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 The conclusion you could get a Saturn V-class launcher, i.e., 100+ ton payload to LEO, using the Starship as a 1st stage and a “mini-Starship” as an upper stage is based on this estimate Elon once made for an expendable Starship dry mass.

 But that is for an upper stage use where it did not have enough engines for liftoff from ground. Assume for 1st stage use it needs 9 engines. Increase the dry mass now to 50 tons for the greater engine mass. 
 For the mini-Starship, an upper stage commonly is 1/3rd to 1/4th the size of the lower stage, so call it 420 tons propellant mass. As an upper stage it doesn’t need high engine thrust so assume same mass ratio of ~30 to 1 as for Elon’s expendable Starship estimate, giving it a dry mass of 14 tons.

Take Starship exhaust velocity as ground launched as comparable to that of the Superheavy, 3,500 m/s. And take the upper stage’s vacuum exhaust velocity as 3,800 m/s. Then we could get ~120 tons to LEO: 

3,500Ln(1 + 1,200/(50 + 434 + 120)) + 3,800Ln(1 + 420/(14 + 120)) = 9,200 m/s. 

  In that last post I cited Zubrin’s comment that Elon’s says the Starship production cost could be brought down to ~$10 million. But that undoubtedly is for high production rates. But the current production cost for Superheavy/Starship is estimated to be ~$90 million, with about 30%, $27 million, for Starship:

STARSHIP COST ANALYSIS
OVERVIEW
Note: This is Payload's current estimate and not based on access to any internal Space data or
proprietary information.
Current Estimated Starship & Booster Full Stack Cost (S in thousands)
39 Raptor Engines                                   39,000
Labor.                                                               35,000
Structure, plumbing, tiles, parts      13,000
Avionics                                                             3.000
Total                                                                  90,000

*Payload costs estimates are based on a post-R&D 1-2 year forward-looking model. This is an educated best estimate and not based on Space internal data. Further cost reductions are expected in the long-run. $90M cost: Payload estimates it costs $90M to manufacture a fully integrated Starship based on a post-R&D/test production phase near-term model. The go-forward cost does not factor in the near $5B SpaceX has spent on R&D to date.
~70% of costs accrue to Super Heavy and ~30% to Starship upper stage.
Future Starship (upper stage) cost reductions: As Starfactory comes online and Raptor production is refined, Space aims to reduce costs even further. A focus on Starship's upper stage: When SpaceX achieves full reusability, production of Starship second stage vehicles will be an order of magnitude higher than booster production.
• The company plans to eventually build multiple second stage Starships per week and reduce
Raptor engine's production cost to $250K a pop. If successful, the long-term cost to mass produce second-stage Starships could drop to $10M to $15M a vehicle. However, for purposes of this report, we will analyze costs as they are today.
Raptor 2 engines ($39M) Payload estimates each Raptor 2 engine costs ~$1M to build. The 39 engines-which include three additional upper-stage engines that will be added in the future-are by far the biggest Starship cost,
adding $39M to total cost. SIM per Raptor 2 engine is half as expensive as its $2M+ Raptor 1 predecessor. 20 SpaceX hopes to eventually bring the cost per engine down to ~$250K.
Payload Research
18. Elon Musk on X 19. Space 20.Elon Musk on X 21. Elon Musk on X

https://docsend.com/view/fi9wuazzeex57iig

 Say, for a mini-Starship upper stage its cost would be a 3rd of the $27 million production cost of the Starship, so $9 million. So the full vehicle production cost at $36 million. So a Saturn V-class launcher capable of 100+ tons to LEO at ca. $36 million.

 Note also SpaceX demonstrated with the Falcon 9 landing just the first stage, i.e., partial reusability, much easier than full reusability. Then this Starship now as first stage could be reused cutting its cost to, say, $2.7 million per launch, for the total partial reuse cost of $11.7 million per launch.

This is a Saturn V-class vehicle capable of single launch Mars or Moon missions we could launch now. No thermal tile problems, or needing to master orbital refueling, or stretching tanks, or increasing Raptor thrust.

 We have this capability now.

  Bob Clark

 

 

Edited by Exoscientist
Clarity
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On 11/16/2024 at 1:28 PM, Exoscientist said:

 

This is a Saturn V-class vehicle capable of single launch Mars or Moon missions we could launch now. No thermal tile problems, or needing to master orbital refueling, or stretching tanks, or increasing Raptor thrust.

 We have this capability now.

 Cool, if all SpaceX wanted to do is send a flag and footprints mission to the moon or *maybe* Mars. And that might be a sensible way forward (for the getting Orion to the moon portion of Artemis before Starship gets rated for lunar returns) if SLS gets cancelled.

But that is *not* what SpaceX wants to do.

SpaceX wants a permanent base on the moon. They want a city on Mars. They want the ability to brake hundreds of tonnes of mass into orbit of the outer planets arriving off a fast trajectory. And they want all that to be affordable on their own budget. 

Starship Superheavy expendable can accomplish some useful missions soon in the short term for a reasonable price. But frankly SpaceX would find that to be a distraction from what they actually want to do.

If, as a nation, the US has different priorities, then I'm sure SpaceX wouldn't say no to a big cheque. But humanity would advance faster by investing in the long term goals SpaceX are pursuing rather than distracting them with short term dead-end avenues like flag and footprints (again).

Edited by RCgothic
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On 11/15/2024 at 8:41 PM, Nuke said:

kicking the tires and lighting the fires again, already. i guess the bureaucrats really want to keep their jobs before they get doged out of existence.

It almost sounds like you think it is a good thing if billionaires buy access to the government in order to intimidate the people regulating their companies from doing the job that the people of the country hired them to do.

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28 minutes ago, mikegarrison said:

It almost sounds like you think it is a good thing if billionaires buy access to the government in order to intimidate the people regulating their companies from doing the job that the people of the country hired them to do.

where have you been? this has been the norm as far back as i can remember. bureaucrats are the second most wasteful thing in government right behind war, and im not sure i got the order right. that said no administration that has existed since ive been alive has made one step towards solving the problem.

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38 minutes ago, tater said:

 

If it isn’t obvious this vid is a comparison between the simulation (left) and the reality (right).  What I want to know is whether that is a pre-flight predictive sim, or after the deed.  If the former, even more impressive

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1 hour ago, darthgently said:

If it isn’t obvious this vid is a comparison between the simulation (left) and the reality (right).  What I want to know is whether that is a pre-flight predictive sim, or after the deed.  If the former, even more impressive

I couldn't find the video itself from SpaceX, but I did find a channel reposting it, back in April.

 

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20 minutes ago, GuessingEveryDay said:

I couldn't find the video itself from SpaceX, but I did find a channel reposting it, back in April.

Yeah, it's a sim that predates the flight.

They are substantially less seat of the pants than their critics claim.

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9 hours ago, Deddly said:

I think I smell politics.

Yes. I smell politics. Let's not, please.

 

its getting there, i had to be very careful how much detail i used, but then again i realized that since its such a universal apathy (or perhaps willful intent) that it was apolitical. if everyone is doing it, then its simply human behavior.

Edited by Nuke
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1 hour ago, Nuke said:

thing i worry about here is that spacex lets this fast tracking go to its head and starts making mistakes.

They've been working this for a long time, look at the hardware ahead of launches (eqp rich). There will be problems, but they'll get data and sort them. Second pad is very near completion—if they wreck the current pad, they can't fly until they finish the new pad... if they wait for the backup before flying, they can't fly until they finish the new pad. Seems like no difference to me.

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