then? The weather forecast should be accurate enough for hurrican.

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5yleop1m t1_ivwjs38 wrote

NASA had just moved it back either friday or saturday, and back then the chances of Nicole becoming a hurricane were very low. NASA has other time limits too, the batteries, abort explosives, and the solid rocket boosters all have limited life spans.

NASA moved it back to the pad as early as possible so they could meet the next launch time. After that one the next launch window isn't till December I believe. If the launch slips to 2023 NASA will have to bring back the rocket to redo all the things that have fully expired.

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destraight t1_ivuym06 wrote

why does it take multiple days? how far did they move the damn thing?

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5yleop1m t1_ivv2dbd wrote

The whole launch stack and rocket are hooked up to various plumbing and electrical systems on the pad. Disconnecting those properly and safely takes many hours.

An example of some data from LC39 https://www.nasa.gov/pdf/168440main_LC39-06.pdf

Then the whole tower launch platform has to be readied for moving.

The launch tower doesn't move that fast either, about 1mph max but with something like SLS they will stay lower for the sake of safety. It takes about 24 hours to move it from the VAB to the Launch pad. That distance from LC39B to the VAB is about 4 miles.

Another thing to consider is that rockets are basically massive water towers in that their supporting structure is on the outside and then inside is basically empty space. They are built to withstand vertical forces from launch first, and everything else second because the chances of them facing those other forces are muuuch lower. When its already costing billions to build it as is, it'd be insane to build it to withstand things that are lower on the chances.

I was trying to find a document on the whole process, which should be available to the public but finding it is another story.

I found the stuff below, which is mostly for marketing purposes so its really dumbed down which is unfortunate because it simplifies a lot of things.

https://www.nasa.gov/pdf/168440main_LC39-06.pdf

https://www.nasa.gov/sites/default/files/atoms/files/combined_crawler-transporters_fact_sheet_final.pdf

The two handbooks below have a ton of juicy technical details. https://www.nasa.gov/sites/default/files/atoms/files/nasa_systems_engineering_handbook_0.pdf

https://ntrs.nasa.gov/api/citations/19660024575/downloads/19660024575.pdf

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destraight t1_ivw1sao wrote

1 mile an hour? well thats the problem right there. no wonder why it takes soo long to bring it back into the garage

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Mike_Ma t1_ivtldky wrote

Absolutely. 100 miles per hour is 15 more miles per hour than what the rocket is rated for, 85 miles per hour.

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CallMeJeeJ t1_ivtmfrm wrote

Wait that can’t be right.

Someone crunch those numbers again!

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GiantRiverSquid t1_ivtpoku wrote

My God! Jensen, he's right! Someone call the president.

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[deleted] t1_ivuf0oc wrote

85mph is 83mph faster than average walking speed, which is 2mph, and 98mph slower than the highest gust on SLS

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Desertbro t1_ivvvt8y wrote

I'm not from this planet, ****** !!! - YoyoDyne exec, John Bigbootay

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BlueWhoSucks t1_ivtvjvb wrote

I am pretty sure the actual wind speeds it can sustain are much higher than the rated amount.

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zerbey t1_ivu1sqm wrote

Doesn't matter, if it exceeds the rated amount then it's exceeded safety margins.

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yourlocalFSDO OP t1_ivulilg wrote

It exceeded the rated amount by about 17% That's a really big number

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SleepyCatSippingWine t1_ivtldpi wrote

Hope a hydrogen line on the tower did not develop leaks

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whattheeffg t1_ivuzifb wrote

I think they made sure this could never happen again. I just went to the KSC the other day

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_AdAstra_PerAspera t1_ivtqqir wrote

Ruh-roh. Some NASA/USSF weather forecasters (and program managers) will be facing some tough questions about this. That’s a lot of taxpayer-funded hardware to be left blowing in the wind.

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patrick66 t1_ivu5hrp wrote

The big problem is they had to make the call Sunday and on Sunday the chance of these winds actually being this strong at the cape was <5%. Moving the rocket just takes too long and they’re getting burned because of it

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Xaxxon t1_ivuc3xb wrote

When something has a non-zero possibility that means it can happen.

As long as when you say there's a 15% chance of stuff happening, about 15% of the time it happens, you're doing your job.

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Decronym t1_ivuzn0j wrote

Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:

|Fewer Letters|More Letters| |-------|---------|---| |KSC|Kennedy Space Center, Florida| |SLS|Space Launch System heavy-lift| |USSF|United States Space Force| |VAB|Vehicle Assembly Building|

^(4 acronyms in this thread; )^(the most compressed thread commented on today)^( has 16 acronyms.)
^([Thread #8252 for this sub, first seen 10th Nov 2022, 20:22]) ^[FAQ] ^([Full list]) ^[Contact] ^([Source code])

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Howzball t1_ivtubvn wrote

I'm curious as to what supposedly happens to the rocket at 100 mph wind speeds that wouldn't at 85 mph and are some of EB's Twitter post a little bit sensationalized? I mean the guy is Media after all, overhype is part of how they sell stories. I guess I just wonder is this simply more fuel for the "doomed rocket" conspiracy theories?

On the other hand, if something bad does end up happing to Artemis 1 then they'll always have a hurricane to blame it on.

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