Author Topic: The Starship "I risk sending a thread off topic" Homeless Posts Thread 2  (Read 256508 times)

Offline KBK

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I still don't know what the nosecone test structure is for.  I WAS thinking that it was to give to NASA, and the structure would let them tip and roll it while people were inside, to simulate zero g, let them clamber about and get to all areas and plan out the crew arrangements.

But now they're rolling it out to the pad.  To do what?  It doesn't have any RCS or landing thrusters to test.  And if those were to be installed, wouldn't they do that on the factory side?

To test structural integrity under flight loads while pressurized.

John

To add:

And.. it exists as a static mount...due to the untoward levels of pollution of the measurement noise floor which would occur if the measurements were attempted live.

Connectedly, or  from a slightly different  viewpoint, the reliability or correctness of the data is also a problem. The mount offers multiple methods of working toward securing single cause analysis pathways in the given measurement attempts and even offers potentials in repeatability, as in 'test that again, I'm not sure we saw that correctly...'. It's a pathway to reliable science (which becomes engineering semi-dogma for starship) via reliable measurement. Or, that such reliable and consistent measurement pathways can be explored and found, and so on. One mount, and it provides a large set of problem analysis solutions. Or, that it opens the door to that all critical aspect of honing in on reaching toward design and build perfection limits in situ.

Again, the data offered live, is simply not good enough, due to being noisy, and not easily cleared up as to specific stressing as origins of given measuements and so on. One can't make it reliably enough to single cause analysis in live measurements, with no chance of repeated tests with minor alterations to try and find stable single cause source points in measurement data.

It is basically iterative. Where they will stress it, get numbers... and then figure out what those numbers mean, and then go back, and stress it, and then..well..continue refining and stressing and so on, until some form of reliable data based scrutiny appears on the stage of contemplation. which will all be tossed back into the design and build fray, which will cycle through the test stand again. And the test stand will also evolve as they learn more about what it's functionality limits are. Recall: 1000 starships to be built. A test jig of such a nature is the least to be expected when perfecting a starship build.
More in need of philosophy are the sciences where perplexities are greater -- Aristotle

Offline Nevyn72

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Idle musings on through-Super Heavy Starship propellant loading: Is there any situation where using those lines to feed propellants back into Super Heavy from Starship while in flight would be desirable (basically increasing the effective propellant capacity of Super Heavy at the expense of draining Starship)? The only thing I can think of would be a desire to increase Super Heavy velocity at stage separation, which doesn't seem all that useful. Maybe if you have such a monumentally heavy Starship (that for some reason you need to strip most or all of the Raptors of of too) that you need to expend Super Heavy to lift it, and stage at damn near orbital velocity in order to minimise gravity losses.

Or more out there: stick a 'drop tank' between Starship and Super Heavy that is nothing more than a pair of propellant tanks and two feed passthroughs. Use this to increase Super Heavy effective tank capacity (without draining Starship), then discard it at staging. Losing a tonne or two of stainless sheet and some short plumbing runs may be worth the extra capability for extreme loads that would otherwise be marginal for Super Heavy recovery.
I have suggested something similar in various "Can Superheavy SSTO without starship, and why would you want to" type threads- draining fuel from a "drop tank" starship, then "in flight abort" it off superheavy so superheavy can reach orbit.

Alas, concensus was that the fuel lines intended to load a starship in 20 minutes with fuel for 6 raptors for 5 minutes, cannot keep up with the fuel required  for 28 raptors at once.

The lines don't need to keep up with 28 Raptors, they just need to deliver the fuel before the 28 Raptors drain the main tanks completely.

Online xvel

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Yes they have to, SS is a dead mass and needs to be drained first, it doesn't make sense otherwise.
And God said: "Let there be a metric system". And there was the metric system.
And God saw that it was a good system.

Offline tbellman

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Idle musings on through-Super Heavy Starship propellant loading: Is there any situation where using those lines to feed propellants back into Super Heavy from Starship while in flight would be desirable (basically increasing the effective propellant capacity of Super Heavy at the expense of draining Starship)? The only thing I can think of would be a desire to increase Super Heavy velocity at stage separation, which doesn't seem all that useful. Maybe if you have such a monumentally heavy Starship (that for some reason you need to strip most or all of the Raptors of of too) that you need to expend Super Heavy to lift it, and stage at damn near orbital velocity in order to minimise gravity losses.

There is one situation I can think of where such a "backfeed" could be useful: if you have a tanker Starship with tanks capable of holding more than the standard 1200 tonnes.  With tanks stretched into the nosecone, such a tanker could hold up towards 2000 tonnes of propellant, but that would stage significantly lower and slower than a normal SuperHeavy/Starship combination.  With a backfeed from Starship to SuperHeavy, that could be mitigated a bit, allowing staging to happen closer to the "ideal" staging point, and hopefully allow bringing more propellant to orbit.

Whether it is worth the complexity, is a different question...  The idea is somewhat similar to the crossfeed that SpaceX were planning to do between the boosters of Falcon Heavy, but that was abandoned because it was much more difficult than they anticipated.

Offline kliph

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I'm planning on doing a road trip to see the SN16 launch and just ballparking when to set aside 2 weeks for vacation. Let me know if this sounds right:

4/1 (@_brendan_lewis update) - SN15 Nose stacked
4/26 - SN16 Nose stacked

So I'm looking at late May/Early June right? Of course will be following the update threads closely and start booking hotels and stuff as SF approaches. I've seen vids and posts on etiquette and what to expect when in the area. Anything else I should know? Is there a NSF meetup group? Thanks.

Offline Fchavis

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Was watching the LabPadre feed this morning and they were doing a flap test on SN15, and that got me to thinking about the test rig right next to it.  They have to want to test cycles on the flap system without having to be in the middle of a live fire exercise, right? so at least part of the 'test rig' might be structure that can simulate the pressure of air flow over the flaps so that they can test wear to the motors and gearing over multiple reentry cycles. 

That test rig has been bothering me for a while, and this is the first scenario that has made and sense. Why bring it down to the launch site? Only reason that I can come up with is that they wanted the GSE hook ups. Anyway, that's my thought.  Wear test on the Flap assembly, and whatever the nose press is for.

Offline schuttle89

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I'm planning on doing a road trip to see the SN16 launch and just ballparking when to set aside 2 weeks for vacation. Let me know if this sounds right:

4/1 (@_brendan_lewis update) - SN15 Nose stacked
4/26 - SN16 Nose stacked

So I'm looking at late May/Early June right? Of course will be following the update threads closely and start booking hotels and stuff as SF approaches. I've seen vids and posts on etiquette and what to expect when in the area. Anything else I should know? Is there a NSF meetup group? Thanks.

I would love to say your timescale is too late but you're probably right on timing. Good luck!

Offline Tangilinear Interjar

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That test rig has been bothering me for a while, and this is the first scenario that has made and sense. Why bring it down to the launch site? Only reason that I can come up with is that they wanted the GSE hook ups. Anyway, that's my thought.  Wear test on the Flap assembly, and whatever the nose press is for.

While this may seem trite, it's not. The reason to bring the test rig to the test site is because it's the TEST SITE.

They probably don't need to pressurize with any cryo fluids but they do need hp nitrogen which is readily available there. Plus they have all the data acquisition for all of their test channels.

And while they probably won't be blowing anything up, they could have something fail and it's very easy to keep people back a bit at the test site where the manufacturing facility needs to be clear for building stuff.

Online Ben Baley

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I'm planning on doing a road trip to see the SN16 launch and just ballparking when to set aside 2 weeks for vacation. Let me know if this sounds right:

4/1 (@_brendan_lewis update) - SN15 Nose stacked
4/26 - SN16 Nose stacked

So I'm looking at late May/Early June right? Of course will be following the update threads closely and start booking hotels and stuff as SF approaches. I've seen vids and posts on etiquette and what to expect when in the area. Anything else I should know? Is there a NSF meetup group? Thanks.

I would love to say your timescale is too late but you're probably right on timing. Good luck!

I'm jealous of the opportunity and I wish you the best of luck but depending on how SN15 does and how booster construction goes you might be watching a booster test instead at that time.

Online neoforce

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Watching the SLS core stage rollout made me think of a Starship question...

Clearly Starship is designed for vertical construction and transport.  But if for some reason they wanted/needed to transport horizontally on a barge, could they?

To my non-rocket scientist mind, there seems to be two main issues.  1) tipping it, as all of the structural lift points are designed around vertical stress forces and 2) Is there enough structural integrity for it to not have damage when laying down on its side? 

I've poked around some on the forums and most discussion in this area is simply that it is designed to be vertical. 

Offline rakaydos

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Watching the SLS core stage rollout made me think of a Starship question...

Clearly Starship is designed for vertical construction and transport.  But if for some reason they wanted/needed to transport horizontally on a barge, could they?

To my non-rocket scientist mind, there seems to be two main issues.  1) tipping it, as all of the structural lift points are designed around vertical stress forces and 2) Is there enough structural integrity for it to not have damage when laying down on its side? 

I've poked around some on the forums and most discussion in this area is simply that it is designed to be vertical.

The barges that Superheavy is supposed to operate with will have a tower designed to catch said superheavy on landing, with some degree of x/y dampening. That same tower could also provide support for a vertical Superheavy even in rough seas during transport.

Offline schuttle89

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Watching the SLS core stage rollout made me think of a Starship question...

Clearly Starship is designed for vertical construction and transport.  But if for some reason they wanted/needed to transport horizontally on a barge, could they?

To my non-rocket scientist mind, there seems to be two main issues.  1) tipping it, as all of the structural lift points are designed around vertical stress forces and 2) Is there enough structural integrity for it to not have damage when laying down on its side? 

I've poked around some on the forums and most discussion in this area is simply that it is designed to be vertical.
It can survive the belly flop so it can be tipped and kept on side but might have to be partially pressurized to do so. Whether they will eventually transport it this way is a different question, in Boca Chica I don't see a reason. Elsewhere, such as if they start a production line in Florida or move them there, either by barge or point to point, then maybe.
« Last Edit: 04/29/2021 02:06 pm by schuttle89 »

Offline raivo45

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Clearly Starship is designed for vertical construction and transport.  But if for some reason they wanted/needed to transport horizontally on a barge, could they?

They seemed to have plans to transport MK2 horizontally before it was scrapped so it probably is possible.

Offline Prae_

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Clearly Starship is designed for vertical construction and transport.  But if for some reason they wanted/needed to transport horizontally on a barge, could they?

They seemed to have plans to transport MK2 horizontally before it was scrapped so it probably is possible.

Not unless it was pressurized.

Offline steveleach

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Watching the SLS core stage rollout made me think of a Starship question...

Clearly Starship is designed for vertical construction and transport.  But if for some reason they wanted/needed to transport horizontally on a barge, could they?

To my non-rocket scientist mind, there seems to be two main issues.  1) tipping it, as all of the structural lift points are designed around vertical stress forces and 2) Is there enough structural integrity for it to not have damage when laying down on its side? 

I've poked around some on the forums and most discussion in this area is simply that it is designed to be vertical.

The barges that Superheavy is supposed to operate with will have a tower designed to catch said superheavy on landing, with some degree of x/y dampening. That same tower could also provide support for a vertical Superheavy even in rough seas during transport.
That sounds really difficult. Maybe SpaceX need to find someone who has experience with supporting large rocket-booster-shaped loads in a vertical orientation on barges.

I heard a rumour that there was a company somewhere that used autonomous barges and something called a "hexa-holder" or something.

Offline RotoSequence

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Does Lockheed's Venture Star SSTO design and its numbers close if it uses Methalox, Vacuum Raptors, and stainless steel?

Offline philw1776

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Does Lockheed's Venture Star SSTO design and its numbers close if it uses Methalox, Vacuum Raptors, and stainless steel?

Don't have Venture Star #s (mass, cubic meters tankage, etc.) but I'd estimate instead of closing, it's much worse.
Stainless steel is heavier
Raptor ISP is markedly less than theoretical Hydrolox
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Offline RotoSequence

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Does Lockheed's Venture Star SSTO design and its numbers close if it uses Methalox, Vacuum Raptors, and stainless steel?

Don't have Venture Star #s (mass, cubic meters tankage, etc.) but I'd estimate instead of closing, it's much worse.
Stainless steel is heavier
Raptor ISP is markedly less than theoretical Hydrolox

Stainless Starship exists because it ends up being lighter than carbon fiber Starship, and Raptor uses methalox because it gets better performance than hydrolox.

Offline gefere

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Does Lockheed's Venture Star SSTO design and its numbers close if it uses Methalox, Vacuum Raptors, and stainless steel?

Don't have Venture Star #s (mass, cubic meters tankage, etc.) but I'd estimate instead of closing, it's much worse.
Stainless steel is heavier
Raptor ISP is markedly less than theoretical Hydrolox

Stainless Starship exists because it ends up being lighter than carbon fiber Starship, and Raptor uses methalox because it gets better performance than hydrolox.
Sure but like, situationally. Not always-and-everywhere. Venture Star's big idea was, "Sure, hydrogen's low density means you waste a lot of mass on tanks, but what if we dual-purpose those tanks as aerosurfaces?" Get that to work and you've bought back some of hydrogen's dry mass disadvantage, and you can delight in its optimum ISP without regret.

Likewise if you're going to build weird-shaped tanks that hold less than a cylinder of the same mass would, you're really going to want the lightest possible material that can do the job. It's a different tradeoff than Starship makes, where a heavier material is paid for by needing less heat shielding.

I haven't done any math here, so who knows, maybe there's some way to make it work. But I doubt it. As a rule the peaks in the design space of launch vehicles are really narrow.  Almost nothing works. You need a bunch of design choices to come together just so to get to orbit.

Offline Slarty1080

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Watching the SLS core stage rollout made me think of a Starship question...

Clearly Starship is designed for vertical construction and transport.  But if for some reason they wanted/needed to transport horizontally on a barge, could they?

To my non-rocket scientist mind, there seems to be two main issues.  1) tipping it, as all of the structural lift points are designed around vertical stress forces and 2) Is there enough structural integrity for it to not have damage when laying down on its side? 

I've poked around some on the forums and most discussion in this area is simply that it is designed to be vertical.

The barges that Superheavy is supposed to operate with will have a tower designed to catch said superheavy on landing, with some degree of x/y dampening. That same tower could also provide support for a vertical Superheavy even in rough seas during transport.
That sounds really difficult. Maybe SpaceX need to find someone who has experience with supporting large rocket-booster-shaped loads in a vertical orientation on barges.

I heard a rumour that there was a company somewhere that used autonomous barges and something called a "hexa-holder" or something.
Or just fly Superheavy / land Starship where it is needed - probably good for KSC and any off shore platforms in the Gulf
My optimistic hope is that it will become cool to really think about things... rather than just doing reactive bullsh*t based on no knowledge (Brian Cox)

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