[New] Space Launch System / Orion Discussion Thread

[tater]

 

[RCgothic]

Surely they don't just go "that was fine, fly this thing" after exceeding rated maximums?

Surely there's a rollback for inspection after this?

Edit:

 

 

Edited November 10, 2022 by RCgothic

[Beccab]

 

[RCgothic]

Which is why you don't take chances with hurricanes. Better to be left looking stupid for being over-cautious than for the other way around.

Edited November 10, 2022 by RCgothic

[StrandedonEarth]

No need to inspect, just light that candle...

I mean really, how are they going to check for fatigue over that entire massive structure?

[RCgothic]

I wouldn't want to be the engineer trying to justify that decision to an accident board.

[Beccab]

20 minutes ago, StrandedonEarth said:

No need to inspect, just light that candle...

I mean really, how are they going to check for fatigue over that entire massive structure?

Ideally you wouldn't have to, because you'd delay the rollout of a couple days if there's the risk of a hurricane/tropical storm hitting Cape

[tater]

22 minutes ago, Beccab said:

Ideally you wouldn't have to, because you'd delay the rollout of a couple days if there's the risk of a hurricane/tropical storm hitting Cape

There wasn't a risk I think when they rolled out, but even if there was, they need an arbitrary time extension on the SRBs come December 9. (and I think that is already an extension)

 

5 hours ago, RCgothic said:

Surely they don't just go "that was fine, fly this thing" after exceeding rated maximums?

Surely there's a rollback for inspection after this?

There is no alternative where they don't have to say, "Yeah, those limits we set X years ago? We're gonna ignore those and go"

Wind, or rollbacks, or FTS battery life, or SRB stack time limits, or specifics of prop loading, etc, ad nauseum.

There is no way to inspect the vehicle either than rolling it back (which also stresses it), then having a bunch of guys look at it in the VAB and say, "Yeah, that looks like an SLS all right. We're good."

They can't even x-ray seams, since I think they'd at the least need to unstack the SRBs (assuming they can ignore the foam and various racetracks)

 

[Beccab]

2 minutes ago, tater said:

There wasn't a risk I think when they rolled out, but even if there was, they need an arbitrary time extension on the SRBs come December 9. (and I think that is already an extension)

We're actually already at the extension of an extension, since the first was until March this year and was extended of 6 months iirc, so September. So, in the event they don't launch in November (which I'm starting to believe at this point), we're looking for an extension of an extension of an extension

[tater]

18 minutes ago, Beccab said:

We're actually already at the extension of an extension, since the first was until March this year and was extended of 6 months iirc, so September. So, in the event they don't launch in November (which I'm starting to believe at this point), we're looking for an extension of an extension of an extension

Now they can blame the weather if there is a problem, not their multiple extensions!

[Beccab]

 

[cubinator]

I hope the safety factor is better than 1.01

[RCgothic]

https://arstechnica.com/science/2022/11/nasas-artemis-i-rocket-just-endured-hours-of-hurricane-like-wind-gusts/

 

 

[darthgently]

After all the taxpayer treasure and engineers' blood, sweat, and tears I really hope it wasn't damaged.

But if it is only mildly compromised with a 90-ish% chance of success,  I say go for it anyway.  At least we can get some Kerbal joy out of the dramatic tension as it soars upward

Edited November 10, 2022 by darthgently

[tater]

If they rolled it back over this, then they have to fly the next time they roll out or they are in the same boat, breaking "design limits."

OMG, "The rocket is designed to withstand 74.4-knot gusts." !

It's also "designed to withstand X round trips from the VAB" and "designed to be safe to fly the SRBs after they have been stacked 12 months  18 months some number of months we will know when we get there!"

 

[darthgently]

Given the hurricane prevalence in that area, the distance and time required for a rollback/rollout it might be worth having some way to quickly better shelter such a huge investment.   Something that could withstand the winds but be erected in half a day or less.  Maybe talk to the big tent companies that build those huge tensegrity structures, but make it hydraulically deployable from the ground surrounding the pad with a Kevlar and CF based fabric skin. 

The final form could be twice as wide as tall with cables extending 3x to 4x horizontally and secured to the ground and launch tower. The shape would deflect wind upwards and around sideways.  

Expensive, yes, but the givens suggest something feasible might be worth considering.

I'm just semi seriously pondering here

[RCgothic]

Well it would seem sensible to have a mobile service and hurricane shelter structure at the pad, but it was going to fly so infrequently that they wanted a clean pad for multi-user operation.

Of course that fell through, so now there's just no ability to service or shelter at the pad at all. And just as well nobody else wanted to use the pad with SLS hogging it for months on end!

Also going to mention that part of the reason transporting it is so difficult is because the SRBs are so heavy, so that's another self-inflicted design choice.

[tater]

Or the ML tower (they still need to build the second one, right? Or at least finish it) could have a strongback on the MLP.

The stress from rollbacks is the same concern as wind, the vehicle is attached to the ML at the base (hold downs). The pad is up a slope, so the top of the vehicle makes a known excursion vs when the ML is level (unsure how much if any self-leveling the ML does). Instead of measuring wind speeds, it would be more useful to put a sensor on the tip of the LES, then watch how the vehicle moves relative to the fixed base. Then they would have real world data they could model with.

Anyway, seems like at stage interfaces they could put attachments for a roll-away strongback. This would make the stack more rigid both for wind concerns, and for rollback operations.

[Beccab]

20 minutes ago, tater said:

they still need to build the second one, right? Or at least finish it

The first one was correct, construction hasn't even begun yet. Ugh, Bechtel

[darthgently]

I wonder if 2 or 3 F9s could replace those SRBs, lol

[tater]

17 minutes ago, Beccab said:

The first one was correct, construction hasn't even begun yet. Ugh, Bechtel

Then they could improve it... cept that would likely add 10 years of planning.

8 minutes ago, darthgently said:

I wonder if 2 or 3 F9s could replace those SRBs, lol

No.

F9 is ~7600kN thrust, each SRB is ~15,000kN. So you'd need 4. Plus a new ML, and all the associated GSE.

[RCgothic]

However if you did replace the two SRBs with 4xF9s, the boosters would be much lighter, cheaper, and the thrust would come at a higher ISP so they'd burn a similar length of time whilst still having a propellant reserve for landing for full reuse.

The performance of SLS would be enormously improved.

But you'd need to redesign everything such that it basically wasn't SLS anymore, and the rebuild of GSE would cost more than 20x falcon heavies, so...

[tater]

Gotta wonder what the real options are, if they actually worked within their constraints. Course they would have already unstacked the SRBs, and they'd not be in this situation, as it would not be flying til next year. But ignore THAT extension...

Say they rolled back to avoid hurricane. Next time they roll out they must fly, and before the 9th. So basically they roll out in a few days, and they fly, or not. If they don't fly for any reason, they go back, keep the parts they can keep, Orion, and ICPS, unstack the rest, throw the core away (saving the RS-25s), and refill and restack the SRBs. They use the Artemis II core and start over.

 

[darthgently]

30 minutes ago, tater said:

Then they could improve it... cept that would likely add 10 years of planning.

No.

F9 is ~7600kN thrust, each SRB is ~15,000kN. So you'd need 4. Plus a new ML, and all the associated GSE.

4 would look great landing in unison though

[RCgothic]

Wind speeds at various altitudes. Definite limit violations.