NASA SLS/Orion/Payloads

[tater]

24 minutes ago, _Augustus_ said:

Nope. SLS is a rocket that could literally have been built in the 1970s with the exception of the avionics. No reuse of even the boosters, which is actually a step backwards because they did that with the Shuttle.

They're not reflying the boosters? Wow. I knew that was likely never cost effective anyway, but that's pretty funny given the fact  that the boosters retain the segments that were the cause of the Challenger loss.

[Canopus]

27 minutes ago, _Augustus_ said:

Nope. SLS is a rocket that could literally have been built in the 1970s with the exception of the avionics. No reuse of even the boosters, which is actually a step backwards because they did that with the Shuttle.

Nothing was won by reusing the Boosters. So not a step back.

[tater]

5 minutes ago, Canopus said:

Nothing was won by reusing the Boosters. So not a step back.

Agreed, nothing about Shuttle really saved money. That said, why use boosters with the same failure mode? The segmented nature was because they had to be refurbished and refilled, at least in part. Why not a single part booster with no segmented failure mode?

 

Aerojet offered a non-segmented SRB for Shuttle, for example, but they were in the wrong district... why intentionally add a failure mode known to have caused a LOC incident?

Edited January 18, 2018 by tater

[DerekL1963]

55 minutes ago, tater said:

Why not a single part booster with no segmented failure mode?

Because the SLS was designed to maximize employment in key congressional districts re-use of Shuttle components.

But even if it wasn't, we still haven't solved the issues with large monolithic solids that lead them to spec segmented solids in the first place.  (Some of them probably aren't solvable.)

 

1 hour ago, tater said:

the boosters retain the segments that were the cause of the Challenger loss.

Soyuz retained the parachutes and the re-pressurization valve that killed two crews.  Apollo retained the O2 tank that nearly killed a crew....  Which is basically a snarky way of saying it's not the segments that caused the loss but poor joint design (it's much more than the O-rings).  That joint hasn't flown since 1986.  The replacement has flown, without failure, 176 times.

[DAL59]

The SSMEs are great engines: reusable, restartable, and extremely high isp.  Now they are going to use them up, wasting the reuse capability, in just 4 launches. Though of course, it will be while...      

[Bill Phil]

31 minutes ago, DAL59 said:

The SSMEs are great engines: reusable, restartable, and extremely high isp.  Now they are going to use them up, wasting the reuse capability, in just 4 launches. Though of course, it will be while...      

Those SSMEs are quite finicky. Really, the only problem is that they're not using 5 of them on the core. According to some guys at Marshall, that would alleviate a lot of issues.

[Nibb31]

36 minutes ago, Bill Phil said:

Those SSMEs are quite finicky. Really, the only problem is that they're not using 5 of them on the core. According to some guys at Marshall, that would alleviate a lot of issues.

If they did that, they would run out of them before the end of the program.

[PB666]

5 hours ago, DerekL1963 said:

Soyuz retained the parachutes and the re-pressurization valve that killed two crews.  Apollo retained the O2 tank that nearly killed a crew....  Which is basically a snarky way of saying it's not the segments that caused the loss but poor joint design (it's much more than the O-rings).  That joint hasn't flown since 1986.  The replacement has flown, without failure, 176 times.

Yes, but by artificially limiting the launch windows that would not affect other rockets (as much*)

*While most rockets would not be affected by low outside temperatures, at some-point high altitude windsheer is dangerous to all craft because it alters the angle of attack of a hypersonic vehicle and can cause those pesky destructive aerodynamic forces that are talked about in the STS51-L 'event'.

[Bill Phil]

16 minutes ago, Nibb31 said:

If they did that, they would run out of them before the end of the program.

They're already going to run out of them before the end of the program, since they plan on flying more than 4 times. I'd say get the old engines out of the way ASAP, and replace them with a new variant.

[_Augustus_]

53 minutes ago, Bill Phil said:

They're already going to run out of them before the end of the program, since they plan on flying more than 4 times. I'd say get the old engines out of the way ASAP, and replace them with a new variant.

IMO reusing the RS25s is pointless. It's just as expensive to refurbish/test the existing ones, and restarting production will be ridiculous. They should've used RS68 like Ares or developed a new engine, maybe powered by methalox, that can either be returned like Vulcan's engines or is cheap enough to throw away.

[tater]

The entire point of using shuttle components was to streamline things by having stuff already characterized as man-rated. They’ve long since wasted any streamlining (if any) hey gained.

for the ~40 billion they will have spent by the time of EM-1, they could have built a clean sheet design with many innovations.

[sh1pman]

16 minutes ago, tater said:

The entire point of using shuttle components was to streamline things by having stuff already characterized as man-rated. They’ve long since wasted any streamlining (if any) hey gained.

for the ~40 billion they will have spent by the time of EM-1, they could have built a clean sheet design with many innovations.

Don’t even need to make their own design, just pump these 40bn into SpaceX and BO, and get much better SHLVs (BFR and NG) much faster. 

That would, of course, leave a lot of shuttle contractors unhappy. And thousands of jobs cut.

[tater]

That’s not how NASA works. On programs like that, it’s one company makes the capsule, another the SM, yet another the upper stage, and so forth.

You have to remember that it’s not like they have XX billion over Y years, then they spend it. They get money to spend precisely because the contractors are spread in different districts.

The new space way would require a totally new paradigm of procurement and project management.

Edited January 19, 2018 by tater

[Nibb31]

8 hours ago, Bill Phil said:

They're already going to run out of them before the end of the program, since they plan on flying more than 4 times. I'd say get the old engines out of the way ASAP, and replace them with a new variant.

They don't have more than 4 flights in the manifest at this point. We'll have to wait until 2024 or later to see if it's worth restarting RS-25 production or moving on to a new pork barrel. My hunch is that we will not see new RS-25s.

[PB666]

11 hours ago, tater said:

That’s not how NASA works. On programs like that, it’s one company makes the capsule, another the SM, yet another the upper stage, and so forth.

You have to remember that it’s not like they have XX billion over Y years, then they spend it. They get money to spend precisely because the contractors are spread in different districts.

The new space way would require a totally new paradigm of procurement and project management.

That's why is better for NASA to contract out services, not part's procurement.

[_Augustus_]

7 hours ago, Nibb31 said:

They don't have more than 4 flights in the manifest at this point. We'll have to wait until 2024 or later to see if it's worth restarting RS-25 production or moving on to a new pork barrel. My hunch is that we will not see new RS-25s.

At the rate that flights are being delayed EM-3 could be in the late 2020s. I would be surprised to see a flight after Europa Clipper or EM-2 since BFR will be running by 2027 at the latest.

[tater]

I'd wait til at least the FH static fire to be very optimistic about BFR flying in any particular timeframe. If 27 engines turns out to be an issue, BFR is likely back to the drawing board.

[PB666]

1 hour ago, tater said:

I'd wait til at least the FH static fire to be very optimistic about BFR flying in any particular timeframe. If 27 engines turns out to be an issue, BFR is likely back to the drawing board.

What are you expecting the problem to be, heat trapping?

I think with 27 engines it would me like a wall of thrust versus point thrust so I would think that some of the density-waveform issues would cancel each other out. The way to avoid this is to make sure that turbopumps are not all matching Θ as they turn. You just put a sensor on the axle that then makes sure that theta of all the pumps are spread over 2pi/symmetry by using a dampener (for example momentarily attenuating fuel flow to the turbine preburning by  a few percent. 

The only problem I could foresee is that if the engines are not tuned properly you could get resonance between the engines (this could actually be carried through the gimbaling system which is why its probabiy good to limit gimble functionality to the core during ascent and activate gimble on the boosters during RTLS).

Edited January 19, 2018 by PB666

[magnemoe]

On 18.1.2018 at 4:20 PM, _Augustus_ said:

Nope. SLS is a rocket that could literally have been built in the 1970s with the exception of the avionics. No reuse of even the boosters, which is actually a step backwards because they did that with the Shuttle.

This, now the exiting thing happened with boosters is reuse. This will inprove and move to second stage in next generation. 
Now you can run an space program for prestige and to launch your spy satellites if you don't trust the US, EU, Russia or China. 
In this case you probably have bigger problems. Note it make sense for India, Brazil and Israel to have their own spy satellites but it would be expensive birds. 
 

[Canopus]

https://www.sncorp.com/press-releases/snc-nasa-sign-two-nextstep-2-contracts/

[_Augustus_]

31 minutes ago, Canopus said:

https://www.sncorp.com/press-releases/snc-nasa-sign-two-nextstep-2-contracts/

I thought DSG was dead.......

[Canopus]

9 minutes ago, _Augustus_ said:

I thought DSG was dead.......

Don‘t know where you got that idea from. DSG seems to be guaranteed to happen.

Edited January 27, 2018 by Canopus

[tater]

They’ve been pushing dsg as the busy work for SLS/Orion.

Presumably the talk of dumping ISS in 2025 is related.

[Canopus]

https://www.nasa.gov/sites/default/files/atoms/files/nextstep-2-isru-baa-industry-forum_11dec2017_0.pdf 

Also interesting

[DDE]

19 hours ago, tater said:

They’ve been pushing dsg as the busy work for SLS/Orion.

Presumably the talk of dumping ISS in 2025 is related.

The date under Obama was 2024, mind you; and DSG existed in some form for a decade. I'm really annoyed at all the coverage slyly implying that Trump is out to destroy the ISS.