Boeing's Starliner

[Meecrob]

15 hours ago, tater said:

I don't pretend to understand all of the complexities behind NASA's communication strategy regarding Starliner. But from the outside it appears poor, and non-responsive. What I'm hearing is not great news, so that may explain the reticence to engage.

— Eric Berger (@SciGuySpace) May 21, 2024

_______________________________________________________________________________________________________________________________________________

 

I suspect that if they say anything, they will get bombarded with jokes about how the helium actually keeps the door attached (or some other joke about the door blowing off the MAX). Whether this is fair or not, the message of the press release will be overshadowed.

 

 

[tater]

 

[tater]

(what I was hearing earlier, but it was not for public consumption)

Guess I will watch on my phone (or wife's laptop) from London.

[tater]

This ticking clock issue reminds me of the SLS round trips from/to VAB issue, FTS battery replacement, etc. Seems plausible.

[kerbiloid]

Quote

We have slightly modified the valves

Before

Spoiler

After

Spoiler

[AckSed]

Summary (from here):

They didn't want to give updates before now because information was changing too quickly as they were working through the issues

There were three issues: the Centaur O2 leak, the Starliner helium leak, and a deorbit burn scenario that they found when considering the helium leak.

For the Centaur leak, they find that the valve had exceeded its rated number of cycles.

It was a complicated activity to change the valve, as Centaur is only stable under pressure or under tension, and they needed to depressurize it to change the valve

To put it under tension, they attached a crane to Starliner, which is how they install it so not an issue, but since, in addition to its own weight, it also had to apply tension to Centaur to stabilize it, they had to confirm it was capable of handling the extra strain.

For the helium flange, it sounds like it's a defective rubber seal (but they're not sure). After a few cycles, the leak rate got worse, but then stabilized. The flange is part of an assembly that is exposed to NTO, so they can't replace the seal without destacking Starliner and moving it to a place where that hazard can be neutralized.

The leak rate is low enough and stable enough that they are comfortable launching; even if the seal failed completely, they would still be comfortable with the leak rate. No other seals are leaking.

They had no way of noticing the leak during launch; they only noticed it during post-scrub operations. If they had launched, the mission would still have been safe and successful.

Nonetheless, they will fix it for Starliner-1.

The de-orbit scenario that they discovered is a rare one (0.7% of failure modes). They have two pairs of OMAC thrusters and would need to lose one of each pair, so that they had to deorbit using only RCS thrusters. On top of that, they would need to lose two helium manifolds immediately adjacent to each other. They did not have a plan for if this scenario occurred; now they do (instead of an 8-RCS-thruster burn, this scenario would require two 4-RCS-thruster burns).

Part of the delay until the next launch opportunity is so that the team, who have been working long hours and seven day weeks the past two weeks, get the long weekend off.

Nothing on the rocket or Starliner should expire until late June at the earliest (at which point the FTS pyrotechnics would need to be changed out). They're good to remain stacked until then.

The changes have impacted Starliner's interim human rating for CFT, so they're holding a Delta Flight Readiness Review to make sure that it still qualifies for human rating with the changes. The FRR will be Wednesday, May 29.

[lajoswinkler]

One hour until launch.

 

I hope the front doesn't fall off.

 

[tater]

Getting close. Showed wife, and she said the stack looks like a rectal stapler. Since I have to be horrified such a thing exists, so do you all  

[Minmus Taster]

5 minutes ago, tater said:

Getting close. Showed wife, and she said the stack looks like a rectal stapler. Since I have to be horrified such a thing exists, so do you all  

One second let me consult Urban Dictionary on this..

T-5 Minutes

Issue?

[tater]

Hold, so no trip today

[mikegarrison]

From NASA:

NASA, Boeing, and ULA (United Launch Alliance) scrubbed today’s launch opportunity due to the computer ground launch sequencer not loading into the correct operational configuration after proceeding into terminal count.

Next attempt is tomorrow, assuming they figure out what caused the problem and fix it.

Edited June 1, 2024 by mikegarrison

[CBase]

1 hour ago, mikegarrison said:

due to the computer ground launch sequencer not loading into the correct operational configuration

Okay seriously are there more than one correct configurations before ground sequencer takes over control ? Did really nobody believed that starliner would make it that far and double checked the loaded configuration ?

Come on we never see it fly if we stumble over studded visors or such stuff

[mikegarrison]

Now skipping tomorrow in order to have more time to try to fix the launch computer issue. Current target date in June 3.

I don't know why they need these launch computers anyway. What always worked for me was to watch the timer count down and then hit the spacebar.

[Ultimate Steve]

19 minutes ago, mikegarrison said:

Now skipping tomorrow in order to have more time to try to fix the launch computer issue. Current target date in June 3.

I don't know why they need these launch computers anyway. What always worked for me was to watch the timer count down and then hit the spacebar.

That's the issue, the space bar is broken.

[kerbiloid]

  From the Movie Cliches that NEED to Die! thread.

On 5/12/2024 at 7:47 PM, Fizzlebop Smith said:

THE COUNTDOWN

I want to look away whenever I see a countdown. It is like a car wreck or those indie skateboarder videos from the 90s where you look on in dread hoping to see / not see a compound fracture. What happened to appropriately timed segue with a well done track or score? Each and every time I see a bomb (on screen) with a timer ticking away to that fateful moment, I begin taking bets in my head on when the timer will finally stop.
Based on the tone of the movie / show up to that point, the perceived subtlety of those writing and the quality of the music to try and anticipate where the time will stop.
<...>
I sincerely wish bomb scenes / countdowns in general would get a facelift

Do you see, @Fizzlebop Smith, what have you done there?

The whole NASA can't launch rockets after they had followed your advice and touched the countdown sequence...

I hope, you are happy now!

[CBase]

Quote

. All three computers must be fully functioning in the final phase of the countdown to ensure triple redundancy. At the moment of liftoff, these computers control things like retracting umbilical lines and releasing bolts holding the rocket to its mobile launch platform.

Two of the computers activated as the final countdown sequence began at T-minus 4 minutes. A single card in the third computer took about six more seconds to come online, although it did boot up eventually, Bruno said.

"Two came up normally and the third one came up, but it was slow to come up, and that tripped a red line," he said.

From https://arstechnica.com/space/2024/06/boeings-starliner-test-flight-scrubbed-again-after-hold-in-final-countdown/?comments=1&comments-page=1

So tripple redundancy is actually tripple fault triggers regarding the computer itself. Although it was not a problem in the past, it sounds like an area of improvement if they want higher flight reliability.

8 hours ago, Ultimate Steve said:

Current target date in June 3.

*fingers crossed*

[Meecrob]

13 hours ago, mikegarrison said:

I don't know why they need these launch computers anyway. What always worked for me was to watch the timer count down and then hit the spacebar.

This statement requires engraving on a plaque

o7

4 hours ago, CBase said:

*fingers crossed*

You and me both!

[kerbiloid]

8 hours ago, CBase said:

Two of the computers activated as the final countdown sequence began at T-minus 4 minutes. A single card in the third computer took about six more seconds to come online

Damned splashscreens...

Spoiler

Having disabled them on two, but forgot on the third one.

 

Btw, SLS also should not smile too much.

Spoiler

Edited June 2, 2024 by kerbiloid

[CBase]

From Boeings official page:

Quote

NASA’s Boeing Crew Flight Test mission teams are preparing to support a launch at 10:52 a.m. EDT Wednesday, June 5

 

[Codraroll]

June 5, huh? Looks like it will be the second most interesting flight that day.

[Flavio hc16]

16 minutes ago, Codraroll said:

June 5, huh? Looks like it will be the second most interesting flight that day.

It will be the first, the other flight slipped to the 6th

[mikegarrison]

Turns out, the computer had a bad power supply.

[Flavio hc16]

16 hours ago, mikegarrison said:

Turns out, the computer had a bad power supply.

First rule of building a PC: never cheap out on the PSU

[darthgently]

1 hour ago, Flavio hc16 said:

First rule of building a PC: never cheap out on the PSU

I would think with the highly increased reliance on computers in flight that redundancy of PSUs would be a thing with a simple circuit comparing output and throwing an error flag when their output voltage didn't agree enough.  Both (all) of the redundant PSUs would be powered up, but only the chosen one would be loaded and doing external work, so the others wouldn't be using near as much power.  Preflight checks would require all agree, in flight failures would isolate bad supply from pool?  Something like that

Edited June 4, 2024 by darthgently

[kerbiloid]

The third computer boot sequence.

Spoiler

 

 

Notice: the lamps are blinking, too.