If you’re reading this, there’s a very good chance you’ve seen this famous image of three iterations of SpaceX’s Raptor rocket engine.

248 points•JumpCrisscross•13 days ago•125 comments•

125 comments

WalterBright12 days ago
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%.

xondono12 days ago
> According to Isaacson's biography

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.

inglor_cz12 days ago
It seems to me that partisan/political hate blinds some people so much that they are becoming ridiculous.

"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.

sebmellen12 days ago
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.

greenhat7611 days ago
Look man I'm not a fan of Elon, but it's ridiculous to say the starship is the "worst". It's coming out of early development and has had some minor success already.
ETH_start11 days ago
He was the chief engineer and head of product at SpaceX and Tesla for over 20 years, respectively.

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.

nickff12 days ago
>"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.

panick21_10 days ago
Vertical integration is one thing SpaceX does but its not unique and magical as many other space companies have tried the same without achieving results similar.

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.

s1artibartfast12 days ago
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"

saturn860112 days ago
>This removal of surplus-age is common in the automotive industry, and one of the reasons that cars are such an amazing value.

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.

nortlov12 days ago
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.

WalterBright12 days ago
If you aren't failing now and then, you aren't really trying.
WalterBright12 days ago
I've been inspired by that to refactor my code so that function parameters are minimized (many pass TMI).
avmich13 days ago
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.

benjaminl12 days ago
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

panick21_10 days ago
Tory was just wrong. Yes TVC wasn't there but that's because that's not inherent to the design, some Raptors are attached with TVC some without. But everything else was there.

And if you see Raptor integrated on Starship you can see this clearly.

brandonagr212 days ago
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?
numpad012 days ago
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.
w8vY7ER13 days ago
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.
ecshafer12 days ago
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?

doctoboggan12 days ago
> 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.

pbkompasz12 days ago
> I am amused that SpaceX uses cybertrucks to tow their rocket engines around the grounds and not a normal cheaper truck

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...

MSKJ12 days ago
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...

jackmott4212 days ago
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.
fbd_010012 days ago
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
btilly12 days ago
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

reportingsjr12 days ago
Apple uses some 3d printed components at volume, i.e. the ultra 3 and 4 watch cases.
thinkcontext12 days ago
> 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.

Tuna-Fish12 days ago
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.
advisedwang12 days ago
> A full-flow staged combustion engine is very complex, and prior to the Raptor only two had been built, neither of which successfully flew on a rocket.

Isn't the Space shuttle main engine / SLS engine a full-flow staged combustion engine?

Tuna-Fish12 days ago
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.

nbadg12 days ago
No, it's a fuel rich staged combustion cycle: https://en.wikipedia.org/wiki/RS-25
pixl9712 days ago
As it said raptor was the first and the SLS engines are way older.

I think China has made a full flow engine too.

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