totm nov 2023 SpaceX Discussion Thread

[Nuke]

1 hour ago, tater said:

I can drag over it to select as well, I was just curious about the how on some of his posts this happens. Never see it on any other posts, unsure if an explicit font/color change, or maybe a cut and paste that keeps formatting? And I'm just being difficult

So yeah, a huge runway... someplace. Which means designing a new vehicle, yada, yada, yada.

paste as plain text is your friend. you dont know what kind of formatting the text may contain, so its better to strip it out. 

Edited January 9 by Nuke

[tater]

 

[darthgently]

 

 

[SunlitZelkova]

2 hours ago, darthgently said:

 

 

I know it's too early to talk about real life cadence, but launching in February or March would put the time between two launches on par with that of the Saturn V I think. The average between Saturn V launches prior to Apollo 13 was something like every 3-4 months (I think, it's been awhile since I looked at the list of launches in detail). Meanwhile, prior to the second launch that destroyed the launchpad, the N1 took five months to launch two rockets.

Not counting Shuttle, the only other SHLV to fly more than one time, Energia, had a year inbetween its two launches.

SLS... even if Artemis II launches in 2025, who knows how long it will be until Artemis III? If it takes three years between two flights, how are they supposed to jump to once a year?

By the way, this may be a dumb question, but will this launch license process be required once Starship is actually flying payloads? Or will things become more streamlined?

The time between each test flight feels very guda guda (グダグダ), which translates as tedious or sluggish. Will people be watching the regulatory process when operational flights begin? They don't do that for F9 right now, as far as I can tell.

[Ultimate Steve]

22 minutes ago, SunlitZelkova said:

The time between each test flight feels very guda guda (グダグダ), which translates as tedious or sluggish. Will people be watching the regulatory process when operational flights begin? They don't do that for F9 right now, as far as I can tell.

5 months between first two Saturn Vs, 6 months between first two shuttles, 4 months between the first two N1s, 6 months between the first two Falcon 9s. Seven months between the first two Starships is more than the average for this sort of thing but not significantly above average, especially given that the first mission blew up their launch pad and the legal challenges they faced. And especially considering that it is arguably the most ambitious rocket ever. We are looking at late March for flight 3 (applying typical delay constants), so that should be 4 months between flights 2 and 3, quite an acceleration.

[darthgently]

4 hours ago, SunlitZelkova said:

I know it's too early to talk about real life cadence, but launching in February or March would put the time between two launches on par with that of the Saturn V I think. The average between Saturn V launches prior to Apollo 13 was something like every 3-4 months (I think, it's been awhile since I looked at the list of launches in detail). Meanwhile, prior to the second launch that destroyed the launchpad, the N1 took five months to launch two rockets.

Not counting Shuttle, the only other SHLV to fly more than one time, Energia, had a year inbetween its two launches.

SLS... even if Artemis II launches in 2025, who knows how long it will be until Artemis III? If it takes three years between two flights, how are they supposed to jump to once a year?

By the way, this may be a dumb question, but will this launch license process be required once Starship is actually flying payloads? Or will things become more streamlined?

The time between each test flight feels very guda guda (グダグダ), which translates as tedious or sluggish. Will people be watching the regulatory process when operational flights begin? They don't do that for F9 right now, as far as I can tell.

From what I've gathered, which could be wrong of course, normal launches would be from their Florida stage 0 that has been under construction for some time, at Canaveral, I recall. 

So a lot of the EPA regulatory fog would decrease relative to Boca Chica, (which would remain a test site?).  Once SS is proven and launches happen at Canaveral, a lot of non-EPA regulatory ferocity should settle to a more normal intensity also, I would think

[Exoscientist]

On 1/8/2024 at 5:53 PM, tater said:

Whatever you did starting there, the font changes and it's practically unreadable in dark mode (an my forum is always on dark mode). There are a few of your posts where you do this. Do you intentionally change font/color, or is it a non-plain text quote or something?

I'm not changing my forum theme to read the post (can see it in your quote), but is that the booster, or the ship? In the case of the ship—doesn't work on Mars. Off the table. For the booster, you are of course exactly right.

…

 

 I frequently copy and paste from other forums which may introduce new fonts this forum is not familiar with. When putting them together I frequently use the “Note” app on the Apple iPad. That might introduce other fonts. Here’s an experiment: I’ll try using the “Pages” app on the iPad instead which allows you to select the font.

 So here’s the previous post you couldn’t read in “dark mode” but copied into “Pages” and put in Arial font then recopied onto this forum:

_____________________________________________________________________________________________________

I have been accused of being anti-SpaceX because of my criticism of the Starship. Actually, after a calculation I'm convinced the Starship can be operational, like, tomorrow, with relatively small design changes:

Towards advancing the SpaceX Starship to operational flight: SpaceX should lower the Raptor chamber pressure and thrust level.
https://exoscientist.blogspot.com/2024/01/towards-advancing-spacex-starship-to.html

The Raptor engine has shown continued failures on all of test stands, Starship low altitude landing test flights, and the two orbital test flights. But the Raptors on the booster on the last test flight were able to complete the ascent part of the flight without failures. They failed only after the attempted to relight. 

Multiple-lines of evidence suggest that on that last test flight SpaceX throttled down the Raptors on the booster to less than 75% while those on the Starship were run at ~90%. I've suggested this is why the booster engines were able to fire reliably during the ascent and those on the upper stage were not.

If this is the case, then it suggests a method to get Raptor reliability: run them at ~75% throttle on both stages. But if keeping the same stage dry masses this would result in the payload of the reusable version being reduced to approximately in the range of 100 tons from 150 tons.

Instead, I advise first start with reducing the dry masses by optimally lightweighting the expendable versions of both stages. Surprisingly this gives a greater expendable payload than the expendable payload of the current version. Secondly, I suggest using winged, horizontal approach to reusability gives a much reduced payload loss due to reusability. Thirdly, basic orbital mechanics shows high delta-v missions such as to the Moon or Mars are done more efficiently by using more stages. Then a third stage is suggested for the Superheavy/Starship, a mini-Starship as it is called by Robert Zubrin.

This allows single launch and fully reusable missions to the Moon or Mars. No refueling flights required. 

_____________________________________________________________________________________________________

  Let me know if this is legible. By the way, about your question I wanted to do the optimal lightweighting for both the Starship and SuperHeavy as expendables.  The savings in weight would be more extreme in the case of the Starship though.  

 My  entire argument is based on this one Elon tweet:

Elon Musk @elonmusk

Probably no fairing either & just 3 Raptor Vacuum engines. Mass ratio of ~30 (1200 tons full, 40 tons empty) with Isp of 380. Then drop a few dozen modified Starlink satellites from empty engine bays with ~1600 Isp, MR 2. Spread out, see what’s there. Not impossible.

9:14 PM · Mar 29, 2019
https://x.com/elonmusk/status/1111798912141017089

 The difference of 80 tons between this Elon estimated dry mass of 40 tons for the expendable Starship and the current reusable dry mass of 120 tons is *huge*, especially for an upper stage where the difference subtracts directly from the payload mass.

  Robert Clark

 

Edited January 10 by Exoscientist

[tater]

Just now, Exoscientist said:

 I frequently copy and paste from other forums which may introduce new fonts this forum is not familiar with. When putting them together I frequently use the “Note” app on the Apple iPad. That might introduce other fonts. Here’s an experiment: I’ll try using the “Pages” app on the iPad instead which allows you to select the font.

When you paste, there's a thing that pops up offering the ability to post as plain text. That might make it more reliably in tune with the forum's way of rendering text. For some reason it uses a gray that is almost the dark gray of the background on dark mode. My kids could probably read it, but not me any more

[NFUN]

I can just barely read it without needing to out my phone in my face

[sevenperforce]

3 hours ago, Exoscientist said:

By the way, about your question I wanted to do the optimal lightweighting for both the Starship and SuperHeavy as expendables.  The savings in weight would be more extreme in the case of the Starship though.  

There would be virtually no weight saving on SuperHeavy because it is already as lightweight as it can be apart from relatively lightweight things like grid fins. You can't apply the mass ratio of a lightened Starship to Superheavy because they don't correspond. Not at all. 

So when you plug your numbers into Silverbird and it gives you a wildly high figure, and you conjecture "This surprising result must be due [to] the greatly reduced dry mass of both stages," this should be a clue. If you put nonsense numbers in for the Superheavy 

3 hours ago, Exoscientist said:

 My  entire argument is based on this one Elon tweet:

Elon Musk @elonmusk

Probably no fairing either & just 3 Raptor Vacuum engines. Mass ratio of ~30 (1200 tons full, 40 tons empty) with Isp of 380. Then drop a few dozen modified Starlink satellites from empty engine bays with ~1600 Isp, MR 2. Spread out, see what’s there. Not impossible.

9:14 PM · Mar 29, 2019
https://x.com/elonmusk/status/1111798912141017089

 The difference of 80 tons between this Elon estimated dry mass of 40 tons for the expendable Starship and the current reusable dry mass of 120 tons is *huge*, especially for an upper stage where the difference subtracts directly from the payload mass.

In your blog post you eventually propose that your super lightweight expendable Starship be converted into a horizontally-landed upper stage. This would require a fairing, wings, and a heat shield...all of the things that were removed to get it down to ~40 tonnes.

See the problem?

[darthgently]

Gawd how I wish I had some SpaceX/Starlink stock options right now

 

 

Edited January 11 by darthgently

[Exoscientist]

13 hours ago, NFUN said:

I can just barely read it without needing to out my phone in my face

 How does this look?

——————————————————————————————————————————-

I have been accused of being anti-SpaceX because of my criticism of the Starship. Actually, after a calculation I'm convinced the Starship can be operational, like, tomorrow, with relatively small design changes:

Towards advancing the SpaceX Starship to operational flight: SpaceX should lower the Raptor chamber pressure and thrust level.
https://exoscientist.blogspot.com/2024/01/towards-advancing-spacex-starship-to.html

…

—————————————————————————————————————

 I applied the option the forum offers of inserting text in plain-text format.

 

  Robert Clark

[Ultimate Steve]

Yeah that looks better. You can also do ctrl-shift-v to paste without formatting instead of ctrl-v and save a few clicks. That will also remove italics and such, though, and might break links, not sure.

[RCgothic]

https://spacenews.com/spacex-targets-february-for-third-starship-test-flight/

Next flight hardware ready in Jan, FAA license expected Feb after closeout of IFT-2 mishap investigation actions. Not forthcoming on what those actions are.

[Hannu2]

On 1/8/2024 at 8:07 PM, Exoscientist said:

 Consider, that is the standard industry practice. It is not just SpaceX and Nasa doing in that way in the past. Every company in the industry does it that way. Every company could just test single engines on test stands if they wanted to. That would be much cheaper. Instead they follow the accepted practice of doing full flight analog testing prior to test flights.

 That the Soviet N-1  experienced not just engine shutdowns but engine explosions on every test flight and the  SuperHeavy/Starship also experienced the same thing, including the engine explosions, suggests this is not a better approach to getting reliable engines.

Industrial standards will change when completely new products are developed. Single raptors have been tested but whole booster is too powerful to full duration full power static tests. Materials able to handle that stress probably do not exist. It is faster and cheaper to build flying expendable test objects than to development technomagical test stand for static test.

[Exoscientist]

On 1/9/2024 at 2:33 PM, Shpaget said:

The very bottom of the forums.

It's quite fugly and looks unfinished, but at least it's dark.

Thanks for that. I can tell now when I am copying something from another forum with different formatting when it becomes unreadable on this forum when reading in dark mode. 

By the way, I just realized that Elon tweet I copied from twitter where he says the expendable Starship might have a dry mass of only 40 tons, has that same problem. But you can read the tweet by clicking the link to the twitter post.

  Bob Clark

[JoeSchmuckatelli]

Posting this so I can find my way back here later.  (Kraken-Banned... again).

 

Thank you 

[magnemoe]

16 hours ago, Hannu2 said:

Industrial standards will change when completely new products are developed. Single raptors have been tested but whole booster is too powerful to full duration full power static tests. Materials able to handle that stress probably do not exist. It is faster and cheaper to build flying expendable test objects than to development technomagical test stand for static test.

Its not that you could not build an full duration static fire test stand, just that it would be many times more expensive and take much longer to build than an second launch tower.
Benefit is that it might catch issues with first launch, but second launch worked well until hot staging. 

[Exoscientist]

 

Toby Li @tobyliiiiiiiiii
Jan 6
Elon Musk to provide 2024 Starship Update on January 11. Confirmed on an X livestream,

@elonmusk announced he will conduct a SpaceX company talk including a Starship update next Thursday. I'm hoping to hear details regarding Starship IFT-2's post-flight analysis, plans for IFT-3 & beyond, and updates on Starship HLS milestones.
https://twitter.com/tobyliiiiiiiiii/status/1743529920322846812

 

 This is supposed to be an internal speech to SpaceX employees, but in the past was released to the public.

  Robert Clark

Edited January 12 by Exoscientist

[tater]

 

[Spaceception]

Here's today's talk, no tl:dr since I don't have time to watch it right now, and it came out half an hour ago (it's nearly an hour long)

 

 

Edited January 12 by Spaceception

[darthgently]

Not sure if included in Musk's update above, but I'll leave this here

 

[Spaceception]

"Ironically if it had a payload it would've reached orbit." Hmm, could this be one of the reasons IFT-3 is going to have a payload bay? They're going to have that payload so they don't need to vent the LOX again?

IFT-3 is going to work, I can feel it.

[Exoscientist]

1 hour ago, darthgently said:

Not sure if included in Musk's update above, but I'll leave this here

 

 Odd they didn’t just partially fill the tanks.

  Bob Clark

[Ultimate Steve]

52 minutes ago, Exoscientist said:

 Odd they didn’t just partially fill the tanks.

  Bob Clark

Probably wanted margin in case of engine outs, and a similar acceleration and vibration environment to what would be on a normal flight.

This kind of reminds me of the very first Centaur mission, where the boiloff vent for the propellants was not adequately separated from the main engines and led to an explosion.