totm nov 2023 SpaceX Discussion Thread

[CBase]

56 minutes ago, magnemoe said:

But as they scrub launches is an stupid boat get into the launch trajectory I have problems seeing them allowing reentry over populated areas, Starship is 100 ton and pretty sturdy build so it will be large parts coming down.  On the other hand a shuttle broke up and they continued to fly them overland.

Launch and landing are two different things. Breaking up is exactly the risk you want to avoid. With engines firing during ascent a lot of failures lead to RUD and therefore high danger of breaking up. So you don't want launch trajectories over land. For reentry the failures are breaking up due to aerodynamic forces and material failures due to overheating. And of course powered landing.

So I guess @darthgently is right, if they have shown with several sea landings that they won't break on reentry a passive trajectory over land is probably fine.

[SunlitZelkova]

20 hours ago, mikegarrison said:

Aren't you forgetting Kennedy's 1961 speech saying the US "should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to the Earth"?

I was listing lofty goals. Kennedy’s challenge was not a lofty goal because it gave the US almost a decade of time to complete it.

Whereas the Soviet Moon project and Shuttle had five years or so.

[mikegarrison]

40 minutes ago, SunlitZelkova said:

I was listing lofty goals. Kennedy’s challenge was not a lofty goal because it gave the US almost a decade of time to complete it.

Whereas the Soviet Moon project and Shuttle had five years or so.

Wow.

Apollo in less than a decade was "not a lofty goal"? When the US had not yet even put a person into orbit at that point? And no one else has landed a person on the moon in more than 60 years since? I mean, it gave rise to the use of the word "moonshot" as meaning an ultimate all-hands-on-deck stretch goal.

But whatever. I guess you have your opinion.

[Exoscientist]

On 9/2/2023 at 12:34 AM, tater said:

You have to expand to read, but Zack thinks they will need to test boosters while the stand is occupied with boosters readying for flight. Also, the OLM is limited to 50% thrust static fires due to the nature of the launch hold-downs, he thinks these will clamp the booster down hard.

Thanks for that. He suggests two reasons: they want to do higher than 50% thrust tests and the OLM wasn’t designed for that and they want to do longer than just 5 second tests, perhaps full flight duration, and the water deluge system is not capable of delivering that amount of water.

 Also notable he suggests these new test stands will have true flame diverters, as NASA has always used for their launch stands and static test stands. In this regard it should be remembered the SpaceX engineers wanted to have flame diverters for the SuperHeavy/Starship launch but they were overruled by Elon for cost and time reasons. Elon really wanted to make that 4/20 date.

  Robert Clark

[SunlitZelkova]

2 hours ago, mikegarrison said:

Apollo in less than a decade was "not a lofty goal"? When the US had not yet even put a person into orbit at that point? And no one else has landed a person on the moon in more than 60 years since? I mean, it gave rise to the use of the word "moonshot" as meaning an ultimate all-hands-on-deck stretch goal.

With hindsight it’s pretty clear that not only was the US fully capable of putting a man on the Moon prior to 1970, but the Soviets also had no chance at beating them.

Politically lofty? Yes, as you said no one has had the will to go back for 50 years. I’ll concede it was very lofty to get Congress to continue to fund it especially when the Vietnam War was a big priority.

Technically lofty? It was cutting edge technology for sure, but as to whether that means it was somehow absurd for it to be built by 1970, I personally think no.

[mikegarrison]

1 hour ago, SunlitZelkova said:

With hindsight it’s pretty clear that not only was the US fully capable of putting a man on the Moon prior to 1970, but the Soviets also had no chance at beating them.

Politically lofty? Yes, as you said no one has had the will to go back for 50 years. I’ll concede it was very lofty to get Congress to continue to fund it especially when the Vietnam War was a big priority.

Technically lofty? It was cutting edge technology for sure, but as to whether that means it was somehow absurd for it to be built by 1970, I personally think no.

With hindsight, everything that anyone has already accomplished was obviously quite possible to accomplish.

[magnemoe]

On 9/2/2023 at 6:34 AM, tater said:

You have to expand to read, but Zack thinks they will need to test boosters while the stand is occupied with boosters readying for flight. Also, the OLM is limited to 50% thrust static fires due to the nature of the launch hold-downs, he thinks these will clamp the booster down hard.

A bit skeptical to lots of this. Yes an test stand makes some sense, an flame trench can not be very deep because of the water level. Its also not really needed as you can just build higher, more likely its the foundation and the water sprayer system. An flame diverter also makes sense, but less so for the test stand as its here you will do engine maintenance and replacements. 
Also a bit skeptical about holddown clamps limited to 50%, probably not safe without an fully loaded Starship on top however. 
You will also need a lot more water for an longer test burn. 

But I can easy imagine SpaceX realizing the launch mount has weaknesses but rater than taking time modifying it they make an new mount just for testing and also experiment with new designs. 
At KSC they will need an directional flame diverter for one. 

[JoeSchmuckatelli]

There is a possibility of building a second tower and table as part of this, maybe? 

I can't see the utility of two test tables feeding one tower if launch cadence is being leaned into.  But one test stand with one tower ready to launch and the other looking up ready to catch? 

Shrug - maybe? 

[tater]

 

[mikegarrison]

1 hour ago, JoeSchmuckatelli said:

There is a possibility of building a second tower and table as part of this, maybe? 

I can't see the utility of two test tables feeding one tower if launch cadence is being leaned into.  But one test stand with one tower ready to launch and the other looking up ready to catch? 

Shrug - maybe? 

Probably they should make some successful launches with the tower they have before they build a third one. (Don't they already have a second one built or being built in Florida?)

[tater]

 

[magnemoe]

3 hours ago, mikegarrison said:

Probably they should make some successful launches with the tower they have before they build a third one. (Don't they already have a second one built or being built in Florida?)

The Florida one is on hold, I assume its much more red tape at KSC because its NASA property and has multiple users. 
An second launchpad at starbase make much more sense than two static fire test platforms. Not because launch numbers but redundancy and testing builds for KSC,  but static fires will also go down as superheavy matures and then the overall design is sound its just about testing engines before launching again. 
 

[StrandedonEarth]

My four cents (inflation adjusted):

The Florida SH launch tower at LC-39A is visible front-and-center in tater's post five posts back, and progress has slowed or stopped while LC-40 is upgraded to crew capable, to minimize risks to the crew program.

Increasing launch cadence will run into heavy environmental opposition at Boca Chica, as IIRC the current permits only allow a few launches per year

 

[CatastrophicFailure]

13 hours ago, Exoscientist said:

SpaceX engineers wanted to have flame diverters for the SuperHeavy/Starship launch but they were overruled by Elon for cost and time reasons. Elon really wanted to make that 4/20 date.

[citation needed]

[tater]

 

[tater]

Youtube link to upcoming launch this evening pulled.

All streams to be done on twitter/X now.

I should say all SpaceX streams. I imagine they'll do YT for NASA missions still.

[JoeSchmuckatelli]

3 hours ago, tater said:

All streams to be done on twitter/X now.

I am disappoint

Surprised I am not

[tater]

 

max q

 

stage 1 landed

 

[tater]

 

[tater]

 

[SunlitZelkova]

23 hours ago, mikegarrison said:

With hindsight, everything that anyone has already accomplished was obviously quite possible to accomplish.

Perhaps I was using the wrong word, but I defined “lofty” as “having proven to have been impossible to complete [on time]”.

[mikegarrison]

37 minutes ago, SunlitZelkova said:

Perhaps I was using the wrong word, but I defined “lofty” as “having proven to have been impossible to complete [on time]”.

That's survivor bias.

If you have 1000 people drawing lots, and one wins, you are exhibiting survivor bias if you go ask the winner how he got to be so good at drawing lots.

Likewise, if there are 1000 lofty goals, and 999 fail, that doesn't mean the one that succeeded wasn't lofty. It just means they were the survivor.

If you judge the initial challenges by whether they were ultimately met or not, you are going to end up claiming that all successful attempts were actually easy, and all failures were hard. But that's survivor bias.

Edited September 4, 2023 by mikegarrison

[JoeSchmuckatelli]

9 hours ago, tater said:

 

Just amazing what people are doing with photography these days. 

[tater]

JFK's goal was incredibly audacious. No one working on it at the time thought it was a foregone conclusion by a long shot, it's honestly hard to even imagine a more lofty goal.

[JoeSchmuckatelli]

2 hours ago, tater said:

JFK's goal was incredibly audacious. No one working on it at the time thought it was a foregone conclusion by a long shot, it's honestly hard to even imagine a more lofty goal.

Yeah - I can't watch Hidden Figures or The Right Stuff and see anything but both audacity and deep thinking.  If you contextually think about the risk Kathryn Johnson was taking being the person able to compute Glenn's return and recovery?  There was a lot of bravery beyond just the guys who strapped in.