[New] Space Launch System / Orion Discussion Thread

[tater]

2 hours ago, linuxgurugamer said:

Frankly, I think you are bashing them too much.  It's a brand new system, new hardware in many areas, and there have only been a couple of scrubs.  Don't bash them for what are normal development glitches.

My issue is with some of the decision making made a long time ago, I expect teething issues.

They must have known that LH2 could present problems, so over a decade, with 10s of billions spent... make a simple test tank large enough to test fast fill. Slap a QD connect on that puppy, and beat the heck out of it for years, so that when the real McCoy arrives, it's old hat.

[SunlitZelkova]

3 hours ago, intelliCom said:

This too. Also, for being a lot of re-used tech, it sure does seem to have a lot of unusual issues that never plagued its predecessor (the shuttle), doesn't it?

Well, it is only “reused” to a certain extent. tater put it best in a post awhile back.

On 9/3/2022 at 10:08 AM, tater said:

LOL.

Horse very, very dead

Suffice it to say that at the time SLS became a thing, the alternative would have been RP-1 (no methalox engines around)—but that would have been clean sheet. SLS of course is functionally a clean sheet, as any similarity to Shuttle components is nonsense.

The SRBs are—except they changed them to 5 segment, so they started from scratch.

The main tank is! Except they scrapped the External tank tooling, and completely redid it (at great cost), so they might as well have picked a tank diameter that was optimal.

The SSMEs are Shuttle! Except they were reworked at a cost for each that greatly exceeded their cost NEW.

Literally nothing on SLS is so Shuttle derived it was used "off the shelf." As a result, they should have simply stated lift/TLI/whatever requirements, and gone clean sheet—in which case yeah, RP-1 all the way, sustainer architectures are lousy.

It may as well be an entirely new rocket. I think it is really, really, dumb they didn’t just go with something akin Shuttle-C, which would have used identical ground infrastructure to the Shuttle.

A different vehicle would have to be used for crew, although I think DIRECT showed that a side slung Orion would have been possible.

[Beccab]

One thing to note is that there's another rocket that, despite being very old by now, mostly avoided these LH2 leaks problem: the Ariane 5 had a prototype tank built for it so that while the rest of the rocket was still being built they addressed the leaks and problems found by testing it with the pad GSE. This didn't happen with SLS, and I'm pretty sure it didn't with Shuttle either

[RCgothic]

It's the combination of being both heinously expensive and therefore also penny-pinching.

Any other programme with this budget would have had this sorted.

[Barzon]

7 hours ago, SunlitZelkova said:

It may as well be an entirely new rocket. I think it is really, really, dumb they didn’t just go with something akin Shuttle-C, which would have used identical ground infrastructure to the Shuttle.

 

Shuttle C has awful growth options. Hanging off the side of the tank really limits what you can do with an EDS.

[tater]

9 minutes ago, Barzon said:

Shuttle C has awful growth options. Hanging off the side of the tank really limits what you can do with an EDS.

SLS has no growth options that matter, either. It can either send enough to TLI to do a 1 stack lunar mission or it can't.

 

[sevenperforce]

15 minutes ago, Barzon said:

Shuttle C has awful growth options. Hanging off the side of the tank really limits what you can do with an EDS.

Shuttle C at least keeps your pad running long enough to come up with a smooth transition to DIRECT.

[tater]

Just now, sevenperforce said:

Shuttle C at least keeps your pad running long enough to come up with a smooth transition to DIRECT.

It also has the nice side effect of making lunar architectures EOR based. Use all that standing LEO capability to leverage a mission to the Moon/etc, instead of being saddled with bizarre distant lunar orbits you can only visit every few years.

[sevenperforce]

16 minutes ago, tater said:

It also has the nice side effect of making lunar architectures EOR based. Use all that standing LEO capability to leverage a mission to the Moon/etc, instead of being saddled with bizarre distant lunar orbits you can only visit every few years.

There was a time when we had the capability to keep an extra shuttle ready on the other pad for a rescue mission every time we launched. No reason we couldn’t have maintained both pads, transitioning one to Shuttle-C and one to DIRECT in order to ultimately set up for EOR lunar missions.

Shuttle-C would have been able to put 71 tonnes into LEO. That, surely, is sufficient for an all-hypergol lunar lander including LOI braking propellant. Combined in LEO with Orion launched on Jupiter-246, with the JUS upper stage performing the TLI for the whole stack, you surely would have had enough performance for the whole mission. 

[darthgently]

Is it simplistic to wonder if a Dreamchaser on an F9 could be on standby? A half dozen dockable TLI  modules could be staged in LEO in case it needed to go to the moon.  Thunderbirds are Go!

Edited September 22, 2022 by darthgently
Dreamliner on F9 would be cool, Dreamchaser is what I was going for

[sevenperforce]

6 hours ago, darthgently said:

Is it simplistic to wonder if a Dreamchaser on an F9 could be on standby? A half dozen dockable TLI  modules could be staged in LEO in case it needed to go to the moon. 

Good idea.

Unfortunately:

1. Dreamchaser's heat shield isn't rated for high-energy returns from the moon
2. Dreamchaser doesn't have enough propellant to enter or return from lunar orbit
3. There aren't any upper stages with storable propellants that have enough dV to push Dreamchaser into TLI. 

[darthgently]

8 minutes ago, sevenperforce said:

Good idea.

Unfortunately:

1. Dreamchaser's heat shield isn't rated for high-energy returns from the moon
2. Dreamchaser doesn't have enough propellant to enter or return from lunar orbit
3. There aren't any upper stages with storable propellants that have enough dV to push Dreamchaser into TLI. 

Negative thinking doesn't achieve anything, ha ha.  Thunderbirds!

[darthgently]

1 hour ago, sevenperforce said:

Good idea.

Unfortunately:

1. Dreamchaser's heat shield isn't rated for high-energy returns from the moon
2. Dreamchaser doesn't have enough propellant to enter or return from lunar orbit
3. There aren't any upper stages with storable propellants that have enough dV to push Dreamchaser into TLI. 

1.  Dreamchaser XL + looping inverted around the fringe of the atmo a few times as required using lift to pull earthward

2.,3. Vacuum SRBs staged in orbit 

4+.  Thunderbirds!  GO!

 

 

 

 

 

[kerbiloid]

6 hours ago, darthgently said:

.  Dreamchaser XL + looping inverted around the fringe of the atmo a few times

Inside the radiation belts and with poor to no ability to reenter at controlled angle of attack, so on the second or third reentering falling like a stone without chutes and at stone overloads.

6 hours ago, darthgently said:

Vacuum SRBs

Very low ISP, useful only on launch thanks to high thrust because military rocketeers need their piece of pie (originally NASA was planning liquid fueled boosters).

6 hours ago, darthgently said:

4+.  Thunderbirds!  GO!

Go-go, but first they need to find Tracy Island. It's a necessary condition.

[RCgothic]

Hurricane now forecast around Florida 27th/28th/29th.

Surely they have to roll back to the VAB. It's too big a risk to assume there won't be a scrub that strands SLS on the pad, or to assume the storm will pass by Kennedy.

The next viable launch opportunity would probably then be in November.

[tater]

 

I'm hearing rollback extremely likely.

 

[RCgothic]

This forcast is way too close for comfort. Plus storm force winds and cloud rules on the 27th guarantee SLS would still be on the pad on the 28th. Certain scrub.

 

 

Edited September 23, 2022 by RCgothic

[tater]

They still have a little time to pull the trigger on rollback. See when the thing turns.

[tater]

 

[tater]

 

[RCgothic]

80% weather violation on the 27th. It's clearly not happening. I expect the decision to roll back will be taken tomorrow.

[tater]

2 minutes ago, RCgothic said:

80% weather violation on the 27th. It's clearly not happening. I expect the decision to roll back will be taken tomorrow.

Yeah, waiting til they have no choice makes sense though. They don't want the thing to decide to track west, then look like morons.

[RCgothic]

They can always change their minds about the roll-back after prep is underway. Shuttle turned back to the pad half way to the VAB one time.

[RCgothic]

 

 

 

 

Edited September 23, 2022 by RCgothic

[RCgothic]