totm nov 2023 SpaceX Discussion Thread

[Delay]

1 hour ago, magnemoe said:

Coverage tend to get lost as the rocket landing bump the barge around so it looses satellite up-link. 

You could clearly see the stage drift away from OCISLY, and they would've had enough time to switch to a different shot like they did with CRS-17/16 (can't remember).

[Brotoro]

Does anybody know about the landing abort modes that a Falcon first stage has? I know about the "aim to the side and require the landing burn to move the trajectory over to the landing point" procedure. But has anybody ever heard that it has a last-second "Oh, crap, I'm not gonna make it! RUN AWAY!" mode?

Do they orient the landing ship in the same direction every time? Does the Falcon always approach from the port/starboard/bow/stern? If so, which is it? And what direction on the ship is that standard landing camera view facing?

Edited June 25, 2019 by Brotoro

[Xd the great]

26 minutes ago, Brotoro said:

Does anybody know about the landing abort modes that a Falcon first stage has? I know about the "aim to the side and require the landing burn to move the trajectory over to the landing point" procedure. But has anybody ever heard that it has a last-second "Oh, crap, I'm not gonna make it! RUN AWAY!" mode?

Never heard of such a mode. I think there is a threshold for speed and heading during recovery attempt. If something goes wrong, they don't abort. The continue to send the booster on its "I want to dive" trajectory

Had they have a runaway attempt, the "How not to land an orbital class booster" might be a little less 4th of July.

[cubinator]

41 minutes ago, Brotoro said:

Does anybody know about the landing abort modes that a Falcon first stage has? I know about the "aim to the side and require the landing burn to move the trajectory over to the landing point" procedure. But has anybody ever heard that it has a last-second "Oh, crap, I'm not gonna make it! RUN AWAY!" mode?

I know there is building avoidance. 

[Xd the great]

14 minutes ago, cubinator said:

I know there is building avoidance. 

There are also explosives that can tear the rocket apart if it went out of control during reentry. It will be switched off after reentry burn. But these measure are early on in the landing part.

[CatastrophicFailure]

This is how it went down:

Computer pulled a Noble Sacrifice:

 

 

 

[Guest]

16 minutes ago, CatastrophicFailure said:

Computer pulled a Noble Sacrifice:

I salute you center core

o7

[CatastrophicFailure]

B1057’s last transmission:

Spoiler

 

[zolotiyeruki]

TVC = Thrust Vectoring Controller?  Also, it seems like everything was operating nominally until the end of the landing burn.  Is that because the grid fins were able to compensate for the failed TVC until the airspeed dropped too low?

Edited June 26, 2019 by zolotiyeruki

[RCgothic]

Could be throttle valve controller. Failure to throttle down might trigger a last moment abort.

[tater]

TVC is gimbal. Towards the end the engines are gimbaling pretty hard, and failure doesn't mean centered. It could have failed hard over.

[RealKerbal3x]

34 minutes ago, RCgothic said:

Could be throttle valve controller. Failure to throttle down might trigger a last moment abort.

I looked it up and it appears that TVC stands for thrust vector controller. So it looks like the stage wasn’t able to steer properly during the landing burn and the computer was forced to abort the landing.

[Flying dutchman]

So aparently 1200km downrage was just too much for the poor falcon..

[Jaff]

So a few things. It was a centre engine that had TVC fail which makes sense as this was a 1-3-1 burn. So it was working until the outer engines shut down when it lost control, hence the high accuracy up until the last minute.

 

and does this mean we have found the limit of returning a booster? Or will they beef up the heat shielding? Longer entry burn? Or will we never see a booster attempt something this far out again? 

Doesnt bode well for starship suborbital if they have a similar entry profile 

[Brotoro]

Starship comes in sideways. Skydiver!

[Ho Lam Kerman]

Were any of you also watching the center core crash live? I was so disappointed. 

The curse... lives on...

[RCgothic]

Nearly, I was watching on a minute delay. Actually had more of a heart in throat moment for the side booster entry burn. The centre core was disappointing, but we knew that was a dicey prospect going in.

[Jaff]

31 minutes ago, Brotoro said:

Starship comes in sideways. Skydiver!

Comes in sideways from orbital speeds, we don’t know what’s happening sub orbital...

 

 

[Wjolcz]

6 minutes ago, Jaff said:

Comes in sideways from orbital speeds, we don’t know what’s happening sub orbital...

 

 

They will probably do a couple of swan dives first. Just like the DC-X did.

[Guest]

2 hours ago, Jaff said:

Comes in sideways from orbital speeds, we don’t know what’s happening sub orbital...

 

 

It wouldn’t flip over until it shed most of its velocity, that’s the whole point of the design o_o

[Elthy]

Its the first time a landing failed due to reentry damage, isnt it?

[Geonovast]

12 minutes ago, Elthy said:

Its the first time a landing failed due to reentry damage, isnt it?

Can we call it a failure if the rocket succeeded in what it was trying to do?  I would say in this instance that smacking the boat would have been the failure. 

[mikegarrison]

2 hours ago, Geonovast said:

Can we call it a failure if the rocket succeeded in what it was trying to do?  I would say in this instance that smacking the boat would have been the failure. 

Yes, you can clearly call this part of the mission a failure. They ended up with a bunch of rocket pieces in the water instead of one rocket landed safely on the boat.

Edited June 26, 2019 by mikegarrison

[tater]

2 hours ago, Elthy said:

Its the first time a landing failed due to reentry damage, isnt it?

Yes, it's a landing failure, though it might be fair to call it "destructive testing" as they were unsure it would survive. Apparently this mission originally considered (if they had both ASDS in the ATL) landing the boosters at sea, and expending the core because of the required margin for the S2 burns.

2 hours ago, Geonovast said:

Can we call it a failure if the rocket succeeded in what it was trying to do?  I would say in this instance that smacking the boat would have been the failure. 

The only mission that mattered here was the 24 payloads hitting their target orbits, everything else is secondary. SpaceX has yet to drop their prices to the point where recovery makes much of a difference, it's just a bonus.

11 minutes ago, mikegarrison said:

Yes, you can clearly call this a failure. They ended up with a bunch of rocket pieces in the water instead of one rocket landed safely on the boat.

While it was a landing failure, I think this characterization is unfair. They put many boosters into the ocean developing landing in the first place---all were already paid for by their customers.

The AF apparently paid ~160 million for this flight. The side boosters were already paid for (Arabsat), and that price is basically what a fully expended FH costs. This loss cost nothing, and the mission alternative to trying to land it would have simply been to intentionally expend the core. The latter would have saved them 4 grid fins. They rolled the dice on an extreme landing, the alternative case was intentionally expending it.

 

Edited June 26, 2019 by tater

[mikegarrison]

5 minutes ago, tater said:

The AF apparently paid ~160 million for this flight. The side boosters were already paid for (Arabsat), and that price is basically what a fully expended FH costs. This loss cost nothing, and the mission alternative to trying to land it would have simply been to intentionally expend the core. The latter would have saved them 4 grid fins. They rolled the dice on an extreme landing, the alternative case was intentionally expending it.

I had already changed my post by the time you posted this. This part of the mission (landing the core) was clearly a failure. I think it was obvious from the context that we were not discussing the other elements of the mission, like delivering the payload or landing the side boosters.

Edited June 26, 2019 by mikegarrison