Author Topic: Navigating the twists and turns steering SLS Development  (Read 34309 times)

Offline Chris Bergin

FEATURE ARTICLE: Navigating the twists and turns steering SLS Development -

https://www.nasaspaceflight.com/2018/10/navigating-twists-turns-steering-sls-development/

- By Philip Sloss.

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Offline BrianNH

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Re: Navigating the twists and turns steering SLS Development
« Reply #1 on: 10/01/2018 07:36 pm »
Excellent article!   

I wonder what sort of changes (besides the booster) would be needed by Block 2 to achieve the 130mt LEO target?  This is the first I remember reading of "a major redesign of the vehicle would be necessary to get the required performance."

Also, NASA recently announced that the expected performance of Block 1 went up from 70 to 95 mt to LEO.  I've been curious how this would change their estimate of the performance of Block 1B (currently 110 mt LEO if I remember correctly).

Great work, psloss.

Offline IRobot

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Re: Navigating the twists and turns steering SLS Development
« Reply #2 on: 10/01/2018 10:10 pm »
As expected, SLS/Orion plans are run on a parallel universe where there are no alternative launchers or architectures.

Side point to the article, the NASA metrication is a bit inconsistent across slides.
Some slides (and part of the article) use "mt", others just "t".
Most use "m" but some "ft" still visible.

I guess that people still think first in imperial units and then some of them convert them to metric.

Offline ncb1397

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Re: Navigating the twists and turns steering SLS Development
« Reply #3 on: 10/02/2018 01:30 am »

Also, NASA recently announced that the expected performance of Block 1 went up from 70 to 95 mt to LEO.  I've been curious how this would change their estimate of the performance of Block 1B (currently 110 mt LEO if I remember correctly).

Figure 68 in this article seems to indicate that Block 1B is 117-123 t to LEO. I tried to run the numbers for roughly quadrupling the size of the upper stage from Block 1 and got similar numbers based on 95 t being the baseline. I did this two months ago without having seen this slide, because a 10 t boost didn't make much sense intuitively.

https://forum.nasaspaceflight.com/index.php?topic=46066.msg1842127#msg1842127

Online Steven Pietrobon

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Re: Navigating the twists and turns steering SLS Development
« Reply #4 on: 10/02/2018 11:17 am »
Figure 68 in this article seems to indicate that Block 1B is 117-123 t to LEO. I tried to run the numbers for roughly quadrupling the size of the upper stage from Block 1 and got similar numbers based on 95 t being the baseline. I did this two months ago without having seen this slide, because a 10 t boost didn't make much sense intuitively.

Boeing said Block IB is 93.1 t to LEO in a 2013 paper, which agrees with your 95 t figure. NASA has been saying 105 t, but I believe that includes the dry mass of EUS. The 117-123 t values must be a typo. Block 2B is listed as 118-137 t, so having the minimum value increase by only 1 t does not make any sense. Also, I don't understand why a range of values are given, unless one is with Orion and one without. Another strange thing is the difference in values:

Block 1A (+DK) 106-119 t (13 t)
Block 1A (+CPS) 106-119 t (13 t)
Block 2A (+J-2X) 122-130 t (8 t)
Block 2A (+RS-25) 138-147 t (9 t)

Block 1B (+EUS) 117-123 t (6 t)
Block 2B (+DK) 118-137 t (19 t)

Block 1B (+DK) 106-119 t (13 t)
Block 2B (+EUS) 118-137 t (19 t)

Why is the range only 6 t for Block 1B, but 19 t for Block 2B? For someone making a decision based on this graph, the wrong values given for Block 1B could have led to a huge error in judgement.
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline Zed_Noir

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Re: Navigating the twists and turns steering SLS Development
« Reply #5 on: 10/02/2018 03:46 pm »
<snip>
Also, NASA recently announced that the expected performance of Block 1 went up from 70 to 95 mt to LEO.  I've been curious how this would change their estimate of the performance of Block 1B (currently 110 mt LEO if I remember correctly).
<snip>

According to a NASA web page the LEO payload of 95 mT for the Block 1 that NASA is quoting is for a parking  orbit of about 155 km altitude ("almost 100 miles"). ::)

Quote
After SLS loses the weight of its first stage propulsion systems and fuel, more power is still needed to send Orion to the Moon. At this point, the upper part of the rocket and Orion are soaring almost 100 miles above Earth, accelerating at more than 17,500 miles per hour, and beginning a circular orbit around Earth. This is low-Earth orbit, often referred to as LEO. SLS can deliver more than 95 metric tons (209,439 pounds) to this orbit with a Block I configuration. However, a deep space mission requires a rocket that can travel beyond LEO with enough power and speed to overcome the pull of Earth’s gravity and send the spacecraft even farther to reach the Moon. The upper part of rocket prepares for the next big move to send Orion out of LEO without even completing a full orbit of Earth.

The quoted paragraph is after the expanded view diagram of the Block 1 on the web page.

edit: fixed web link
« Last Edit: 10/03/2018 09:10 pm by Zed_Noir »

Online envy887

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Re: Navigating the twists and turns steering SLS Development
« Reply #6 on: 10/03/2018 12:42 pm »
<snip>
Also, NASA recently announced that the expected performance of Block 1 went up from 70 to 95 mt to LEO.  I've been curious how this would change their estimate of the performance of Block 1B (currently 110 mt LEO if I remember correctly).
<snip>

According to a NASA web page the LEO payload of 95 mT for the Block 1 that NASA is quoting is for a parking  orbit of about 155 km altitude ("almost 100 miles"). ::)

Quote
After SLS loses the weight of its first stage propulsion systems and fuel, more power is still needed to send Orion to the Moon. At this point, the upper part of the rocket and Orion are soaring almost 100 miles above Earth, accelerating at more than 17,500 miles per hour, and beginning a circular orbit around Earth. This is low-Earth orbit, often referred to as LEO. SLS can deliver more than 95 metric tons (209,439 pounds) to this orbit with a Block I configuration. However, a deep space mission requires a rocket that can travel beyond LEO with enough power and speed to overcome the pull of Earth’s gravity and send the spacecraft even farther to reach the Moon. The upper part of rocket prepares for the next big move to send Orion out of LEO without even completing a full orbit of Earth.

The quoted paragraph is after the expanded view diagram of the Block 1 on the web page.

Your link is broken. Altitudes are typically given in nautical miles. 180-185 km is "almost 100" nautical miles, and is a typical parking orbit such as used by Apollo before TLI.

Offline docmordrid

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Re: Navigating the twists and turns steering SLS Development
« Reply #7 on: 10/03/2018 06:41 pm »
>
According to a NASA web page the LEO payload of 95 mT for the Block 1 that NASA is quoting is for a parking  orbit of about 155 km altitude ("almost 100 miles"). ::)
>

Un-busted link...

Link....

Quote
The initial configuration of SLS can send more than 26 metric tons (57,000 pounds) to lunar orbits and future upgrades will enable the rocket to send at least 45 metric tons (99,000 pounds).
« Last Edit: 10/03/2018 06:46 pm by docmordrid »
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Offline docmordrid

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Re: Navigating the twists and turns steering SLS Development
« Reply #8 on: 10/03/2018 06:54 pm »
>
Altitudes are typically given in nautical miles. 180-185 km is "almost 100" nautical miles, and is a typical parking orbit such as used by Apollo before TLI.

Here in the plain-speaking Midwest "almost 100 miles" means "not quite 100 miles," and claiming it's more would receive considerable side-eye.

Someone needs to work on their messaging.
« Last Edit: 10/03/2018 06:54 pm by docmordrid »
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Online envy887

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Re: Navigating the twists and turns steering SLS Development
« Reply #9 on: 10/03/2018 08:07 pm »
>
Altitudes are typically given in nautical miles. 180-185 km is "almost 100" nautical miles, and is a typical parking orbit such as used by Apollo before TLI.

Here in the plain-speaking Midwest "almost 100 miles" means "not quite 100 miles," and claiming it's more would receive considerable side-eye.

Someone needs to work on their messaging.

NASA uses exclusively nautical miles and not statue miles for altitudes, as far as I can tell. 185 km = 99.9 nautical miles. "Almost 100 miles above Earth" seems pretty clear to me in that context.

Offline lucspace

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Offline MATTBLAK

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Re: Navigating the twists and turns steering SLS Development
« Reply #11 on: 10/05/2018 12:31 pm »
I called this happening some months back - don't know which thread, it doesn't matter. Seems now that it might use the Centaur V/ACES stage, Delta IVH stage with another stretch and stronger engine. Or nothing...

...Seems to me that Dr Steve Pietrobon might have to do some more calculations for SLS capabilities: based on those stages I just mentioned :(
« Last Edit: 10/05/2018 12:33 pm by MATTBLAK »
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Offline Crispy

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Re: Navigating the twists and turns steering SLS Development
« Reply #12 on: 10/05/2018 12:37 pm »
Cancellation of EUS? https://twitter.com/DJSnM/status/1048001681600831488?s=20

For those who can't see the tweet, it's from Scott Manley and is an image of these words:

"Development of the Exploration Upper Stage has been officially halted in that contractors have been directed to stop work immediately on it (not even much of a tailoff phase). Officially, it's 100 day pause, but unofficially, we've been told not to expect that work to come back for minimum 1 year and likely multiple years. Core stage is in sufficient schedule/budget trouble that they're planning on just flying Block 1 a bunch of times and indefinitely postpone Block 1B and Block 2 into the farther future. Which makes the SLS project have even less of a niche than it already was clinging to, if the unofficial word's real. "

Offline ncb1397

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Re: Navigating the twists and turns steering SLS Development
« Reply #13 on: 10/05/2018 12:41 pm »
Considering the project just got an additional installment of funding in the CR and is apparently unsourced, I'm calling this questionable.
« Last Edit: 10/05/2018 12:43 pm by ncb1397 »

Offline speedevil

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Re: Navigating the twists and turns steering SLS Development
« Reply #14 on: 10/05/2018 12:44 pm »
"Development of the Exploration Upper Stage has been officially halted in that contractors have been directed to stop work immediately on it
I assume this would have obvious knock-ons for the mobile launcher designed for it.
Who would have the authority to make this sort of decision - wouldn't this have to come from Congress - or at least the strong intimation of support for it?
It seems unlikely Bridenstine woke up yesterday and decided to.
« Last Edit: 10/05/2018 01:37 pm by speedevil »

Online envy887

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Re: Navigating the twists and turns steering SLS Development
« Reply #15 on: 10/05/2018 01:32 pm »
Cancellation of EUS? https://twitter.com/DJSnM/status/1048001681600831488?s=20

For those who can't see the tweet, it's from Scott Manley and is an image of these words:

"Development of the Exploration Upper Stage has been officially halted in that contractors have been directed to stop work immediately on it (not even much of a tailoff phase). Officially, it's 100 day pause, but unofficially, we've been told not to expect that work to come back for minimum 1 year and likely multiple years. Core stage is in sufficient schedule/budget trouble that they're planning on just flying Block 1 a bunch of times and indefinitely postpone Block 1B and Block 2 into the farther future. Which makes the SLS project have even less of a niche than it already was clinging to, if the unofficial word's real. "

The tweet is still live, not sure why the error message says it doesn't exist. Here's the photo that's attached to it:

Offline Rebel44

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Re: Navigating the twists and turns steering SLS Development
« Reply #16 on: 10/05/2018 03:35 pm »
https://arstechnica.com/science/2018/10/rocket-report-spacex-targeted-chinese-rocket-scientist-goes-viral-sls-slips/

"An official slip acknowledgement ... NASA is finally (officially) acknowledging that EM-1, the maiden launch of SLS, will slip from December 2019 until at least June 2020. Sources tell us to expect another slip to 2021, official or not. Expect to see more news related to this emerge next week."

Offline AncientU

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Re: Navigating the twists and turns steering SLS Development
« Reply #17 on: 10/05/2018 04:21 pm »
Time to privatize SLS/Orion. 

Let Boeing, LM, NG(boosters), and AJR pick up the rest of development overruns.
Compete all launches after 2 Block 1 flights -- when 'development' is complete (and taxpayers have paid enough).
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Offline FinalFrontier

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Re: Navigating the twists and turns steering SLS Development
« Reply #18 on: 10/05/2018 04:36 pm »
If they can't fly in 2020 this program is cooked. Also postponing EUS effectively cooks the program anyway, rocket can't really do anything useful at that point.

As I have said before, at the current rate BFR will be operational before SLS, or before SLS does anything useful. So will Vulcan so will New Glenn maybe even New Armstrong. If this happens SLS is invalidated. Of course we know it already is useless.
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Offline speedevil

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Re: Navigating the twists and turns steering SLS Development
« Reply #19 on: 10/05/2018 06:37 pm »
If they can't fly in 2020 this program is cooked. Also postponing EUS effectively cooks the program anyway, rocket can't really do anything useful at that point.

As I have said before, at the current rate BFR will be operational before SLS, or before SLS does anything useful. So will Vulcan so will New Glenn maybe even New Armstrong.
F9 fully reusable, FH fully reusable are also possibilities for this sort of timescale.

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