Updates SLS Updates

[GLS]

The core can only be tanked 9 times, so here's another reason not to repeat the test... ?

 

[N_Molson]

Yup supercooling the metal stresses it and you get fatigue cracks...

 

[GLS]

Did 1 second of gimballing.

 

[DaveS]

Another note: CAPU-2 shut down did not affect the engine shut down sequence. All 4 engines shut down under hydraulic control, which is unlike what would happen with a APU shut down during a shuttle launch (this did happen, on STS-3 when Water Spray Boiler-3 that cools the lubrication oil for APU-3 shut down which caused the APU to auto shut down).

 

[N_Molson]

Is the administrator giving up or is it the end of his mandate ?

 

[DaveS]

Is the administrator giving up or is it the end of his mandate ?

End of mandate. It is customary for political appointees to submit their resignations when a new Presidential Administration comes in. The oncoming Administration can ask that they stay on until they have nominated a replacement.

 

[Gargantua2024]

So, whatever happens the actual launch of Artemis 1 would go ahead anyway?

 

[Urwumpe]

So, whatever happens the actual launch of Artemis 1 would go ahead anyway?

Likely yes. Why should they delay a test flight, as long as it is still possible to test everything there?

 

[DaveS]

January 21 blog update: https://blogs.nasa.gov/artemis/2021...met-many-objectives-test-assessment-underway/

"Currently, the SLS core stage can still be loaded with propellant and pressurized 20 more times for a total of 22 cycles. Rocket stages like the core stage are designed to be loaded with cryogenic propellant and pressurized a specific number of times. These are called cryogenic loading cycles. Before Green Run testing began, SLS had allocated nine cryogenic cycles for testing at NASA’s Stennis Space Center in Bay St. Louis, Mississippi and has used two of those during the hot fire and wet dress rehearsal, with seven cryogenic cycles remaining for additional testing. For the Artemis I Iaunch, NASA is preserving 13 of the remaining 20 cryogenic loading cycles. These can be used for multiple launch attempts, a wet dress rehearsal on the launch pad, and other activities that require propellant loading and tank pressurization."

This is actually more than what the STS ET was certified for, it had a 13 cryo/press cycle certification.

 

[GLS]

2 or 3 days ago they said that they might not test again as the core had a life-time of 9 tankings, and now we see that actually it's 9 for testing... information seems to be flowing well in the program. ?

 

[N_Molson]

PR is not what they are best at, that's not new. It can be embarassing but as long as stuff flies...

 

[DaveS]

Well, it's official, a second hot fire will happen, currently NET last week of February and it will only last four minutes to capture the last bit of outstanding data: https://blogs.nasa.gov/artemis/2021...proceeds-with-plans-for-second-hot-fire-test/

This will place the Core Stage on dock at KSC in early April.

 

[GLS]

After evaluating data from the first hot fire and the prior seven Green Run tests, NASA and core stage lead contractor Boeing determined that a second, longer hot fire test should be conducted

Nice PR bit, making the reader think that they will to do more than tried before, when actually they will do less...

 

[Gargantua2024]

Isn't that what government-funded companies always do?

 

[Gargantua2024]

Second attempt at hot-fire Green Run test rescheduled for Thursday, March 18:
https://www.space.com/nasa-sls-megarocket-engine-test-march-2021-date

 

[Urwumpe]

Second attempt at hot-fire Green Run test rescheduled for Thursday, March 18:
https://www.space.com/nasa-sls-megarocket-engine-test-march-2021-date

Lets hope the hydraulics work better then.

 

[Notebook]

SLS: Nasa assembles twin boosters for its 'megarocket' - BBC News

 

[DaveS]

Lets hope the hydraulics work better then.

Well, the real hydraulics worked great during the first attempt. What got them was too conservatively set test parameters that was derived from computer models of the system. Now that they have updated the models with real world data gained from the 67 seconds of actual run time, things should be better. And of course the MCF was just a redundant leg of instrumentation which is why the test continued last time until the hydraulics system parameters got them.

So all issues from the first attempt have been resolved and understood.

 

[Urwumpe]

Well, the real hydraulics worked great during the first attempt. What got them was too conservatively set test parameters that was derived from computer models of the system. Now that they have updated the models with real world data gained from the 67 seconds of actual run time, things should be better. And of course the MCF was just a redundant leg of instrumentation which is why the test continued last time until the hydraulics system parameters got them.

So all issues from the first attempt have been resolved and understood.

Sorry, but I don't buy this. If the parameters had been derived from conservative calculations, they should have been far on the safe side and working. Especially if you have computer models for hydraulics instead of just using paper and slide rule.

The SLS had a lot of visible issues in the stage and I really hope, the next test will look much more like a proper test firing as the first one.

 

[N_Molson]

I'd say some people are probably a bit under pressure right now. Which might not be a bad thing.