totm nov 2023 SpaceX Discussion Thread

[Pthigrivi]

Watching Scott's breakdown though you see one engine fail to relight post-separation and it seems like others start to go out in proximity. It may be that an issue with this one engine then spread to those around it. 

[magnemoe]

6 minutes ago, JoeSchmuckateli said:

Yeah - but I'm talking about a system to close down baffles after fuel has been expended.  To keep the fuel where it should be.  Mind you - I know nothing about liquid rocket fuel and the problems of tank pressurization - and had never even considered slosh until @sevenperforce mentioned it.  

So my lay image is that once the flip happens and centrifugal forces are keeping the fuel together, that any slosh taking fuel past the baffles = fuel staying past the baffles.  (Assumes that engine cutoff = coasting / freefall)  So without a way to cut off baffles, what you effectively get is puddles of fuel between baffles - all separated by gasses.  Relighting the engines should pull all the fuel back towards the engines, of course, but doesn't that mean a problem with bubbles/gas in the intakes?

Shrug.  Don't know - just spitballing.

Think the movement was to violent for the baffles.  Assume they are pretty open to the top for one. 

[RCgothic]

2 minutes ago, Royalswissarmyknife said:

Starship had FTS activated Around T+ 8 Minutes. So the ship was destroyed long before reentry.

Thinking more about the debris path there I think.

[magnemoe]

Just now, Royalswissarmyknife said:

Starship had FTS activated Around T+ 8 Minutes. So the ship was destroyed long before reentry.

Did not catch that, knew the booster blew up but not Starship.  Why was it blown up? watched some streams after the launch and they talked about loss of communication after second stage end of burn and it was going at orbital velocity? 
So I missed the part then the terminated the mission. 

[Minmus Taster]

2 minutes ago, RCgothic said:

Thinking more about the debris path there I think.

Is the sky falling in the Bahamas yet? Just checking in

[Codraroll]

1 hour ago, JoeSchmuckatelli said:

Quick - bum rush the beach and find Tiles! 

EBay here we come! 

Never mind the tiles. The real treasure buried at the bottom of the sea would be the Superheavy grid fins. Those cost an absolute fortune to manufacture, and may have survived the explosion somewhat intact.

They're probably stuck several meters deep in the mud, in mile-deep seas halfway to Florida, though ...

Edited November 18, 2023 by Codraroll

[Royalswissarmyknife]

1 minute ago, magnemoe said:

Did not catch that, knew the booster blew up but not Starship.  Why was it blown up? watched some streams after the launch and they talked about loss of communication after second stage end of burn and it was going at orbital velocity? 
So I missed the part then the terminated the mission. 

No one except for maybe SpaceX knows.

Its theorized to be an issue with the engines or tank pressurization. Or it could have been off course.

A good thing to note is that the plume noticeably expanded a lot before FTS activation.

[JoeSchmuckatelli]

21 minutes ago, Codraroll said:

Never mind the tiles. The real treasure buried at the bottom of the sea would be the Superheavy grid fins. Those cost an absolute fortune to manufacture, and may have survived the explosion somewhat intact.

They're probably stuck several meters deep in the mud, in mile-deep seas halfway to Florida, though ...

Turns out it is harder than I thought to google a quick answer to the terminal velocity of an object dropped into the ocean as it hits the bottom.

Anyone know how fast the gridfins were going on sea-floor impact?

Edited November 18, 2023 by JoeSchmuckatelli

[Minmus Taster]

3 minutes ago, JoeSchmuckateli said:

Turns out it is harder than I thought to google a quick answer to the terminal velocity of an object dropped into the ocean as it hits the bottom.

Anyone know how fast the gridfins were going on sea-floor impact?

Depends on how they flow through the water. When a ship sinks they usually travel between 30 to 60 MPH on descent and I'd assume the grid fins wouldn't have fallen much faster after ocean impact. Not sure how much would be left though, rewatched the footage and it seems the boosters destruction was pretty much total (even more damaging then last time) which is good for public safety regarding the FTS but not good if you want to hunt for rocket parts. That and the fact the impact with the water would total them even more. But assuming that one survived the breaking up of B9 and the impact the surface I'd wager it's possible that it's going to be detectable if one had the time and money too look for them. That being said it would be better to consider looking for the B7 gridfins instead because it was slightly less explosive and more of a big 'pop'.

[magnemoe]

4 minutes ago, Royalswissarmyknife said:

No one except for maybe SpaceX knows.

Its theorized to be an issue with the engines or tank pressurization. Or it could have been off course.

A good thing to note is that the plume noticeably expanded a lot before FTS activation.

I saw that but think that was above 100 km up as in vacuum. One comment was that it was because they turned of the surface level engines. Anyway the burn was done and it looked like they had fuel left in the tanks so could compensated. 
Now it could well been off course and they then had issues communicating. Now some places in Asia they will have an spectacular light show  then 100 ton deorbits, it misses just 100 m/s something to be in orbit. Mir was 140 ton. 

3 minutes ago, Minmus Taster said:

Depends on how they flow through the water. When a ship sinks they usually travel between 30 to 60 MPH on descent and I'd assume the grid fins wouldn't have fallen much faster after ocean impact. Not sure how much would be left though, rewatched the footage and it seems the boosters destruction was pretty much total (even more damaging then last time) which is good for public safety regarding the FTS but not good if you want to hunt for rocket parts. That and the fact the impact with the water would total them even more. But assuming that one survived the breaking up of B9 and the impact the surface I'd wager it's possible that it's going to be detectable if one had the time and money too look for them. That being said it would be better to consider looking for the B7 gridfins instead because it was slightly less explosive and more of a big 'pop'.

Assuming the top with the hot staging top staid structural impact who is pretty likely as that is an beefy structure. 

Now if I was not SpaceX the interesting part is the raptor engines. Its the most advanced rocket engine in use as I know  and has an high value in the new space race. Yes lots of this is software and know how you will not get. 

[Royalswissarmyknife]

5 minutes ago, magnemoe said:

I saw that but think that was above 100 km up as in vacuum. One comment was that it was because they turned of the surface level engines.

The plume is seen as weird because it looks like it just appears out of nowhere and then is followed by FTS activation. It could be the camera acting strange though.

It would be very bad if the sea level engines got shutoff because they are the only engines on the ship with gimbal.

[Minmus Taster]

8 minutes ago, Royalswissarmyknife said:

The plume is seen as weird because it looks like it just appears out of nowhere and then is followed by FTS activation. It could be the camera acting strange though.

It would be very bad if the sea level engines got shutoff because they are the only engines on the ship with gimbal.

Is it possible it's a tank rupture and not a rocket plume? Seemed too large to be from the engines.

[mikegarrison]

42 minutes ago, Minmus Taster said:

Not sure how much would be left though

They are large chunks of metal -- titanium, IIRC. Likely would survive an explosion like that more or less intact.

[Minmus Taster]

 

[AckSed]

It doesn't look quite as zippy as SLS, but then I realise SH's carrying a lot more and I give it some slack.

Those shockwaves look immense.

RGV Aerial's view of the launch pad afterwards:

https://i.redd.it/6eobv3gi451c1.jpg

[Minmus Taster]

11 minutes ago, AckSed said:

It doesn't look quite as zippy as SLS, but then I realise SH's carrying a lot more and I give it some slack.

Those shockwaves look immense.

RGV Aerial's view of the launch pad afterwards:

https://i.redd.it/6eobv3gi451c1.jpg

Looks mostly intact, if a little charred. They'll probably have to reenforce the tank farm in between flights though, I don't think that unused tank is gonna take another flight.

[tater]

4 hours ago, kerbiloid said:

The single launch has destroyed the number of engines equal to 8 Proton failures (250 tf * 30 / (6 * 160 tf)).

They're not a ghetto mfg than can't afford to test. It's just money.

[kerbiloid]

25 minutes ago, tater said:

They're not a ghetto mfg than can't afford to test. It's just money.

2 attempts more left till the N-1 record.

And 2x30 engines, like for the N-1 as well.

[JoeSchmuckatelli]

I'm actually surprised at the lack of debris reentry projections. 

[tater]

11 minutes ago, kerbiloid said:

2 attempts more left till the N-1 record.

And 2x30 engines, like for the N-1 as well.

So what? The N-1 record resulted in them cancelling. There are a few more sitting around already waiting to fly, they'll make it work, they're not pikers.

 

 

Edited November 18, 2023 by tater

[JoeSchmuckatelli]

3 minutes ago, JoeSchmuckatelli said:

I'm actually surprised at the lack of debris reentry projections. 

Spoke too soon 

Puerto Rico

 

 

https://www.reddit.com/media?url=https%3A%2F%2Fpreview.redd.it%2Fbooster-and-ship-weather-radar-debris-clouds-from-re-entry-v0-or8dmedi151c1.jpg%3Fwidth%3D1826%26format%3Dpjpg%26auto%3Dwebp%26s%3D84968b88c0b6af7d978b238a20a74ff1163f6322

 

(debris track) 

[CBase]

For me the biggest question is why did thy trigger FTS on starship ?

3 hours ago, RCgothic said:

The Starship plume anomalies prior to FTS suggested a loss of attitude to me.

Seems likely. At T+5:00 they reported nominal trajectory. Starship already picked up 9500 km/h velocity. With (speculated) gimbal control it is extremly unlikely that the trajectory was messed up until SECO. Starship had even some fuel left. So either SECO was too early or shutdown was not happening evenly and therefore attitude lost. It might be that flight programm was not fexible enough to adjust for any unplanned loss during stage separation, but hey SpaceX should have a quite mature flight control loop. So even without seeing plume anomalies I would agree RCgothic: starship was tumbling.

But overall it seems like a major success: They managed to get into safe territority with a nice launch and FTS was working as intended. There is no reason why test pace should not pick up and pretty soon we will see a reentry.

 

[tater]

One thing I notice with the drone view is the soot plume... does it vent CH4, or something else going on?

[JoeSchmuckatelli]

35 minutes ago, tater said:

they're not pikers

What site is there that speculates with some reliability about the differences between iterations?  Is there anything significant between Ship 25 and Ship 28?  Or Booster 9 vs 10 (besides the obvious hot staging vent ring being missing)? 

Just wondering, given the speed of the iteration's production vs launch attempts and lessons learned whether they can do much more besides software / easily accessible exterior equipment. 

[Nuke]

only about 7 hours late to the party. i understand there were fireworks. 

noticed there was some serious thrust asymmetry during the boostback burn before the rud. is that intentional, cause i was under the impression that only the centermost engines would be used. others may have been lit to compensate. 

i doubt that hot staging was the cause, it looked like they overstressed trying to turn it around. they might have to land their booster further down range and take a more ballistic trajectory with passive deceleration. its time to revisit and scale up ocean recovery (something like the now retired flip, but with 3 or 4 pylons instead of one, operating like a catamaran in travel mode, brownie points if its self propelled).

upper stage burned most of its fuel before being scuttled. this is a good sign. its also a good indication that we got good data about the flight.

Edited November 18, 2023 by Nuke