_Augustus_

NASA SLS/Orion/Payloads

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1 hour ago, Canopus said:

Can we please leave this artificial feud between SpaceX and Nasa out of this thread? 

Better yet can we just leave Space X's Mars dreams out of the thread, it seems to permeate all threads ad nausea and has been rehashed over and over again.

 

Well the RL10b-2 which only ways 277 kg is 13.6 ft long about the same length, and 7 feet across (about 1 foot less wide). Maybe the presenter does not understand too much about rocket engines.
Size is not a useful metric, thrust, ISP, expansion ratios, chamber pressure and mass are.

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Agreed. This is about SLS stuff.

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1 hour ago, Starman4308 said:

The other major issue with the RS-25 is that it's even less fit for expendable use. The magnificent performance obtained by the RS-25 came at the cost of being one of the most complicated engines ever produced. Not really economical to refurbish, comically expensive to just throw away like the SLS plans to.

I dunno. The Merlin engine just sent something to a Mars-crossing orbit. While technically speaking the Shuttle was used for missions like Galileo, that was all with the assistance of the IUS: the RS-25 itself never left LEO.

Historically, then, the record seems to be in favor of the company you seem to rag on so much.

The whole idea of re-using Shuttle components to save money is incredibly stupid, as re-certifying/upgrading the RS25 and boosters costs so much and takes so long. 

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1 hour ago, _Augustus_ said:

The whole idea of re-using Shuttle components to save money is incredibly stupid, as re-certifying/upgrading the RS25 and boosters costs so much and takes so long. 

What makes you think designing, building and certifying a completely new engine and booster would cost less and take less time?  

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3 hours ago, Bill Phil said:

To be fair, the RS-25 is an excellent engine. It has decent sea level isp and high vacuum isp. With 70s technology. It's behind the curve in the modern world, yes, but it's performance is quite high. 

It's not really fit for reuse, though, as they learned from the Shuttle program. 

It's certainly impressive that they got so much performance out of the RS25. But did they do so economically? Does the application depend on squeezing every last drop of usable performance out of the engine? Why won't a cheaper, less efficient engine with a denser fuel or slightly larger tank do? There's no point in building a Bugatti Veyron if a Ford Transit will do.

Maybe the RS25 was the closest they could get to a solution for shuttle, but even then it didn't quite work. 

For an expendable first stage engine it's wholly unsuited.

And then treating the test due of an engine that probably wasn't even built this century as a milestone. SMH.

SLS certainly isn't going to Mars. It can't loft enough mass in one go for an Apollo-style mission to the red planet, and it can't be constructed fast enough to enable on-orbit construction of a mothership. The upper stage propellant would simply boil off before the next launch was ready, and it would take more than one launch worth of upper stage propellant to perform the TMI. For the same reason it's questionable it can even land us back on the moon. Even if NASA had the funding to develop the landers and habs it would require.

It's sad to see NASA reduced to this. It's not even NASA's fault.

Edited by RCgothic

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7 minutes ago, RCgothic said:

And then treating the test due of an engine that probably wasn't even built this century as a milestone. SMH.

The video said the RS-25 engine has been significantly modified and upgraded for its new mission. If an engine is significantly modified and upgraded that's a milestone in my book. 

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3 minutes ago, Kerbal7 said:

The video said the RS-25 engine has been significantly modified and upgraded for its new mission. If an engine is significantly modified and upgraded that's a milestone in my book. 

So now you've got an engine specification that's never been flown before negating the safety argument and you've spent even more money on redesigning, stripping it down and rebuilding it. 

It was a Ferrari. Now it's a Koenigsegg. What would be appropriate is a Mercedes-Benz Actros.

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11 minutes ago, RCgothic said:

So now you've got an engine specification that's never been flown before negating the safety argument and you've spent even more money on redesigning, stripping it down and rebuilding it. 

I'm sure the engine will be extensively tested for safety before it ever gets put out to fly. If I'm significantly modifying and upgrading an engine for a new mission I am expecting it to cost money. And I've seen no reason to think designing and building a completely new engine would have been a cheaper route.

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45 minutes ago, Kerbal7 said:

I'm sure the engine will be extensively tested for safety before it ever gets put out to fly. If I'm significantly modifying and upgrading an engine for a new mission I am expecting it to cost money. And I've seen no reason to think designing and building a completely new engine would have been a cheaper route.

SpaceX has marginally upgraded Merlin for Falcon 9, Block 5, so they have to fly it successfully, unmanned 5 times in a row before it gets man-rated. Doesn't this upgrade un man-rate RS-25? Why not? If F9 changed S2, can they fly astronauts on the first flight of a new S2 (EM-2 will fly people on the first flight of their EUS)?

Most of the cost arguments for SLS/Orion discuss safety, etc, yet it meets less rigorous testing standards. I'd understand using the large amount of Shuttle era data---had they not modified the engines at all, or if the EUS used shuttle OMS, instead of a stage that has never flown before at all.

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6 minutes ago, tater said:

SpaceX has marginally upgraded Merlin for Falcon 9, Block 5, so they have to fly it successfully, unmanned 5 times in a row before it gets man-rated. Doesn't this upgrade un man-rate RS-25? Why not? If F9 changed S2, can they fly astronauts on the first flight of a new S2 (EM-2 will fly people on the first flight of their EUS)?

Most of the cost arguments for SLS/Orion discuss safety, etc, yet it meets less rigorous testing standards. I'd understand using the large amount of Shuttle era data---had they not modified the engines at all, or if the EUS used shuttle OMS, instead of a stage that has never flown before at all.

OMS is hypergolic so not a good choice for a Hydrolox upper stage. You also have to remember that EUS is flown with Europa clipper before EM-2 and the RL10 is already man-rated because it also has to carry the Starliner to orbit.

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7 minutes ago, Canopus said:

OMS is hypergolic so not a good choice for a Hydrolox upper stage. You also have to remember that EUS is flown with Europa clipper before EM-2 and the RL10 is already man-rated because it also has to carry the Starliner to orbit.

The CST-100 upper stage will be flown for the first time ever on Atlas V on the unmanned CST-100 demo flight. It has flown only once before, on Atlas III.

Individual components can be man-rated, but apparently so does the entire stack, or specific stages in the case of SpaceX, but NOT in the case of other providers. I'm all for rigorous standards, but they seem arbitrary.

Vacuum Merlin has flown dozens of times now, and I'm not sure if they've had any failures of the engine. M1D, also seems pretty reliable, considering every one is fired multiple times, and there are 9 per vehicle. They've literally been tested many hundreds of times full duration. None the less, marginal stage changes require man-rating. Substantial stage changes on Atlas? No effect. Flying crew on the very first "all-up" stack of SLS? No problem.

Edited by tater

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7 minutes ago, tater said:

The CST-100 upper stage will be flown for the first time ever on Atlas V on the unmanned CST-100 demo flight. It has flown only once before, on Atlas III.

I think it has actually never flown before. This new 2 engine centaur is called Centaur-5-DEC and the stage flown on Atlas 3 was called Centaur-3 DEC and it was shorter. So you definitely have a point.

Edited by Canopus

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1 minute ago, Canopus said:

I think it has actually never flown before. This new 2 engine centaur is called Centaur-5-DEC and the stage flown on Atlas 3 was called Centaur-3 DEC and it was shorter. So you definitely have a point.

Wow, you're right. Least they have flown a 2-engine variant, lol.

 

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35 minutes ago, tater said:

SpaceX has marginally upgraded Merlin for Falcon 9, Block 5, so they have to fly it successfully, unmanned 5 times in a row before it gets man-rated. Doesn't this upgrade un man-rate RS-25? Why not? If F9 changed S2, can they fly astronauts on the first flight of a new S2 (EM-2 will fly people on the first flight of their EUS)?

Most of the cost arguments for SLS/Orion discuss safety, etc, yet it meets less rigorous testing standards. I'd understand using the large amount of Shuttle era data---had they not modified the engines at all, or if the EUS used shuttle OMS, instead of a stage that has never flown before at all.

Do you seriously think SLS is going to launch 5 times?  Of course, the White House may tell NASA to put astronauts on the first mission (this has certainly been suggested), but I can't see NASA following those rules themselves.  The shuttle flew manned from day one (although this was certainly a design flaw, Buran [and all other US manned rockets] could fly unmanned), but this doesn't mean it was a good idea.

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1 minute ago, tater said:

Wow, you're right. Least they have flown a 2-engine variant, lol.

 

It seems that before Atlas 3, all Centaurs flew with two engines.

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2 minutes ago, wumpus said:

Do you seriously think SLS is going to launch 5 times?

I'm unsure how many times it will fly. Flying crew early is partially because NASA doesn't have the money to pay for 5 tests, or payloads. They cannot increase cadence, either. 1 per year is about the best possible case, and when proposed they said it needed to fly 2X per year to make any sense.

 

Just now, Canopus said:

It seems that before Atlas 3, all Centaurs flew with two engines.

Yeah, I meant a version of this stage (same diameter, etc).

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27 minutes ago, wumpus said:

Do you seriously think SLS is going to launch 5 times?

Yep. I do.

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31 minutes ago, wumpus said:

Do you seriously think SLS is going to launch 5 times? 

Otherwise where should they put all that stuff?

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32 minutes ago, tater said:

Flying crew early is partially because NASA doesn't have the money to pay for 5 tests, or payloads.

Space shuttle is over. The ISS is coming down or being handed over to private actors. They'll have the money.

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2 minutes ago, Kerbal7 said:

Space shuttle is over. The ISS is coming down or being handed over to private actors. They'll have the money.

No they won't. ISS is ~2 B$/yr, much of which is the resupply launch budget.

You can look at the SLS flight manifest (proposed). EM-1 is the ONLY test flight. The SM is not the real thing (no life support), nor is the Orion capsule a full flight article.

SLS has NO all-up test flights. None. Assuming Europa Clipper uses SLS (not certain, BTW, they said yesterday they were open to other LVs), then the first all-up stack will be with a godawful expensive payload on top.

The SLS program costs about as much as ISS/Shuttle to run each year, even doing nothing yet. So ~2 B$/yr. So until 2025, NASA has to spend on both. Starting SLS payload dev in 2025 because money is freed up, means nothing done by NASA would be seen til when? 2035? 2040? Do you really think SLS will still be flying then?

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3 hours ago, Kerbal7 said:

What makes you think designing, building and certifying a completely new engine and booster would cost less and take less time?  

SpaceX.

2 minutes ago, tater said:

Do you really think SLS will still be flying then?

Exactly.  They'll lauch EM-1, EM-2, and Clipper, then there will be no point.

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2 minutes ago, DAL59 said:

Exactly.  They'll lauch EM-1, EM-2, and Clipper, then there will be no point.

Where will the Point go?

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6 minutes ago, tater said:

No they won't. ISS

NASA won't what? Bring down the ISS? 

7 minutes ago, DAL59 said:

SpaceX.

SpaceX is a contractor for NASA. It's had lots of help from NASA and government subsidies all along the way to develop their capabilities. 

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11 minutes ago, Canopus said:

Where will the Point go?

BFR and NG.  

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9 minutes ago, Kerbal7 said:

NASA won't what? Bring down the ISS? 

 

25 minutes ago, Kerbal7 said:

They'll have the money.

No, they won't (have the money). I then told you why they would not have the money.

1 minute ago, DAL59 said:

BFR and NG.  

SLS will only get killed when it is demonstrably thrashed by other vehicles, not before. NG and BFR will have to be operating, really operating, then SLS likely dies.

Boeing and SpaceX could obviate the need for Orion as well, honestly. CST-100 was originally a bid for the same contract that Lockheed Martin won for Orion, after all. It was designed for the same job.

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