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I wonder what they were actually testing. They chill everything they can for a normal firing. When running, the gas temperature in the throat is over 3000K. Does it matter if it starts at 30K in space or 300K in atmosphere? That represents an increase of 2970K vs 2700K. Perhaps they fully expected everything to be fine, but wanted the test to be sure.
I wonder if they were more concerned about icing of the propellants while sitting at such low temperatures for a long time without running the engines. Stuck valves, chunks of material going through the plumbing, turbines and such.
Yes, I would guess that’s what they were testing. Stuck valves especially. And little tubes that could “ice” up with frozen oxygen or whatever.
Incidentally, the new Issacson book has some tidbits about Raptor 2. Elon pushed his engineers to replace a lot of exotic materials (even simple copper plates) with stainless steel for manufacturing speed and cost reasons. The design engineers were a bit too exuberant with going with the “best” materials in Raptor v1.
Buckminster
Well-Known Member
Whoops:
But the goals for the 1337 (leet-speak, lol), engine are pretty nuts... 450 bar??:
The name tells me that this is another Elonism of declaring aggressive aspirational goals. In other words, he made this up so his Raptor engineers have something to shoot for. Without a goal like that, his teams might just be content to pat themselves on the back for achieving 350 bar. It's the same as his Mars colony goals, his robotaxi goals, etc. In truth, it's like JFK telling NASA to get to the Moon "before this decade is out". Challenge your people. The best will rise to the challenge and achieve things they never knew they could.
I invite anyone who hasn't read the short story Noise Level by Raymond F. Jones to read it. It's a clever illustration of this idea. From 1952.
I suspect there's indeed some truth to that. But I'm not sure that Elon sets "stretch goals" in the typical managerial sense, which are ofeten not necessarily achievable, but indeed just aspirational goals.
I think that Elon has enough of a physics/engineering grasp that, other than schedule, it seems that many of his overall goals have been reachable. He's evaluated enough from a first-principles perspective to realize there's no fundamental obstacle. The final product will often take a different form or approach, like transpirational cooling, but the overall goal, the bely-flopping Starship[1] , have been achievable.
I'm sure JFK relied on some smart folks to advise him regarding the moon landing before the decade was out, but I suspect that was as much of a guess that it as even possible as anything. I bet Elon has seen enough in terms Raptor development to believe that there's a reasonable path with materials science, chamber design, turbo pump impellers/seals, etc.. that 450 bar is doable...
I think that Elon has enough of a physics/engineering grasp that, other than schedule, it seems that many of his overall goals have been reachable. He's evaluated enough from a first-principles perspective to realize there's no fundamental obstacle. The final product will often take a different form or approach, like transpirational cooling, but the overall goal, the bely-flopping Starship[1] , have been achievable.
I'm sure JFK relied on some smart folks to advise him regarding the moon landing before the decade was out, but I suspect that was as much of a guess that it as even possible as anything. I bet Elon has seen enough in terms Raptor development to believe that there's a reasonable path with materials science, chamber design, turbo pump impellers/seals, etc.. that 450 bar is doable...
JFK had NASA. He asked them for a goal that the US could achieve and the Soviet Union could not. The NASA guys knew that the Soviet Union already had orbital capability via Korolev's rocket designs. But they also knew that a new rocket was going to be needed for anything beyond LEO. So NASA told JFK that the US could reach the Moon before the Soviet Union could. I assume they told him something like "If we pushed really hard and had the resources, we could do it by 1970".
In the end, America famously made it to the moon. The NASA guys were right. Even if Korolev had lived, the Soviet program just couldn't match the technical and industrial might of a mobilized America. It was another one of those "sleeping giant" moments for America. When we're motivated, we can do incredible stuff.
Elon is competent in some areas, but aspirational in all. That's why some of his companies achieve such amazing results; where there is unrealized potential in an industry, his people realize it. Where there is no unrealized potential, his people beat their heads against the problem. Electric cars and reusable rockets are examples of the former. Neuralink and FSD are examples of the latter. Composite rockets would have been an example of the latter, and if Elon and his people had stuck with it, they'd still be beating their heads against that problem instead of digging holes with stainless steel super heavy lift vehicles.
So in the end, Elon sets aspirational goals all over the place. Where the technology is ready to go that far, his people will succeed. Where it is not, his people will fail. But as Wayne Gretzky is famously known to have said, "You miss 100% of the shots you don't take". Elon shoots.
Will his people ever reach 450 psi chamber pressures? Maybe. Eventually. I think it's an FSD problem, where it's the sort of thing that's possible, but nobody yet knows how to do it. So it'll require fundamental research by the SpaceX guys, and that always takes time.
This is not directly related to Raptor, but it is a rocket engine firing, as covered by the The Slo Mo Guys. This was a single-camera single-take effort, so Gavin didn't get a chance to film at various speeds, framings, and stops to get the best coverage. I'd love it if he did more of this sort of thing, including about ten times the frame rate and pointed into the nozzle as much as possible. I wonder if SpaceX bothers with this sort of thing.
I don't know that FSD and Neuralink are examples of unrealized potential. There's great potential for each... they simply are incredibly difficult. Taking time doesn't mean that they aren't achievable... that's my point : I believe Elon has a good grasp of what is within the realm of practically possible. even if incredibly difficult.
And composite rockets are an example of what I mentioned earlier: they may have to change course (and in fact are unusually willing to do so), in order to reach the goal. A composite rocket was not the goal, it was one possible approach to reach the actual goal: A more fully re-usable heavy lift rocket.
Nit pick: 450 BAR.
Yep, 450 PSI is only 31 BAR.
450 BAR is 7,832 PSI.
Yikes!
For now, Raptor 3.2 is plenty powerful. Get them to be more reliable and get to orbit.
450 BAR is 7,832 PSI.
Yikes!
For now, Raptor 3.2 is plenty powerful. Get them to be more reliable and get to orbit.
Why? It was on the Merlin test stand and smoke was pretty sooty looking.
Because for some reason I overlooked that this was the Merlin stand.
Thanks for the correction.
It looked more like a test stand failure. Perhaps just a leak. The engine seemed perfectly fine, but there was burning propellant everywhere just as they fired the engine. At least, that's how I saw it.
New Raptor test failure (likely intentional)
Looked quite engine rich. Possibly insufficient film cooling.
So, based on these frames at the moment of the RUD, it appears the engine is on the left, as that's where the explosion starts, and up that point the plume to the right tapers off in brightness.. in other words the engine is "firing" to the right:
However, in the frame to the left of the engine, as thrust picks up, you can see atmosphereic distortion and actually some exhaust flame shortly before teh explosion:
What are we seeing here? is there some sort of ducting or other mechanism to redirect the exhaust? I don't see a dirt berm or anything...
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