Author Topic: SpaceX Starship : First Flight : Starbase, TX : April 2023 - DISCUSSION THREAD 2  (Read 493093 times)

Online FutureSpaceTourist

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https://arstechnica.com/science/2023/04/so-what-was-that-was-starships-launch-a-failure-or-a-success/

Quote
So what was that? Was Starship’s launch a failure or a success?
SpaceX's development process is messier, but it's also much faster.

ERIC BERGER - 4/20/2023, 6:33 PM

SOUTH PADRE ISLAND, Texas—It began with a bang, as big things often do.

From later in the article:

Quote
I used to regret coming into this world mere months after the final Apollo mission …

[…]

So I no longer have any regrets about missing Apollo. I am thrilled to be alive at this very moment in human history.


Offline sevenperforce

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Not sure it would have mattered anyway. Too much engine damage.
Looking at the imbalanced prop consumption their equivalent of the RD-180 mixture ratio valve might have been all the way over. Bad sensor or something? Maybe some of the engines didn't like burning that oxygen rich leading to engine rich combustion.
Maybe one (or more) of the engines lost due to debris impingement exploded with enough force to rip the LOX feed line open and so LOX was just being dumped out of the gaping wound the entire time.

Online ZachF

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The more footage that's coming in from the remote cameras the more it looks like they just got very lucky.
Super heavy is quite a vehicle to have survived so much ground damage.
HPU shrouds were both torn off and missing after liftoff HPUs were exposed to the air stream. Subsequently exploded between 30 seconds and 50 seconds into flight.
Probably due to ground damage.

What are the HPU shrouds?

Hydraulic Power Unit covers, referred to as “chines” here.

IIRC the next booster won’t even use hydraulic TVC.
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Offline Alberto-Girardi

The more footage that's coming in from the remote cameras the more it looks like they just got very lucky.
Super heavy is quite a vehicle to have survived so much ground damage.
HPU shrouds were both torn off and missing after liftoff HPUs were exposed to the air stream. Subsequently exploded between 30 seconds and 50 seconds into flight.
Probably due to ground damage.
What are the HPU shrouds?
Hydraulic Power Unit covers, referred to as “chines” here.
IIRC the next booster won’t even use hydraulic TVC.
B9, the next booster, won't have hydraulic tvc. The "chimes", the three long covers that run to around half the height of the lox tank do not house the HPU, they house COPVs. The HPU are housed in smaller covers nearly at engine level.

[zubenelgenubi: Fixed nested 🪹 quotes.]
« Last Edit: 04/20/2023 08:32 pm by zubenelgenubi »
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Offline yg1968

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The more footage that's coming in from the remote cameras the more it looks like they just got very lucky.
Super heavy is quite a vehicle to have survived so much ground damage.
HPU shrouds were both torn off and missing after liftoff HPUs were exposed to the air stream. Subsequently exploded between 30 seconds and 50 seconds into flight.
Probably due to ground damage.

What are the HPU shrouds?

They cover the hydraulic power unit assemblys which were used to provide all hydraulic pressure on the vehicle. There were two one on each side of the vehicle.
Both shrouds were missing after liftoff and each unit can be seen exploding and igniting prior to the 1 minute mark. So no surprise hydraulic control was lost.
This is why the vehicle went into a tumble. No hydraulics=no thrust vector control.

Given the shrapnel on all the remote cam video from the concrete disintegrating that's probably where the damage came from. Not for sure on this until/unless they publish official findings but it sure looks that way on all the footage.

Not sure it would have mattered anyway. Too much engine damage. Not sure if the vehicle would have had enough velocity for the flight plan having lost that many engines that quickly. They may have ended up having to terminate starship even if it had survived to stage SEP to ensure it didn't end up somewhere it wasn't supposed to be due to lost velocity.

The point is the lack of flame diverter was a really bad idea.

How long does building a flame diverter take? They said 3 months on the NSF stream.

I am assuming that there is a flame diverter at Pad 39A?
« Last Edit: 04/20/2023 06:13 pm by yg1968 »

Offline FinalFrontier

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Not sure it would have mattered anyway. Too much engine damage.
Looking at the imbalanced prop consumption their equivalent of the RD-180 mixture ratio valve might have been all the way over. Bad sensor or something? Maybe some of the engines didn't like burning that oxygen rich leading to engine rich combustion.

Probably the result of nozzle damage and subsequent fuel leaks from shrapnel impacts.

This is the same thing that happened to the SSME on STS 93 when the nozzle was split by the injector plug, only it's happening on multiple engines at once.
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Offline Lars-J

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Wow....

Positives:
- The rocket structure is built like a tank, impressive to tumble several times without breaking up. But due to engines out they did not reach expected Max Q speed.
- The blast shielding between Raptors worked great it seems. It lost maybe 8 engines before it started tumbling, and none of those engine failures caused a cascading failure. Nice!
- The launch mount ring with hold-downs appears to have weathered the damage quite well.

Negatives:
- The flame diverter - or lack of one. They really YOLO:ed away the flame diverter, eh? Many of us were worried about that - correctly - and now it looks like the launch mount needs substantial repairs and maybe a complete rebuild. This seems like a decision that comes straight from the top, someone who's philosophy is "best part is no part" and who's name begins with "M" and end with "usk".

I don't think we'll see flight 2 until late fall at the earliest. But I have been wrong many times before. :)

Offline FinalFrontier

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No flight 2 until next year is my guess would be happy to be dead wrong on that.

And likely flight 2 will be KSC. It will be easier to modify the KSC pad structure to resolve the problem than it's going to be to rebuild Boca Chica.

Ultimately starship will fly from Texas again but it may be quite some time until then.

And again. No sense in just trying to do a quick fix here. This problem wouldn't be resolved and you'd just damage the vehicle again and also the surrounding pad infrastructure again.
Yes you could just repour all the slabs but that would solve nothing. And next time around you might pop a hole in the aft dome and then it does explode on the pad.
The FAA would not like that.
« Last Edit: 04/20/2023 06:14 pm by FinalFrontier »
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Offline JamesH65

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Many people saying SX dodged a bullet etc, but has anyone considered the results may be close to what they expected? They perhaps knew the pad would suffer*, that debris would hit the tanks, that they might lose engines due to fod, but launched knowing that because they needed all the early flight data they could get, so they know how to build the next versions. As I said above, they can fix the stand and fix the rocket in parallel now. It's going to be a few months, perhaps 6 or even more. But they now have a LOT of data to work.

* Of course, it's also possible that the damage is more than expected, but a lot more? Seems unlikely.

Offline meekGee

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People need to understand that the priority of this flight was survival, not performance or orbital insertion.

As such, if I were them, I'd be shutting down engines at the first hint of non-nominal performance just to be safe, as long as I felt that the thrust puck could handle it.

This was not an SLS-like flight.

It was only one of many test flights with expanding sets of goals.

Watching the inability of some to understand that there are other ways of doing things is sobering.
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Offline FinalFrontier

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Damaging the launch vehicle prior to ascent (because of something on the ground equipment design) badly enough that it affects ascent is not expected.

I think they modeled the concrete performance extensively prior to and after the static fires and believed the data showed it could handle the exhaust environment. They probably were doing that modeling even before the pad was built.
Their models were wrong simple as that.

This is why modeling while useful, is no substitute to flying actual flight tests. This was the subject of alot of frustration from many of us during the long development of the SLS. Too much modeling not enough actual flying.
Blue origin should also take note here for New Glenn.

Sometimes flight tests and static fires are the best way to learn things. This was a hard lesson to learn however.
« Last Edit: 04/20/2023 06:20 pm by FinalFrontier »
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Online chopsticks

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"The best part is no part" Well, now there are less parts, so I guess that must be better, right? Right?

(Probably true for the deluge installation!)

Offline meekGee

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Also, I'd love to hear from a first-hand source whether clamp release was late.  It seemed like forever, I was sure it was a gonner.

If it was late, maybe it's connected to the underpad damage.

And also how the hell did the bottom or the booster survive that debris blast.
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Offline novo2044

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Do we have any actual confirmation it was debris that caused the engine outs?

Offline FinalFrontier

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Also, I'd love to hear from a first-hand source whether clamp release was late.  It seemed like forever, I was sure it was a gonner.

If it was late, maybe it's connected to the underpad damage.

And also how the hell did the bottom or the booster survive that debris blast.
Combination of luck and a testament to whoever the vehicle primary structures team is.
They did a great job and those guys deserve some free champagne.
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Offline FinalFrontier

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Do we have any actual confirmation it was debris that caused the engine outs?
Nothing official lots of video evidence of debris chunks flying vertical up the side of the vehicle. Implies heavily it was blasting up into the engine bay as well.

Same thing happened during one of the starship static fires they had to re build the entire back end of the vehicle after and replace the engines due to the damage.
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Online FutureSpaceTourist

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Might want to bookmark this. I trust for conversations outside of NSF forums …

https://twitter.com/kenkirtland17/status/1649091078962782208

Quote
Allow me to introduce you to the conversation you'll be having for the next 2-3 years

« Last Edit: 04/20/2023 06:53 pm by FutureSpaceTourist »

Online ugordan

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This problem wouldn't be resolved and you'd just damage the vehicle again and also the surrounding pad infrastructure again.
Yes you could just repour all the slabs but that would solve nothing. And next time around you might pop a hole in the aft dome and then it does explode on the pad.

That does raise the question. The fact that 3 Raptors shut down virtually immediately after launch commit does point to concrete-induced damage, but what about the other 5 ones?
Raptor 2 still unfit for flight or?
The fact that of all the outer 6 raptors that failed, all of them were on the same semicircle kind of lends credence to the possibility of their nozzles also being damaged by spalled concrete, and the damage to the pad concrete does appear to be asymmetrical (worse away from the tower), from that one, admittedly unclear aerial photo.

Concrete? Raptor problems? Plumbing issues on the booster?

Could this have been a much more successful flight if there was a proper flame diverter underneath?
Time will tell.  ???

Offline Lars-J

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To see the amount of concrete debris - and how far it went - look at this video closer, starting at the 14 sec mark. Big splashes in the ocean.

https://twitter.com/SpaceX/status/1649097087248891904

Online chopsticks

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I have to wonder if there was a launch commit if the TWR exceeded 1 (however many engines that would be I'm not sure). Seeing how much worse the pad and tank farm damage is now vs the 31 engine static fire, they surely would have known that if engine ignition happened on say 31 engines, they would still launch since the pad repairs would be significant if an abort were to be triggered.

I know that the NSF broadcasters were saying that they thought spacex wouldn't launch without 33 engines, but based on the evidence today, it does seem like they launched without 33 burning.

Perhaps the risk of lengthy pad repairs weren't worth aborting for, or maybe those 3 engines were offline due to FOD. It would be nice to know.

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