totm nov 2023 SpaceX Discussion Thread

[Nuke]

2 hours ago, sevenperforce said:

Yes, correct; I said tempered glass but I meant laminated glass. Good catch.

Ok, gotcha. So this would still be a reusable two-stage-to-orbit design, just with a third stage that is reusable BLEO.

yea, technically 2-stage to orbit. though im not sure how were going to have a heatshiled on a middle stage. you need to connect up structurally without any attachment points through the heatshield. that second stage is going to be mostly starship like, but able to have a stage above it. 3rd stage will be like a mini-starship/lunar starship hybrid.  the only real difference is that fuel depot is on the moon rather than in leo. frankly i question the long term viability of an on orbit fuel dump. on the grounds of space debris. and granted this is step 3 or 4 on a process that ends in us eventually having a nuclear powered milk run from leo to the lunar surface (with connections to phobos, deimos, and mars). 

1 hour ago, Piscator said:

As far as I know, the charges worked immediately. It's just that it took the vessel 40 seconds to sufficiently depressurize to finally loose enough rigidity to be torn apart by aero forces.

i think the devices used are pretty common in flight termination systems, however i think starship's material choice probibly reduce their effectiveness. these things are usually fired against a different alloy (usually some kind of aluminum). perhaps stainless is a bit tougher and needs more boom to rupture. 

Edited May 4, 2023 by Nuke

[sevenperforce]

16 minutes ago, Nuke said:

technically 2-stage to orbit. though im not sure how were going to have a heatshiled on a middle stage. you need to connect up structurally without any attachment points through the heatshield.

Why not just give the middle stage a hinged fairing and have the third stage inside that fairing?

16 minutes ago, Nuke said:

3rd stage will be like a mini-starship/lunar starship hybrid.

If it's not coming back to Earth EDL for a landing, then it won't need flaps or a heat shield or anything, really -- just tanks and engines.

16 minutes ago, Nuke said:

 i question the long term viability of an on orbit fuel dump. on the grounds of space debris.

What space debris?

If you have an orbiting propellant depot that is refilled with reusable tankers, there's no space debris left over at all.

[Nuke]

6 minutes ago, sevenperforce said:

Why not just give the middle stage a hinged fairing and have the third stage inside that fairing?

If it's not coming back to Earth EDL for a landing, then it won't need flaps or a heat shield or anything, really -- just tanks and engines.

What space debris?

If you have an orbiting propellant depot that is refilled with reusable tankers, there's no space debris left over at all.

having a third stage in an internal bay would impinge on the amount of fuel the second stage can carry. the possibility of having the second stage deliver to a high eccentric orbit seems too good to pass on. 

im talking from other sources. leo is significantly a higher risk fuel storage location than the lunar surface. lots of swarms going up means a lot of lost wayward parts (perhaps the aftermath of a decade of starship operation barring serious effort at leo cleanup). 

Edited May 4, 2023 by Nuke

[tater]

51 minutes ago, sevenperforce said:

If it's not coming back to Earth EDL for a landing, then it won't need flaps or a heat shield or anything, really -- just tanks and engines.

Tug!

 

[mikegarrison]

59 minutes ago, sevenperforce said:

What space debris?

All the debris currently in space. Any of which could hit an orbital tank.

It seems like a tank would have to have the ability to dodge, just like a space station, or else it is eventually going to take some hits.

(Well, take more hits. Everything up there takes some hits. Usually from stuff too small to track.)

[kerbiloid]

The Soyuz stages happily fall almost intact (just smashed), so the air pressure is unlikely enough to tear them apart without explosions.

The SuperStarship propellants are cryogenic, but the tanks are bulky. So, it looks wise to cut the tanks into sheets, which in turn will be quickly slowed by air drag, and land and relatively low speed.

12 hours ago, sevenperforce said:

Why not just give the middle stage a hinged fairing and have the third stage inside that fairing?

So, the fairing will make the third stage structure be several times heavier. (The tanks themselves + much bigger external envelope).

12 hours ago, sevenperforce said:

If you have an orbiting propellant depot that is refilled with reusable tankers, there's no space debris left over at all.

The tanks are bulky and thin, so a reusable tanker will bring very little cargo, because it must be strong and heatproof.

P.S.
Why Musk doesn't just buy Port Isabel and declare it a part of the test site?

P.P.S.
Starship Superheavy: TSTO = "too stage to orbit".

[tater]

 

[sevenperforce]

The perforated steel pancake idea is very Elon but I don't see any clear reason why it wouldn't work.

[Exoscientist]

 In addition to the three alarming facts about the launch I discussed  previously there was another fact just as alarming, the lean the rocket initiated soon after launch. It was assumed this was commanded by launch control. But Elon revealed this was done by the rocket itself to compensate for the 3 shut down engines:

Elon Musk pushes for orbital goal following data gathering objectives during Starship debut
written by Chris Bergin May 3, 2023
…
“Those engines did not explode, but they were just, the system didn’t think they were healthy enough to bring them to a full thrust,” added Musk during a post-flight Twitter spaces call, adding that is why the vehicle appeared to lean away from the Tower during ascent.
It was assumed the lean could have been related to pad avoidance, but Musk quickly noted that it is undesirable due to the “blowing torch” of the Raptor 2 engines on the OLM ring.
“If you move sideways sooner, you are moving that big, cutting torch across the launch ring. So, you can think of this thing like the world’s biggest cutting torch, basically. Depending on how close the engines are, they erode that steel at a roughly — I think half an inch to an inch per second of high strength steel is eroded by the cutting torch.”
“(The lean was actually) related to the engines out, and we do not normally expect to lean. It should be aspirationally going straight up.”https://www.nasaspaceflight.com/2023/05/musk-orbital-goal-starship-debut/

This is extremely concerning because if this really was a fully automated compensation maneuver then if the shut down engines were on the other side the lean would have been towards the launch tower! The result would have been a catastrophic explosion.

  Bob Clark

[Brotoro]

Yes, but they decided to fly without those three engines. Now that they know how much side-slide you get with engines out on the same side, they can just abort a launch and not release if that happens again. So this is not an ongoing problem.

[Meecrob]

1 hour ago, Exoscientist said:

~snip~

I would agree if this was a finished commercial product and not an experimental prototype.

[darthgently]

3 hours ago, Exoscientist said:

This is extremely concerning because if this really was a fully automated compensation maneuver then if the shut down engines were on the other side the lean would have been towards the launch tower! The result would have been a catastrophic explosion.

Not necessarily.  The software could be set up to shutdown all engines and do a full abort if the lean would have predictably been toward stage 0 (clearly the case if the unready engines had been on the other side.)   Do I know this is the case?  No more than you know it isn't

Edited May 7, 2023 by darthgently

[magnemoe]

14 minutes ago, sevenperforce said:

The perforated steel pancake idea is very Elon but I don't see any clear reason why it wouldn't work.

Agree, it should work if enough water is pushed to stop it from overheating. 

[tater]

6 hours ago, Exoscientist said:

This is extremely concerning because if this really was a fully automated compensation maneuver then if the shut down engines were on the other side the lean would have been towards the launch tower! The result would have been a catastrophic explosion.

It's not that concerning unless you are the one writing the checks. The guy writing the checks seems relatively unconcerned (past his normal level of concern with wanting it to work).

It's not like he followed those statements he made with "we're just gonna do exactly the same thing again until it works." He said they identified issues they would work.

 

[magnemoe]

56 minutes ago, darthgently said:

Not necessarily.  The software could be set up to shutdown all engines and do a full abort if the lean would have predictably been toward stage 0 (clearly the case if the unready engines had been on the other side.)   Do I know this is the case?  No more than you know it isn't

A valid point, now you have engine gimbal and differential trust but I guess this has some lag especially on such an large rocket, think steer an large ship. 
Now you could gimbal while holding, but I don't imagine they will launch an operational Starship with an engine out at launch. 

I say its a bit strange they used an starship with heat tiles for first launch, more so with 90% trust. First reach orbit and get data for superheavy boost back and landing simulation as in water landing. 
You might sacrifice starship for superheavy data and you don't need an serious boost back burn, just stay inside the crash zone.
That is unlike they assumed they would reach orbit. 
 

[kerbiloid]

On 5/3/2023 at 12:04 AM, tater said:

How about we just give up on doing anything interesting with spaceflight and use crappy existing rockets forever, instead?

How about at least building a proper test stand for the full engine assembly, digging an exhaust trench like others do, and probably not putting so many engines in a cramped skirt where they burn each other (square-cube law?) ?

(And that's even before the aerobraking cylinder, which will bring more surprises in its time).

Private companies still use public physics. There is no special PhysicX for SpaceX.

They talk about the Mars colony, but don't spend money at least on a proper launch site. Nuff said.

Edited May 7, 2023 by kerbiloid

[tater]

17 minutes ago, kerbiloid said:

How about at least building a proper test stand for the full engine assembly, digging an exhaust trench like others do, and probably not putting so many engines in a cramped skirt where they burn each other (square-cube law?) ?

The proper test stand is a launch pad. They have what, 17 acres to play with?  Any flame diverter they build would need to be under the pad anyway.

Digging a trench at ~1m above sea level is not a thing, BTW. They'd have to first build a hill, then they'd need the space to have a workable slope for transporting the vehicles, which I doubt fits in the small property (the road is owned by the state).

As for proper launch sites, there are not many places to build any—all proper launch sites are on a coast, and there is limited coastal real estate.

[kerbiloid]

36 minutes ago, tater said:

The proper test stand is a launch pad.

The proper test stand is a simple but strong concrete structure with pipelines bringing propellant from safe place.

36 minutes ago, tater said:

They have what, 17 acres to play with? 

Point the torches up. It needs 9 m in diameter. Two trucks aside under a tent take more place.

36 minutes ago, tater said:

Digging a trench at ~1m above sea level is not a thing,

Then the choice of the launchpad place is sick. So, they should either buy a better village, or build a launch ziggurat with exhaust channels from top.

It's like building a solar plant in London and saying that the place is fine, just the weather is cloudy.

36 minutes ago, tater said:

As for proper launch sites, there are not many places to build any

US occupies almost a half of continent, and has ocean to the right. It has a lot of mountains and deserts. But they preferred a swamp.

NK and Japan are much smaller, but they did it right.

P.S.
I heard about "2 bln" loss cost.

How many acres could be bought for that price?

Edited May 7, 2023 by kerbiloid

[Hannu2]

34 minutes ago, kerbiloid said:

US occupies almost a half of continent, and has ocean to the right. It has a lot of mountains and deserts. But they preferred a swamp.

NK and Japan are much smaller, but they did it right.

I think practically every meter of coast is privately owned and builded or natural protection area. Estate on coast line is the most wanted and expensive. Owners' rights are much more important thing in USA and other western countries than space plays of nerds.

 

34 minutes ago, kerbiloid said:

P.S.
I heard about "2 bln" loss cost.

How many acres could be bought for that price?

Probably much less that you would expect. Even normal market price of properties with piece of coast line is crazy. And when owners understand that some big and rich company want to have larger continuous area their demands increase to totally ridiculous level and there are always some stubborn individuals who do not sell at any price. It would probably be impossible for even state to buy honestly decent launch complex with safety area around it in optimal place. I do not know if there is legal ways to force owners to sell their land at market price in that kind of situations.

[kerbiloid]

8 minutes ago, Hannu2 said:

I think practically every meter of coast is privately owned and builded or natural protection area. Estate on coast line is the most wanted and expensive. Owners' rights are much more important thing in USA and other western countries than space plays of nerds.

Iirc, these nerds are launching military and spy sats.
In 1940s the land was owned, too, but in never made a problem with removing a rocky planet from the highway to be built.

***

https://texasfarmcredit.com/resources/texas-land-pricing-guide/#:~:text=The average price per acre,%244%2C297%2Facre average in Q2

Quote

The average price per acre of rural land in Texas was more than $4,000 per acre in 2022, according to the Texas Real Estate Research Center. That average climbed each quarter: $4,116/acre average in Q1 of 2022. $4,297/acre average in Q2.11 янв. 2023 г.

 

• $4,116/acre average in Q1 of 2022 
• $4,297/acre average in Q2
• $4,426/acre average in Q3

2 000 000 000 / 5 000 = 400 000 acres ?

[FleshJeb]

From a former SpaceX engineer:

https://thenext30trips.com/p/scrappy-special-edition

"Honestly, if this was any company other than SpaceX I would declare them toast."

Another good look at SpaceX company culture:

https://thenext30trips.com/p/team-friendship

Several years ago I wrote about working as a subcontractor for Tesla--The experience lines up pretty well, and its a worrying one.

What I predict happening with SpaceX is that the chaos will catch up with them. Sure, you can push really hard and ride the edge of catastrophe and keep squeaking out wins. However, that causes a lot of burnout and the company gets a reputation. Your really talented people either start quitting earlier and earlier, or they run out of energy and focus, or they just cease applying for the jobs at all. Eventually you run out of luck and talent and the mistakes get bigger and harder to recover from because there just aren't enough human resources to keep things from falling off the edge. You don't want the lines of talent_needed and talent_available to converge.

Coincidentally, I just left a job at this kind of engineering company after 15 years.

There's no reality in the spin, "We just wanted to clear the tower, 50/50 chance." My evidence being, there's a picture of some ATV/golf cart things at Starbase that got a bit munched in the launch. Sure that's a small budget item for SpaceX, but if they really thought there was a good chance the rocket was going to blow up on the pad, don't you think that someone would have taken 5 minutes to move them well out of the way? Or did SpaceX get "valuable data" from destroying some of their site transports. /s

I'll close with a joke an elderly client told me 20-something years ago. I had been hustling around his property trying to get him the absolute best result I could, and we had a brief moment to pause. Fair warning, it's incredibly sexist and heteronormative, but the framing helped a dumb young man internalize the message:
 

Spoiler

An old bull and a young bull are standing at the top of a hill, surveying their herd.

The young bull turns to the old bull and says, "Mmmm, I'm gonna run down there and get me one of those!"

The old bull turns to they young bull and says, "I'm gonna WALK down there and get 'em ALL."

I won't be upset if the mods choose to scrub that, but it's an important lesson.

[Hannu2]

32 minutes ago, kerbiloid said:

Iirc, these nerds are launching military and spy sats.
In 1940s the land was owned, too, but in never made a problem with removing a rocky planet from the highway to be built.

Then military aspect was important. But now there are rockets and launchpads already for military use. Starship is civilian project. It takes probably decades after Starship will be ready before there will be military payloads which need Starship's capacity. Maybe there  will be military forces and huge armored space stations with scifi weapons in space in very far future but not any time soon.

 

 

32 minutes ago, kerbiloid said:

***

https://texasfarmcredit.com/resources/texas-land-pricing-guide/#:~:text=The average price per acre,%244%2C297%2Facre average in Q2

2 000 000 000 / 5 000 = 400 000 acres ?

Estate with coastline from area you can get permission to build is more than one order of magnitude more expensive than average rural land here. I wonder it it is different in Texas. There are probably as more billionaires wanting coastal mansions in Texas than total inhabitants in region I live.

And also if someone really want to buy a large area prices increase rapidly. In Finland there are legal ways to force people to sell their land in certain situations to a company or city but I do not know if it is possible in USA.  Or is space industry enough severe reason to use such force.

[kerbiloid]

51 minutes ago, Hannu2 said:

Starship is civilian project.

While it's on paper.

Once it starts flying, it will be a military project as well.

52 minutes ago, Hannu2 said:

Starship will be ready before there will be military payloads which need Starship's capacity.

Orbital lasers, orbital maneuvering sat depots, orbital hypersonic maneuvering reentry vehicles.

Nothing such capable can be just civilian.

Just currently it looks like ULA+military competes with NASA+SpX+intelligence, and it's not obvious who will win, so everyone makes honest eyes "it's not ours, Musk is doing it for fun and pays his money".

Once SuperStarship gets ready, all territorial problems would magically disappear.

56 minutes ago, Hannu2 said:

Estate with coastline from area you can get permission to build is more than one order of magnitude more expensive than average rural land here. I wonder it it is different in Texas. There are probably as more billionaires wanting coastal mansions in Texas than total inhabitants in region I live.

The 10⁹aires don't live in boggy wasteland, they prefer (miami) beaches and (beverley) hills.
That land costs definitely greater than what a rocket test site needs for a safety zone.

[Hannu2]

5 minutes ago, kerbiloid said:

While it's on paper.

Once it starts flying, it will be a military project as well.

Orbital lasers, orbital maneuvering sat depots, orbital hypersonic maneuvering reentry vehicles.

It takes decades before those prjocts are accepted in military bureaucracy and build even to test objects. I do not believe that military givea any adavantage to Starship in this phase.

 

5 minutes ago, kerbiloid said:

Just currently it looks like ULA+military competes with NASA+SpX+intelligence, and it's not obvious who will win, so everyone makes honest eyes "it's not ours, Musk is doing it for fun and pays his money".

I understand it well. ULA operates discreetly like traditional military contractor and can provide all needs military have in foreseeable future (when they get Vulcan ready). It certaily shows much more reliable business partner to military than eccentric space enthusiast billionaire's strange company which wants to colonize Mars. It is one thing why I said that SpaceX is civilian project. It is not necessary even competition but separation of development and economic to two branches. SpaceX sells cheap launches for civilian companies and research organizations and ULA specialices to special customers like military.  I am sure than at this moment no one in military severely counts on Starship. It is very uncertain and there are not anything similar projects in potential enemy countries. 

 

[RCgothic]

Short of putting the launch site at the tip of Florida in Southern Glades Wildlife & Environmental area, there's basically no eastern seafront that isn't densely populated.

Boca Chica was an ideal location and it's frankly miraculous they got a site as good as they did.