totm nov 2023 SpaceX Discussion Thread

[tater]

40 minutes ago, sevenperforce said:

Is it a berthing port or a docking port? It looks pretty clear to me that it's a docking port.

I was assuming berthing because of the canadarm attachment, but I suppose that is for it to crawl, berthing with that light lag would be hard. Yeah, it's docking.

So they are unpressurized payload mounts I presume.

[RCgothic]

13t including payload and propellant seems very light compared to FH's expendable or semi-expendable capability. Both configurations could easily send the heaviest payload either falcon has ever lofted - 15.6t - to TLI. With a payload attachment upgrade it could easily manage 13t of spacecraft NOT INCLUDING 5t of cargo, 18t total.

But at the same time 13t is way too heavy for a fully reusable configuration. That'd be more like 8.5t.

Not sure why they're reserving semi-expendable performance TBH.

Edited March 18, 2021 by RCgothic

[RealKerbal3x]

SpaceX appears to be ready to stack BN1's sections in the high bay:

It looks like the SLS core stage won't be 'the world's largest rocket stage' for much longer.

[RCgothic]

This time BN1 actually is in stack up.

(Last time I mistook preparations for the engine section mate for fore and aft section mate :-/)

[Barzon]

4 hours ago, sevenperforce said:

Interesting that it appears to have a Canadarm grapple target on the side for berthing but an LIDS/NDS-compliant docking port on the nose like Dragon 2.

 

I believe the grapple target is present because Canadarm3 is too short to reach external payloads on Dragon XL from Gateway, so has to move itself onto Dragon to reach the payloads.

[tater]

[RealKerbal3x]

BN1's LOX section is now being lifted.

[Spaceception]

Not even a half hour since the SLS firing, and they're getting ready to stack their own Superheavy lift booster.

[RealKerbal3x]

Just now, Spaceception said:

Not even a half hour since the SLS firing, and they're getting ready to stack their own Superheavy lift booster.

This can't be a coincidence. I mean, it's Elon...

[Spaceception]

That gap looks narrow from a distance

[RealKerbal3x]

WOW

 

[Scotius]

Wow That is a lot of metal. A LOT. And it's still only a prototype.

[tater]

The test regime for SH is actually interesting. Think about it vs SS.

SS first got thrust simulators for the load when full, and under acceleration.

SH needs to simulate it's own mass... and 1300t of SS on top.

My guess is the usual tank testing on BN1, a SN5/6 like hop to validate landing with BN2, then the first hop above low alt is a real flight.

 

 

The July date doesn't really seem all that crazy.

Edited March 18, 2021 by tater

[RCgothic]

 

 

 

[RyanRising]

Unless plans have changed, calling BN1 a booster is like calling SN11 a spacecraft.

[tater]

 

[Spaceception]

Guessing that there's a good chance that the first full stack will be for the intended orbital mission, and not a publicity shot.

[insert_name]

4 hours ago, Spaceception said:

Guessing that there's a good chance that the first full stack will be for the intended orbital mission, and not a publicity shot.

Or it will be used for pad fit checks and not built to flight standards, as is common with most first boosters

[cubinator]

8 minutes ago, insert_name said:

Or it will be used for pad fit checks and not built to flight standards, as is common with most first boosters

It will be used for fireworks.

[tater]

1 hour ago, insert_name said:

Or it will be used for pad fit checks and not built to flight standards, as is common with most first boosters

No.

This is a real booster, just not a complete one.

I think it gets cryo-proofed, and likely even a static fire. I'm unsure how they can load it enough to represent SS on top, it needs to support 1300t on top while accelerating at however many gs.

Wonder if they would move it to a stand away from the pad and destructively test it at some point?

[kerbiloid]

They always think the first booster is real. All of them. Naive like children.

Edited March 19, 2021 by kerbiloid

[tater]

8 hours ago, insert_name said:

Or it will be used for pad fit checks and not built to flight standards, as is common with most first boosters

Maybe I was wrong and they won't pressure test it?

 

[Spaceception]

20 minutes ago, tater said:

Maybe I was wrong and they won't pressure test it?

 

He did say transport, presumably to the pads. Maybe they'll pressure test if they're able, and go on from there? MK1 was a Pathfinder iirc (that they originally wanted to fly but that's besides the point), and they still attempted to pressure test. BN1 has much better build quality. But if that doesn't work out, they'll try their chances with BN2.

[sevenperforce]

19 hours ago, RCgothic said:

13t including payload and propellant seems very light compared to FH's expendable or semi-expendable capability. Both configurations could easily send the heaviest payload either falcon has ever lofted - 15.6t - to TLI. With a payload attachment upgrade it could easily manage 13t of spacecraft NOT INCLUDING 5t of cargo, 18t total.

But at the same time 13t is way too heavy for a fully reusable configuration. That'd be more like 8.5t.

Not sure why they're reserving semi-expendable performance TBH.

It may be that going heavier than 13 tonnes all-up would run into problems for using the Dragon 2 system. Those four inline Draco thrusters will already have to do a half-hour insertion burn at NRHO. If they increased the mass much more, they would eventually have to start adding new inline thrusters, additional control thrusters, and do a complete avionics overhaul. Staying with 13 tonnes allows them to use exactly double the number of propellant tanks, with the exact same docking port and inline thruster configuration as Dragon 2. 

I feel like Dragon XL is really a stopgap to allow them to compete for Lunar Gateway operations until Starship is up and running. They didn't want to develop an entirely new vehicle.

42 minutes ago, tater said:

Maybe I was wrong and they won't pressure test it?

 

I don't see why they wouldn't pressure-test it. Even if BN2 has a wildly different thrust puck design or something, there would surely be some value in pressure-testing to validate the rest of the design. Unless I miss my guess this is already the single tallest liquid rocket stage ever constructed. It is definitely the first one anywhere near this size made of stainless steel. What kind of forces do you get with a structure that massive? Do you get resonance issues during cryo press? How do the stiffener rings hold up?

I doubt they will ever fire it but I predict they will test transportation and they will do a nitrogen press test. If that goes smoothly they might do a cryo proof and then a destructive nitrogen test.

26 minutes ago, Spaceception said:

He did say transport, presumably to the pads. Maybe they'll pressure test if they're able, and go on from there? MK1 was a Pathfinder iirc (that they originally wanted to fly but that's besides the point), and they still attempted to pressure test. BN1 has much better build quality. But if that doesn't work out, they'll try their chances with BN2.

I'm glad MK1 blew up. Those forward fins looked horrible.

[tater]