Author Topic: Starship Launch Mount / Pad / Table Discussion  (Read 261968 times)

Offline Corvus Corax

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Starship Launch Mount / Pad / Table Discussion
« on: 04/23/2023 02:27 pm »
Can we divert discussion of the OLM / OLT / Pad discussion to its own thread?

Discussion topics:

-What happened?
-Damage assessment
-Future work & revisions to design
-Flaws
-Flame diverter
-Time / schedule

[FST edit: added Starship to thread title for clarity in thread list]
« Last Edit: 04/25/2023 05:45 pm by FutureSpaceTourist »

Offline Eric Hedman

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Re: Starship Launch Mount / Pad / Table Discussion
« Reply #1 on: 04/23/2023 04:48 pm »
A question I would like to ask is, is this rocket pushing or exceeding the practical limits for building an affordable launch pad due to the thrust levels?

Offline SpeakertoAnimals

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Re: Starship Launch Mount / Pad / Table Discussion
« Reply #2 on: 04/23/2023 04:54 pm »
A question I would like to ask is, is this rocket pushing or exceeding the practical limits for building an affordable launch pad due to the thrust levels?
This is what is being tested. They are pushing to find those limits.

Online DanClemmensen

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Re: Starship Launch Mount / Pad / Table Discussion
« Reply #3 on: 04/23/2023 05:09 pm »
A question I would like to ask is, is this rocket pushing or exceeding the practical limits for building an affordable launch pad due to the thrust levels?
Pad "affordability" depends on frequency of use. If you use it once every two years (Artemis) then it's hideously expensive per launch. If you use if twice a day it can cost a lot more and still be inexpensive per launch.

I think the images show that if they stay with this overall approach, they need to spend more on GSE that they did, or spend smarter: thayt's why you test. Wait for SpaceX' analysis, or go ahead and make your own guess as to how much more should have been spent as a percentage of the GSE cost to date.

My uneducated impression is that they almost got it right, and they would need to spend less than 10% more if they started from scratch.  They may be able to repair the damage to avoid starting from scratch, but total cost (already spent plus repair and upgrade) will be higher than a new start.

By extension, I do not think we are anywhere near the limit for a rapidly reusable launch pad.

Offline magicsound

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Re: Starship Launch Mount / Pad / Table Discussion
« Reply #4 on: 04/23/2023 05:29 pm »
A question I would like to ask is, is this rocket pushing or exceeding the practical limits for building an affordable launch pad due to the thrust levels?

Video of the launch at lift-off showed that the exhaust plumes merge into a coherent stream, with a single train of mach diamonds visible in later moments. Are the chamber conditions (2000°C at 300 bar) enough to dissociate combustion products into plasma?  Combining that with the hypersonic collimated shock waves might produce the worlds biggest cutting torch. How much ablative steel would then be needed?

Offline steveleach

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Re: Starship Launch Mount / Pad / Table Discussion
« Reply #5 on: 04/23/2023 06:00 pm »
I was under the impression that SpaceX had already identified the problem and come up with a solution, but had hoped that they could get away without it for this one test.

If they had delayed the test to put their water-cooled steel plate under the OLM then that would also have delayed getting the full-stack flight performance data they need to validate their models.

They would also have had to hope that their solution addressed all the actual issues, not just the expected ones. As it is, they know both the expected and unexpected problems, and can adjust the solution as necessary before implementing it.

Offline joek

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Re: Starship Launch Mount / Pad / Table Discussion
« Reply #6 on: 04/23/2023 06:25 pm »
I was under the impression that SpaceX had already identified the problem and come up with a solution, but had hoped that they could get away without it for this one test.

If they had delayed the test to put their water-cooled steel plate under the OLM then that would also have delayed getting the full-stack flight performance data they need to validate their models.

They would also have had to hope that their solution addressed all the actual issues, not just the expected ones. As it is, they know both the expected and unexpected problems, and can adjust the solution as necessary before implementing it.

That is a reasonable assessment; Musk's statements confirm as much. Much of the debate appears to center around the short term solution was inadequate "they should have known better". We could debate that forever, as endless posts on various threads demonstrate.

My opinion (FWIW): they made an informed decision to buy down risk with B7/SN24 which was otherwise scheduled for scrap. They took the shot. In hindsight they screwed up. Live and learn; or more properly test and learn.

Online Coastal Ron

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Re: Starship Launch Mount / Pad / Table Discussion
« Reply #7 on: 04/23/2023 06:58 pm »
...
My opinion (FWIW): they made an informed decision to buy down risk with B7/SN24 which was otherwise scheduled for scrap. They took the shot. In hindsight they screwed up. Live and learn; or more properly test and learn.

In business, and life, we are constantly making "informed" decisions. Sometimes they work out, and sometimes they don't. And sometimes there is only one way to know for sure - to try it.

SpaceX made such a decision with this launch, and what they learned was that they seriously underestimated the strength of the heat resistant pad material. They suspected as much before the launch, but they decided to go ahead with the launch anyways.

The term "fail fast" that is used in the startup world is actually a misnomer, since the goal is not to fail, the goal is to LEARN, with failure being one of the outcomes for each test or experiment.

SpaceX learned a LOT with this launch, and they learned things that they could only learn by launching. Pad strength was one of those things, but as it turns out they were already planning to add water-cooled flame diverters anyways, so their hope was that the cost of this launch was worth the delay it would have cost them if they waited for the new flame diverter.

I'm reminded of the Apollo 13 movie, and this quote after they performed a manual course correction:
Quote
Well, let's hope we don't have to do that again.

Sometimes you just don't know till you try, and once you try, you learn. SpaceX did a LOT of learning with this test flight. And I'd call that a success...
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Online Lee Jay

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Re: Starship Launch Mount / Pad / Table Discussion
« Reply #8 on: 04/23/2023 07:12 pm »
I fear that one of the things they learned from this is that some failures are more painful than others.  Imagine if they are required to go pick up every piece of concrete from the ocean floor, the beach and everything within, say, a kilometer of the pad.  Imagine if they have to do extensive repairs like demolishing the OLM and rebuilding it, re-building the tank farm or repairing the tower systems (or all of them).  It's entirely possible that waiting for a deflector to be built would have been faster than launching without it.

Offline steveleach

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Re: Starship Launch Mount / Pad / Table Discussion
« Reply #9 on: 04/23/2023 07:13 pm »
I was under the impression that SpaceX had already identified the problem and come up with a solution, but had hoped that they could get away without it for this one test.

If they had delayed the test to put their water-cooled steel plate under the OLM then that would also have delayed getting the full-stack flight performance data they need to validate their models.

They would also have had to hope that their solution addressed all the actual issues, not just the expected ones. As it is, they know both the expected and unexpected problems, and can adjust the solution as necessary before implementing it.

That is a reasonable assessment; Musk's statements confirm as much. Much of the debate appears to center around the short term solution was inadequate "they should have known better". We could debate that forever, as endless posts on various threads demonstrate.

My opinion (FWIW): they made an informed decision to buy down risk with B7/SN24 which was otherwise scheduled for scrap. They took the shot. In hindsight they screwed up. Live and learn; or more properly test and learn.
I'm not sure I agree with the term "screwed up", tbh. They took a risk to gain some time, and it didn't pay off for them.

Let's say I offer you 3-1 odds on a coin toss; you put a dollar on heads, but it comes up tails. You've lost your dollar but, in hindsight, did you screw up?

To call it a screw-up, or just a bad decision, you have to know both the cost of the problem and cost of the delay that avoiding the problem would have resulted in.

Offline spacester

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Re: Starship Launch Mount / Pad / Table Discussion
« Reply #10 on: 04/23/2023 10:48 pm »
Three questions:

Did the armor do its job?

They armored everything they were worried about, so if the armor worked those systems are fine.

Were there systems under the concrete and were they damaged?

If not, then this is just a matter of rapid redistribution of rock.

Is the interface with the Booster too badly gronked?

They can lower a booster onto it and find out.

***

If the goal is to build hundreds of boosters and given rapid re-usability, the limiting factor becomes how fast they can build OLMs.

If you're willing to dispose of a Stage 1, why should blowing up a Stage 0 be so outrageous?

The first OLM was a pathfinder. Future OLMs will be much better, similar to the upgrade from Raptor 1 to Raptor 2.

Offline GmP

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Re: Starship Launch Mount / Pad / Table Discussion
« Reply #11 on: 04/23/2023 10:49 pm »
I fear that one of the things they learned from this is that some failures are more painful than others. …….. It's entirely possible that waiting for a deflector to be built would have been faster than launching without it.

Yes, but how to know that upfront? I work in an industry where we know exactly the (material) cost of different failures. Semiconductors/chip designs, in an advanced, but not cutting edge technology. If all is ok, no redo costs; if I can fix a mishap with just metal routing: four months delay, little less then 1M$; if more extensive fail: at least six months and more then 1.5M$.

Tell me how much time I should spend upfront to verify everything before committing to fab? In hindsight every mishap would have been able to be found upfront if I would be aware it could happen. In real life we model what we can, verify what we expect, check coverage as far as possible; and then take a risk decision. Only when the chip comes back we know how good it is. And only then do we know if we better had spend more time upfront verifying.

Online Lee Jay

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Re: Starship Launch Mount / Pad / Table Discussion
« Reply #12 on: 04/23/2023 10:53 pm »
If you're willing to dispose of a Stage 1, why should blowing up a Stage 0 be so outrageous?

They have a factory to build stage 1's.  Stage 0's are probably way more expensive and slow to build.

Online DigitalMan

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Re: Starship Launch Mount / Pad / Table Discussion
« Reply #13 on: 04/23/2023 10:56 pm »
If you're willing to dispose of a Stage 1, why should blowing up a Stage 0 be so outrageous?

They have a factory to build stage 1's.  Stage 0's are probably way more expensive and slow to build.

If P2P (and/or multiple daily launches) becomes an actual thing it will be interesting to see (1) what such a reliable stage 0 looks like and (2) how are they going to build so many of them for a reasonable price?

Offline GmP

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Re: Starship Launch Mount / Pad / Table Discussion
« Reply #14 on: 04/23/2023 10:58 pm »
The Boca Chico stage 0 is not intended for very rapid reuse, is it? Spending a few weeks between TestFlights is OK, they are allowed only a limited number of flights anyway. Of course less damage or no damage would have been better, but now realizing the destruction that happend is also a very useful lesson learned. Now they know what is needed. And can find/build a fix for that.

Btw: the damage on the OLM concrete is very visible and real. And some of the tank farm.  But some of the other damage on the OLM deck and OLT I find hard to judge. Is a lot really structural damaged, or “just” some new pipe and wires, and fresh paint will make it all whole again?


(Typos fixed)
« Last Edit: 04/23/2023 11:01 pm by GmP »

Offline spacester

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Re: Starship Launch Mount / Pad / Table Discussion
« Reply #15 on: 04/23/2023 10:58 pm »
If you're willing to dispose of a Stage 1, why should blowing up a Stage 0 be so outrageous?

They have a factory to build stage 1's.  Stage 0's are probably way more expensive and slow to build.

The second one will be much easier and quicker than the first one, and future revenue will dwarf the marginal cost of refurbishment.

Online Lee Jay

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Re: Starship Launch Mount / Pad / Table Discussion
« Reply #16 on: 04/23/2023 11:01 pm »
I fear that one of the things they learned from this is that some failures are more painful than others. …….. It's entirely possible that waiting for a deflector to be built would have been faster than launching without it.

Yes, but how to know that upfront?

Since far smaller rockets, including those from SpaceX use more than a flat slab, and since this happened to them before with just one Raptor firing, one would argue this was foreseeable.

Online DigitalMan

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Re: Starship Launch Mount / Pad / Table Discussion
« Reply #17 on: 04/23/2023 11:08 pm »
I fear that one of the things they learned from this is that some failures are more painful than others. …….. It's entirely possible that waiting for a deflector to be built would have been faster than launching without it.

Yes, but how to know that upfront?

Since far smaller rockets, including those from SpaceX use more than a flat slab, and since this happened to them before with just one Raptor firing, one would argue this was foreseeable.

I am in the camp wondering where did the concept of a "minimum viable launchpad" ever include a flat base.

Online Lee Jay

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Re: Starship Launch Mount / Pad / Table Discussion
« Reply #18 on: 04/23/2023 11:25 pm »
If you're willing to dispose of a Stage 1, why should blowing up a Stage 0 be so outrageous?

They have a factory to build stage 1's.  Stage 0's are probably way more expensive and slow to build.

The second one will be much easier and quicker than the first one, and future revenue will dwarf the marginal cost of refurbishment.

Maybe, but it had better also include features that the original did not, like a flame diverter at a minimum.

Sometimes it's faster to build something new from scratch than to fix something that's already there but not in great shape.

Online Vultur

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Re: Starship Launch Mount / Pad / Table Discussion
« Reply #19 on: 04/23/2023 11:54 pm »
Question is how much time this actually cost them.

Is the 1-2 months claim pure "Elon Time" or is there a logic behind it?

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