[New] Space Launch System / Orion Discussion Thread

[sevenperforce]

1 hour ago, tater said:

3 hours ago, sevenperforce said:

I wonder if a core based on the original SLWT with just two RS-25s would have been able to reach orbit. Probably not; if so, DIRECT-3.0 presumably would have suggested it as an intermediate step. It’s just a shame that we wasted so much time and money on Ares I and Ares V when we could have kept servicing the ISS and Hubble using Shuttle-C or Jupiter-130.

Yeah, Direct was cool.

The problem with a "Jupiter-120" configuration, with just two RS-25s on the core, is that T/W ratio at booster is a measly 66.7%, which is obviously unacceptable.

However, if you simply detank the core to around two thirds of its propellant load, then a DIRECT with just two RS-25s and the old four-segment boosters could send Orion to the ISS with 18 tonnes of comanifested payload. That surely would have been cheaper (and faster to fly) than all of the nonsense NASA has been working on since 2005.

They would have been able to keep the pork flowing and keep flying from American soil this entire time with a progressively-evolving launch architecture based on the same core:

• Jupiter-120d (4-segment boosters, 2 RS-25s, partially-detanked): Orion+18 tonnes to ISS, Orion+6 tonnes to Hubble
• Jupiter-130 (4-segment boosters, 3 RS-25s): Orion+25 tonnes to ISS or 65 tonnes to LEO.
• Jupiter-231 (4-segment boosters, 3 RS-25s, DCSS): Orion to TLI free-return
• Jupiter-246d (4-segment boosters, 4 RS-25s, 6 RL10B-2s, partially detanked upper stage): Orion + 57 tonnes to LEO
• Jupiter-246 (4-segment boosters, 4 RS-25s, 6 RL10B-2s): 100 tonnes propellant to LEO

[Beccab]

9 minutes ago, sevenperforce said:

The problem with a "Jupiter-120" configuration, with just two RS-25s on the core, is that T/W ratio at booster is a measly 66.7%, which is obviously unacceptable.

However, if you simply detank the core to around two thirds of its propellant load, then a DIRECT with just two RS-25s and the old four-segment boosters could send Orion to the ISS with 18 tonnes of comanifested payload. That surely would have been cheaper (and faster to fly) than all of the nonsense NASA has been working on since 2005.

They would have been able to keep the pork flowing and keep flying from American soil this entire time with a progressively-evolving launch architecture based on the same core:

• Jupiter-120d (4-segment boosters, 2 RS-25s, partially-detanked): Orion+18 tonnes to ISS, Orion+6 tonnes to Hubble
• Jupiter-130 (4-segment boosters, 3 RS-25s): Orion+25 tonnes to ISS or 65 tonnes to LEO.
• Jupiter-231 (4-segment boosters, 3 RS-25s, DCSS): Orion to TLI free-return
• Jupiter-246d (4-segment boosters, 4 RS-25s, 6 RL10B-2s, partially detanked upper stage): Orion + 57 tonnes to LEO
• Jupiter-246 (4-segment boosters, 4 RS-25s, 6 RL10B-2s): 100 tonnes propellant to LEO

I agree that this would have been a much better development path than the one designed by a couple random congressmen aided by Boeing's lobbying, but there's still a problem with this: Orion would still be the same as the real one, which despite two decades of development still doesn't have flight ready ECLSS for Artemis I, which means you put people on it until the 2020s even with Jupiter

[sevenperforce]

4 hours ago, Beccab said:

I agree that this would have been a much better development path than the one designed by a couple random congressmen aided by Boeing's lobbying, but there's still a problem with this: Orion would still be the same as the real one, which despite two decades of development still doesn't have flight ready ECLSS for Artemis I, which means you put people on it until the 2020s even with Jupiter

I would hope that in an alternate universe where we didn't spend decades and a zillion bucks on trying to make pork fly, we would have managed to get Orion working by now.

[SunlitZelkova]

5 hours ago, Beccab said:

I agree that this would have been a much better development path than the one designed by a couple random congressmen aided by Boeing's lobbying, but there's still a problem with this: Orion would still be the same as the real one, which despite two decades of development still doesn't have flight ready ECLSS for Artemis I, which means you put people on it until the 2020s even with Jupiter

How would you put people on it without ECLSS?

1 hour ago, sevenperforce said:

I would hope that in an alternate universe where we didn't spend decades and a zillion bucks on trying to make pork fly, we would have managed to get Orion working by now.

Was there a pork problem with Orion too? Considering the development time for the CSM one would think it would have been ready.

Or was it a victim of the changes from Constellation to ARM to Artemis?

[sevenperforce]

23 minutes ago, SunlitZelkova said:

How would you put people on it without ECLSS?

I think that was a typo; @Beccab meant we wouldn’t have been able to put people onto it until the 2020s.

24 minutes ago, SunlitZelkova said:

Was there a pork problem with Orion too? Considering the development time for the CSM one would think it would have been ready.

Or was it a victim of the changes from Constellation to ARM to Artemis?

There’s a bit of a pork problem inherent with Orion, but repeatedly changing the mission profile and requirements certainly didn’t help.

Originally, Ares I was supposed to do double duty: sending a clean-sheet-design Crew Exploration Vehicle to the ISS periodically and setting the CEV up for lunar sorties with Altair on Ares V. But of course Ares I was a terrible idea and never had a workable upper stage, and building a CEV (which became Orion) for cislunar operations was overkill for the ISS. 

If we had transitioned to an immediately-flyable Shuttle-derived architecture like Shuttle-C or Jupiter-DIRECT, without immediately worrying about rating the clean-sheet crew vehicle for cislunar operations, we could have had an Orion Lite flying to the ISS shortly after the last flight of the Shuttle. And then we could have focused on upgrading Orion Lite to allow cislunar operations rather than pushing out development endlessly.

By now Orion would be a mature crew vehicle and we could have upgraded the service module to make it actually useful BLEO, and we could have a workable deep space crew lander based on the Orion pressure vessel and ECLSS. A service module large enough to take Orion from TLI to LLO and back to earth interface would be approximately the right size to take an Orion-based lander capsule from the lunar surface to LLO.

Instead we have a 23-billion-dollar monstrosity sitting on the launch pad, that can’t even execute a proper wet dress rehearsal, without a functioning capsule, with the only “Shuttle-Derived” elements being the rebuilt engines that cost more than brand new ones.

[tater]

 

[Autochrome]

Just a question, how many RS-25s can SLS Block 1 lose during ascent and still get to orbit? I would think it could get to orbit still on three or two engines, but I might be wrong about that.

[Beccab]

7 minutes ago, Autochrome said:

Just a question, how many RS-25s can SLS Block 1 lose during ascent and still get to orbit? I would think it could get to orbit still on three or two engines, but I might be wrong about that.

It has a single engine out capability, which means it can get to orbit almost always with 3 engines, but this impacts the mission profile since unless it happens very late into the flight it will either get to a highly elliptic Earth orbit or even only to LEO

[sevenperforce]

8 minutes ago, Autochrome said:

Just a question, how many RS-25s can SLS Block 1 lose during ascent and still get to orbit? I would think it could get to orbit still on three or two engines, but I might be wrong about that.

The SLS can manage a single engine loss, as long as it doesn't happen too early in flight.

Once SLS is past the initial flight phase, an early engine loss on Artemis I would result in an alternative mission profile to put ICPS and Orion into as lofted a trajectory as possible, thus allowing an accelerated heat shield test without a lunar flyby. If the engine loss happened later in flight, it would do an adjusted MECO but otherwise largely fly the same mission. Late in flight, it can press on to expected MECO just by differential throttling.

Loss of more than one engine would be a commanded abort.

Here's more discussion of that from NASA:

https://ntrs.nasa.gov/api/citations/20205001579/downloads/SLS Engine Out.pdf

[Autochrome]

And for Block IB, I assume it would have no engine out capability early in-flight, because of the heavier mass of the upper stage? Or would it still be able to compensate with the EUS for the first stage thrust under-performance? 

[Beccab]

24 minutes ago, Autochrome said:

And for Block IB, I assume it would have no engine out capability early in-flight, because of the heavier mass of the upper stage? Or would it still be able to compensate with the EUS for the first stage thrust under-performance? 

This is just speculation, but I'd say with Block 1B you could definitely have some issues with an early SSME shutdown

[Beccab]

I'm sorry but this is just too funny. I can't help but imagine the guy behind the PR laughing while sending 15 fully blacked pages of SLS timelines

[Autochrome]

1 hour ago, Beccab said:

This is just speculation, but I'd say with Block 1B you could definitely have some issues with an early SSME shutdown

Might be better than SLS Block I with the ICPS, because the EUS has more fuel to compensate with if the payload is only just Orion. The ICPS is so underpowered it can't even send the Orion all the way to the Moon on a nominal flight, as the Orion has to perform the final burn for TLI for the first few missions that use the Block I.

[sevenperforce]

2 hours ago, Beccab said:

2 hours ago, Autochrome said:

And for Block IB, I assume it would have no engine out capability early in-flight, because of the heavier mass of the upper stage? Or would it still be able to compensate with the EUS for the first stage thrust under-performance? 

This is just speculation, but I'd say with Block 1B you could definitely have some issues with an early SSME shutdown

I don't think this is likely to be an issue. It certainly won't be an issue before booster separation. At booster separation, SLS has burned less than 27% of its propellant load, so the core still weighs in at a whopping 814 tonnes, plus Orion's 33 tonnes including the abort tower. The difference between EUS (~140 tonnes) and ICPS (~31 tonnes) is significant, but at booster separation Block 1B only weighs about 12% more which shouldn't be enough to cause problems. Plus, Block 1B can fly a less lofted trajectory due to the higher thrust on EUS.

[tater]

That's as close as they can get the date, huh?

 

 

 

[tater]

 

[tater]

The middle of August is out, so it has to be the beginning, or end. The 2 months where the most tropical storms impact FL are September, followed by August. September also has the middle of the month not possible (launch windows).

[tater]

 

[tater]

 

[tater]

I'm hearing late Aug early Sept earliest for launch

 

Edited June 5, 2022 by tater

[tater]

 

[tater]

https://www.tmahlmann.com/2022/06/346-3-mp-pano-sls-ready-for-another-wdr/

Giant zoomable SLS image

[Aerodynamic Kerbal]

21 minutes ago, tater said:

https://www.tmahlmann.com/2022/06/346-3-mp-pano-sls-ready-for-another-wdr/

Giant zoomable SLS image

I refuse to believe that humanity has upgraded its technologies so far that now we have this.

Just imagine how great actual James Webb pictures will be!

[tater]

 

[tater]