totm nov 2023 SpaceX Discussion Thread

[RCgothic]

Looks like B7 has done an SN3 internally:

 

Likely to be scrapped IMO.

[darthgently]

29 minutes ago, RCgothic said:

Likely to be scrapped IMO.

Looks like it self-scrapped during last pressure test.  I think they need less of a straight developable tubular shape and more of a double-ended "horn" shape, or a non-zero gaussian curvature.  Like a saddle, or dome, or horn.  And more stringers/longerons maybe.

42 minutes ago, RCgothic said:

Looks like B7 has done an SN3 internally:

Considering the downcomer isn't needed until the tank around it is nearly empty anyway, could it be made out of a thick flexible silicone or something that was meant to be flattened when the surrounding tank was full?  Not sure silicone would deal with the temps though

[StrandedonEarth]

Or they need to update the testing procedures to ensure the downcomer pressure isn’t too far below the tank pressure, including the pressure at the bottom of the column of liquid in the tank!

The Twitterheads are saying it’ll get scrapped. Can they not just replace the downcomer, if the rest of B7 passes inspection?

It certainly won’t be the first  to fly now though…

[Beccab]

1 hour ago, darthgently said:

Looks like it self-scrapped during last pressure test.  I think they need less of a straight developable tubular shape and more of a double-ended "horn" shape, or a non-zero gaussian curvature.  Like a saddle, or dome, or horn.  And more stringers/longerons maybe.

Considering the downcomer isn't needed until the tank around it is nearly empty anyway, could it be made out of a thick flexible silicone or something that was meant to be flattened when the surrounding tank was full?  Not sure silicone would deal with the temps though

 

1 hour ago, StrandedonEarth said:

Or they need to update the testing procedures to ensure the downcomer pressure isn’t too far below the tank pressure, including the pressure at the bottom of the column of liquid in the tank!

The Twitterheads are saying it’ll get scrapped. Can they not just replace the downcomer, if the rest of B7 passes inspection?

It certainly won’t be the first  to fly now though…

Rumour (preceding the image that was posted) is that during the raptor thrust simulator+cryo test LOX loading happened too quickly compared to LCH4, and that caused damage on the downcomer. While that means (imo) that B7 is scrapped, at least it isn't a design issue but something that requires changes in the procedure, which means B8+ don't need fixes

[Elthy]

13 hours ago, RCgothic said:

Looks like B7 has done an SN3 internally:

 

Likely to be scrapped IMO.

The link doesnt work for me, also cant find the picture on his profile...

[RCgothic]

3 minutes ago, Elthy said:

The link doesnt work for me, also cant find the picture on his profile...

The tweet was deleted, but the picture is still up in this article:

https://spaceexplored.com/2022/04/22/leaked-image-shows-damage-inside-spacexs-starship-booster-7-prototype/

 

[Beccab]

The F9 booster that launched Axiom 1 is already being prepared to fly again! Current record is 27 days, as compared to the Shuttle's pre-Challenger record of 54 days (with post-Challenger being 88 days). That leaves a bit of margin for B1062 to still beat the current record even with some delays

[tater]

 

This will push Crew-4 out a day as well.

[Beccab]

Let's see what happens next, I'd say they're either made to fix B7 or to prevent B8 from reaching the same fate

[RCgothic]

I would say these are for B8. B7's header tank is all but certain to be damaged too where the transfer tube ripped away, and I don't see it being repaired internally. And if they have to separate B7 to get to it, well that reduces B7 to a similar level of assembly as B8.

[Beccab]

23 minutes ago, RCgothic said:

I would say these are for B8. B7's header tank is all but certain to be damaged too where the transfer tube ripped away, and I don't see it being repaired internally. And if they have to separate B7 to get to it, well that reduces B7 to a similar level of assembly as B8.

Yep, B8 is either two or three stackings away from completion (aerocovers excluded)

[RCgothic]

B1049, oldest booster to reach 10 flights and oldest still in service, is scheduled to be expended on its eleventh launching Nilesat-301.

https://en.m.wikipedia.org/wiki/List_of_Falcon_9_first-stage_boosters

Edited April 24, 2022 by RCgothic

[Beccab]

9 minutes ago, RCgothic said:

B1049, oldest booster to reach 10 flights and oldest still in service, is scheduled to be expended on its eleventh launching Nilesat-301.

https://en.m.wikipedia.org/wiki/List_of_Falcon_9_first-stage_boosters

Rest in peace, B1049. You were good

[Minmus Taster]

38 minutes ago, RCgothic said:

B1049, oldest booster to reach 10 flights and oldest still in service, is scheduled to be expended on its eleventh launching Nilesat-301.

https://en.m.wikipedia.org/wiki/List_of_Falcon_9_first-stage_boosters

[sevenperforce]

3 hours ago, RCgothic said:

B1049, oldest booster to reach 10 flights and oldest still in service, is scheduled to be expended on its eleventh launching Nilesat-301.

https://en.m.wikipedia.org/wiki/List_of_Falcon_9_first-stage_boosters

Nilesat-301 is only four tonnes. I wonder what kind of performance enhancement they’ll be able to get out of expending the booster.

Nominally, Falcon 9 can take up to 8.3 tonnes to GTO if the booster is expended. By my math, the upper stage has a whopping 1.21 km/s more dV with a four-tonne payload than with an 8.3-tonne payload. Circularization in GEO is only 1.63 km/s. I wonder if they’ll make the upper stage a frankenstage and try to do a near-GEO injection. Of course the upper stage still needs enough residuals to either graveyard or deorbit itself. 

[tater]

Ax-1 undocking this evening:

 

[sevenperforce]

4 hours ago, sevenperforce said:

Circularization in GEO is only 1.63 km/s. I wonder if they’ll make the upper stage a frankenstage and try to do a near-GEO injection.

All speculation of course, but in the future this could lead to customers paying a premium for the extra capability of “swan song” expendable booster flights, and SpaceX will officially discontinue offering expendable flights of new boosters. “Sure, we’ll expend a booster for you, but you’re gonna have to get in line because we only have three EOL flights per year.”

This also tends to cannibalize Falcon Heavy. There’s little incentive to pay for a Falcon Heavy flight to send your 7-tonne megasat to GTO when you could just adjust your schedule and use a swan song flight of a Falcon 9. Falcon Heavy looks increasingly less useful for full reuse; its use case is primarily government/science missions BLEO with the core expended. FH reusable can send frankenstages direct to GEO in the 6-8 tonne range, I believe, but since comsats always carry their own propulsion, it’s almost always more efficient just to let the comsat circularize. With the inclination change needed for GEO, bi-elliptic transfers are just ridiculously more efficient than direct Hohmanns. 

[StrandedonEarth]

1 hour ago, sevenperforce said:

This also tends to cannibalize Falcon Heavy.

I know converting an F9 stick into an FH stick is not trivial, but it makes me wonder if they could use EOL F9 sticks as side cores (or if it’s possible, a center core) for expendable Heavies, for when they really need every last bit of dV…

[Geonovast]

From what I understand the FH center core is fundamentally different, and a normal F9 cannot be substituted. 

I'm not sure how much expending a F9 would cannibalize the FH at this point.  You gotta wonder how much energy SpaceX wants to put into a fully reusable FH now.

1. All three launches have failed to bring back the center core intact.  I know #2 was due to the lack of an octograbber, but that doesn't guarantee the booster would have actually been reusable.
2. The next FH launch is already planning on expending the center.
3.  With Starship looming, I don't think SpaceX wants to dump much more effort into F9 anyway (much to my chagrin).
4. They've already stated the FH was more difficult than they'd initially thought.

Are there any scheduled FH flights that are attempting to land the core?

[insert_name]

Ax-1 just separated from the ISS

https://youtu.be/GBFZghqrI_4

 

[sevenperforce]

58 minutes ago, StrandedonEarth said:

I know converting an F9 stick into an FH stick is not trivial, but it makes me wonder if they could use EOL F9 sticks as side cores (or if it’s possible, a center core) for expendable Heavies, for when they really need every last bit of dV…

They have used F9 sticks as side cores, although they have recovered them all. It’s not entirely trivial but it’s not far from it, either. It would absolutely make sense to use EOL F9s for the rare expendable FH mission.

It is not possible to use a F9 booster as a FH core. They are incompatible.

The Merlin clusters on F9 have sufficient gimbal to do a cursed 3-2-1 FH launch, where one booster is jettisoned early for boostback and landing and the other booster is expended, but the FH core cannot handle the unbalanced thrust forces.

[sevenperforce]

1 hour ago, Geonovast said:

Are there any scheduled FH flights that are attempting to land the core?

The USSF-52 launch in Q3 will use a fully-recoverable FH; it is only sending 6.2 tonnes to GTO (which I must point out is well within the capability of an expended EOL F9, thus supporting the cannibalization claim). The ViaSat-3 launch this August will supposedly use a fully-recoverable Falcon Heavy for direct-to-GEO ascent, but at 6.4 tonnes I have my doubts about the core surviving.

I dunno beyond 2022. 

[Admiral Fluffy]

11 hours ago, RCgothic said:

B1049, oldest booster to reach 10 flights and oldest still in service, is scheduled to be expended on its eleventh launching Nilesat-301.

That scared me, until I realized that isn't the one i saw launch. Still sad though.

[Beccab]

Splashdown in ~9 hours and a half

[Beccab]

This is the second airline to sign with Starlink after last week's JSX deal

Edited April 25, 2022 by Beccab