SpaceX (general discussion)

Dagger said:
That's a great photo. Now I can see that the whole structure is even flimsier than I already feared.

I see no rivets or bolts but merely spot welds.

That X is merely a plate in the shape of an X, not real crossed struts.
The three "struts" in front of the X are not real struts either, just bent vertical plates serving no real purpose as they support nothing.

And that also applies to the other "struts" around the outside of the structure. These bent plates seem to be there only to provide some additional bending moment to the struts on the inside which also look flimsy. Looks like a fix added later.


This is very very very very very bad. Wake up, Elon!!!!!!!!
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My god, the concern trolling when it comes to SpaceX is out of control. You should call Elon and tell him how stoopid SpaceX is and save them. Jesus.
 
Dagger said:
That's a great photo. Now I can see that the whole structure is even flimsier than I already feared.

I see no rivets or bolts but merely spot welds.

That X is merely a plate in the shape of an X, not real crossed struts.
The three "struts" in front of the X are not real struts either, just bent vertical plates serving no real purpose as they support nothing.

And that also applies to the other "struts" around the outside of the structure. These bent plates seem to be there only to provide some additional bending moment to the struts on the inside which also look flimsy. Looks like a fix added later.


This is very very very very very bad. Wake up, Elon!!!!!!!!
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You are completely wrong and have no idea about what you are talking about. . This design was load tested. They built another one and applied loads greater than flight to it.
 
https://twitter.com/x/status/1694019925667459409
View: https://twitter.com/nasaspaceflight/status/1694019925667459409


Booster 9 is rolling back to the Launch Site. Currently showing off its hot staging ring to the Ships.

There will be a dedicated commentary livestream.

SBL until then:
nsf.live/starbase
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www.youtube.com

SpaceX Booster 9 Rollout to the Pad For Flight

SpaceX is rolling out Booster 9 potentially for the final time ahead of the second Starship test flight. The booster now features the hot staging ring, which...
www.youtube.com www.youtube.com
 
Falcon 9 brought 21 Starlink into Orbit and landed safe

Booster 9 rolled out and put on Launch pad
new is this: engine covers
F4JgLZFXsAgVq2V
 
Byeman said:
You are completely wrong and have no idea about what you are talking about. . This design was load tested. They built another one and applied loads greater than flight to it.
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Indeed. Everything fails if you apply enough stress. The issue is whether it withstands the actual stress resulting from its intended performance with a sufficient margin of safety while being light enough to get off the ground. I'm pretty sure Starship isn't meant to get involved in dogfights.
 
Dagger said:
That X is merely a plate in the shape of an X, not real crossed struts.
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This shows a fundamental ignorance of materials and engineering. A flat steel plate is indeed poor in compression but good in sheer and excellent in tension. If you look at the calculations for even a simple straight truss, with all of the elements considered as a system and not in isolation, you'll see an elegant alternation of compression and tension in the distribution of stress along its length. In fact the structure will not work without tension resistance. Now bend it round in a continuous ring and you have something quite sturdy, with each part compensating for the others and fit for intended purpose.

This is why no-one's found it necessary to build a rocket out of granite.
 
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Rhinocrates said:
This shows a fundamental ignorance of materials and engineering. A flat steel plate is indeed poor in compression but good in sheer and excellent in tension. If you look at the calculations for even a simple straight truss, with all of the elements considered as a system and not in isolation, you'll see an elegant alternation of compression and tension in the distribution of stress along its length. In fact the structure will not work without tension resistance. Now bend it round in a continuous ring and you have something quite sturdy, with each part compensating for the others and fit for intended purpose.

This is why no-one's found it necessary to build a rocket out of granite.
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The proof is as always in the pudding, isn't it?
 
Rhinocrates said:
This shows a fundamental ignorance of materials and engineering. A flat steel plate is indeed poor in compression but good in sheer and excellent in tension.
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That silly X is spot welded to a flat steel plate with struts behind it, so that won't change much. They probably realized that too, so on top of all that they added those vertical bent plates which presumably are added to prevent buckling.
To me that are two added fixes on top of each other. That's rather desperate.

Rhinocrates said:
Now bend it round in a continuous ring and you have something quite sturdy, with each part compensating for the others and fit for intended purpose.
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That continuous ring is irrelevant when this structure is subjected to lateral forces, due to vibration or torsion or ........., which will occur during flight. This structure can simply collapse sideways, either in one direction, or by rotation of top relative to bottom. That continuous ring does not prevent that. If you have a problem visualizing that then you should consider drinking less.

A support with only vertical struts is unstable. That is very basic mechanics that every engineering student already learns.
To make it stable sufficient triangular or diagonal struts are necessary, but those are missing in the present design.

sferrin said:
You should call Elon and tell him how stoopid SpaceX is and save them.
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I would love to explain my genuine concerns to Elon personally but I don't see how I can.
Therefor I post my concerns here in the hope they will eventually reach SpaceX.
That I get bullied by nitwits here is a small price to pay.
 
Dagger said:
That silly X is spot welded to a flat steel plate with struts behind it, so that won't change much. They probably realized that too, so on top of all that they added those vertical bent plates which presumably are added to prevent buckling.
To me that are two added fixes on top of each other. That's rather desperate.


That continuous ring is irrelevant when this structure is subjected to lateral forces, due to vibration or torsion or ........., which will occur during flight. This structure can simply collapse sideways, either in one direction, or by rotation of top relative to bottom. That continuous ring does not prevent that. If you have a problem visualizing that then you should consider drinking less.

A support with only vertical struts is unstable. That is very basic mechanics that every engineering student already learns.
To make it stable sufficient triangular or diagonal struts are necessary, but those are missing in the present design.


I would love to explain my genuine concerns to Elon personally but I don't see how I can.
Therefor I post my concerns here in the hope they will eventually reach SpaceX.
That I get bullied by nitwits here is a small price to pay.
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You know what they say about opinions. BTW there is a lot of "spot welding" that occurs in aircraft too. You probably don't want to fly on them.
 
Dagger said:
That I get bullied by nitwits here is a small price to pay.
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You think highly of yourself, when you are just making a fool out of yourself.
Dagger said:
That silly X is spot welded to a flat steel plate with struts behind it, so that won't change much. They probably realized that too, so on top of all that they added those vertical bent plates which presumably are added to prevent buckling.
To me that are two added fixes on top of each other. That's rather desperate.
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No, you are just clueless about the design.
a. You don't acknowledge that it passes a 150% load test
b. The part I have circled is one of three primary attach points and you are ignoring what is behind it.
 
That continuous ring is irrelevant when this structure is subjected to lateral forces, due to vibration or torsion or ........., which will occur during flight. This structure can simply collapse sideways, either in one direction, or by rotation of top relative to bottom.
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That the structure is being subjected to forces outside of the design flight envelope is indicative of greater problems than structural design.

These issues are normally rendered moot by the timely application of a suitably designed Flight Termination System.

Part of the problem with the Starship flight is that the vehicle was too sturdy for the FTS that was installed and the destruction of the vehicle was inordinately delayed.

(In other words, if your vehicle is flying sideways at Mach 10, your first concern is not an incipient failure of the trans stage. Your vehicle has already bought the farm. You no longer have the Delta V to get to orbit. Do not collect $200. IMHO.)
 
aim9xray said:
These issues are normally rendered moot by the timely application of a suitably designed Flight Termination System.
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The FTS designed for the vehicle seems to have been completely inadequate for the task.
 
Dagger said:
That is very basic mechanics that every engineering student already learns.
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Typically you have misrepresented or ignored essential points. Airily saying 'irrelevant' gives you no credibility.

Dagger said:
This structure can simply collapse sideways, either in one direction, or by rotation of top relative to bottom.
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The best way to mitigate this is to space some plates around the circumference, maybe X-shaped ones connecting the top and bottom rings so they can work in efficiently tension (there's that word again) without wasting mass... oh, hang on...

I think that a dozen years studying industrial design and architecture and decades teaching them in my nation's premier architecture and design schools thereafter gives me some knowledge of engineering. Doing it in a city regularly subjected to severe lateral forces in the form of earthquakes with curriculum and building regulations to suit does give me some theoretical and practical insight into lateral forces and how to compensate for them in the real world. Certainly more than one would get from watching the odd YouTube video.
 
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Byeman said:
You think highly of yourself, when you are just making a fool out of yourself.
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Spoken by the person who is not able to distinguish a rivet from a spot weld.

Rhinocrates said:
Typically you have misrepresented or ignored essential points. Airily saying 'irrelevant' gives you no credibility.


The best way to mitigate this is to space some plates around the circumference, maybe X-shaped ones connecting the top and bottom rings so they can work in efficiently tension (there's that word again) without wasting mass... oh, hang on...

I think that a dozen years studying industrial design and architecture and decades teaching them in my nation's premier architecture and design schools thereafter gives me some knowledge of engineering. Doing it in a city regularly subjected to severe lateral forces in the form of earthquakes with curriculum and building regulations to suit does give me some theoretical and practical insight into lateral forces and how to compensate for them in the real world. Certainly more than one would get from watching the odd YouTube video.
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Yes, if there would be many X-shapes all around the structure, but there are not. The few X's there are, are on top of plates that are already the strongest elements against torsion, so they don't add much.

My reference to Youtube was merely to illustrate that insufficient or no triangular or diagonal braces causes accidents all over the world in all kinds of structures.

Be honest: if you were asked to design the vented interstage would you have come up with the present SpaceX design? (no, of course not).
 
Dagger said:
Spoken by the person who is not able to distinguish a rivet from a spot weld.
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Pardon my French but whether it's a "rivet" or a "spot weld" means sweet fuck all if the resulting joint meets requirements. "Spot welding" is used all over that thing and it certainly held together as it was flying sideways with a flight termination system trying to tear it apart.
 
Transactional pseudo-debate is not going to earn anyone's respect. That is, one propelled by distraction and ignoring essential issues while picking up on straw men instead. In other words: trolling.

To be honest (why do you insinuate that I am not?), I'd rely on thorough modelling of the stresses that would occur in the required flight profile and allow the necessary safety margin. I'd know about the performance of the grades of steel involved, and the good old calculations of the rocket equation, mass, and payload fraction. Then I'd juggle that with the manufacturing costs and methods and what emerges in the end would be an actual design.

The hot staging is intriguing and we'll see what happens. Musk's philosophy has been 'build a little, fly a little', perhaps with 'explode a little' in there somewhere too. Actual qualified engineers with access to the necessary data are not going to rely on their guts. I don't have access to these data, so to be honest, I won't rely on my gut to decide if a design works because I know what guts are full of and what comes out of them. Instead, I assume, that as a commercial entity, SpaceX has hired competent engineers and given them the necessary data to make their calculations and then produce their designs and that impossibility is unprofitable.

Now, please describe your experience and qualifications as an engineer, and remember that you're addressing an audience with many engineers who have long experience. I respect their assessment and note how they have described yours.

A little learning is a dangerous thing;
drink deep, or taste not the Pierian Spring;*
there shallow draughts intoxicate the brain,
and drinking largely sobers us again.

Alexander Pope, 'Essay on Criticism' 1709

*https://en.wikipedia.org/wiki/Pierian_Spring

Now contemplate this: plenty of concrete struts that struttingly rely on strutting with struts to laterally resist lateral forces through sheer struttiness (ooh, that sounds dirty, doesn't it?). There's one problem though: it won't fly.

p-4427-enz_1.jpg
 
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Dagger said:
I would love to explain my genuine concerns to Elon personally but I don't see how I can.
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R-7 use diagonals?
Maybe a drawing here? I would think the conic sections add strength

SuperHeavy is "semi" balloon tank... the pressure helps with rigidity.

On a side note. For the sake of argument...If a Lunar Starship we're filled with hypergolics brought up from tankers...might it be able to do multiple missions without refueling?

With cryogenics...each mission needs refueling...so to stretch things... maybe a less full Starship could gradually raise an orbit...then dock with a Falcon Heavy launched fast taxi.


Maybe a full belly of hypergolics might allow multiple landings in one mission?
 
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Dagger said:
Spoken by the person who is not able to distinguish a rivet from a spot weld.


Yes, if there would be many X-shapes all around the structure, but there are not. The few X's there are, are on top of plates that are already the strongest elements against torsion, so they don't add much.


Be honest: if you were asked to design the vented interstage would you have come up with the present SpaceX design? (no, of course not).
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A small oversight since I did not zoom in, but at least I could distinguish "X" plates from "only" vertical struts.

There are many X-shapes, there are 6, one every 60 degrees.
You have no analysis to support your claim that they "don't add much" or that there isn't enough.

Again, this design has been loaded tested to 25-50% above flight loads, so what does it matter?

Yes, one would come up with this design if they are following the same construction techniques throughout the rest of the vehicle.
 
publiusr said:
1. R-7 use diagonals?
Maybe a drawing here? I would think the conic sections add strength

2. SuperHeavy is "semi" balloon tank... the pressure helps with rigidity.

3. On a side note. For the sake of argument...If a Lunar Starship were filled with hypergolics brought up from tankers...might it be able to do multiple missions without refueling?
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1. Of course it does, but that is irrelevant here
2. Not for this section
3. no and no. It can't get to orbit with hypergols. And there is no production capability in the US for that amount anymore.
 
It can't get to orbit on hypergolics...but a rump Starship (Starkicker I have heard it called) might put a hypergolic craft in orbit.

Hypergolics production could be ramped up.
 
https://twitter.com/x/status/1694749030843052408
View: https://twitter.com/thesheetztweetz/status/1694749030843052408


The DOJ lawsuit against SpaceX centers around the hiring under ITAR and EAR regulations.

"Export control laws and regulations do not prohibit or restrict employers from hiring asylees and refugees."

Highlights mine. You can read the full lawsuit here:
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www.cnbc.com

DOJ sues SpaceX, alleging hiring discrimination against refugees and asylum seekers

The U.S. Department of Justice sued SpaceX on Thursday, alleging Elon Musk's company discriminated against refugees and asylum seekers in its hiring practices.
www.cnbc.com www.cnbc.com
 
https://twitter.com/x/status/1694404156373573701
View: https://twitter.com/devenperez/status/1694404156373573701


Previously aiming for a NET August 31st date, SpaceX is now targeting NET September 8th for the second Integrated Test Flight of Starship.
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https://twitter.com/x/status/1694400219272695946
View: https://twitter.com/starshipgazer/status/1694400219272695946


SpaceX has filed an updated NOTMAR with the U.S. Coast Guard that says the next Starship launch will be on approximately Sept. 8th. T - ~ 16 days from now.
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publiusr said:
It can't get to orbit on hypergolics...but a rump Starship (Starkicker I have heard it called) might put a hypergolic craft in orbit.

Hypergolics production could be ramped up.
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no, there is no longer a US production facility and any production level is not going back to shuttle/Titan days
 
Let's do facts and not opinion. This is the Titan II interstage. There are 24 "segments" between stringers. 16 of them are open and 8 have sheet metal between the stringers. so 33% of the circumference (8/24) has a sheet metal web for shear stability.
My previous post with the photo of the Starship, the interstage has 96 "segments". The "X" web can be counted as 4 or 6 segments for covering 25% to 37.5% of the circumference. 2 of the segments on the six positions are completely enclosed by sheet metal including the "X" doubler. An additional 2-4 segments are cover by portions of the "X" "doubler". Add in the large "pedestals", there is plenty of shear support.
 

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GTX said:
www.politico.com

Feds accuse SpaceX of discrimination against asylum recipients and refugees

A Justice Department complaint says that Elon Musk’s rocket company violated federal law by refusing to hire certain foreign nationals with U.S. work permits.
www.politico.com www.politico.com
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politically motivated perhaps. companies that deal with classified technology or knowledge tend to avoid immigrant hiring all together 'cause they don't want to deal with implications later. Yes it's illegal but if you gonna sue spaceX there are about 20 tech companies that you can add to the lawsuit. Not to say it's right or wrong it's just sadly the way it is.

my friend recruited tech and areospace folks, and one thing he always advised Indian root applicants to always use English name (even if made up) and put in cap underneath their name "AMERICAN CITIZEN" because he knows the unwritten rule that alot of hiring managers he works with have.
 
Byeman said:
There are many X-shapes, there are 6, one every 60 degrees.
You have no analysis to support your claim that they "don't add much" or that there isn't enough.
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Welding a relative thin X-shape on to a solid rectangular plate does not add much. That should be obvious. If strength was to be added they had better welded a whole plate on top of the existing one.
All that the X adds are four small triangles at the corners. Not nothing, but not much either.

Byeman said:
Again, this design has been loaded tested to 25-50% above flight loads, so what does it matter?
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So you keep saying, but where can we find the test procedure and test results?

Byeman said:
Let's do facts and not opinion. This is the Titan II interstage. There are 24 "segments" between stringers. 16 of them are open and 8 have sheet metal between the stringers. so 33% of the circumference (8/24) has a sheet metal web for shear stability.
My previous post with the photo of the Starship, the interstage has 96 "segments". The "X" web can be counted as 4 or 6 segments for covering 25% to 37.5% of the circumference. 2 of the segments on the six positions are completely enclosed by sheet metal including the "X" doubler. An additional 2-4 segments are cover by portions of the "X" "doubler". Add in the large "pedestals", there is plenty of shear support.
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I love facts and will add a few more:

My eyes tell me that each of the 6 plates cover only a distance of 3 slots like between 4 vertical struts.
I count 14 slots between each of the 6 plates.
So the plates cover 3/(3 + 14) = 17.6 % of the circumference. Not 25 % or 37.5 %.
The ends of the X add small triangles at the corners of each plate. I will give some rigidity credit for that by rounding the 17.6 % up to 20 %.

The mass of a fully loaded Starship 2nd stage is 1,450,000 kg incl. payload.
The diameter of Starship is 9.0 meter, so circumference is 28.3 m, of which 5.66 m (20 %) is actually providing resistance to shear.
Now imagine Starship is flying at an angle of say 35 degrees before stage separation:
The shear force on the Starship vented interstage would then be 1,450,000 kgf * cos(35) = 1,188,000 kgf.
That would be equivalent to 1,188,000 kgf / 5.66 m = 210,000 kgf/m.

The mass of a fully loaded Titan II 2nd stage is 33,000 kg incl. payload.
The diameter of Titan II is 3.05 m, so circumference is 9.58 m, of which 3.19 m (33 %) is actually providing resistance to shear.
Now imagine Titan II is flying at an angle of say 35 degrees before stage separation:
The shear force on the Titan II vented interstage would then be 33,000 kgf * cos(35) = 27,000 kgf.
That would be equivalent to 27,000 kgf / 3.19 m = 8460 kgf/m.

That is a ratio of 25 at the disadvantage of Starship.

I don't know the thickness (or type) of the metal used on Starship or Titan II, so to compare I simply express the shear force in kgf/m instead of kgf/m2. It's therefor just a rough comparison but it nevertheless shows that the shear force on the Starship vented interstage is not comparable with that of Titan II.
That it held on Titan II does not prove that a similar design will hold on Starship.
Hence my concern about the present SpaceX design.
 
As a thought experiment, I can not imagine any circumstance where a 35 degree Angle of Attack can be considered as being within the structural design envelope for any large liquid-fueled rocket at altitudes where atmospherically induced drag forces predominate. (I'll admit to a lack of imagination.)

The F-16 (a lightweight fighter with a 9-G structure) has an AOA limiter or it will depart controlled flight at about 28 units AOA. (From memory, a B-58 bomber suffered an in-flight breakup at Mach 2 when yaw diverged by 7 degrees; tearing the tail off.)

Does anyone know what the maximum flight path angle divergence was allowed for a Saturn V stack, say at 50,000 feet? The same for Starship?
 
Dagger said:
So you keep saying, but where can we find the test procedure and test results?
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Why would you expect a commercial company to publicly divulge any proprietary information without any justified government coercion? And no, in order to preempt any misguided speculation, I am decidedly NOT a libertarian, but rather a social democrat at heart, but that does by no means imply that, contrary to how certain other political factions might like to misinterpret or misrepresent my position, I have no respect for property rights. And yes, I am awaiting with bated breath that certain elements in the mouthbreathing peanut gallery will still only glum onto very specific strategically excised parts of this posting, so fire away!
 
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Byeman said:
You don't rank enough nor matter to get them. If you did, you wouldn't be on the outside watching through a knothole in the fence yelling at the workers, telling them that they are doing things wrong.
Did you get the equivalent results for Vulcan, SLS, Falcon 9, Atlas V or Delta IV tests?
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Let me rephrase my question so that even you can understand it: where did you get the test data that you were quoting?

Byeman said:
BTW, your eyes are failing and so is your ability to count.
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There is nothing wrong with my eyes or my ability to count. The problem is solely with those of you.

This is primary school stuff:
Imagine a row of trees at 10 meters spacing.
What is then the distance between tree #1 and tree #4 ?

In my universe the correct answer is 30 meters, but apparently in your universe it is 40 meters.
One has to count the number of spaces, not the number of trees.
 

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