totm nov 2023 SpaceX Discussion Thread

[JoeSchmuckatelli]

30 minutes ago, tater said:

 

Okay:

1.  That was COOL!

2.  I'd have loved to be in the room when they pitched that to Shotwell.

 

The fact it got approved?

Very merry indeed!

[magnemoe]

6 hours ago, JoeSchmuckatelli said:

Okay:

1.  That was COOL!

2.  I'd have loved to be in the room when they pitched that to Shotwell.

The fact it got approved?

Very merry indeed!

LOL, thinking of putting an clapper inside the bell  

[JoeSchmuckatelli]

3 hours ago, magnemoe said:

putting an clapper inside the bell

... Then they'd have to change the song to 'Supersonic'! 

[StrandedonEarth]

10 hours ago, JoeSchmuckatelli said:

Okay:

1.  That was COOL!

2.  I'd have loved to be in the room when they pitched that to Shotwell.

 

The fact it got approved?

Very merry indeed!

“We want to do a TVC test with this specific pattern…” 

[Nuke]

great success leads to epic showboating.

[CatastrophicFailure]

On 12/22/2024 at 10:02 PM, JoeSchmuckatelli said:

2.  I'd have loved to be in the room when they pitched that to Shotwell.

Shotwell, When the Thing was Pitched:

 

[tater]

Loads of stuff in this long article: https://ringwatchers.com/article/s33-tanks

 

[darthgently]

10 hours ago, tater said:

Loads of stuff in this long article: https://ringwatchers.com/article/s33-tanks

 

That was very tasty.

I’m guessing the header feeders are filled along with the header tanks at launch and that actually amounts to a lot of the total hover/landing capacity.

So, are the tanks themselves going to be double layer like the feeders?  Very hard to imagine eating that mass increase happily but how else to reduce boiloff?

If so, it occurs to me that, in theory, the insulative gap could be full of propellant for ascent and converted to a vacuum gap on orbit once empty but that is probably too clever.  It would have to also be pressurized as emptied on ascent.

Actually, having to go to double layer tanks for the props transfer milestone could explain the bigger tanks to account for the mass penalty

Edited December 28, 2024 by darthgently

[JoeSchmuckatelli]

I keep seeing renders like the above and realize that SS is going to need creative payload geometry. 

Something like Shuttle bay doors. 

This 'forward lighted' section is never going to work. 

But this view probably will

https://nextbigfuture.s3.amazonaws.com/uploads/2023/12/Screen-Shot-2023-12-03-at-9.05.41-AM-1.jpg

 

[magnemoe]

11 hours ago, darthgently said:

That was very tasty.

I’m guessing the header feeders are filled along with the header tanks at launch and that actually amounts to a lot of the total hover/landing capacity.

So, are the tanks themselves going to be double layer like the feeders?  Very hard to imagine eating that mass increase happily but how else to reduce boiloff?

If so, it occurs to me that, in theory, the insulative gap could be full of propellant for ascent and converted to a vacuum gap on orbit once empty but that is probably too clever.  It would have to also be pressurized as emptied on ascent.

Actually, having to go to double layer tanks for the props transfer milestone could explain the bigger tanks to account for the mass penalty

The header tanks has pretty low surface area compared to the feeders.  Now as you say they could fill the gap with liquid for launch then drain gap with the tanks, in orbit probably pump out rest liquid from tanks to top off header tanks. Probably during end of burn to orbit and / or deobit burn. Then went gap to space. I say it depend on the size of the gap between feeder and insulating wall.  
Header tanks has contact with outs skin including heat tiles so having double walls here makes lots of sense, the feeders are inside the tanks who will contain pressurized gas for integrity but less heating? 

Also the block 2 design has some weird stuff like the extra feeders for methane to the vacuum engines. any liquid in them is wasted after reaching orbit and you don't want free flowing liquid in the tank anyway so I assume methane feeder from header going down to the common bulkhead. 
 

[Exoscientist]

  

The new era of heavy launch.  
By Gary Oleson  
The Space Review  
July 24, 2023  
https://www.thespacereview.com/article/4626/1

 The author Gary Oleson discusses the implications of SpaceX achieving their goal of cutting the costs to orbit to the $100 per kilo range. His key point was costs to orbit in the $100 per kilo range will be transformative not just for spaceflight but because of what capabilities it will unlock, actually transformative for society as a whole.  

 For instance, arguments against space solar power note how expensive it is transporting large mass to orbit. But at $100/kg launch rates, gigawatt scale space solar plants could be launched for less than a billion dollars. This is notable because gigawatt scale nuclear power plants cost multiple billions of dollars. Space solar power plants would literally be cheaper than nuclear power plants.  

 Oleson makes other key points in his article. For instance:    

The Starship cost per kilogram is so low that it is likely to enable large-scale expansion of industries in space. For perspective, compare the cost of Starship launches to shipping with FedEx. If most of Starship’s huge capacity was used, costs to orbit that start around $200 per kilogram might trend toward $100 per kilogram and below. A recent price for shipping a 10-kilogram package from Washington, DC, to Sydney, Australia, was $69 per kilogram. The price for a 100-kilogram package was $122 per kilogram. It’s hard to imagine the impact of shipping to LEO for FedEx prices.

 Sending a package via orbit transpacific flight would not only take less than an hour compared to a full day via aircraft, it would actually be *cheaper*.  

 Note this also applies to passenger flights: anywhere in the world at less than an hour, compared to a full day travel time for the longer transpacific flights, and at lower cost for those longer transpacific flights.   

Oleson Concludes:   

What could you do with 150 metric tons in LEO for $10 million?
The new heavy launchers will relax mass, volume, and launch cost as constraints for many projects. Everyone who is concerned with future space projects should begin asking what will be possible. Given the time it will take to develop projects large enough to take advantage of the new capabilities, there could be huge first mover advantages. If you don’t seize the opportunity, your competitors or adversaries might. Space launch at FedEx prices will change the world.

 These are the implications of SpaceX succeeding at this goal. However, a surprising fact is SpaceX already has this *capability* now! They only need to implement it:  

SpaceX routine orbital passenger flights imminent.  
http://exoscientist.blogspot.com/2024/11/spacex-routine-orbital-passenger.html

 

  Bob Clark

[darthgently]

2 hours ago, magnemoe said:

The header tanks has pretty low surface area compared to the feeders.  Now as you say they could fill the gap with liquid for launch then drain gap with the tanks, in orbit probably pump out rest liquid from tanks to top off header tanks. Probably during end of burn to orbit and / or deobit burn. Then went gap to space. I say it depend on the size of the gap between feeder and insulating wall.  
Header tanks has contact with outs skin including heat tiles so having double walls here makes lots of sense, the feeders are inside the tanks who will contain pressurized gas for integrity but less heating? 

Also the block 2 design has some weird stuff like the extra feeders for methane to the vacuum engines. any liquid in them is wasted after reaching orbit and you don't want free flowing liquid in the tank anyway so I assume methane feeder from header going down to the common bulkhead. 
 

I was imagining not just double layer header tanks, but main tanks (!).

For long term propellant storage on orbit. 

[magnemoe]

13 minutes ago, darthgently said:

I was imagining not just double layer header tanks, but main tanks (!).

For long term propellant storage on orbit. 

One option at least down the line then you want to reuse the deep space tankers, either for transporting fuel to moon orbit or then tanking up fleets for mars. 
In the start I guess they use sunshade and / or foam insulation. An inflatable sunshade does not disable return to earth if you an drop it and land. 
For going to mars one option is header tanks inside the main tanks who you keep in vacuum during transit.  

[CatastrophicFailure]

16 hours ago, JoeSchmuckatelli said:

This 'forward lighted' section is never going to work. 

Welp, not necessarily. The header tanks are in the nose for balance as much as anything else. When you have tons of “permanent” living space there instead that alleviates some of that extra ballast. 

[darthgently]

4 Astranis sats deployed.  Yay

 

Edited December 29, 2024 by darthgently

[magnemoe]

19 hours ago, CatastrophicFailure said:

Welp, not necessarily. The header tanks are in the nose for balance as much as anything else. When you have tons of “permanent” living space there instead that alleviates some of that extra ballast. 

And the header tanks give some very interesting abort option that it unless you drain it all into the feeders for touchdown or catch, might end up with an more complex system. 
The obvious most dangerous part of an SS mission is the flip and land not liftoff.  See an escape system for SS more as an escape pod as in ejecting the cockpit on an bomber not an true space capsule. 

For cargo missions you would starting bringing stuff back who require flexibility for down mass. 

Edited December 29, 2024 by magnemoe

[tater]

Header tanks might also be nominally used for burns in space, or at least until the thrust generates "down" for proper flow.

[JoeSchmuckatelli]

4 hours ago, magnemoe said:

most dangerous part of an SS mission is the flip and land

Well - and now that you mention downmass, given that as a priority for the performance / purpose of the craft - won't the cargo bay have to be basically in the middle to ensure the COM loaded is similar to what they're presently landing for the craft?  Top heavy & full of moon/Mars Colony gear or return samples or Psyche's gold, platinum and other fun stuff will put some pretty serious stresses on the craft and performance.  

I'd guess it would be much easier to control when the COM is central rather than distal.

[tater]

32 minutes ago, JoeSchmuckatelli said:

Well - and now that you mention downmass, given that as a priority for the performance / purpose of the craft - won't the cargo bay have to be basically in the middle to ensure the COM loaded is similar to what they're presently landing for the craft?  Top heavy & full of moon/Mars Colony gear or return samples or Psyche's gold, platinum and other fun stuff will put some pretty serious stresses on the craft and performance.  

I'd guess it would be much easier to control when the COM is central rather than distal.

The stated downmass has always been way lower than upmass payload for this reason.

[darthgently]

1 hour ago, JoeSchmuckatelli said:

Well - and now that you mention downmass, given that as a priority for the performance / purpose of the craft - won't the cargo bay have to be basically in the middle to ensure the COM loaded is similar to what they're presently landing for the craft?  Top heavy & full of moon/Mars Colony gear or return samples or Psyche's gold, platinum and other fun stuff will put some pretty serious stresses on the craft and performance.  

I'd guess it would be much easier to control when the COM is central rather than distal.

Also, maybe not in lunar gravity, but probably in Mars gravity, those props tanks, even if empty, would have to be somewhat pressurized to support the weight of everything above them once landed.  Of course this depends on ambient pressure to some degree I imagine.

 Don’t want another Atlas crumple

Edited December 29, 2024 by darthgently

[tater]

Aimed for 140, got 134. Aiming for 180 in 2025. Every 2 days seems like a stretch, tbh, unless they have more drone ships, or way more RTLS.

[Flavio hc16]

1 hour ago, tater said:

Aimed for 140, got 134. Aiming for 180 in 2025. Every 2 days seems like a stretch, tbh, unless they have more drone ships, or way more RTLS.

IMHO they will start to compromise on weight of the Starlink launches to get the 1st stage either RTLS or the drone ship closer to home.

If a full launch of 23 Starlink need a 630km downrange landing,

and an RTLS can carry 14 Starlink  ( mass wise),

maybe launch 20 starlinks and land the booster on a droneship 200 KMs downrange starts to make sense.

 

Or they could buy more droneship, but knowing how Elon operates, I doubt it.

[Ultimate Steve]

21 minutes ago, Flavio hc16 said:

IMHO they will start to compromise on weight of the Starlink launches to get the 1st stage either RTLS or the drone ship closer to home.

If a full launch of 23 Starlink need a 630km downrange landing,

and an RTLS can carry 14 Starlink  ( mass wise),

maybe launch 20 starlinks and land the booster on a droneship 200 KMs downrange starts to make sense.

 

Or they could buy more droneship, but knowing how Elon operates, I doubt it.

I wrote out a really long analysis (like I tend to do) but I really didn't like it as it got too rambly so I'll summarize.

• They can already do 5 day drone ship turnarounds, they have even done 4 day turnarounds but those are definitely not the average and I only read off the date, so it could have all been like 4 days 23 hours or something like that for all I know
• The average drone ship turnaround time was about 10 days in 2023
• The average drone ship turnaround time for September 2024 through December 2024, excluding the long turnaround times that were caused by that hurricane, the grounding from the Crew-9 anomaly, and that drone ship landing failure taking ASOG out of action for 48 days, the average drone ship turnaround was just over 7 days
• I don't think you can range-wise get 2/3 of an RTLS for 1/3 of the payload hit of a full RTLS. More realistically you'd get about 3/4 as much Starlink on a 200km ASDS than you would on a full ~600km ASDS, not 87% as you posit, though that is a vibes based linear approximation, I wouldn't be surprised if there are surprising results once you factor in the different burns and the trajectories and the gliding and such
• This bit is incredibly sensitive to various assumptions so I wouldn't put too much stock into the analysis. But if you can decrease average drone ship turnaround from 8 days to 6 days by saving an entire day (on average, under perfect conditions it can be more) off of each outbound and inbound trip by going roughly 3x closer to shore, your drone ship landing capacity increases by +33%.
  • I will reiterate, this is incredibly sensitive to assumptions. Don't put too much stock in this, it is pretty flimsy.
  • Transit is some percentage of total turnaround, including safeing, disconnecting and reconnecting (and moving in and out of safe range), unloading the booster, maintenance, waiting for weather, etc. So it is difficult to tell how much decreasing transit time will actually increase flight capacity.
  • Under optimal conditions, transit time from 600+km out can be as little as 50 hours (this was a record setting launch from March of this year) (and that includes the time to octograb and safe Falcon and hook up to the drone ship). If this was typical (4 days between launches) and unloading could be completed instantly and there was no maintenance, thirding the distance could increase drone ship landing capacity by +200% to +300%.
  • Alternatively, if transit takes 3 days each direction on average, and of that, 12 hours is non-transit operations, thirding the distance saves 40 hours per flight, and if you are averaging 10 days per ASDS flight as you did in 2024, this is only a +20% increase in flight rate
  • It is easy to justify any number you want to pick
  • But generally I settled on saving about 2 days per launch this way, and on using a 8 day cadence as baseline. Changing these two numbers leads to drastically different results. Beware math.
• 33% more launches but only 75% as much benefit from each launch. That comes out to exactly the same number of satellites launched, but you have to take up more launch pad time, add more wear and tear to your boosters and fairings, build more second stages, incur more costs, and generally go through far more hassle for the same result.

What I found is that the trade isn't worth it, what you gain in increased flight rate is offset (and possibly more than offset) by the lower payload and increased logistical difficulties. If they find themselves in a position where they need more Starlink launch throughput, I expect them to continue maxing out each ASDS launch, and then adding additional RTLS launches on top of that. I don't think that will happen, though, as they should be able to tackle the 2025 cadence with their existing drone ship fleet, and they are not likely to increase their target cadence beyond their 2025 targets with the introduction of Starship.

I do think that a faster drone ship cadence is needed for their goals. I forget the exact math I did and deleted (too long) but I estimated that if 85% of their launches are RTLS they need a ~7 day average cadence compared to their ~10 day average in 2024, but discounting outliers they already have a ~7 day running average since September. They will need to be faster as outliers happen, but seeing as they frequently do 5 day turnarounds, focus will likely be on making the 12 day turnarounds faster instead of making the 5 day turnarounds faster.

Notably, the two east coast drone ships are slightly underutilized compared to the west coast drone ship. Though this difference may be due to Florida weather or due to a small sample size.

I don't think they will build a new drone ship. It wouldn't be ready for a while, and hopefully by that time Starship will be taking over Starlink launches so there's not much point in scaling past where they aim to be in 2025. Tangentially related. I predict that 2025 will be the year of peak Falcon. It could also be 2026 depending on how Starship's milestones go. It is very close in my mind. It is likely that Falcon 9 is going to stick around until at least the early 2030s, but Starlink will transition to being majority Starship launched likely sometime in the second half of 2026 I'd guess, barring Starship not doing another design refresh. Falcon will taper off as a result, I expect that the fall-off will be quite dramatic as Starlink is the vast majority of Falcon's manifest.

 

[magnemoe]

39 minutes ago, Ultimate Steve said:

Notably, the two east coast drone ships are slightly underutilized compared to the west coast drone ship. Though this difference may be due to Florida weather or due to a small sample size.

I don't think they will build a new drone ship. It wouldn't be ready for a while, and hopefully by that time Starship will be taking over Starlink launches so there's not much point in scaling past where they aim to be in 2025. Tangentially related. I predict that 2025 will be the year of peak Falcon. It could also be 2026 depending on how Starship's milestones go. It is very close in my mind. It is likely that Falcon 9 is going to stick around until at least the early 2030s, but Starlink will transition to being majority Starship launched likely sometime in the second half of 2026 I'd guess, barring Starship not doing another design refresh. Falcon will taper off as a result, I expect that the fall-off will be quite dramatic as Starlink is the vast majority of Falcon's manifest.

Agree, had SS  been in an worse state another drone ship would make sense but sure they will launch starlink on SS in 25, pretty sure experimental don't exclude any useful payload. 
But falcon will stay around far into the 2030's its very reliable and man rated. 

[tater]

(it includes the SS/SH test flights for SpaceX)