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SCFalken

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I would suggest that this launch showed primarily that they've fixed every one of the major issues they had with the first launch - no significant debris from the launch pad, so no damage to the engines. Proof that the engines can work through and entire launch phase, and the flight termination system for the first stage worked quickly and very thoroughly this time.

They also seem to have shown that the hot stage separation worked properly and that the high expansion nozzles work well on the raptor. (It's unclear to me whether the second stage burned to completion - the telemetry loss occurred a minute or so before planned stage 2 cut off as far as I could tell.

They need to figure out why the first stage RTB burn failed - I'd guess that they had problems with propellant mixture due to the turn over and burned an engine up. If one went pop through overtemperature, it could then take out the others through damage then destruction in a cascading failure.

Of course, in the meta-analysis, one can find out which reporters are still butt-hurt over twitter by looking at whether they report this as a failure, a success or correctly, which is always entertaining.

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Scott Manley mentions hydraulic/vapor lock, because propellant depletion and twisting of the booster, as possible causes of the failure of some engines to reignite. That looks like a reasonable hypotheses.

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Not only did a number of engines fail to ignite, a couple of the three engines that never turned off also flames out. Definitely some kind of fuel starvation problem. I’m guessing either the flip maneuver or perhaps the back blast of hot staging; Manly noted that the velocity of the first stage actually went negative for a moment. That might of caused some kind of fuel slosh even before the flip.

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8 hours ago, sunday said:

Scott Manley mentions hydraulic/vapor lock, because propellant depletion and twisting of the booster, as possible causes of the failure of some engines to reignite. That looks like a reasonable hypotheses.

If his analysis is correct, it would imply that they need to come up with some gentler maneuver for the booster recovery 'flip': current one gets the fuel moving violently in the tanks.

Alternatively they could come up with some structural solutions, but that might cut into payload.

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I wonder if some ullage motors on the 1st stage would help the slosh issues. 

1st Stage MECO just after the 2nd stage ignites. 

Let the stack separate. 

Maneuvering jets flip the 1st stage. 

Ullage motors fire to settle, if they get good pressure on the inlets, then fire the engines for the retro burn. 

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  • 1 month later...

Summary of space launches during 2023. I am in awe of the achievements of Space X. 98 launches. There are reliable, reusable rockets landing automatically, for instance.

A private company launched more mass to orbit that all the governments of the world together. Musk is on the path to be to space launch what Commodore Vanderbilt was to steamships. I wonder how the budgets compare.

So it seems the 21st century arrived, at last, in space-related things.

 

Edited by sunday
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  • 2 weeks later...

...

Artemis 3, the first crewed moon landing under the program using SpaceX's Starship, is now scheduled for September 2026, previously planned for late 2025, NASA said.

The precursor to that moon landing mission, Artemis 2, was also delayed, now planned for September 2025, NASA said. Artemis 2 involves four astronauts flying the Lockheed-built Orion capsule around the moon and back. Reuters reported on Monday the moon mission delays were imminent.

...

https://www.reuters.com/technology/space/nasa-delays-astronaut-moon-landing-2026-amid-spacecraft-challenges-2024-01-09/

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  • 3 weeks later...

Just watched this incredibly well done overview video on calculating generalized solutions regarding how to get from A to B in space (either optimizing for time, fuel, or combination of them), which offers advantages such as unexpected or unintuitive solution sets, as well as how they work around the computer processing limitations with the various approaches.
 





After my initial takeaway that confirms that as a C+ physics minor, I'm not soon going to be making any groundbreaking progress in astrodynamics (though I'm incredibly grateful such minds exist), my second takeaway is that it's incredible what scientists did in the 50s and 60s with the technology they had at the time.  Finally, I believe if we had the educational resources we have today, from khan academy and well produced videos like this (other content creators do similar work, like 3Blue1Brown) back when I was a kid, it almost certainly would have sparked a much deeper interest in mathematics, science and engineering in me personally (less daunting than simple text based explanations along with luck of the draw with regards to teachers), and therefore would probably have a similar effect on kids today. 

 

It's an interesting feeling butting up against the limits of my own comprehension... 

Edited by Burncycle360
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1 hour ago, Burncycle360 said:

Just watched this incredibly well done overview video (...)

Wow.

This is the most wonderful headache I have ever experienced.

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  • 3 weeks later...

Great vid. And there was still place for improvement, IIRC Clark stated that calculations hinted that rubidium instead of lithium would have increased specific impulse to more than 700s. :D

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Caesium is already liquid at room temperature, so that could be an advantage.

Francium would be another candidate, but only for the laughs, as it is very scarce and radioactive too.

Edited by sunday
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47 minutes ago, rmgill said:

On the Lithium and Florine Rocket, I wonder if there's a Derek Lowe article on the subject. 

Related. Dioxygen Difluoride

Yes! That is the blog that put me on the track of this hilarious historical assay on the development of liquid rocket propellants, Ignition!

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On 2/22/2024 at 5:24 PM, sunday said:

In space nobody can use journal bearings

 

So I saw the part in a still and thought "EDM". Do I need to watch beyond "....from the man who runs an electric bandsaw..." to know how they did it?

Clickbait title undermines the amazing capabilities of the system in my mind.

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33 minutes ago, DB said:

So I saw the part in a still and thought "EDM". Do I need to watch beyond "....from the man who runs an electric bandsaw..." to know how they did it?

Clickbait title undermines the amazing capabilities of the system in my mind.

The intermediate steps are interesting, as they need to leave enough material to minimize deformation due to processing stresses.

That outfit tends to produce really interesting videos, despite the use of clickbait titles.

Edited by sunday
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I think a lot of good quality video makers subject themselves to clickbait titles and cover images. Might be similar to how publishers have a say in the title of the book, with a tendency to have more attention grabbing titles. Or why sensationalism is so present in the news. The same meaning but in the opposite way to the old expression of never judge a book by it's cover. If your honest, you're a loser, in the money game. 

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Government denies knowledge. 👽

Quote

US: Pentagon study says no evidence of alien life

1 hour ago

The investigation into reports of UFO sightings also concluded that there have been no efforts by US governments to keep the information of aliens hidden from the public.

There is no evidence of aliens or extraterrestrial intelligence, a Pentagon report that examined the sighting of Unidentified Flying Objects (UFOs) over the last century said on Friday.

The report concluded that most of the sightings reported were misidentified ordinary objects and phenomena, a conclusion that matches the assessment of past US governments into the claims.

The report from the Defense Department's All-domain Anomaly Resolution Office (ARRO) analyzed US government investigations since 1945 of UFO sightings.

The study which followed a 2022 Pentagon announcement also said that there were no efforts by the US government or private firms to keep the information about them secret.

"All investigative efforts, at all levels of classification, concluded that most sightings were ordinary objects and phenomena and the result of misidentification," said the report, which was mandated by Congress.

Why was the investigation conducted?

Over the past several years, US authorities have received a slew of reports of UFO sightings.

In 2021, a government report that examined 144 sightings held that no evidence of any extraterrestrial life was found and it called for better data collection.

The issue was once again brought to the fore last year after a retired Air Force intelligence officer testified to Congress that the US government hides a longstanding plan that reverse engineers unidentified flying objects.

[...]

https://www.dw.com/en/us-pentagon-study-says-no-evidence-of-alien-life/a-68479510

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