Developing the BFS - Phase 1 Big Falcon Hopper (BFH) Discussion - THREAD 1

[IntoTheVoid]

What was the "no" about?  "Instead" of what?

Do you think the switch to metal happened in between the F9US announcement and the metal announcement?

Primarily, I think it muddied the waters to not be sure about the F9US.
He could have said something along the lines of 'No, it's not really a mini-BFR; it's BFR-like mods to the US' if that was what he meant, but instead he just said 'No, accelerating BFR' without any mention of F9.
Did the switch to metal happen in that time? IDK, maybe. We don't know what the actual mods to the US were/are. If it had something to do with TPS on the sides, then perhaps the switch to metal obviated it.
I'm not making any hard claims other than, I'm not buying into any F9US hard claims without further info leaking out.

[Johnnyhinbos]

Nomadd - Do you have any insight on the roadway expansion project from the Port of Brownsville that would allow realistic transport of large (9m or more) structures to the Boca Chica site?

As I’ve mentioned in the past, part of why where seeing the BFH take shape the way it is is because of (lack of) infrastructure and a big part of that is ground transportation issues.

The true prototype for the BFS will be (is being?) built in San Pedro, but it can’t get to the BC site before this road work has been completed. Therefore I personally consider this road work a key milestone.

[su27k]

F9US-MiniSS was because they had "free time" and needed something to do.
SSSS eliminated the "free time" and therefore eliminated F9US-MiniSS.

But they knew about BFH when they announced F9US.

It could be that switch to steel and active cooling happened at different times, they may have decided to switch to steel fairly early (around dearMoon announcement), and they have been planning the hopper since then. But the idea of using active cooling instead of TPS may have only happened in November, this late change eliminated the mini-BFS.

[meekGee]

F9US-MiniSS was because they had "free time" and needed something to do.
SSSS eliminated the "free time" and therefore eliminated F9US-MiniSS.

But they knew about BFH when they announced F9US.

It could be that switch to steel and active cooling happened at different times, they may have decided to switch to steel fairly early (around dearMoon announcement), and they have been planning the hopper since then. But the idea of using active cooling instead of TPS may have only happened in November, this late change eliminated the mini-BFS.

Except mini f9us is in order to test brakerons at very high approach speeds..  made sense even b4 metal...

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ABCD: Always Be Counting Down

[su27k]

F9US-MiniSS was because they had "free time" and needed something to do.
SSSS eliminated the "free time" and therefore eliminated F9US-MiniSS.

But they knew about BFH when they announced F9US.

It could be that switch to steel and active cooling happened at different times, they may have decided to switch to steel fairly early (around dearMoon announcement), and they have been planning the hopper since then. But the idea of using active cooling instead of TPS may have only happened in November, this late change eliminated the mini-BFS.

Except mini f9us is in order to test brakerons at very high approach speeds..  made sense even b4 metal...

Not just brakerons, you can find exact quote in the mini-BFS thread, it's also to test "Ultra light heat shield", this part becomes unnecessary after switching to active cooling. Not sure what will happen to brakerons under the new design...

[bocachicagal]

Just a few more pics.

[Nomadd]

Nomadd - Do you have any insight on the roadway expansion project from the Port of Brownsville that would allow realistic transport of large (9m or more) structures to the Boca Chica site?

As I’ve mentioned in the past, part of why where seeing the BFH take shape the way it is is because of (lack of) infrastructure and a big part of that is ground transportation issues.

The true prototype for the BFS will be (is being?) built in San Pedro, but it can’t get to the BC site before this road work has been completed. Therefore I personally consider this road work a key milestone.

They're reconstructing 511 but not really expanding it much and I have a hard time picturing a BFS getting down it. The hope was for a new highway they're working on from the Mexican border to the port that will cross Boca Chica highway east of town. Engineering contracts have been issued, but no work on the hwy 4 to port leg yet.

[FutureMartian97]

Just a few more pics.

Amazing pictures as always. Are they working today, or do they have the day off?

[Nomadd]

Just a few more pics.

Dang, that gal is fast. I like the middle section angle. Looks like two eyeballs staring out.

[Nomadd]

Just a few more pics.

Amazing pictures as always. Are they working today, or do they have the day off?

She forgot to photoshop the workers in.

[SpacePhileon]

Just a few more pics.

Dang, that gal is fast. I like the middle section angle. Looks like two eyeballs staring out.

Just noticed those holes after your comment... they do look strange...

Why are they there? Fueling perhaps?

[envy887]

Just a few more pics.

Thank you for posting these!

Can you try to get a shot of the upper part of the engine, through the gap by the leg? It's visible but rather dark in one of your previous shots. Might need to overexpose the rest of the image to pull out details under the vehicle.

[Johnnyhinbos]

Just a few more pics.

Dang, that gal is fast. I like the middle section angle. Looks like two eyeballs staring out.

Just noticed those holes after your comment... they do look strange...

Why are they there? Fueling perhaps?

RCS attachment points?

[RotoSequence]

Just a few more pics.

Dang, that gal is fast. I like the middle section angle. Looks like two eyeballs staring out.

Just noticed those holes after your comment... they do look strange...

Why are they there? Fueling perhaps?

RCS attachment points?

Doesn't seem like a good spot for RCS.

[brainbit]

Just joined up the pics

[GORDAP]

F9US-MiniSS was because they had "free time" and needed something to do.
SSSS eliminated the "free time" and therefore eliminated F9US-MiniSS.

But they knew about BFH when they announced F9US.

It could be that switch to steel and active cooling happened at different times, they may have decided to switch to steel fairly early (around dearMoon announcement), and they have been planning the hopper since then. But the idea of using active cooling instead of TPS may have only happened in November, this late change eliminated the mini-BFS.

Except mini f9us is in order to test brakerons at very high approach speeds..  made sense even b4 metal...

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ABCD: Always Be Counting Down

But MeekGee, if SpaceX intended to make an F9 US with brakerons to test the BFS flight regime, the first word in Elon's reply would not have been 'No'.  The simplest explanation is that they did once intend to do the modified F9 US, but shortly thereafter changed their minds when they saw a way to accelerate BFS development (which appears tied to the switch to stainless steel and active cooling).

[Johnnyhinbos]

Just a few more pics.

Dang, that gal is fast. I like the middle section angle. Looks like two eyeballs staring out.

Just noticed those holes after your comment... they do look strange...

Why are they there? Fueling perhaps?

RCS attachment points?

Doesn't seem like a good spot for RCS.

Guess this is why this section was placed on the jig - looks like they’re installing some “stuff” in this section.

Man this is so much fun!

[AJW]

Just joined up the pics

'You came in that thing?  You're braver than I thought!'

[Wargrim]

After mulling over how all these developments fit together, i came to 3 conclusions that i expect to be more likely true than false:

A: Those are the real development Raptors. They will fly the hop tests. SpaceX must have been aware of the timelines for the hopper program and the production Raptors, and known for quite a while they would need 3 pre-production Raptors for the Hopper. The first production Raptors will go into the first production Starship, the Hopper program will not wait for them.
- These engines are built to handle martian roundtrips, highly reuseable, robust. Sitting in Texan air should not be a problem.
- SpaceX has had plenty of engines (and other rocket parts) recovered from the big global saltwater pool. They know what the worst case corrosion looks like and how much abuse the engines can take.
- Any saltspray-air corrosion over the lifetime of the test Hopper program is likely negligible.

B: That foil Airframe is sturdier than it looks. It is the real test Hopper airframe, both for the 500m hops and the 5 km hops. There will be no second airframe built for the test hopper. The 5km hops will feature higher airodynamic loads and more agressive manouvers than straight up and down movement. But nothing close to orbital/reentry loads/belly flop flights. Those will be tested with the production Starship, that also features the first active cooling system and the moveable control surfaces. Falcon 9 upper stage tests for either control surfaces or active cooling are very unlikely imho. Wrong architecture - i think that was an option for the carbon fiber + advanced passive heatshield tech path, which is now not the active development path.

C: The method of assembling the test Hopper is informative for the assembly of the production Starship. Not in the sense that every Starship is assembled in a texan swamp welding sheet metal together, but in the sense that to the maximum extend practical, final assembly will be near launch sites from road-transportable segments/sections/modules. I do not know to which extend the Booster or the production Starship will still feature large monolithic carbon composite tubes and domes. But it would not surprise me if those are either Booster only or even disappear completely. And the benefits of road transport over ship transport are obvious - apart from cost, a more flexible assembly logistics is much better fitted for the iterative approach of development and production that SpaceX has always prefered. So depending on how much carbon composite elements still play a role in the production Starship, it might never take a barge trip from the LA factory to any East Coast launch site. But the booster might.

Last thought, not Hopper related though: I am pretty sure that the launch options for the Booster are the next big super hot topic of internal SpaceX discussion. Not just about where, sea platforms or land, but also how. Someone must have asked the question: If the Starship can launch and land on a bare concrete/steel/soil surface, what does it take for the booster to do the same? This is exactly the kind of crazy that SpaceX has demonstrated multiple times. I do not expect such minimum launch infrastructure configurations to materialize with Booster V1.0, but who knows...

[meekGee]

I agree the "foil section" is sturdier than it appears to be, but that's a very low bar...

Here's a purely speculative idea. What if there are three more tubes to be installed, from the vertices of the upper horizontal tube triangle (inside the water tower) to a common vertex up top - forming a tall pyramid.

After the two foil sections are installed, the cone piece (which according to this theory has a hard mount point inside) is welded to this top vertex.


Shrug.

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ABCD: Always Be Counting Down