Author Topic: SLS General Discussion Thread 6  (Read 222902 times)

Offline gongora

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SLS General Discussion Thread 6
« on: 03/27/2021 03:53 pm »
New Discussion Thread for SLS.

SLS Articles (lots of them):
https://www.nasaspaceflight.com/?s=SLS

L2 SLS (Vast):
https://forum.nasaspaceflight.com/index.php?board=48.0

--

Do not argue. Make sure your posts are on topic and interesting. Don't bandwagon. There's a lot of SLS news out there (well mainly just via our articles as there's very little else out there on the technical side).

Attempt to derail this with "But Falcon Heavy" etc.....and your post will be removed. Plenty of "vs" threads. This one is about discussing SLS.

Other available thread include:
Discussion/Comparison of the new generation of American heavy lift launchers
Discussion on Alternative Launchers to SLS for Artemis

Offline Avatar2Go

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Re: SLS General Discussion Thread 6
« Reply #1 on: 03/27/2021 10:24 pm »
Thanks Gongora.  Just wanted to say congratulations once again to the SLS Green Run team, for a successful full-duration launch simulation test. 

There is a new 4-view B-roll video of the firing posted in the NSF twitter feed.  It presents clear views of the 3 gimballing tests, as well as the supplemental cork insulation and adhesive burning from the static heat load.  The second gimbal test was especially interesting as they induced different resonance frequencies in the core stage.

Also there is a new NSF article from Philip about the 13 cubesat secondary payloads for Artemis 1, and the stacking and launch preparation schedule.  I appreciate NSF covering the technical details of SLS and providing progress reports.

Artemis 1 launch now early 2022, most probably.  Late 2021 still possible but not likely
« Last Edit: 03/27/2021 10:39 pm by Avatar2Go »

Online eeergo

Re: SLS General Discussion Thread 6
« Reply #2 on: 03/28/2021 11:53 am »
Thanks Gongora.  Just wanted to say congratulations once again to the SLS Green Run team, for a successful full-duration launch simulation test. 

There is a new 4-view B-roll video of the firing posted in the NSF twitter feed.  It presents clear views of the 3 gimballing tests, as well as the supplemental cork insulation and adhesive burning from the static heat load.  The second gimbal test was especially interesting as they induced different resonance frequencies in the core stage.

Also there is a new NSF article from Philip about the 13 cubesat secondary payloads for Artemis 1, and the stacking and launch preparation schedule.  I appreciate NSF covering the technical details of SLS and providing progress reports.

Artemis 1 launch now early 2022, most probably.  Late 2021 still possible but not likely

For reference: https://images.nasa.gov/details-SSC_2021-03-18_Hot_Fire_B-roll_4_Views

Online jadebenn

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Re: SLS General Discussion Thread 6
« Reply #3 on: 03/28/2021 05:49 pm »
I guess I see why they kept the focus on the cloud shots. Look at all the fire! That cork is just burning near the end, there.
« Last Edit: 03/28/2021 05:49 pm by jadebenn »

Offline Avatar2Go

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Re: SLS General Discussion Thread 6
« Reply #4 on: 03/28/2021 07:44 pm »
Yes, for many people watching it might have seemed that something was terribly wrong.  I suspect the flames were mostly from the first layer of adhesive as it was exposed.  Cork was a good choice as it insulates against both sound and heat energy, is waterproof, and doesn't burn with an open flame.  It chars and ablates away.

https://www.corkor.com/blogs/corkor/why-use-cork
« Last Edit: 03/28/2021 07:54 pm by Avatar2Go »

Offline Khadgars

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Re: SLS General Discussion Thread 6
« Reply #5 on: 03/28/2021 11:34 pm »
Yes, for many people watching it might have seemed that something was terribly wrong.  I suspect the flames were mostly from the first layer of adhesive as it was exposed.  Cork was a good choice as it insulates against both sound and heat energy, is waterproof, and doesn't burn with an open flame.  It chars and ablates away.

https://www.corkor.com/blogs/corkor/why-use-cork

That video was sweet to watch!
Evil triumphs when good men do nothing - Thomas Jefferson

Online FutureSpaceTourist

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Re: SLS General Discussion Thread 6
« Reply #6 on: 03/29/2021 04:37 pm »
https://twitter.com/nasagroundsys/status/1376569107139727364

Quote
Last week, teams with EGS conducted prototype testing of a new rainbird system that will be used for future missions under @NASAArtemis. The system, large water nozzles installed on the mobile launcher, will help protect the infrastructure around @NASA_SLS when it lifts off. 🚀

Online jadebenn

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Re: SLS General Discussion Thread 6
« Reply #7 on: 03/29/2021 06:51 pm »
Is this because of the 1% overpressure on Artemis I that NASA had to waive?

Offline Avatar2Go

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Re: SLS General Discussion Thread 6
« Reply #8 on: 03/29/2021 07:34 pm »
Very well may be, as this is for ML-2.  NASA said they would need to address the 1% overpressure waiver for future missions.  This would appear to be adding one or more rainbirds in new positions for ML-2.

Offline russianhalo117

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Re: SLS General Discussion Thread 6
« Reply #9 on: 03/29/2021 08:18 pm »
Very well may be, as this is for ML-2.  NASA said they would need to address the 1% overpressure waiver for future missions.  This would appear to be adding one or more rainbirds in new positions for ML-2.
The selected replacement design will be installed on ML-1 after Artemis I before Artemis II. The new design will also be used on ML-2.

Online DaveS

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Re: SLS General Discussion Thread 6
« Reply #10 on: 03/29/2021 11:24 pm »
Very well may be, as this is for ML-2.  NASA said they would need to address the 1% overpressure waiver for future missions.  This would appear to be adding one or more rainbirds in new positions for ML-2.
The selected replacement design will be installed on ML-1 after Artemis I before Artemis II. The new design will also be used on ML-2.
Yes, it will be quite similar in scope to what NASA did with MLP-1 after the first shuttle launch when it was discovered that the SRB Ignition Overpressure (IOP) effects on the vehicle had been greatly misquantified and they to had install the large pipes around the two SRB exhaust chambers to combat the IOP effects along with the water bags. The two subsequent MLPs had them from the start and needed no modifications.

They also took the opportunity to troubleshoot the GOX Vent Arm failures that they had seen during the pad flow of STS-1 and make the necessary modifications to it.
« Last Edit: 03/29/2021 11:26 pm by DaveS »
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Offline Avatar2Go

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Re: SLS General Discussion Thread 6
« Reply #11 on: 03/30/2021 04:58 am »
Today NASA has CFD tools that run on the Pleiades supercomputer to simulate the ignition overpressure event.  Here is an article that mentions the STS-1 problem.  Scale models used at that time for prediction and design.

https://www.nas.nasa.gov/SC15/demos/demo10.html

Here is an article with recent results of the CFD model for an SRB.

https://www.nas.nasa.gov/publications/articles/feature_LociCHEM_launch_sound_suppression.html

Interesting that they used vinyl water bags beneath the engines and SRBs to absorb the initial shock waves, in addition to the water deluge system and rainbirds.  Bags may not be needed on SLS since Orion is much farther from the nozzles.
« Last Edit: 03/30/2021 05:56 am by Avatar2Go »

Online jadebenn

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Re: SLS General Discussion Thread 6
« Reply #12 on: 03/30/2021 06:43 am »
Interesting that they used vinyl water bags beneath the engines and SRBs to absorb the initial shock waves, in addition to the water deluge system and rainbirds.  Bags may not be needed on SLS since Orion is much farther from the nozzles.
It's my understanding that the primary issue was the Shuttle's lateral movement causing the sound to reflect off the bare MLP deck and back onto the spacecraft, which isn't a vulnerability shared with SLS. Don't quote me on that, though.

Offline Avatar2Go

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Re: SLS General Discussion Thread 6
« Reply #13 on: 03/30/2021 02:36 pm »
The data from STS-1 showed a pressure wave traveling up the orbiter fuselage, with a frequency of 5 to 10 Hz, and an amplitude of 4 g's.  That was within the range of structural resonance for the orbiter, it dislodged & damaged TPS tiles and buckled an oxidizer tank strut within the RCS system in the nose.

Offline Jim

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Re: SLS General Discussion Thread 6
« Reply #14 on: 03/30/2021 07:13 pm »
It's my understanding that the primary issue was the Shuttle's lateral movement causing the sound to reflect off the bare MLP deck and back onto the spacecraft, which isn't a vulnerability shared with SLS. Don't quote me on that, though.

The sound reflection was there regardless of the shuttle lateral movement.

Offline Jim

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Re: SLS General Discussion Thread 6
« Reply #15 on: 03/30/2021 07:14 pm »
Rainbirds for deck sound reflections
water deluge for GH2 burnoff during engine start
Water bags and SRB exhaust water injection for IOP.

Offline Avatar2Go

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Re: SLS General Discussion Thread 6
« Reply #16 on: 03/31/2021 10:21 pm »
Actually from what I've found, all three elements were/are part of IOP/SS.  All address different factors, with cooling being one as well.  Not sure if lateral movement played a role, but there was particular concern for the shuttle bay doors and payloads.  Data from STS-1 showed the peak amplitude occurred at 4 to 5 seconds after ignition, so the shuttle would not yet have cleared the tower, and reflections would be a major factor.

Offline VSECOTSPE

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Re: SLS General Discussion Thread 6
« Reply #17 on: 04/01/2021 04:45 am »

Covid impact to SLS at $363M and three months.

Quote
The Space Launch System had the second-highest cost increase in terms of overall dollars, at $363 million, of which $8 million was in fiscal year 2020 and $355 million in fiscal years 2021 through 2023. A three-month delay in the first SLS mission, Artemis 1, along with “rephrasing production” each accounted for about one-third of the costs. The rest came from “surge costs” to compress schedules as well as the costs of facility shutdowns.

https://spacenews.com/pandemic-to-cost-nasa-up-to-3-billion/

Offline Avatar2Go

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Re: SLS General Discussion Thread 6
« Reply #18 on: 04/01/2021 10:54 am »
For organizations like NASA that could not furlough workers, COVID deferred progress but not costs.  Which means the cost of the lost progress must be paid in future years.  Same thing happened at my school.

Offline Khadgars

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Re: SLS General Discussion Thread 6
« Reply #19 on: 04/01/2021 02:57 pm »
Anyone know how long the barge trip from Stennis to KSC will take for CS-1?
Evil triumphs when good men do nothing - Thomas Jefferson

Tags: SLS Ares cost 
 

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