How SpaceX streamlined the Raptor engine
construction-physics.com
construction-physics.com
Everything in the manufacturing process is also challenged to justify its existence.
This is how he managed to reduce the costs by 90%.
You win some, you lose some.
This removal of surplus-age is common in the automotive industry, and one of the reasons that cars are such an amazing value. It seems like Musk's remarkable ability to achieve cost reductions (at least in the aerospace context) is attributable to his pursuit of vertical integration. Airframers (aeronautical vehicle designers & manufacturer) are bound by the costs dictated by their component suppliers, especially after a configuration has achieved regulatory approval. SpaceX has managed to avoid being 'held hostage' by pseudo-monopoly suppliers.
Elon's strength is his willingness to pull the plug and transition away from suboptimal solutions. This is bolstered by his willingness to double down.
Imagine if Boeing said "screw all this recertification technical debt for the 737 MAX airframe, we will start fresh. Customers can take it or leave it"
Taking a step back, I think it's more than that. It's just the company structure. It remains to be seen if SpaceX and Tesla survive long term. But if they do, a lot will be attributed to the company structure that Elon designed. When you have a company that does stuff like this: https://www.youtube.com/shorts/1InUlHXv718
Compared to Airbus: https://www.youtube.com/shorts/KS9Xt6hmbTU
You just think to yourself, even if the airplane was completely safe, and they are incredibly safe, this is just not a great look. Both doors accomplish the task but little thought was put into the operator of the door. The little things matter and I notice them more and more everywhere I go with a lot of legacy American companies.
In fact, I would say there's probably a very narrow set of circumstances where his back to the drawing board approach can be deployed successfuly.
That said, the 787 Dreamliner remains statistically one of the safest widebody long-haul aircraft in commercial aviation history, which I think is a Counterpoint. It achieves this despite any more globally diverse supply chain, and moving production out of unionized Boeing manufacturing plants.
Safety by Design and design for manufacturability can help eliminate the possibility of quality issues during production.
He applied it to Tesla and SpaceX, which are very very different.
His approach probably wouldn't work as well if you threw him in as CEO of a random company like JC penny or Pizza Hut. Other CEO's are good at different things - like squeezing the extra 0.1% out of a 40 year old brand or product line
Now I'm thinking about him firing the pizza cooks and bringing in a crack team of engineers to redesign the concept of Pizza from first principles.
I.e. products that everyone else dismisses as impractical/impossible. And then people complain when he's late delivering the impossible products.
And Boeing upper management overruled the engineers.
There was nothing wrong with the MCAS concept. The implementation of it, however, wasn't very good.
Unfortunately, two of the 3 crews did not understand the runaway stabilizer trim procedure. The 3rd crew did, and landed safely, and the media never reports on that.
The runaway stab trim procedure is a "memory item", meaning pilots shouldn't need a checklist to deal with it.
But doesn’t apply to MCAS because the symptoms and recovery procedures are distinct.
The MCAS system wasn’t documented, pilots weren’t trained on it, it didn’t indicate anything distinct in the cockpit, and it could rapidly put the plane into an unrecoverable attitude where pilots no longer had the physical strength to overcome the forces involved.
Yes, it applies to MCAS.
> the symptoms and recovery procedures are distinct
Nope. MCAS failure manifests itself as runaway trim, and the emergency procedures for it are exactly what is needed to recover from it.
1. the stab trim switches override the MCAS signals. Override. That means the pilot can trim to normal using the column mounted trim switches. The column switches will power the trim back to normal. No physical strength is required.
2. there's a "stab trim cutoff" switch on the console. That turns off the trim system. MCAS cannot bypass it.
The proof is the 3rd MCAS incident. The pilots trimmed it back to normal, and turned the stab trim system off.
That's all they had to do.
This is supposed to be a "memory item". The other two crews did not remember the memory item. Boeing even sent out an Emergency Airworthiness Directive reiterating this information. It was ignored by the EA pilots, who did everything wrong (including overspeeding the airplane at full thrust).
The narrative you wrote is the typical one in the mass media, which is utterly wrong. The proof of that is they ignore the 3rd incident which didn't fit the narrative.
I've talked with two 737 pilots about this. They agree with me, though I knew I was right anyway.
Food for thought: ever wonder why the stab trim cutoff switch is in a prominent place on the center console in easy reach?
What exactly are you accusing the pilots involved with the accident of? That they had some perverse incentive to die?
Nope. I wrote: "The implementation of it, however, wasn't very good"
> What exactly are you accusing the pilots involved with the accident of?
Not following the runaway stabilizer trim procedure. This is supposed to be a "memory item", meaning a checklist is not required.
There were 3 MCAS incidents:
1. crew trimmed to normal with the thumb switches, then turned off the trim system. Flew the rest of the flight, landed safely.
2. crew trimmed it back to normal at least 11 times (if I recall correctly) and never turned off the trim system. Crashed.
3. Boeing Emergency Airworthiness directive was sent to all MAX pilots. In a nutshell, it says to restore normal trim using the thumb switches then turn off the trim system. EA pilots instead turned off the trim system while the airplane was pointed down at full throttle. Crashed.
The two 737 pilots I talked to about this both asserted pilot incompetence.
Personally, I assign half the blame on Boeing and the other half on the pilots. Flying is not a joke. Not paying attention to an Emergency Airworthiness Directive is not acceptable.
It was purposefully deceptive -- Boeing management actively decided to hide its existence from pilots.
The narrative that the pilots were at fault was Boeing leadership covering their ass.
The MCAS symptoms did not match runaway trim. It's not continuous. It stops and starts.
MCAS would also re-activate with a five second delay, just long enough to confuse pilots.
More importantly, deactivating the electrical trim system would make it all too easy to enter a regime where the pilots couldn't physically recover the plane.
This is a Catch-22 scenario: Activate the electrics and be killed by MCAS, or deactivate the electrics and be killed by physics.
I could go through each of your comments in this thread and point out how NTSB crash investigators proved that Boeing was directly or indirectly at fault in almost every aspect, but I don't want to write out ten pages. Others have done so already, more eloquently, and often with more colourful language. Most professional pilots were rightly furious with Boeing.
Boeing's arguments have been mutually exclusive with each other: "Just remember how to operate MCAS... which we hid from you!" and "Just disable the electric trim... which will pit you against forces you can't overcome"... "Which is not a problem because you can turn electric trim back one... but then MCAS will try to kill you again"... "It won't do that because it is dual redundant... an option... that nobody purchased... and we didn't even tell most customers about."
I expect this kind of self-contradictory "logic" from narcissists and sociopaths -- I know one of each and I'm now intimately familiar with the self serving arguments that make no sense, especially in combination.
I'll pick this one. I've heard it before. Runaway trim is uncommanded movement. It does not have to be continuous, it can stop and start. That behavior can certainly happen with a short circuit or faulty wiring. It's like the speaker connections on my home stereo - the connectors corrode over time, and the sound cuts in an out randomly.
The MCAS behavior absolutely presents as runaway trim behavior. Remember I worked for 3 years on the 757 stab trim system. I know what runaway trim is.
> deactivating the electrical trim system would make it all too easy to enter a regime where the pilots couldn't physically recover the plane.
That's why the instructions provided to the pilots said to use the thumb switches first to restore normal trim. All three crews had managed to do just that to restore normal trim. The second instance the pilots restored it ELEVEN TIMES and it never occurred to them to then turn off the trim system.
You might want to review the first incident. The MCAS system came on 2 or 3 times, and each time the crew used the thumb switches to restore normal trim. Then they turned off the trim system. The flight continued and they landed safely. They knew nothing about MCAS - they just followed the runaway stab trim procedure.
> I expect this kind of self-contradictory "logic" from narcissists and sociopaths
Being nasty doesn't lend credibility to your arguments.
You say that and then a company like Ford releases this as their EV to show the world that they are competitive with Tesla.
[1]: https://youtu.be/C1dQtlrI7uU?t=70
How does something like this happen despite Ford knowing all the 'secrets' a company like Tesla or the Chinese know? I have a few guesses:
1. Its the structure of the company. In this video the presenter talks a lot about all the hoses and clamp connectors etc. The cooling department thinking they had to stay relevant made sure the car incorporated a design that had all this nonsense.
2. Maybe they didn't put their 'A' engineers on this car. Its plausible: the F-150 is their massive money maker. However this car was supposedly developed under some skunkworks program and yet here we are.
3. Maybe there was sabatoge from elsewhere (suppliers, middle management etc.) You watch a movie like Ford vs Ferrari and while im sure a lot is dramatized, I can't help but think man they were talking about the dysfunction of Ford way back then?!
Then we have Youtube documentaries like this one about the Ford Taurus SHO talking about how they screwed up so much that they had one chance left to get serious...like what? Shouldn't they be serious every day? Thats what the Chinese are doing.
[2]: https://youtu.be/5VTRhCC3gZI?t=56
The presenter further added how they had to ship entire engine blocks to Japan so that they could 'fix' them and unlock 80 more horsepower that Ford just left on the table. If factual, this should be a total embarrassment: You had to send your handiwork to a entity with a better reputation so that they could 'fix' your mess?
[3]: https://youtu.be/5VTRhCC3gZI?t=212
At some point, you have to acknowledge that the naysayers were wrong: Thinking (especially among the short community) was that Tesla had some cool ideas but their implementation was horrific, they couldn't just make up for 100+ years of institutional knowledge that the legacy companies had. The Tesla cars showed some of this thinking: quite poor build quality, poor after sale support, poor parts network. These things improved over the years but still isn't perfect.
But at the same time you have to acknowledge that the legacies suffer from their own problems that dont put them as far ahead as newcomers as you'd think. Sometimes a lot of that institutional knowledge becomes a liability when a paradigm shift occurs.
I will not attempt to break all the reasons for SpaceX success in this post, but its certainty more complex then just vertical integration. And vertical integration isn't absolute, in some cases they reversed their vertical integration again.
Team building by Musk, consistent having engineers work on hard project after hard project, willing to invest in a next generation even if the existing system works in the current market context (canalizing yourself), believing in increasing scale overtime (only when planning to build 100s of engine iteration makes sense) are just some of the relevant parts of SpaceX success as an organization.
People claiming Musk has nothing to with this or is just some irrelevant figurehead money guy are idiots. At the same time, the brilliance of the team he build ultimately is far more important then his own suggestion about ideas with engines.
In case of the engine its actually Tom Mueller who basically off hand suggested to him that to reach his goals, he would have to design something nobody had ever done on a large engine, and was only used for smaller engines (phase shut off). Musk jumped on that and imitatively said that this is what they should do. Mueller said he wasn't sure if it could be done, but since they knew of no other way to achieve the goals, the team went off and eventually achieved it.
Mueller himself said he thought going after this was a mistake and a less aggressive simplification should have been done, but said he proved himself wrong and it was a massively important innovation.
This shows some important aspects of Musk. Not that he is some genius that magically design an amazing engine. Rather that he listened to his engineers and gave them the finances and confidence that they could achieve outlandish targets, and continued to support them even if they couldn't hit the target instantly. We see this again with Raptor, they had a target in mind and followed every line of design to achieve something close to as good as a 2 fuel engine is going to get.
One can argue that this is just blind optimism and then throwing money at the engineers, and that is certainty partly a fair critic of this approach. It did not work with self driving in the same way at Tesla. But the difference is that with evolution of Merlin and Raptor he listen to engineers who proposed challenging ideas that were still iterative and he supported them.
I have followed Space for a long time. Musk isn't some magical unique genius, but he certainty isn't do nothing idiot some of his haters want us to believe.
SpaceX success deserve series study and SpaceX without Musk is basically really understandable as an institution.
Isaacson’s “biographies” are glorified puff pieces. Musk is as unrecognizable in his as Jobs was in his.
Both Tesla and SpaceX had teams keeping Musk busy on bs just so that the engineering teams could do their work.
The second he took control, we got the cybertruck and the starship, the worse products both companies ever built (or attempted, in the case of the starship).
> Musk relentlessly challenges the existence of every part
This sounds insightful until you find yourself debating with the CEO for the eleventh time about how his high-school understanding of the physics involved breaks down in a particular case.
Musk is very lucky to be moving such quantities of money that his companies are big enough to protect themselves from him, if you ever wonder how Musk would fare on a tight budget, look no further than the Oceangate.
This is Tumblr origin nonsense, especially given that he's allegedly been involved with Engineering work he's not cleared for.
Regardless your thoughts on Elon, his drug habits, and his political brashness, I don’t think you can say he’s in any way close to the Oceangate guy. There is something legitimately special about him and his collective.
I would read a deep dive though into the history of Twitter (with the financials) to understand better and I do get that for a single product company there really is a point at which you give up on finding the next big thing and just optimize on your main thing and you really just need a few dozen awesome people and a rotation of new hires to keep things rolling but not thousands of engineers.
That said, do you remember these kinds of articles?
> Musk summons engineers to Twitter HQ as millions await platform’s collapse
Source: https://www.washingtonpost.com/technology/2022/11/18/twitter...
> “Former Twitter employees fear the platform might only last weeks.” Melissa Ingle: “I don’t see how it lasts the month.” “All signs point to some catastrophic failure of the system, and very soon.”
Source: https://www.technologyreview.com/2022/11/18/1063467/former-t...
> Twitter ‘to lose 32m users in two years after Elon Musk takeover’
Source: https://www.theguardian.com/technology/2022/dec/13/twitter-l...
Elon was firing people left and right and literally physically destroying Twitter’s data centers. I remember hundreds of these hysterical articles and tweets that very clearly did not come to pass. He obviously did something more clever than the authors of these articles expected… is all I’m claiming.
Just claiming, you know.
But we can separate the financial inanity of his empire from the question, which is whether Elon is a capable engineering mind or simply an ‘Isaacson puff piece recipient’.
Twitter has certainly been a glowing success at becoming a right-wing propaganda chamber for Musk but as a commercial venture not really. Revenue is down 60% since Musk bought it.
https://www.businessinsider.com/elon-musk-approach-advertise...
And even with all of that, the new users, the AI, the paid subscriptions, None none of that actually fixed the major underlying issues that Twitter is not profitable. Jack Dorsey couldn’t fix it and neither did Elon. I think he just realized having a modern media platform he controls is more powerful than it making money. He inherited a platform built by someone else, and keeps the lights on with a skeleton crew. I don’t see that as a success
They both have loud, stupid, and obviously wrong ideas about how hard diving in the sea is or isn't.
The only reason Twitter has more active users is that it removed some of the protections for bots, in particular broad filtering coming from certain country involved in a war.
You don’t think Musk is any close to the Oceangate guy? Let’s review some interesting decisions by his companies then:
- Musk mucking around with the blue checks and the bot filters in Twitter skyrocketed the amount of scams in the platform.
- Tesla uses very strict NDAs and settlement to silence the reporting of accidents
- The infamous electric door handle that locks up Teslas when power goes out was an obvious point of failure, it was ignored, people died, and now several countries have legislation against it
- Reportedly Musk had safety lines and other safety features in the factories removed for serious reasons like “not liking yellow”
- Any understanding of how to parse public insurance data will show you Tesla’s have accident rates that are multiples of other brands
- The Starship, a vessel that is intended for human transport, has no safe abort system, no way to fit one in its current state, and no plans to modify that.
Just a reminder that even a very SpaceX-friendly count (in which flights that did not attempt to land are considered “good”) puts the current reliability rate at <40%.
As a naive boundary, for clearing the 97.5% predicted crew survival, SpaceX would need to fly in the order of 300 good Starship launches.
Those are just of the top of my head.
Measuring bot activity became harder after the API changes (I wonder why!), but there’s been some attempts at finding ways to estimate bot activity. All those measures are compatible with increases in bot activity, and incompatible with bot decline.
Everything you’re talking about is trivial to automate with playwright.
i mean, you can also read liftoff and re-entry by eric berger and you will see the same kind of thing being mentioned.
Cut your crap.
"This sounds insightful until you find yourself debating with the CEO for the eleventh time about how his high-school understanding of the physics involved breaks down in a particular case"
Musk has a bachelor's degree in physics from the University of Pennsylvania. While not a full scientist, I doubt that "his high-school understanding of the physics involved breaks down" anytime often.
Have you ever been in such a situation that you describe, or is this just your prejudice speaking? AFAIK the discussions in SpaceX revolve more around things like "can this part be 3d-printed", "do we keep the actuators for part X or can it just stick out into the wind" or "should we use landing legs or not", which have nothing to do with high-school physics and everything to do with actual engineering tradeoffs.
"the starship, the worse products both companies ever built (or attempted, in the case of the starship)."
This is what tells me that you are speaking in bad faith. Starship is not yet a finished product. Judging it now makes about as sense as judging Edison's lightbulb a year before it was introduced into the market.
Starship has several issues to fix, but we can already see that a) the Raptor engines are about the best on the planet, doubly so when considering their extremely low unit cost; b) the vessel itself is very tough and performed well even in really bad situations; c) the heat shield developed a lot and the last Starship (the one which was dragged to the Christmas Island) survived reentry in very good condition; d) the amount of control (belly flops, slowing down to hover) that they have over that huge thing is unique in the history of spaceflight.
Clarification, Musk bought a B.A. in physics. In the Paypal S-1 in 2002, [1] Paypal's lawyers claimed that he graduated with a B.S. in Physics and B.S. in Economics in 1995.
Yet the actual degrees subpoenaed from UPenn indicate a B.A. in Physics and B.S. in Economics in 1997, two years later. He could not even remember the year he graduated or the degree he received just 5/7 years after their purported completion. I have yet to meet a single person who actually graduated from college who can not accurately recollect the year of their graduation, have you?
Most likely he did this because he was in the USA on a student visa and dropping out of UPenn in 1995 made him a illegal immigrant which his brother, Kimbal Musk, corroborated in a interview [2].
[1] https://www.sec.gov/Archives/edgar/data/1103415/000091205702...
[2] https://www.reddit.com/r/EnoughMuskSpam/comments/1az29vs/elo...
There you go, now you've met one!
Starship is already the largest orbital rocket ever build and is the second rocket to actually reuse its first stage.
In addition to that the second stage has managed to land intact, something only the Shuttle did before.
People who claim like there was some superior alternative to Starship that SpaceX could 'just' have build are just ignorant. There isn't a magical 'just' build the largest rocket ever and make it fully reusable playbook you can simply execute.
On Falcon 1 and 9 he worked directly on major components of the vehicles.
In Tesla, he was heavily involved in the design of every single product they came out with. He also micromanaged Model 3 assembly automation in 2017-18.
And, DOGE!!
didn't musk study physics?
Raptors can be used without TVC. Be that by using differential thrust, or just not needing that - because rocket is controlled using other means, or other engines - it's possible. Tory Bruno specifically explained that he meant - among other things - that absence.
A picture of the engine working on the test stand can be that for the engine - or for the chamber, a significant component of the engine, with or without turbopumps involved.
And yes, the TVC adds very little to the complexity of Raptor 3's appearance: it still looks like science fiction, even when operating in Starship. Had TVC been present in the original SP1 image that had Tory accusing SpaceX of misleading everyone, it would have made no difference.
> TLDW
That video has beautiful shots of Raptor 3 firing and gimbling. It's worth watching.
In addition, SpaceX isn’t cheating by not including TVCs. They purposely designed their rocket to need a minimum of them and fully take advantage of the space savings the lack of TVCs affords them.
[1] “So, there is no need to exaggerate this by showing a partially assembled engine without controllers, fluid management, or TVC systems, then comparing it to fully assembled engines that do.”
And if you see Raptor integrated on Starship you can see this clearly.
From the article links, I am amused that SpaceX uses cybertrucks to tow their rocket engines around the grounds and not a normal cheaper truck. They also do it in a totally uncovered trailer, which must be good for the guys taking pictures for forums. But isn't that also good for guys taking pictures for competitors / Russians/ China?
The strength loss comes from the fact that not all alloys are 3d-printing friendly, so you often have to compromise and you end up with a less than ideal alloy for your application.
3D printed parts are chock-full of these microscopic flaws, porosity, and have horrible surface roughness (most parts you see in production are post-machined to improve the finish). Additionally, the repeated heating-cooling of the layers as they are deposited builds up residual stress in the part. All just due to the nature of how they are manufactured.
Re: surface roughness, I can understand that the powder grain size creates a sort of minimal structure size, and can in principle be the start of a crack if a surface grain gets knocked loose. Is that the sort of thing you mean? I can see that for any internal or external surfaces, and a rocket engine combustion is certainly applying a lot of heat and pressure on surface grains. Can this be alleviated by smaller grain sizes, or is there some limit there?
Re: repeated heating/cooling and internal stresses, this strikes me as just requiring standard post-printing stages like tempering to alleviate internal stresses.
Similarly, annealing a 3D-print to relieve residual stress does work, but it also will cause warping as those stresses are relieved. Again, sacrificing dimensional accuracy. Frontier AM companies have ways to compensate for all of these effects but it's a trial and error process for each part essentially.
At this point you're now stacking multiple processes on each other just to try to get to near-billet properties. Calibration Trials > Print > HIP > Anneal > Machine. The cost adds up quickly. It can be justified especially in non-fatigue-critical applications but it's no free lunch
You could have a cooling plate the work is on. But the higher temperature difference is apt to cause warping.
[Slightly related https://en.wikipedia.org/wiki/Cavitation The problem is that the bubbles are filled with vapor instead of CO2 like in sparkling water.]
I assume you can just anneal or print then recast in sand or whatever, maybe even lostwax with Al as wax, but the point is that porosity in a print itself is inevitable with current powder based tech.
Also subtractive manufacturing requires paying to melt away a lot of metal. 3D printing saves.
I don't know all of the ways in which SpaceX is using
This hasn't been true for over a decade. High value relative to weight, highly complicated internal geometry, or repeated need for one off parts are all reasons to choose 3d printing today for production parts.
https://newsroom.bugatti.com/en/press-releases/bugatti-refin...
If they buy $131M worth of Cybertrucks[1], they might as well use it for something...
[1] https://www.businessinsider.com/spacex-bought-tesla-cybertru...
And several engines failed to relight on the booster for flight 13. I believe ice in feed lines is viewed as the most likely cause.
Isn't the Space shuttle main engine / SLS engine a full-flow staged combustion engine?
I think China has made a full flow engine too.
The SSME uses the same kind of fuel-rich combustion chambers for both preburners. This presents a problem for the oxidizer side because any leaking along the shaft between ox pump and turbine in either direction would be catastrophic. This is resolved by an extremely expensive and complex multi-stage helium-purged rotating seal.
One of the cool parts about most FFSC designs, and the raptor in particular, is that they can afford slight leaking from high pressure to low pressure through any seal in the system and it's broadly safe, and only marginally reduces performance. This allows them to be made much more cheaply.
I'm surprised the author was surprised that a component of a multi-billion dollar company which is vital to it's future success in the industry and is covered by US regulations governing information export wasn't available as a cut-away diagram.
It got taken down.
It’s certainly an achievement of SpaceX engineering what they can do despite his constant meddling.
It has not yet proven to be as reliable reusable as Merlin, but the test programs they have put Raptor threw are considerable.
Raptor has successfully landed a rocket, and has successfully landed even an upper stage. Making it the only engine ever to achieve both.
If at this point you call that 'premature' then you must be an Asian parent in terms of your exception.