totm nov 2023 SpaceX Discussion Thread

[sevenperforce]

15 minutes ago, Geonovast said:

26 minutes ago, lajoswinkler said:

It survived all that tumbling, went off course and then flight termination system broke the vehicle apart. If it weren't for FTS, Starship would probably fall as one piece into ocean.

You don't need fire for an explosion.

FTS may have been what triggered it, but it still exploded from the fact that it was pressurized.  This is why it breaks up into an incomprehensible number of pieces, not like... 3.

True, but I do get the sentiment. A "Rocket exploded during launch" headline gives a very different vibe from a "Test launch terminated 24 miles over Gulf of Mexico after successful liftoff". The former gives the sense of something like Antares or Challenger or Ariane 5's maiden flight.

[Meecrob]

1 hour ago, Geonovast said:

You don't need fire for an explosion.

FTS may have been what triggered it, but it still exploded from the fact that it was pressurized.  This is why it breaks up into an incomprehensible number of pieces, not like... 3.

An explosion is an exothermic reaction that propagates at greater than the speed of sound.

Lol, I'm not sure we watched the same video. I saw two fireballs that were tamer than when I start my barbecue and have a bit too much propane under the lid.

Pressurization has nothing to do with it because ( I forget who all posted it upthread) the FTS depressurizes the tanks by unzipping them along a pre-determined weak point.

 

Edit: Has anyone on the inside actually given a proper description of the separation sequence in degrees? Or are we all just guessing?

Edited April 21, 2023 by Meecrob

[K^2]

Very mixed feelings. On one hand, yeah, I get that the fact that it flew at all is a success. But I'm also seeing a lot of people trying to over-sell it. Yes, we expected something to go wrong during the flight, but a lot of things went wrong during this flight. Chunks of the platform coming off, fragging 3 of your engines, a bunch of safety equipment, a camera, and a car in the parking lot is not how you expect the engine start to go. And it somehow went worse from there. While I'm sure the damage to the underside of the rocket from liftoff could have led to some of the following problems, it sounds pretty incredible for all of the issues to be related to that. More engines flamed out, some with clear engine-rich exhaust flames. Ok, yeah, I suppose damaged plumbing could have resulted in that. But then we had a separation failure, engine shutoff failure, and was the flip supposed to be part of the booster slow-down procedure post separation? In which case, should that program have ran? Yeah, I get that the ship was lost by that point, but this is supposed to be human-flight rated eventually, and booster doing basically anything but that would be preferable for any sort of an abort procedure. Even if you're going to remote-detonate an uncrewed rocket, keeping the rocket pointing forward would give it better chances to coast clear of population, so this definitely isn't a good failure mode to have.

I also see people pointing out that the rocket didn't disintegrate from the flip as a positive. That's another problem. Not with the structure, obviously, but it makes you pay attention to the numbers, and it was over 30km up going less than Mach 2. Two minutes into the flight, Falcon 9 is going Mach 5. The Superheavy was climbing way too slow and never made it close to its Max Q. I think we had an official flameout of what, six engines? It sounds like way more of them were underperforming. Again, could be damage on liftoff, but holly crap, does it show how the failures cascade on this thing. So yeah, by the time it started flipping, it was over 30km up, where the atmosphere is very thin and the rocket wasn't going that fast. Aerodynamic stress would be significantly below what this rocket is designed to survive during the booster's normal return flip, and certainly nothing like what the Starship is designed to survive on reentry. This test actually failed to see if the rocket is sturdy enough to do its job.

And yeah, to some degree, all of these are nitpicks. But there are a lot of them, and if SpaceX opened up with, "Yeah, that went poorly, we're going to have to go back and look at what went wrong across the board," I'd be happy to focus on the things that went well. But their response has been, "This was great, better than we expected, and we have another one practically ready to go!" And now I'm concerned about the transparency and what exactly being swept under the rug. Obviously outsider's perspective, pound of salt and all that, and I'd love to hear what people working in the industry have to say about this. Just sharing my first impressions.

Edited April 21, 2023 by K^2

[StrandedonEarth]

11 minutes ago, Meecrob said:

Lol, I'm not sure we watched the same video. I saw two fireballs that were tamer than when I start my barbecue and have a bit too much propane under the lid.

Yeah, I must admit that the end of the flight wasn’t as spectacular as it could have been. They were able to unzip the whole thing without igniting much of the methane 

[Meecrob]

2 hours ago, StrandedonEarth said:

Yeah, I must admit that the end of the flight wasn’t as spectacular as it could have been. They were able to unzip the whole thing without igniting much of the methane 

It was so un-spectacular, that I had my buddy wound up for a second or two when I showed him the replay. I was a jerk and told him Starship was a cover for a cloaking device program. The "tumbling out of control" was just the entry maneuver.  The stream's commentary killed that joke, but its almost like the vehicle just slipped beneath the waves...if the sky was water.

Edited April 22, 2023 by Meecrob

[sevenperforce]

59 minutes ago, K^2 said:

I also see people pointing out that the rocket didn't disintegrate from the flip as a positive. That's another problem. Not with the structure, obviously, but it makes you pay attention to the numbers, and it was over 30km up going less than Mach 2. Two minutes into the flight, Falcon 9 is going Mach 5. The Superheavy was climbing way too slow and never made it close to its Max Q. I think we had an official flameout of what, six engines? It sounds like way more of them were underperforming. Again, could be damage on liftoff, but holly crap, does it show how the failures cascade on this thing. So yeah, by the time it started flipping, it was over 30km up, where the atmosphere is very thin and the rocket wasn't going that fast. Aerodynamic stress would be significantly below what this rocket is designed to survive during the booster's normal return flip, and certainly nothing like what the Starship is designed to survive on reentry.

I will push back on this slightly. It's true that the stack was moving much slower than intended when it attempted the separation maneuver, but it was also MUCH lower in the atmosphere than intended.

I mean, we can do the math fairly easily. At 40 km, the density of the atmosphere is 0.003996 kg/m³. At twice that altitude (but still below where the separation was planned), the density of the atmosphere is 0.00001846 kg/m³. That's a factor of 216.5 or thereabouts. You would have to be going 14.7 times faster at 80 km to experience the same amount of drag you experience at 40 km.

Assuming that the separation maneuver was intended to take place at Mach 5 and 80 km but actually took place at Mach 1.5 and 40 kilometers, the drag and moments of torque on the stack were roughly 1949% of what was anticipated. That's a pretty good safety margin if you ask me. And that's before you factor in the number of rotations, the type of tumbling, and everything else going on.

[JoeSchmuckatelli]

1 hour ago, K^2 said:

Very mixed feelings. On one hand, yeah, I get that the fact that it flew at all is a success. But I'm also seeing a lot of people trying to over-sell it. Yes, we expected something to go wrong during the flight, but a lot of things went wrong during this flight. Chunks of the platform coming off, fragging 3 of your engines, a bunch of safety equipment, a camera, and a car in the parking lot is not how you expect the engine start to go. And it somehow went worse from there. While I'm sure the damage to the underside of the rocket from liftoff could have led to some of the following problems, it sounds pretty incredible for all of the issues to be related to that. More engines flamed out, some with clear engine-rich exhaust flames. Ok, yeah, I suppose damaged plumbing could have resulted in that. But then we had a separation failure, engine shutoff failure, and was the flip supposed to be part of the booster slow-down procedure post separation? In which case, should that program have ran? Yeah, I get that the ship was lost by that point, but this is supposed to be human-flight rated eventually, and booster doing basically anything but that would be preferable for any sort of an abort procedure. Even if you're going to remote-detonate an uncrewed rocket, keeping the rocket pointing forward would give it better chances to coast clear of population, so this definitely isn't a good failure mode to have.

I also see people pointing out that the rocket didn't disintegrate from the flip as a positive. That's another problem. Not with the structure, obviously, but it makes you pay attention to the numbers, and it was over 30km up going less than Mach 2. Two minutes into the flight, Falcon 9 is going Mach 5. The Superheavy was climbing way too slow and never made it close to its Max Q. I think we had an official flameout of what, six engines? It sounds like way more of them were underperforming. Again, could be damage on liftoff, but holly crap, does it show how the failures cascade on this thing. So yeah, by the time it started flipping, it was over 30km up, where the atmosphere is very thin and the rocket wasn't going that fast. Aerodynamic stress would be significantly below what this rocket is designed to survive during the booster's normal return flip, and certainly nothing like what the Starship is designed to survive on reentry. This test actually failed to see if the rocket is sturdy enough to do its job.

And yeah, to some degree, all of these are nitpicks. But there are a lot of them, and if SpaceX opened up with, "Yeah, that went poorly, we're going to have to go back and look at what went wrong across the board," I'd be happy to focus on the things that went well. But their response has been, "This was great, better than we expected, and we have another one practically ready to go!" And now I'm concerned about the transparency and what exactly being swept under the rug. Obviously outsider's perspective, pound of salt and all that, and I'd love to hear what people working in the industry have to say about this. Just sharing my first impressions.

Change a few words and you have my review and criticism of KSP2 and its post launch comm strategy. 

[Drakenred65]

Spoiler

 

 A few problems, with anyone myself included, trying to guess what happened.

1) once the rocket started digging a pit the possibility of a shockwave going up the rocket exhaust or being transmitted from the supports into the rocket untill it started climbing off the pad may have caused enough damage to cause some or all of the observed failures, or started a chain reaction that led to a progressive failure.

 

2) a large amount of debree picked up enough energy to cause damage at least 1200 m away from the pad, not counting the wrecked car. So the possibility that some debree got into the engine or plumbing can't be discounted.

 

3) flight termination although inevitable, resulted in the material evidence of the failure  being scattered over miles of gulf coast  bottom, it's not going to be easy or quick to recover anything out there, even in the relatively shallow water where it came down. 

 

4) If one of the root causes of today's failure turns out to be " Should have had a full and proper exhaust diverter/sound suppression system, that failure can and will end up hiding other system failures that would have happened had the flight otherwise launched normally. As it is, he now has to repair if not completely rebuild facility's, including building a proper diverter and sound suppression system....so all the expense he hoped to avoid he has to pay for anyway, oh and he wasted money on the launch.....with the only lesson being you sometimes have to spend money to save money.... 

 

5 failure to separate, it engines were shutting down, were the remaining engines throttling /gimbaling / to maintain trajectory/ flight control , the system may have had a mode that said if we have not stained altitude burn fuel untill we get to a speed/altitude / trajectory that is within perimeters then we can have stage separation and not untill,  because it sounded to me like they could have returned the booster, if this had been a normal flight, but they decided not to because reasons. Honestly it sounded more like the rocket was underperforming untill that point .

[Krakotte]

1 hour ago, Meecrob said:

An explosion is an exothermic reaction that propagates at greater than the speed of sound.

Not exactly. An explosion can be of chemical origin (e.g. fuel-air mixture ignition) or of mecanical origin (e.g. BLEVE).
Then, an explosion can be:
- a deflagration : when a pressure front travels slower than the speed of sound (most fuel-air mixtures, low explosives)
- a detonation : when a choc wave travels faster than the speed of sound (some hydrogen or acetylene air mixtures, high explosives)
It's very unlikely that a methane-air mixture could detonate (not sure about a methane-O2 mixture but I would guess also unlikely).
/off-topic

[Meecrob]

I'm being a bit facetious here, but with regards to the pad destruction, and the aspirational requirements of taking off from Mars, they probably racked up a large percentage of "Edison" data points. (the whole "I know 10,000 ways to NOT make a lightbulb" thing)

 

Seriously though, I have to imagine they knew the pad was going to be destroyed and wanted to see the extent of the damage. Many are comparing to NASA and how they prefer to execute first time, every time, but SpaceX already has a pad with a deluge system being built in Florida, its not like they are going "what happened? It should have been robust enough?" Sure, its probably a lot worse than they calculated, but we are talking about the first prototype pad.

7 hours ago, Krakotte said:

Not exactly. An explosion can be of chemical origin (e.g. fuel-air mixture ignition) or of mecanical origin (e.g. BLEVE).
Then, an explosion can be:
- a deflagration : when a pressure front travels slower than the speed of sound (most fuel-air mixtures, low explosives)
- a detonation : when a choc wave travels faster than the speed of sound (some hydrogen or acetylene air mixtures, high explosives)
It's very unlikely that a methane-air mixture could detonate (not sure about a methane-O2 mixture but I would guess also unlikely).
/off-topic

Sorry, you are correct, overpressures can cause explosions, I was sloppy, wording wise, to imply this was not an overpressure/BLEVE event. Thanks for the correction

Edited April 22, 2023 by Meecrob

[Drakenred65]

I've now seen three different versions of the launch pad hole, and explanations.

 

the problem being  did the exhaust cut though to the water table before the rocket was far enough away to keep steam from adding to any back pressure hitting the engines, or did it just add to the ground debree and apparent damage. I suspect the exposed water at the base probably did not add to the rockets problems, but probably did add to damage caused after that point,

 

[Little 908]

POV:

After the RUD be like

You can always do more training!

[StrandedonEarth]

Probably already posted, but it’s such a gorgeous photo. Instant phone wallpaper 

[sevenperforce]

1 hour ago, Drakenred65 said:

Ithe problem being  did the exhaust cut though to the water table before the rocket was far enough away to keep steam from adding to any back pressure hitting the engines, or did it just add to the ground debree and apparent damage. I suspect the exposed water at the base probably did not add to the rockets problems, but probably did add to damage caused after that point,

Any mention of steam or water tables is entirely off-base. While it is true that the water table in Boca Chica is quite close to the surface, that is not relevant to this discussion. At these temperatures, iron boils; whether or not water boils is entirely insignificant. The soil is probably somewhat saturated but that was not part of the failure cascade.

In other news, it looks like my bad animation has already been picked up and people are running with it wildly.

https://www.reddit.com/r/SpaceXMasterrace/comments/12uoqnv/starship_stage_separation_animation/?utm_source=share&utm_medium=ios_app&utm_name=ioscss&utm_content=1&utm_term=1

It does have a nice sort of beauty to it, though.

[K^2]

4 hours ago, JoeSchmuckatelli said:

Change a few words and you have my review and criticism of KSP2 and its post launch comm strategy. 

Fair on communication, but the rest is bad comparison. SpaceX is nearly 10k strong. For comparison, NASA employs about 18k. SpaceX is one of the largest space orgs, not just compared to other commercial providers, but even among government organizations. It is a huge company.

In contrast, Intercept has about 40 developers. AAA games are typically made by teams of a few hundred and well into 1k+. Intercept is tiny by the industry standard. That's not a blanket excuse, but I expect someone like Intercept to step on rakes that I would be more critical of if it happened to a AAA studio. On top of that, budget for Superheavy has quite a few more zeros attached to it, and the large chunk of funding comes from the government sources - read mine and yours money too, and unlike our choice to get early access for KSP2, this was allocated by the politicians in Washington. Now, I'm not saying it's a bad use of the money, but again, a different standard for transparency is called for. And yes, of course I expect any kind of a space launch to be a much harder problem with way more caveats and hidden risks. But because of that and all of the reasons outlined above, with SpaceX being far from an underdogs these days and the government spending, I expect a lot more diligence and transparency from them than I do from a tiny game studio.

[CatastrophicFailure]

23 minutes ago, K^2 said:

On top of that, budget for Superheavy has quite a few more zeros attached to it, and the large chunk of funding comes from the government sources - read mine and yours money

Sorry but this is incorrect. SpaceX has a contract from NASA to develop a lunar variant specifically, and milestones related to that. This launch, and pretty much all Starship development up to this point, was entirely funded by SpaceX. 

[SunlitZelkova]

So I haven’t seen it mentioned anywhere, but along with the obvious salute to the N1, the manner in which Starship tilted after lifting off is also reminiscent of the other Soviet super heavy lift launch vehicle.

Energia made a big tilt in one direction during its first flight. Like Starship, it quickly corrected itself.

I think Starship is a reincarnation of dead Soviet rockets. Heck, at the same time, Falcon 9 is really the only other rocket to match Soyuz’s legendary-ness too.

[CastleKSide]

11 hours ago, K^2 said:

But their response has been, "This was great, better than we expected, and we have another one practically ready to go!" And now I'm concerned about the transparency and what exactly being swept under the rug

2 things can be true at the same time.

1. A ton of stuff went wrong and resulted in not testing everything that could have been tested, and revealed issues they had not given enough attention to.

2. It went better than they expected. 

This is a move fast and break stuff company, with destructive real world testing firmly woven into thier engineering process. How many starships did they blow up? It's very possible they are planning to do the same with the full stack. Not saying your concern isn't justified esp about stage zero but I think worrying about transparency is a tad premature

[Meecrob]

misread - please delete.

Edited April 22, 2023 by Meecrob

[Spaceception]

5 hours ago, SunlitZelkova said:

I think Starship is a reincarnation of dead Soviet rockets.

Raptor is a reincarnation of the RD-270. This whole time, SpaceX was picking off where the Soviets left off.

On topic, I would like to see a second flight before the end of the year. It's highly dependent on how fast they can repare/upgrade the OLM/GSE to take more than one launch though, but I think it'll get a lot farther the second time around. In the meantime, while there were upgrades to B9/SN25 over B7/SN24, were there any notable improvements to Raptor since that stack was built? While a lot of people say the engine outs/failures was likely due to debris and stuff from the pad, others  are wondering if the Raptors in general need more work.

[lajoswinkler]

15 hours ago, sevenperforce said:

True, but I do get the sentiment. A "Rocket exploded during launch" headline gives a very different vibe from a "Test launch terminated 24 miles over Gulf of Mexico after successful liftoff". The former gives the sense of something like Antares or Challenger or Ariane 5's maiden flight.

The sentiment of the media is "haha, Musk couldn't make it go even with all that money, it went kaboom, serves him well". It's demeaning. There is much more to Starship than just "big rocket go to space". Like with Apollo, it's a thing all humans can share together. Mocking it is pathetic.

Just to be clear, I don't like Musk, but I love SpaceX.

Edited April 22, 2023 by lajoswinkler

[Exoscientist]

10 hours ago, sevenperforce said:

Any mention of steam or water tables is entirely off-base. While it is true that the water table in Boca Chica is quite close to the surface, that is not relevant to this discussion. At these temperatures, iron boils; whether or not water boils is entirely insignificant. The soil is probably somewhat saturated but that was not part of the failure cascade.

In other news, it looks like my bad animation has already been picked up and people are running with it wildly.

https://www.reddit.com/r/SpaceXMasterrace/comments/12uoqnv/starship_stage_separation_animation/?utm_source=share&utm_medium=ios_app&utm_name=ioscss&utm_content=1&utm_term=1

It does have a nice sort of beauty to it, though.

 Is that an accurate representation of how the separation was supposed to work?

 

  Bob Clark

[N_Danger]

Scott Manley take is that it lost control authority well before it reached the altitude for stage separation and stage separation was not attempted. 

Many things went wrong on this one but dang  what a glorious failure.  

 

[magnemoe]

1 hour ago, Spaceception said:

Raptor is a reincarnation of the RD-270. This whole time, SpaceX was picking off where the Soviets left off.

On topic, I would like to see a second flight before the end of the year. It's highly dependent on how fast they can repare/upgrade the OLM/GSE to take more than one launch though, but I think it'll get a lot farther the second time around. In the meantime, while there were upgrades to B9/SN25 over B7/SN24, were there any notable improvements to Raptor since that stack was built? While a lot of people say the engine outs/failures was likely due to debris and stuff from the pad, others  are wondering if the Raptors in general need more work.

I say we see the next launch much faster. Yes they need to repair the pad and finish the next rocket not sure about status here but think second superheavy is ready for start testing. 
They also need to go over the data from this flight no idea how long this will take but 6 months sounds far to long. 

I guess the next starship will be an disposable  as in no tiles or flaps following the planned trajectory for previous flight.  Followed by going into orbit and testing starlink deployment. 
Perhaps a couple of them then the fuel transfer test. While doing this they build another with flaps an tiles for an reentry test. 

[StrandedonEarth]

I have to wonder if the mount could have handled the rocket shutting down and settling back onto the OLM after that blast, although I imagine a lot of the damage was done after release.