totm nov 2023 SpaceX Discussion Thread

[tater]

6 minutes ago, JoeSchmuckatelli said:

Will be interesting to see what they learn from this - and whether they change F9s specs.  Guessing being able to come in hotter means they can throw more weight in the future?

There's a lot they can learn once they look at the vehicle that just landed. It could also inform decision making regarding SH EDL.

[Beccab]

14 minutes ago, JoeSchmuckatelli said:

Will be interesting to see what they learn from this - and whether they change F9s specs.  Guessing being able to come in hotter means they can throw more weight in the future?

Another possibility I could think of is to improve the FH core recovery, which come in much hotter than F9s and was lost one time because of this

[tater]

This launch was basically a replacement for the sats they lost last time, so they sent them into a higher initial orbit. It might well have been partially a necessity (course they could have flown with fewer sats, too).

[Beccab]

 

 

 

[RyanRising]

14 minutes ago, Beccab said:

-some tweets-

Huh. I didn't expect they'd actually find someone willing and able to take their tin cans. Thought those things were pretty high-maintenance as display pieces, and just massive to boot.

[CBase]

1 hour ago, Beccab said:

Looks like SpaceX is testing the limits of the F9 fleet leaders, with higher reentry temperatures and shorter entry burns

Actually I watched last 5 month starlink launches and there have been several before >8000km/h at start of entry burn and ~2200km/h dV for entry burn. Due to high drag at end of burn it is visually not easy to spot 50km/h differences, but if they actually reduced the burn duration, they did it incrementally.

[StrandedonEarth]

*insert Oprah meme*

”A Starship for you, and a Starship for you, and a Starship for you…”

[Minmus Taster]

1 hour ago, Beccab said:

 

 

 

I wonder which one it will be.

15 would be by far the most symbolically prestigious but 22 is more complete in terms of space worthy-ness, or you could send 16 since nobody cares about that one 

 

[Entropian]

6 hours ago, Beccab said:

 

 

 

GIVE IT TO ME NOWWWWWW

https://tenor.com/view/give-me-give-it-to-me-now-gif-6486247

Edited February 22, 2022 by Entropian

[Beccab]

 

This means two things:

- B4 will remain on the OLM for some time, likely to do a WDR soon

- B7 can be fully stacked now, as that needs to happen on the transport stand and the others are either carrying B5 or under construction

As for S22, insiders say that its fate is dependant on how Raptor 2 and S24 go, since S22 is the last R1.5 ship and S24 is the first R2 one

Edited February 22, 2022 by Beccab

[tater]

This is from January, but this guy does pretty good simulations:

Video description has data:

Quote

Here is a CompariSim™ between two Starships with 6 and 9 engines each.

The Super Heavy boosters both have 33 Raptor2 engines. However, the 9 engine Starship has three extra Vacuum Raptor2s, an additional 300t of propellant, giving a liftoff T/W of 1.4, and does not throttle back for MaxQ.

The simulation suggests that these combined changes increase the payload to a 26° inclination (e.g. Boca Chica) from 150 to 200t.

The payload for Starlink satellites to 53° would be about 6% less, or 188t.

 

[Beccab]

pad clear in 5 minutes, unclear what it is for

Edited February 22, 2022 by Beccab

[Beccab]

New S20 cryo it seems

Edited February 22, 2022 by Beccab

[Flying dutchman]

I heard somewhere that there was another FAA delay and that instead of march the approval may take until the end of the year, is this true?

[Beccab]

9 minutes ago, Flying dutchman said:

I heard somewhere that there was another FAA delay and that instead of march the approval may take until the end of the year, is this true?

Nope

[RCgothic]

That 200te payload to reference orbit figure is ridiculous. At 80te dry and 35t reserved propellant that's 315te mass to LEO. Now expend Superheavy for the ~40% payload boost. 525te to the reference orbit. Strip down Starship to just what's needed to acheive orbit. 50te. No reserved propellant. 475te pure payload to the reference orbit. Ridiculous.

Swap out some of that payload for 305te of propellant. Gets 170te through 3200m/s to TLI with 375s ISP. In a single launch.  Truly ridiculous.

And the long-term goal is to reduce raptor 2 to under $1000 per ton of thrust, so that's under $250k per engine. Call it $500k each by the time we're launching the mission just suggested. That's $21 for engines. Plus some pretty cheap stainless steel hull, but let's be conservative and add the engine cost again. $42m for engines and hull. Plus avionics. Let's vastly overestimate and add the entire internal cost of an F9, +$15m. That's $57m. And just to be absolutely sure all launch services are provided, even though we don't have F9's recovery expenses, let's double that again and round up. $120m dollars.

For a booster that can put Orion, *plus* nearly 3 times SLS block 2's TLI throw on a mission to the moon in a single launch.

That's an SLS block 1 plus 3x SLS block 2s.

In a single launch. 

For ~$120m dollars. Instead of ~$12B.

Truly, truly ridiculous.

 

And by ridiculous I mean utterly awesome.

(I initially typed incredible, but the most incredible thing about Starship is that by now it really isn't. And all this without reuse.)

Edited February 23, 2022 by RCgothic

[RyanRising]

1 hour ago, RCgothic said:

That 200te payload to reference orbit figure is ridiculous. At 80te dry and 35t reserved propellant that's 315te mass to LEO. Now expend Superheavy for the ~40% payload boost. 525te to the reference orbit. Strip down Starship to just what's needed to acheive orbit. 50te. No reserved propellant. 475te pure payload to the reference orbit. Ridiculous.

Swap out some of that payload for 305te of propellant. Gets 170te through 3200m/s to TLI with 375s ISP. In a single launch.  Truly ridiculous.

And the long-term goal is to reduce raptor 2 to under $1000 per ton of thrust, so that's under $250k per engine. Call it $500k each by the time we're launching the mission just suggested. That's $21 for engines. Plus some pretty cheap stainless steel hull, but let's be conservative and add the engine cost again. $42m for engines and hull. Plus avionics. Let's vastly overestimate and add the entire internal cost of an F9, +$15m. That's $57m. And just to be absolutely sure all launch services are provided, even though we don't have F9's recovery expenses, let's double that again and round up. $120m dollars.

For a booster that can put Orion, *plus* nearly 3 times SLS block 2's TLI throw on a mission to the moon in a single launch.

That's an SLS block 1 plus 3x SLS block 2s.

In a single launch. 

For ~$120m dollars. Instead of ~$12B.

Truly, truly ridiculous.

 

And by ridiculous I mean utterly awesome.

(I initially typed incredible, but the most incredible thing about Starship is that by now it really isn't. And all this without reuse.)

While that’s awesome indeed, I think the capacity of a hypothetical expendable Starship, even with those optimistic mass figures, is one of the least interesting things about the vehicle. Sure you can get a large amount of payload flung out, but that’s really only because the rocket is so big. The exciting thing for me is not just that we have a massive rocket, but that all of it can then land itself and be put back together. Then flown again, and again, and again. I doubt we’ll see many expendable starships flown once the rocket reaches operational status, ‘cause they’re not really what makes this whole thing work.

…also 475 t to orbit from a  ~5000 t vehicle is above a 9% payload fraction to LEO, which is unprecedented from an orbital rocket and I doubt we’d see it from one with steel tanks. Even the aluminium and hydrolox Delta IV heavy, something you’d expect to get if you’re optimising for GLOW, still falls short of 4%. The Space Shuttle, including the orbiter as payload, only managed ~6.5%.

[RCgothic]

36 minutes ago, RyanRising said:

While that’s awesome indeed, I think the capacity of a hypothetical expendable Starship, even with those optimistic mass figures, is one of the least interesting things about the vehicle. Sure you can get a large amount of payload flung out, but that’s really only because the rocket is so big. The exciting thing for me is not just that we have a massive rocket, but that all of it can then land itself and be put back together. Then flown again, and again, and again. I doubt we’ll see many expendable starships flown once the rocket reaches operational status, ‘cause they’re not really what makes this whole thing work.

…also 475 t to orbit from a  ~5000 t vehicle is above a 9% payload fraction to LEO, which is unprecedented from an orbital rocket and I doubt we’d see it from one with steel tanks. Even the aluminium and hydrolox Delta IV heavy, something you’d expect to get if you’re optimising for GLOW, still falls short of 4%. The Space Shuttle, including the orbiter as payload, only managed ~6.5%.

I agree that reuse is the absolute best application of Starship.

The context of this little analysis was a thread on r/SpaceLaunchSystem that one again suggested SLS was the only vehicle capable of lofting it and co-manifesting cargo.

My thought process went:

1) Well doesn't Starship have comparable TLI throw? You could put Orion on top of an expendable variant and comanifest roughly the same payload.

2) The LAS would cover the abort mode everyone always complains about. Probably massively oversized for a liquid booster anyway.

3) Oh wait, Starships's had an upgrade (Starship Launch System Block 2?). Huh, that's a lot of payload.

4) Forgot to trim the dry mass. Wow.

5) Haha with expendable Superheavy payload goes lol.

6) Wait, that would cost how much? (Not much).

 

I agree 10% payload fraction would be unprecedented. But all the ingredients are there to surpass Shuttle.

The squared cube law is beneficial to large vehicles and Starship Superheavy is 2.5x as massive as Shuttle at liftoff. The tank faction goes down just by benefit of being larger.

Then take away the heavy insulation of the external tank, the poor staging strategy that lugs that tank all the way to orbit, the poor TWR in the middle portion of flight and the draggy cross-section. Also recall that 2/3rds of Shuttle's propellant is solid propellant burned at over 100s less ISP than Raptor.

 The fact that Starship is revolutionary on so many levels is just so exciting!

[tater]

There are many possible "expended" Starship use cases I can imagine. I put expended in quotes for a reason. ULA for years has pitched a cislunar ecosystem with reuse of upper stages, for example. LSS is the most obvious current example where the Starship itself never returns to the surface of the Earth, but it can be reused. Tugs based on SS are another obvious choice here. You could launch large station parts simultaneously with a tug. The tank part has an extra ring or two that contains latch hardware, RCS, etc. It then disconnects the entire payload section—a few rings of cylinder, plus the nose, and no header tanks so the nose might have large docking/latching hardware, or opens to present solar/radiator arrays. We now have a station, and a tug. A second such launch and the 2 crew areas can be attached to each other. The tugs can function as depots for props, or could be used as tugs. They could be used as expendable stages for some missions potentially as well.

[Beccab]

2 minutes ago, tater said:

There are many possible "expended" Starship use cases I can imagine. I put expended in quotes for a reason. ULA for years has pitched a cislunar ecosystem with reuse of upper stages, for example. LSS is the most obvious current example where the Starship itself never returns to the surface of the Earth, but it can be reused. Tugs based on SS are another obvious choice here. You could launch large station parts simultaneously with a tug. The tank part has an extra ring or two that contains latch hardware, RCS, etc. It then disconnects the entire payload section—a few rings of cylinder, plus the nose, and no header tanks so the nose might have large docking/latching hardware, or opens to present solar/radiator arrays. We now have a station, and a tug. A second such launch and the 2 crew areas can be attached to each other. The tugs can function as depots for props, or could be used as tugs. They could be used as expendable stages for some missions potentially as well.

Also iirc DearMoon needs an expendable SH for the direct lunar flyby, so expendable Superheavy has its use cases as well

Edited February 23, 2022 by Beccab

[tater]

First, a cool SS render from the SpaceX page:

 

 

https://www.spacex.com/updates/

Lengthy explanation of their design philosophy WRT Starlink safety (conjunctions, etc)

If the conjunction probability is high enough, the vehicle "ducks" by folding the panel, and orienting edge-on to the crossing object to minimize cross-sectional area available for collision.

[Beccab]

43 minutes ago, tater said:

First, a cool SS render from the SpaceX page:

 

 

https://www.spacex.com/updates/

Lengthy explanation of their design philosophy WRT Starlink safety (conjunctions, etc)

If the conjunction probability is high enough, the vehicle "ducks" by folding the panel, and orienting edge-on to the crossing object to minimize cross-sectional area available for collision.

Other informations are:

- production rate of 45 Starlinks per week

- Starlink reliability is currently higher than 99%, with failed satellites naturally orbiting within 5-6 years since they ceased to function. More often the satellites are propulsively deorbited in a manoeuvre that takes two weeks

Edit: looks like another new info is that Starlinks use whipple shields to defend the most important components of the satellite

Edited February 23, 2022 by Beccab

[Brotoro]

1 hour ago, tater said:

First, a cool SS render from the SpaceX page:

Have they decided against moving the front flaps farther up onto the top of the Starship? I seem to recall mention of moving them to positions 120 degrees apart instead of 180 degrees apart.

[Beccab]

1 minute ago, Brotoro said:

Have they decided against moving the front flaps farther up onto the top of the Starship? I seem to recall mention of moving them to positions 120 degrees apart instead of 180 degrees apart.

That design change has been abandoned at the moment it seems yea. Part of the reason is that it would make catching Starship harder because of the position of the hardpoints, while another reason is speculated to be the smaller payload bay door that 120⁰ flaps would create

[SunlitZelkova]

Could Starship be modified to use the Space Shuttle's payload retention system, to allow it to recover Hubble? Or perhaps even some ISS modules.