Starship is Go...

tahanson43206 · 2021-05-24 09:17:22

For GW Johnson ... would you be willing to check my question in Companion to OF's 17 person expedition?
I'm hoping your computer availability is improving over time.
(th)

louis · 2021-05-24 09:40:32

Thanks for that GW.

Interesting profile, though...

https://www.ekinendustriyel.com/tube-he … xchangers/

"Advantages of Tube Heat Exchangers

They can be designed and manufactured to bear very high pressures
They have extremely flexible and steady design
They can be designed and manufactured to bear very high and very low temperatures
They are resistant to thermal shocks
They have no dimension limit
They can be used in all applications
Pressure loss is at a minimum and can be maintained at a minimum in line with the process purpose.
They can easily be disassembled and assembled back for maintenance, repair and cleaning
Easy maintenance and repair
Pipe diameter, pipe number, pipe length, pipe pitch and pipe arrangement can be altered. So, the designs of tube heat exchangers are quite flexible"

https://en.wikipedia.org/wiki/Shell_and … _exchanger

GW Johnson wrote:

Those odd objects are shell-and-tube heat exchangers. They are not any kind of flyable hardware. They are the very heavy steel construction type of thing you see at chemical refineries. What Spacex needs them for, at Boca Chica, is a public unknown at this time.
Long term storage of manufactured cryogenic propellants requires insulated tanks, even on cold Mars. The cryogenics are far colder, especially the methane. The tanks on Starship are not insulated, so long-term storage is not feasible without the expenditure of enormous power. This is also a problem for months-long interplanetary voyages, for which we have yet to see any solution.
Any propellant plant, on Earth or Mars, will have to feature insulated storage tanks for the methane and for the oxygen, from which the tanks on the vehicle are filled right before launch. We have already seen this in action with the prototypes at Boca Chica. There is radiation heating of the tanks on surfaces and in space, and down on planetary surfaces, there is convective heating from the atmospheres (lower on Mars because of the low densities and lower temperatures), and conductive heating from the surface up the supports for the tanks.
That's just heat transfer physics, which NO ONE can get around. The in-space problem is less because there is only radiational heating to deal with. Some sort of cryocooler is the solution for that. But you do need the power to run it. For months at a time.
The videos whose links Louis so graciously provided do indeed deal with some of the problems we have seen so far in prototype testing. There is one problem no one is yet discussing: the troubles getting a relight on all intended engines. SN-15 was supposed to light 3 engines for the flip, then use 2 or even just 1 to touch down. The announcer said so during the ascent. That failed to happen: only 2 relit for the flip and touchdown.
I suspect without evidence that the failure to relight and the post-touchdown methane leak fires are related in some way. I may be wrong, but all the flights that have landed (even briefly) so far have had relight problems, and post-touchdown methane leaks.
GW

RobertDyck · 2021-05-24 10:04:54

GW Johnson wrote:

Long term storage of manufactured cryogenic propellants requires insulated tanks, even on cold Mars. The cryogenics are far colder, especially the methane. The tanks on Starship are not insulated, so long-term storage is not feasible without the expenditure of enormous power. This is also a problem for months-long interplanetary voyages, for which we have yet to see any solution.

Boiling temperature of methane at 1 Earth atmosphere pressure is -161.6°C, however, at 10 bar absolute (pressure vs vacuum) it close to -125°C.

Here's a table. At 1041 kPa (10.41 bar), boiling temperature of liquid over saturated vapour is 150°K (-123.15°C).

Temperature of deep space is the background radiation from the Big Bang. That's 2.7°K (-270.45°C). If you can shield your spacecraft from the heat of the Sun, that's what you get. However, the sunward side of the spacecraft will experience direct sunlight. You can mitigate that with sun shades, however there will be conduction from the sun shade itself. Temperatures for a spacesuit in Low Earth Orbit are -156°C (-249°F) to 121°C (250°F). This means a sun shade should be able to keep spacecraft tank temperature down to -156°C. That's below boiling temperature for liquid methane at 10.41 bar, so this should work.

Liquid hydrogen requires much colder temperature. Mild pressure and sun shade will never be enough for LH2.

(Ps. Click each image for source of that image.)

louis · 2021-05-25 06:41:08

Annoying robovoice but some interesting shots of work on Boca Chica - proceeding at a phenomenal pace.

https://www.youtube.com/watch?v=JqbDnNbkeWI

GW Johnson · 2021-05-25 08:27:03

Radiational heat transfer is a two-way balance. The object both emits and receives radiation via the equation: Q/A = e sigma (T^4 - Ts^4), where sigma is Boltzmann's constant, and Ts is the effective temperature of the surroundings. e is the emissivity of the object under analysis, which is also its absorptivity.

The "trick" is Ts, which is the temperature of deep space only if you are out in space, and only on the side in shadow (away from the sun). Most folks just use 3 K as typical. On a planetary surface, it is the average effective temperature of the surfaces around you. That is about 300 K for Earth, and I assume about 250 K for Mars, but someone else might have a better figure.

GW

SpaceNut · 2021-05-25 19:55:48

Thanks for the boiloff reminder as the tanks and shell are getting thinner we will see less fuel to land at mars so docking with others in earth orbit to top off cargo might not be such a good thing....

SpaceNut · 2021-05-26 16:56:22

https://youtu.be/S9WTpGFlas4

All raptor sn 15 have problems
videos of the engines before and after
https://www.youtube.com/watch?v=ALLFNTwMDgQ

louis · 2021-05-26 17:34:16

That's not what the video says. They were being taken away for inspection.

SpaceNut wrote:

https://youtu.be/S9WTpGFlas4
All raptor sn 15 have problems

GW Johnson · 2021-05-26 20:17:26

There was a real problem, one way beyond "just inspection". None of the fan/watcher videos on the internet talk about it, either. I would not place a lot of faith in their technical accuracy.

The problem was one engine (I don't know which one) failed to ignite for the flip and touchdown. The plan, as stated by the announcer during the ascent, was to light 3 for the flip, then shut one down, and land on two, or possibly even just one engine. That did NOT happen: they only lit-off two, and they landed on those two.

So, something went very wrong with one engine (the one that failed to re-light). But at least the hardware still exists. It is far easier to figure out "why" if you still have hardware to look at.

We will see whether they really refly SN-15, or just move on to SN-16. Either way, there are still serious problems to fix before they can even think about flying the two stage vehicle to orbit. Such as post-landing methane fires and explosions. Such as landing nearly off the pad in the mud. Such as losing heat shield tiles that are held on mechanically. Need I go on?

Further, you think getting three engines to behave simultaneously is a problem? (And it has proven to be so.) Getting 28+ engines to behave all at once is going to be a real can of worms. It's the same engines in the booster. Just a lot more of them.

This is the sort of thing one just has to deal with when developing brand new vehicle designs from scratch. In the earlier stages of the project you will see a lot of rather abject failures. And we have. Better early, when the costs are lower to fix the issues. Later is bad; it's more expensive, and you may kill somebody.

I think you will see the booster catch-arm notion discarded, before they get a properly-successful orbital flight. That Rube Goldberg notion is going to have even more serious problems than we have seen so far. Better to get that settled early, too.

There is NOTHING quite so expensive as a dead crew.

GW

SpaceNut · 2021-05-26 21:08:18

Not to mention trying to land it in a rocky/ sand covered area that is sloping or uneven with no bulls eye landing target x marks the spot....

Saw that the videos were also showing changes to the active cooling bells being wrapped and there shape being distorted as well.

They very well might fly SN15 again with less than perfect engines just to gather some more data and to work again on the engine not firing problem...

It is doubt full that a stack will fly for a while still as the booster must also have some hops and flight tests before trying to stack and fill one than the other with test fuel levels.

The current live fire testing once built tests will surely change to a lot longer period of time doing these separately before stacking as you only get one shot to fill for flight since they are not doing multiple loading and unloading of fuels...

RobertDyck · 2021-05-27 03:52:09

Elon Musk may order SN20 to launch into orbit anyway. Yes, I agree with everything everyone has said. But Elon is following a rapid development schedule. Remember what NASA did with Saturn V. It was standard practice to test each stage separately. They did test each stage separately in a static test stand. But standard procedure called for launching each stage separately before combining them. They didn't, Apollo 4 was an "all up" test of the full stack. Yes, again, they did test each stage separately in static test stands before doing this. But they didn't launch stages separately. Elon may want to do the same thing, just to keep development pace rapid.

In case someone from SpaceX is reading this, let me give a warning. For Saturn V, they did test each stage in a static test stand. This included the first stage with all 5 engines tested at full thrust, and full duration burn, while held down in a static test stand. This gave engineers the data they needed to ensure it works. And engineers could examine engines and full stage after each test. And not everything worked the first time.

F-1 engines were tested in a separate engine test stand before integration with the stage. They had a problem at first: oscillation until the engine exploded. These were the largest rocket engines ever built. Engineers resolved that problem with baffles, designed to dampen oscillation. For the Russian N-1 rocket, they didn't build a test stand capable to testing a full stage. One Russian politician didn't believe in space, so took away money for the test stand, used it for some aircraft thing. So the first test of the Block A stage was the "full up" test of the rocket. This caused a pogo problem, the rocket exploded (RUD). Second test flight: RUD as soon as it clearing the tower. Third test flight: eddies at the tail of the rocket caused uncontrolled roll. This increased until guidance system went into gimbal lock, vehicle disintegrated due to structural loads. Fourth test flight: normal operation until shutdown of 6 core engines to reduce aerodynamic stress. Abrupt engine shutdown caused a hydraulic shock wave through the propellant feed system. In plumbing this is called pipes "hammering". This caused propellant feed lines to burst. RUD.

Wikipedia: N1 rocket - Launch history

Experience of N1 is particularly appropriate considering N1 had 30 engines. Super heavy booster has how many?

louis · 2021-05-27 15:27:21

I often cite the Apollo rapid development programme as evidence that Musk might still get humans on Mars by 2026. Apollo faced far more serious difficulties in having to develop computer programs that simply didn't exist previously. Pretty sure Space X can buy all the computer power they need "off the shelf". Likewise, the amount of information Space X get back from test flights must be way superior to what was available to the Apollo programme. In terms of putting humans into zero G for long periods, there is now a wealth of info, that NASA are probably willing to share. Likewise, the NASA coms system looks like it will be available to Space X.

RobertDyck wrote:

Elon Musk may order SN20 to launch into orbit anyway. Yes, I agree with everything everyone has said. But Elon is following a rapid development schedule. Remember what NASA did with Saturn V. It was standard practice to test each stage separately. They did test each stage separately in a static test stand. But standard procedure called for launching each stage separately before combining them. They didn't, Apollo 4 was an "all up" test of the full stack. Yes, again, they did test each stage separately in static test stands before doing this. But they didn't launch stages separately. Elon may want to do the same thing, just to keep development pace rapid.
In case someone from SpaceX is reading this, let me give a warning. For Saturn V, they did test each stage in a static test stand. This included the first stage with all 5 engines tested at full thrust, and full duration burn, while held down in a static test stand. This gave engineers the data they needed to ensure it works. And engineers could examine engines and full stage after each test. And not everything worked the first time.
F-1 engines were tested in a separate engine test stand before integration with the stage. They had a problem at first: oscillation until the engine exploded. These were the largest rocket engines ever built. Engineers resolved that problem with baffles, designed to dampen oscillation. For the Russian N-1 rocket, they didn't build a test stand capable to testing a full stage. One Russian politician didn't believe in space, so took away money for the test stand, used it for some aircraft thing. So the first test of the Block A stage was the "full up" test of the rocket. This caused a pogo problem, the rocket exploded (RUD). Second test flight: RUD as soon as it clearing the tower. Third test flight: eddies at the tail of the rocket caused uncontrolled roll. This increased until guidance system went into gimbal lock, vehicle disintegrated due to structural loads. Fourth test flight: normal operation until shutdown of 6 core engines to reduce aerodynamic stress. Abrupt engine shutdown caused a hydraulic shock wave through the propellant feed system. In plumbing this is called pipes "hammering". This caused propellant feed lines to burst. RUD.
Wikipedia: N1 rocket - Launch history
Experience of N1 is particularly appropriate considering N1 had 30 engines. Super heavy booster has how many?

GW Johnson · 2021-05-27 16:18:34

Spacex may well attempt an orbital shot with SN-20 this year. There are problems whose resolution needs demonstrating with SN-16 and AS-17 first. And maybe a re-flight of SN-15. Or maybe not.

My predictions for SN-20 orbital shot in order of likelihood:

1. Booster failure on the pad precludes anything getting into orbit, precludes figuring out why it failed

2. Booster failure during ascent precludes anything getting into orbit, precludes figuring out why it failed

3. Booster functions well enough, but Starship does not, and never reaches orbit; breakup during suborbital entry for any of several dozen reasons; this precludes figuring out why it failed

4. Assuming Starship reaches orbit, it still breaks up during entry, for any of several dozen reasons; this still precludes figuring out the failure

Does that evaluation sort of smell like I might have some engineering development test experience under my belt?

Think I might be nearer correct when I laugh at the notion of sending men to Mars in 2026 with this EXTREMELY-experimental vehicle?

An experimental craft that is STILL very far from being done, blowing itself to smithereens?

GW

Last edited by GW Johnson (2021-05-27 16:21:24)

Oldfart1939 · 2021-05-27 16:56:27

Re RobertDyck's comments in the quote about the Russian engines being shut down. SpaceX seems to understand the waterhammer effect when throttling down to transition Max Q. Falcon Heavy has 27 engines and has flown successfully 3 times with no RUD incidents.

Last edited by Oldfart1939 (2021-05-28 00:01:13)

Calliban · 2021-05-27 17:09:09

Oldfart1939 wrote:

Re RobertDyck's comments in the quote about the Russian engines being shut down. SpaceX seems to understand thee waterhammer effect when throttling down to transition Max Q. Falcon Heavy has 27 engines and has flown successfully 3 times with no RUD incidents.

Waterhammer. I remember that from university days. It requires either close attention to the rate of closure of valves or surge tanks. I remember having to model the effect in a Fortran programme for a hydroelectric dam.

Last edited by Calliban (2021-05-27 17:09:30)

louis · 2021-05-27 18:01:04

Those are definitely all possibilities but we are not in the 1960s so Space X does have a lot of advantages. It can build on a huge body of knowledge about rockets, it has all the computer power it needs, it can derive huge amounts of info from every test flight. One of the things that really impresses me about Space X is that when they identify a fault and find a workable solution that's it, we hardly ever get a repeat error performance. That's why the Falcon 9 has been so incredibly reliable.

Another thing I remember from reading about Saturn V - on every flight there was an average of 4,000 malfunctions! Sounds incredible to a lay person when you read that first. But then you recall its got a million parts or more...there have to be malfunctions happening all the times - bit like our bodies constantly making DNA copy errors. But somehow those Saturn V flights kept going just like our bodies do (on average but not forever).

While I accept that Space X face a blizzard of challenges, it seems like they have no shortage of resources to tackle those challenges. Musk's wish to create a new city at Boca Chica is very astute. He's obviously looking to develop a kind of "new California" in southern Texas which will help him attract the best in every field.

They've shown mastery of the flip so I don't think there will be any problem with orbital flight - the main challenge now is landing. They are clearly finding accurate landing still a challenge and the legs don't help.

GW Johnson wrote:

Spacex may well attempt an orbital shot with SN-20 this year. There are problems whose resolution needs demonstrating with SN-16 and AS-17 first. And maybe a re-flight of SN-15. Or maybe not.
My predictions for SN-20 orbital shot in order of likelihood:
1. Booster failure on the pad precludes anything getting into orbit, precludes figuring out why it failed
2. Booster failure during ascent precludes anything getting into orbit, precludes figuring out why it failed
3. Booster functions well enough, but Starship does not, and never reaches orbit; breakup during suborbital entry for any of several dozen reasons; this precludes figuring out why it failed
4. Assuming Starship reaches orbit, it still breaks up during entry, for any of several dozen reasons; this still precludes figuring out the failure
Does that evaluation sort of smell like I might have some engineering development test experience under my belt?
Think I might be nearer correct when I laugh at the notion of sending men to Mars in 2026 with this EXTREMELY-experimental vehicle?
An experimental craft that is STILL very far from being done, blowing itself to smithereens?
GW

SpaceNut · 2021-05-27 20:57:57

The thinning of the metals thickness for starship can be a problem for the booster as thats got to be able to hold up under being fueled up for launch but also be able to push the starships while the counter pressure of full tanks is dropping and not beer canning collapsing as it pushes the starship upward. Then its got the just as hard to land issue that starship is still trying to nail.

The Falcon heavy is close to the capitation but due to it being some what isolated into 3 its made less through the attachment points from one core to the other.

GW Johnson · 2021-05-28 08:43:10

Don't get me wrong, I am rooting for Spacex success as much as any of you. But I am experienced enough and knowledgeable enough to know what the development of a new vehicle entails.

While there may be a plethora of records and literature to build upon, I would remind some here that "rocket science" (actually "rocket vehicle engineering") ain't just science. It is only about 40% science, which is the stuff that got written down. It's about 50% art, which is passed on one-on-one from old hand to newbie on-the-job (if at all), because no manager wanted to pay for getting it written down, and about 10% blind dumb luck.

That's in production work. In development work, the art and luck portions are a lot higher. And it's not just "rocket science", it's pretty much any kind of engineering you want to talk about. These days, the art doesn't get passed on anymore, because the managers think all engineers are alike, and newbies are cheaper than old hands. Which is partly why many outfits have little or no members over the age of 45 in their organizations. Spacex is one of those, motivated also by the fact that most old hands cannot sustain chronic 80-hour overtime.

Given that situation, the plethora of prior experiences at previous outfits is less useful than it should be. Ugly little fact of today's life, but there it is. Deal with it.

GW

Mars_B4_Moon · 2021-05-29 16:42:31

Some people Love Musk others dislike him, maybe there is a certain alliance of companies and contractors maybe negative press out there is generated by Big Oil, he has a rival at Amazon and there could be bad press or spam bots posting hit-piece articles on behalf of Big Auto, but Musk himself is intelligent, talented and an interesting and unique individual.

Musk Says Becoming 'Multi-planetary' Is One of the Greatest Filters
https://www.sciencetimes.com/articles/3 … netary.htm
Elon Musk is leading the way in the race to reach the solar system, which he believes will guarantee humanity's position in the cosmos in the future.

Following the flight of SN15, the vehicle was moved onto test stand B. This rose questions if SpaceX was going to refly the vehicle or do a static fire. Over the weekend, teams at the pad removed the three Raptor engines, and yesterday a transport mount was moved to the pad. This means that we will see SN15 move back to the manufacturing site sometime this week.
https://spaceexplored.com/2021/05/29/sp … test-site/
What SpaceX will do with it next is unknown. Rumors of a second flight or static fire seem unlikely now, as any flight operations would stall the work on the orbital pad. The focus is now on getting to orbit, with signs of what could be SN20, supposedly the first orbital Starship, being seen around Starbase.

There was talk on social media about Musk going more militarist on Mars, probably because of the odd nature of some of his tweets and social media comments.

Starship development history will continue to be hardware for Mars and the Moon?
or Year 2022 budget proposal shows more Military and Political, Trump Biden vision for a SpaceForce?? The Space Force already operates two Boeing X-37B spaceplanes and that weird USA-299 Orbital Test Vehicle which may have been photographed by amateur astronomers, astro-photographers adn satellite trackers
https://www.space.com/41565-x-37b-space … -otv5.html

I believe people may have confused the Boeing Space Plane with Musk's projects, there is also a Dream Chaser mini shuttle vehicle by Sierra Nevada Corporation, other groups in Europe like ESA and Russia had concepts for space plane vehicles.

The SpaceX Build Sites have been spotted in aerial photography
https://twitter.com/RGVaerialphotos/sta … 0499088384

SpaceX has disclosed details for the first orbital test flight of its next-generation Starship launch system, but the company is still far short of the regulatory approvals needed for the mission.
https://spacenews.com/spacex-outlines-f … st-flight/
“SpaceX intends to collect as much data as possible during flight to quantify entry dynamics and better understand what the vehicle experiences in a flight regime that is extremely difficult to accurately predict or replicate computationally,” the company said in the application. “This data will anchor any changes in vehicle design or [concept of operations] after the first flight and build better models for us to use in our internal simulations.”

As outlined in the application, the Super Heavy booster will shut down 169 seconds after liftoff, separating from the Starship upper stage two seconds later. Super Heavy will fly back not to Boca Chica, but instead to a location 32 kilometers offshore in the Gulf of Mexico, touching down 495 seconds after liftoff. The application didn’t state if the booster would land on a platform, such as an oil rig SpaceX is converting for such uses, or splash down into the ocean.
He has a lot of Futurist and futurologist ideas like linking brains directly to computers...and other things that worry some political people.

However let's get back to real contracts and building plans for Space the Human Landing Systems out there, Which Lander is Best? It would seem Musk is ahead of the game.

The SpaceX Starship launch: Will SN15 or SN16 launch first?
https://www.express.co.uk/news/science/ … n-musk-evg
SPACEX fans are waiting with bated breath for the next launch of the Starship prototype. But what will launch next, the SN15 again or a maiden flight of the SN16?

Astronomers however are very frustrated with the reality of Elon Musk’s satellites which are now blinding their view of space?

louis · 2021-05-29 17:01:16

Musk is the Edison of our age but you could throw in comparisons with Christopher Columbus, Henry Ford, John Lennon and a few others as well.

Musk has warned of the terrible dangers of AI and I think some of his experiments in that direction are designed as a warning, not as promotion of the concept.

Musk is about to realise his dream of making humanity a multi-planetary species. It will be a spectacular achievement - one man pretty much carrying out the equivalent of the Neolithic Revolution...that kind of level of importance.

If he can further establish a community of one million people within 30 years, that would truly be an unbelievable accomplishment. However, I don't believe that's possible - not from a technical point of view but from a social-anthropological angle. But it will be amazing to see him try.

Columbus's attempt to transfer European civilisation to the Americas was basically a failure - it took decades before substantial European settlement took place. I think that may be the pattern we see. There will be bases but Mars will not be a complete human civilisation on Mars for decades.

If I'm wrong, I'll be happily wrong!

Mars_B4_Moon wrote:

Some people Love Musk others dislike him, maybe there is a certain alliance of companies and contractors maybe negative press out there is generated by Big Oil, he has a rival at Amazon and there could be bad press or spam bots posting hit-piece articles on behalf of Big Auto, but Musk himself is intelligent, talented and an interesting and unique individual.
Musk Says Becoming 'Multi-planetary' Is One of the Greatest Filters
https://www.sciencetimes.com/articles/3 … netary.htm
Elon Musk is leading the way in the race to reach the solar system, which he believes will guarantee humanity's position in the cosmos in the future.
Following the flight of SN15, the vehicle was moved onto test stand B. This rose questions if SpaceX was going to refly the vehicle or do a static fire. Over the weekend, teams at the pad removed the three Raptor engines, and yesterday a transport mount was moved to the pad. This means that we will see SN15 move back to the manufacturing site sometime this week.
https://spaceexplored.com/2021/05/29/sp … test-site/
What SpaceX will do with it next is unknown. Rumors of a second flight or static fire seem unlikely now, as any flight operations would stall the work on the orbital pad. The focus is now on getting to orbit, with signs of what could be SN20, supposedly the first orbital Starship, being seen around Starbase.
There was talk on social media about Musk going more militarist on Mars, probably because of the odd nature of some of his tweets and social media comments.
Starship development history will continue to be hardware for Mars and the Moon?
or Year 2022 budget proposal shows more Military and Political, Trump Biden vision for a SpaceForce?? The Space Force already operates two Boeing X-37B spaceplanes and that weird USA-299 Orbital Test Vehicle which may have been photographed by amateur astronomers, astro-photographers adn satellite trackers
https://www.space.com/41565-x-37b-space … -otv5.html
I believe people may have confused the Boeing Space Plane with Musk's projects, there is also a Dream Chaser mini shuttle vehicle by Sierra Nevada Corporation, other groups in Europe like ESA and Russia had concepts for space plane vehicles.
The SpaceX Build Sites have been spotted in aerial photography
https://twitter.com/RGVaerialphotos/sta … 0499088384
SpaceX has disclosed details for the first orbital test flight of its next-generation Starship launch system, but the company is still far short of the regulatory approvals needed for the mission.
https://spacenews.com/spacex-outlines-f … st-flight/
“SpaceX intends to collect as much data as possible during flight to quantify entry dynamics and better understand what the vehicle experiences in a flight regime that is extremely difficult to accurately predict or replicate computationally,” the company said in the application. “This data will anchor any changes in vehicle design or [concept of operations] after the first flight and build better models for us to use in our internal simulations.”
As outlined in the application, the Super Heavy booster will shut down 169 seconds after liftoff, separating from the Starship upper stage two seconds later. Super Heavy will fly back not to Boca Chica, but instead to a location 32 kilometers offshore in the Gulf of Mexico, touching down 495 seconds after liftoff. The application didn’t state if the booster would land on a platform, such as an oil rig SpaceX is converting for such uses, or splash down into the ocean.
He has a lot of Futurist and futurologist ideas like linking brains directly to computers...and other things that worry some political people.
However let's get back to real contracts and building plans for Space the Human Landing Systems out there, Which Lander is Best? It would seem Musk is ahead of the game.
The SpaceX Starship launch: Will SN15 or SN16 launch first?
https://www.express.co.uk/news/science/ … n-musk-evg
SPACEX fans are waiting with bated breath for the next launch of the Starship prototype. But what will launch next, the SN15 again or a maiden flight of the SN16?
Astronomers however are very frustrated with the reality of Elon Musk’s satellites which are now blinding their view of space?

louis · 2021-05-30 14:59:22

29 Raptor engines for the Super Heavy Booster..,

https://www.youtube.com/watch?v=UoXJdW1fDcY

That's going to make a bit of noise!

louis · 2021-05-31 13:32:02

https://i.redd.it/cd9r23o9wd271.png

Exchange with Musk re the engine layout: 3-9-20 with 3 and 9 gimballing in co-ordination.

louis · 2021-05-31 17:31:31

For leg obsessives:

https://www.youtube.com/watch?v=3DHV4mUljww

Enjoy!

GW Johnson · 2021-06-01 12:44:36

Here is where the prototype Starships currently are with the 6-leg rig. Inert mass 120 m.tons (per Musk presentation at Boca Chica in front of one of the earlier protypes). Max fuel residual at touchdown: 10 m.ton (an educated guess on my part). Payload aboard 0. Total landed mass 130 m.ton. Earth weight of that landed mass 1.275 MN.

Each leg has a pad roughly 0.5 x 0.5 meter in dimension, for roughly 0.25 sq.m per pad (almost no matter the detailed shape), 6 pads, for a total landing pad area in contact with surface: about 1.5 sq.m.

Static pressure if exerted evenly: 1.275MN/1.5 sq.m = 0.85 MPa. Factor-up for min touchdown dynamics (if evenly distributed) = 2. Min further factor-up for uneven touchdown = 2. Total factor-up to apply: 4 (could easily be nearer 9). Peak touchdown pressure expected under the first leg to touch: 0.85 x 4 = 3.4 MPa.

Solid rock = reinforced thick concrete capability 5-10 MPa. OK (if factor nearer 4 than 9). Peak force to be carried in the first leg to touch: 1.275 MN x factor 4 = 5.1 MN compressive (could be nearer 10 MN).

If they miss the pad the way SN-15 nearly did: min peak pressure under the pad on the dirt: 3.4 MPa (could be higher). Static pressure under the pad on the dirt: 0.85 MPa. Safe bearing capability of soft sand/soft clay 0.1 MPa, corresponding to 0.2 to 0.3 MPa at failure (failure defined as leg drives deeply into dirt). 0.85 steady/3.4 transient MPa exerted, vs 0.1 MP safe/0.2-to-0.3 MPa at failure: not in any way OK!!!

Conclusion: an off-pad landing in those tidal flats or on a beach, or on a plowed field, or in a blackland clay cow pasture is by definition a failure. Murphy's Law guarantees an uneven stab-in of the legs, for a guaranteed topple-over at more than 5 degree tilt, which topple-over is a guaranteed explosion.

Conclusive prediction: no landing leg design that would ever work on Mars, or the moon, or even on Earth in the dirt, is going to look like the legs they are currently using to land on thick reinforced concrete pads.

Sorry, them's just the numbers.

And Musk knows this, or he would not have tweeted about these legs being a stopgap on the prototypes.

Musk is NOT an engineer, he is a dreamer! He has engineers working for him, trying to make those dreams reality. That is the right combination: it really does take a dreamer at the top to do anything substantive. But for reliable predictive purposes, you don't listen to the dreamer, you listen to his engineers.

I have noticed that Shotwell has not said anything about when any missions outside LEO might be done, even with a NASA contract to do them on the moon. Neither has anyone else. A peculiarity of Musk is that he clearly does not want his engineers making public predictions about anything.

It is simply too early in a difficult development process to predict anything accurately.

So this 2024/2026 thing on Mars is still the height of fantasy. Still nothing but a dream. Musk's dream. The observed ratio of real time to Musk time is still in the 2 to 3 range, just as it has been since the Falcon-1 days.

GW

Last edited by GW Johnson (2021-06-01 12:45:45)

tahanson43206 · 2021-06-01 13:57:03

For GW Johnson re Safe Landing On Mars

Your Post #1224 is another reminder that the early designs of Starship we see during testing on Earth are not suitable for a landing on Mars.

A vehicle intended for landing on Mars does NOT have to be designed in the same way as it would have to be for a landing on Earth.

The atmosphere facing side ** would ** appear (as I understand it) to have to withstand comparable forces during aerobraking, so I'm taking that into account as I toss a suggestion your way.

A Starship designed for landing on Mars could be fitted with landing legs similar to those we see on the Falcon 9 first stage, but MUCH larger.

The Falcon 9 design appears (to my eye) to be optimized to provide ** just ** the right stability needed on a rolling sea barge, at the least possible penalty in mass.

The lower gravity of Mars ** should ** (I would think) permit design of a similar multiple leg foldout structure to be much larger than the one we see proven (many times) on the Falcon9.

Edit#1: The wide legs could (I suppose) be left behind on Mars when the vehicle launches for Mars LMO ... if the vehicle is NOT returning to the surface of Mars. On the ** other ** hand, if the vehicle is intended for shuttle duty, then leaving the legs in place would make sense.

(th)

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#1201 2021-05-24 09:17:22

Re: Starship is Go...

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