The thrust vector control (TVC) subsystem is usually considered a part of the engine. The major change the Soviet NK-33 underwent for a USA model was the addition of TVC, and the engine was named differently, so there are two engines, named differently, which mostly differ by the presence of TVC.
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.
Oh yeah, Tory Bruno made that gaffe of a comment publicly, and completely unprompted, before he abruptly quit. I had forgotten, but you’re right of course.
TLDW but TVC for rocket engines is usually achieved by like one hydraulic suspension rod each for X and Y axes(Y and Z in rocketry? idk) serving as parts of the engine mounting frame. It shouldn't add a lot to the system.
Yes, that's the usual way. With SpaceX, however, Raptor engines are gimbled with electric actuators.
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.
Tony Bruno, when referring to the partially assembled engine, was complaining about the lack of engine controllers, fluid management, and TVCs [1].
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.”
I find it mind boggling that you can 3d print rocket engines. I thought that the standard line is that 3d printing metal wasn't developed enough for anything serious. Not a mechanical/materials engineer, but if you can 3d print rockets what's off the table? Jet Engines and that's about it I think?
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?
3d printing metal has some strength downsides, I'm not sure what it is for the raptor engines, but I've heard other space companies claim ~5% less strength that traditional methods for aluminum structures, but that can be worth it in cases where you are able to make shapes that wouldn't be possible with traditional methods, or if you save enough money by printing it. Rocket engines often can benefit from intricate internal channels and shapes that you can 3d print as once piece with no way to do it via subtractive manufacturing.
It has mild strength downsides, but very severe fatigue and damage tolerance downsides. Knowing this, it makes sense that 3d printing tech would make headway in space industry but not (yet) in aviation
3D printed metal is now as strong as machined metal, assuming an identical alloy. The process has been pretty well perfected.
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.
Sure, but I mean what's the technical reason a material isn't it 3D printing friendly? Are we talking grain structure here? Is it something that can be at least partly mitigated by some post-printing heat treatments, like tempering?
Some alloys don’t like to be melted. If an alloy has a large solidification range, certain areas can partially solidify without the liquid part keeping up to fill in the gaps so to speak. This leads to solidification cracking / hot tearing. This is a simplification and only one possible cause, but there are literal books written about this kind of thing (I like Solidification by Dantzig and Rappaz). This is also why you see things like friction stir welding for rocket bodies. No melting means no solidification means no solidification issues.
crack growth in metals is driven by microscopic flaws that cause high-intensity but very localized stress concentrations. Over time even low stress levels cause these flaws to grow to the point where they start causing strength problems. Even in traditional aluminum machined parts, increased surface roughness can have a large impact on fatigue life.
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.
Is there a known source of internal flaws/porosity in an otherwise solid part? Presumably laser melting produces a puddle which shouldn't allow for internal pores, as long as it isn't printed too fast (or solidifies too fast, which is why I think most chambers are internally heated to near melting temp).
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.
I can't speak to the proximal cause of the roughness and porosity, but if you've ever held a raw printed aluminum part in your hand it is immediately apparent.
That said there are processes to deal with porosity like Hot Isostatic Pressure (HIP) treatment that basically crushes all the voids with immense pressure. This does come at the cost of dimensional accuracy though (HIP will compress the part somewhat).
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
SLS printers lay a layer height worth of powdered metal and fuse it with a laser engraver. Thee bed lowers one layer and the process is repeated. They don't bring materials used like inconel to full melting temperature, only do what it takes for the metal sand to clump together. That's one source of pores.
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.
One of the things that 3-D printing allows is a fine honeycomb structure. This comes with a somewhat bigger strength reduction, but a dramatic weight reduction. Less materials is cheaper.
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
I thought that the standard line is that 3d printing metal wasn't developed enough for anything serious.
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.
I think by one way they are referring to cruise missiles i.e. the engine is only used once or twice. Once during test fire, and once in production environment.
GE9X aircraft engines have 3D printed low pressure turbine blades, so I think the view that jets are somehow exceptional is already disproven. There are real benefits to using additive processes for turbojet/fan applications: many jet components have intricate passages and bizarre shapes to conduct gasses, and they are hideously expensive to manufacture with conventional tools.
There turned out to be less detail available here than I hoped.
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.
And the problems haven’t been completely ironed out: the first launch attempt of Starship’s flight test 13 was aborted automatically by the vehicle’s flight software at T-0 (right before liftoff) this past July when several Raptor 3 engines failed to start
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.
I'm pretty sure that the heat exchanger is going to end up being one part they have to put back in. Pushing CO2 and H2O (both ices at prop temp) into the tanks just seems so ill-advised to me. The amounts of contamination are small, but there are just so many different ways that can go wrong.
In SSME, most of the LOX never goes through a preburner.
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.
According to Isaacson's biography of Musk, Musk relentlessly challenges the existence of every part in Tesla and SpaceX machines. He's willing to go too far, having to sometimes put a part back in.
Everything in the manufacturing process is also challenged to justify its existence.
This is how he managed to reduce the costs by 90%.
Slight aside, he also has driven capability that was challenging to justify existence for, and was later removed re: Dragon 2 propulsive landing via SuperDracos, landing legs, and the ballast sled. I'm sure the Dragonfly programs matured their abort programs, but surely, that was a ton of time and effort wasted.
"According to Isaacson's biography of Musk, Musk relentlessly challenges the existence of every part in Tesla and SpaceX machines."
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.
yes and no. Like you said, automotive and aviation industries are bound by a lot regulatory and path dependent constraints.
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"
This is exactly correct in the context of the decision as it played out, but stretches and re-engines are very common in commercial airlines. Changing that decision without reinforcing the safety culture probably would have ended in the same place.
Wasn't the whole point of the MAX that they had reached the limit of what their existing design had, but due to the demands of the airlines, as well as their current position in the market, they felt it was an easier idea to extend the lifespan of their already tired design by using software to overcome the physical limitations of the aircraft? I do understand that the airplane would have flown fine without the MCAS system, but then it would not have satisfied all their requirements.
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
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.
My point was more too highlight his approach to problems, not make the argument that this would have been successful or profitable for Boeing.
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.
Sure, that is no accident. Elon seeks out markets ripe for disruptive engineering innovation.
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.
According to a version I heard, Boeing engineering did say more or less just that, at which point Southwest, the near-monopoly in some regions, said something like, "Oh yeah? Then we'll plan to leave it."
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.
I know how the stab trim system works. I worked on it (for the 757) for three years.
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?
You just took Boeing adding a secret system that can cause a plane to crash and then blamed the pilots who were unfortunate to be a victim of malfunctioning sensors and then put all the blame on them because pilots who didn't want to die inside a deathtrap aircraft figured out how to avoid their own death the moment they realized that the MCAS crashes were not an isolated incident?
What exactly are you accusing the pilots involved with the accident of? That they had some perverse incentive to die?
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.
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?
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.
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.
Do you remember when he bought Twitter and fired everyone, and the mass media and employee outcry was that a) the service would stop working and b) he would bankrupt the company, yet a few years later it’s massively more successful than Twitter ever was as a public business?
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.
Twitter is definitely not more successful now than before. So many people left and are gone forever.
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.
Maybe I’m overstating “massively more successful” but to my understanding “X” has roughly twice the active use count that Twitter did, although that includes Grok.
That said, do you remember these kinds of articles?
Musk summons engineers to Twitter HQ as millions await platform’s collapse
“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.”
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.
I haven't posted anything on this HN submission yet, but all I'm claiming is that Twitter was so successful under Elon's management that he thought it was better to roll it into SpaceX than to keep it independent. Kind of like solar city was merged into Tesla to bail it out and then it winded down after the acquisition while nobody is looking.
yet a few years later it’s massively more successful than Twitter ever was as a public business?
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.
The thrust vector control (TVC) subsystem is usually considered a part of the engine. The major change the Soviet NK-33 underwent for a USA model was the addition of TVC, and the engine was named differently, so there are two engines, named differently, which mostly differ by the presence of TVC.
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.
Oh yeah, Tory Bruno made that gaffe of a comment publicly, and completely unprompted, before he abruptly quit. I had forgotten, but you’re right of course.
https://www.spacex.com/content/starship/holy-grail-of-rocket... at 13:35 has a good view of a raptor 3 with TVC, do you think that adds substantially to what is pictured at the top of the article?
TLDW but TVC for rocket engines is usually achieved by like one hydraulic suspension rod each for X and Y axes(Y and Z in rocketry? idk) serving as parts of the engine mounting frame. It shouldn't add a lot to the system.
I didn't have a particularly good view from 13:35 frames. TVC is a relatively simple subsystem, but it's there.
Yes, that's the usual way. With SpaceX, however, Raptor engines are gimbled with electric actuators.
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.
That video has beautiful shots of Raptor 3 firing and gimbling. It's worth watching.
Tony Bruno, when referring to the partially assembled engine, was complaining about the lack of engine controllers, fluid management, and TVCs [1].
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.”
https://x.com/SawyerMerritt/status/1821679540973765026?s=20
3d printing metal has come a long way!
I find it mind boggling that you can 3d print rocket engines. I thought that the standard line is that 3d printing metal wasn't developed enough for anything serious. Not a mechanical/materials engineer, but if you can 3d print rockets what's off the table? Jet Engines and that's about it I think?
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?
3d printing metal has some strength downsides, I'm not sure what it is for the raptor engines, but I've heard other space companies claim ~5% less strength that traditional methods for aluminum structures, but that can be worth it in cases where you are able to make shapes that wouldn't be possible with traditional methods, or if you save enough money by printing it. Rocket engines often can benefit from intricate internal channels and shapes that you can 3d print as once piece with no way to do it via subtractive manufacturing.
It has mild strength downsides, but very severe fatigue and damage tolerance downsides. Knowing this, it makes sense that 3d printing tech would make headway in space industry but not (yet) in aviation
What's the current theory for why this is?
3D printed metal is now as strong as machined metal, assuming an identical alloy. The process has been pretty well perfected.
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.
Sure, but I mean what's the technical reason a material isn't it 3D printing friendly? Are we talking grain structure here? Is it something that can be at least partly mitigated by some post-printing heat treatments, like tempering?
Some alloys don’t like to be melted. If an alloy has a large solidification range, certain areas can partially solidify without the liquid part keeping up to fill in the gaps so to speak. This leads to solidification cracking / hot tearing. This is a simplification and only one possible cause, but there are literal books written about this kind of thing (I like Solidification by Dantzig and Rappaz). This is also why you see things like friction stir welding for rocket bodies. No melting means no solidification means no solidification issues.
Eh. A lot of materials get their strength from being worked, which 3d printing doesn't do at all.
Try machining some printed 316 stainless! It’s basically pre work hardened from the thermal stresses!
crack growth in metals is driven by microscopic flaws that cause high-intensity but very localized stress concentrations. Over time even low stress levels cause these flaws to grow to the point where they start causing strength problems. Even in traditional aluminum machined parts, increased surface roughness can have a large impact on fatigue life.
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.
Is there a known source of internal flaws/porosity in an otherwise solid part? Presumably laser melting produces a puddle which shouldn't allow for internal pores, as long as it isn't printed too fast (or solidifies too fast, which is why I think most chambers are internally heated to near melting temp).
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.
I can't speak to the proximal cause of the roughness and porosity, but if you've ever held a raw printed aluminum part in your hand it is immediately apparent. That said there are processes to deal with porosity like Hot Isostatic Pressure (HIP) treatment that basically crushes all the voids with immense pressure. This does come at the cost of dimensional accuracy though (HIP will compress the part somewhat).
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
I'm not sure if it make sense but... is it possible to put the printer inside a vacuum chamber so there is no air to fill the internal bubbles?
SLS printers lay a layer height worth of powdered metal and fuse it with a laser engraver. Thee bed lowers one layer and the process is repeated. They don't bring materials used like inconel to full melting temperature, only do what it takes for the metal sand to clump together. That's one source of pores.
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.
Don't get good crystal/grain structure from 3d printing.
One of the things that 3-D printing allows is a fine honeycomb structure. This comes with a somewhat bigger strength reduction, but a dramatic weight reduction. Less materials is cheaper.
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.
3D printed metal components are also in Hyper cars, Bugatti and Koenigsegg have implemented them for different components
https://newsroom.bugatti.com/en/press-releases/bugatti-refin...
Apple uses some 3d printed components at volume, i.e. the ultra 3 and 4 watch cases.
Beehive is 3D printing jet engines today, albeit small and potentially only going one way.
Why would you want a yet engine to go backwards?
I think by one way they are referring to cruise missiles i.e. the engine is only used once or twice. Once during test fire, and once in production environment.
What makes jet engines less printable than rocket engines?
GE9X aircraft engines have 3D printed low pressure turbine blades, so I think the view that jets are somehow exceptional is already disproven. There are real benefits to using additive processes for turbojet/fan applications: many jet components have intricate passages and bizarre shapes to conduct gasses, and they are hideously expensive to manufacture with conventional tools.
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.
Someone was reverse engineering the engine in public on a spacex owned website.
It got taken down.
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.
I'm pretty sure that the heat exchanger is going to end up being one part they have to put back in. Pushing CO2 and H2O (both ices at prop temp) into the tanks just seems so ill-advised to me. The amounts of contamination are small, but there are just so many different ways that can go wrong.
Isn't the Space shuttle main engine / SLS engine a full-flow staged combustion engine?
No, it's a fuel rich staged combustion cycle: https://en.wikipedia.org/wiki/RS-25
As it said raptor was the first and the SLS engines are way older.
I think China has made a full flow engine too.
In SSME, most of the LOX never goes through a preburner.
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.
According to Isaacson's biography of Musk, Musk relentlessly challenges the existence of every part in Tesla and SpaceX machines. He's willing to go too far, having to sometimes put a part back in.
Everything in the manufacturing process is also challenged to justify its existence.
This is how he managed to reduce the costs by 90%.
Slight aside, he also has driven capability that was challenging to justify existence for, and was later removed re: Dragon 2 propulsive landing via SuperDracos, landing legs, and the ballast sled. I'm sure the Dragonfly programs matured their abort programs, but surely, that was a ton of time and effort wasted.
You win some, you lose some.
If you aren't failing now and then, you aren't really trying.
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.
yes and no. Like you said, automotive and aviation industries are bound by a lot regulatory and path dependent constraints.
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"
This is exactly correct in the context of the decision as it played out, but stretches and re-engines are very common in commercial airlines. Changing that decision without reinforcing the safety culture probably would have ended in the same place.
Wasn't the whole point of the MAX that they had reached the limit of what their existing design had, but due to the demands of the airlines, as well as their current position in the market, they felt it was an easier idea to extend the lifespan of their already tired design by using software to overcome the physical limitations of the aircraft? I do understand that the airplane would have flown fine without the MCAS system, but then it would not have satisfied all their requirements.
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.
My point was more too highlight his approach to problems, not make the argument that this would have been successful or profitable for Boeing.
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.
Sure, that is no accident. Elon seeks out markets ripe for disruptive engineering innovation.
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.
The decision to re-engine the 737 rather than design a new airframe saved the airlines a vast amount of money.
According to a version I heard, Boeing engineering did say more or less just that, at which point Southwest, the near-monopoly in some regions, said something like, "Oh yeah? Then we'll plan to leave it."
And Boeing upper management overruled the engineers.
Color me skeptical.
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.
I know how the stab trim system works. I worked on it (for the 757) for three years.
Yes, it applies to MCAS.
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?
You just took Boeing adding a secret system that can cause a plane to crash and then blamed the pilots who were unfortunate to be a victim of malfunctioning sensors and then put all the blame on them because pilots who didn't want to die inside a deathtrap aircraft figured out how to avoid their own death the moment they realized that the MCAS crashes were not an isolated incident?
What exactly are you accusing the pilots involved with the accident of? That they had some perverse incentive to die?
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.
You can always get help from subject matter experts.
I've been inspired by that to refactor my code so that function parameters are minimized (many pass TMI).
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).
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.
Do you remember when he bought Twitter and fired everyone, and the mass media and employee outcry was that a) the service would stop working and b) he would bankrupt the company, yet a few years later it’s massively more successful than Twitter ever was as a public business?
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.
Apparently 90% of the Twitter staff were simply baggage.
Uh, no, I do not remember how Twitter is massively more successful than it was as a public business. Can you enlighten me?
Twitter is definitely not more successful now than before. So many people left and are gone forever.
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.
Maybe I’m overstating “massively more successful” but to my understanding “X” has roughly twice the active use count that Twitter did, although that includes Grok.
That said, do you remember these kinds of articles?
Source: https://www.washingtonpost.com/technology/2022/11/18/twitter...
Source: https://www.technologyreview.com/2022/11/18/1063467/former-t...
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.
I haven't posted anything on this HN submission yet, but all I'm claiming is that Twitter was so successful under Elon's management that he thought it was better to roll it into SpaceX than to keep it independent. Kind of like solar city was merged into Tesla to bail it out and then it winded down after the acquisition while nobody is looking.
Just claiming, you know.
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...
The article doesn't mention subscription revenue. I subscribed to X in order to not see ads.
And you know this how? ...
It’s extremely premature to celebrate something which hasn’t been shown to work in its intended application, nor at the original specs.
Given the original specs are the kinds of numbers Musk pulls out of his behind, I wouldn’t expect it to anytime soon.
It’s certainly an achievement of SpaceX engineering what they can do despite his constant meddling.