B9 + S25 IFT/General Discussion

[Starmang10]

Use this thread FAA, FWS, and other relevant permits/licenses for Boca Chica (Thread 5) for discussion on these subtopics.

Use this as a forum to spread your opinions, theories, and many more about the B9 + S25's Orbital Flight Campaign.

[zubenelgenubi edit]

[Starmang10]

Any updates on new closures? By the looks of it, 25 was going to roll to the launch site, why I think this is due to cones at the launch site.

[Starmang10]

Surprising that they're planning to launch S25, considering it is kind of outdated hardware

[DanClemmensen]

Surprising that they're planning to launch S25, considering it is kind of outdated hardware

If it's good enough to accomplish the goals of their initial flight test, then why not go ahead and use it? S26 would not tell them anything about SS reentry. Expending S25 gets it off the books.

[wannamoonbase]

Surprising that they're planning to launch S25, considering it is kind of outdated hardware

I don't think so, after 7/24 cartwheeling perhaps it's more important to ensure you can make it to staging anything after that is a bonus.

Also, if they think they can get to a 3rd flight in short order than having S26, 27 or 28 ready for B10 maybe why using a nearly ready S25 is important.

[xyv]

I speculated in the FAA licenses thread that the 24 - 26 - 27 flight order was to:

1) Get info on reentry without the risk of being dead in orbit - hence 'suborbital'

2) Prove on-orbit capability and precision de-orbit entry point (27 is backup for 26 like 25 was(is) for 24)

Since nothing was learned about 1), it follows that you would repeat the test if you could...hence 25 is logically the next launch attempt.

[geza]

I speculated in the FAA licenses thread that the 24 - 26 - 27 flight order was to:

1) Get info on reentry without the risk of being dead in orbit - hence 'suborbital'

2) Prove on-orbit capability and precision de-orbit entry point (27 is backup for 26 like 25 was(is) for 24)

Since nothing was learned about 1), it follows that you would repeat the test if you could...hence 25 is logically the next launch attempt.

What is your theory about lacking the heat shield and the elonerons for test 2? Why don't they use all opportunity to test EDL, as they did with F9?

[RamsesBic]

I speculated in the FAA licenses thread that the 24 - 26 - 27 flight order was to:

1) Get info on reentry without the risk of being dead in orbit - hence 'suborbital'

2) Prove on-orbit capability and precision de-orbit entry point (27 is backup for 26 like 25 was(is) for 24)

Since nothing was learned about 1), it follows that you would repeat the test if you could...hence 25 is logically the next launch attempt.

What is your theory about lacking the heat shield and the elonerons for test 2? Why don't they use all opportunity to test EDL, as they did with F9?

Not sure if it is the main reason for having no tiles, but one reason might be to find out at what point the ship starts to break up. From that as a baseline they could maybe be better able to calculate how many lost tiles are survivable. Just a guess.
The flaps would just complicate things?

[mildom]

Elon said they would repeat the 7/24 test to get data they didn't get the first time around.  This means sending an S24-like ship to near orbit and see how it responds in reentry.  S25 is the only ship like S24.  The test has to be with S25 if Elon holds to his stated plan to redo the test.

[chopsticks]

Since nothing was learned about 1), it follows that you would repeat the test if you could...hence 25 is logically the next launch attempt.

This actually makes sense, I have been surprised that they are going to static fire S25 but they might as well fly it since *nothing was learned from S24.

*in the sense that it never flew on its own, obviously things were learned about the integrated flight

[xyv]

What is your theory about lacking the heat shield and the elonerons for test 2? Why don't they use all opportunity to test EDL, as they did with F9?

Not so much a theroy as a hypothesis.  The first flight does not require orbital operations or control to come down where it is expected.  The FAA license was negotiated over several months and during that time SpaceX started removing tiles from (IIRC) SS26.  I am speculating that SpaceX proposed a non-heatshielded orbital test to minimize the risk of a more survivable random reentry should on orbit operations be more difficult than expected.

Get EDL data on a known trajectory...prove ability to do EDL with a lower risk of large debris orbital test - hence the tile removal.

[DanClemmensen]

What is your theory about lacking the heat shield and the elonerons for test 2? Why don't they use all opportunity to test EDL, as they did with F9?

My guess is that S26 is a specialized variant that will demonstrate transfer of cryo fluids between tanks. Space was awarded a NASA contract for this demo. It is not contractually related to Starship HLS. So, do the demo and get paid, using a minimal Starship. On the same flight, they can get experience with Raptor restart and de-orbiting. flight would last a bit more that 24 hours prior to deliberate deorbit and breakup near Hawaii.

This guess is based solely on the existence of that contract, the odd design  of S26, and the re-entry path in the FAA document for flights two and three (which I suppose will now be flights three and four).

[geza]

and the re-entry path in the FAA document for flights two and three (which I suppose will now be flights three and four).

I missed this. Can you elaborate?

[joek]

My guess is that S26 is a specialized variant that will demonstrate transfer of cryo fluids between tanks. Space was awarded a NASA contract for this demo. It is not contractually related to Starship HLS. So, do the demo and get paid, using a minimal Starship.
...

Are you referring to the $53.2M "Large-scale flight demonstration to transfer 10 metric tons of cryogenic propellant, specifically liquid oxygen, between tanks on a Starship vehicle. ..." (NASA Tipping Point selections, Oct-2020)?

[joek]

I missed this. Can you elaborate?

See SpaceX Starship Super Heavy Project at the Boca Chica Launch Site; and specifically Written Re-Evaluation for SpaceX Starship Super Heavy Reentry.

[DanClemmensen]

I missed this. Can you elaborate?

See SpaceX Starship Super Heavy Project at the Boca Chica Launch Site; and specifically Written Re-Evaluation for SpaceX Starship Super Heavy Reentry.

My guess is that S26 is a specialized variant that will demonstrate transfer of cryo fluids between tanks. Space was awarded a NASA contract for this demo. It is not contractually related to Starship HLS. So, do the demo and get paid, using a minimal Starship.
...

Are you referring to the $53.2M "Large-scale flight demonstration to transfer 10 metric tons of cryogenic propellant, specifically liquid oxygen, between tanks on a Starship vehicle. ..." (NASA Tipping Point selections, Oct-2020)?

Thanks, Joek. Yes, that's exactly what I was referring to. You do need to read the WR carefully, because it refers to the first three flights, not just the first flight. Only the first flight tries for the SS to survive atmospheric re-entry and only the first flight is specifically less than a full orbit. The other two flights are "configurations not surviving atmospheric reentry", and are not restricted to a partial orbit in the WR. Note that the document does not explicitly say that those flights will make more than a partial orbit: that is purely my own interpretation.

[JaimeZX]

Recommend adding a poll as these threads often do, along the lines of:
How far will 25-9 make it?
* Off the pad
* Max Q
* Staging
* B9 landing issue but S25 Full suborbital trajectory
* B9 and S25 complete flight profile as planned
-----------------------

Also... WRT Max Q... I've always wondered if that's something calculated based on velocity & altitude/air density, or does the ship have like... a pitot tube?

[wannamoonbase]

Recommend adding a poll as these threads often do, along the lines of:
How far will 25-9 make it?
* Off the pad
* Max Q
* Staging
* B9 landing issue but S25 Full suborbital trajectory
* B9 and S25 complete flight profile as planned
-----------------------

Also... WRT Max Q... I've always wondered if that's something calculated based on velocity & altitude/air density, or does the ship have like... a pitot tube?

I think: Staging + S25 ignition is likely.

If they stage, S25 ignites and B9 does any part of the RTLS test that would be a big success.

[Vahe231991]

Is it possible that SpaceX could be making refinements to the engine assembly for Booster 9 so that not one or two Raptor engines of the first stage cut off two minutes into the next flight of the Starship?

[TomH]

Recommend adding a poll as these threads often do, along the lines of:
How far will 25-9 make it?
* Off the pad
* Max Q
* Staging
* B9 landing issue but S25 Full suborbital trajectory
* B9 and S25 complete flight profile as planned
-----------------------

Also... WRT Max Q... I've always wondered if that's something calculated based on velocity & altitude/air density, or does the ship have like... a pitot tube?

You left out B9 successful landing, but S25 RUD upon reentry.