Everyday Astronaut did a walkaround with Musk around Starbase a day before the IFT-4 flight. Due to the time it takes to scrub for ITAR material (International Traffic in Arms Regulations–basically anything that we don’t want North Korea to have access to), it was only just released today.
I do have to eat some crow on this:
Musk confirmed that they are using preburner exhaust for pressurization. No heat exchanger.
I still maintain there was no actual evidence of them doing otherwise at the time, but undoubtedly Musk’s “best part is no part” approach won through and they deleted the heat exchanger. That means the pressurant contained small amounts of H2O and CO2, which would have been responsible for the filter blockages when they formed ice in the tanks. Regardless, they seem to have enough filter capacity now as IFT-4 didn’t experience any issues here. Not sure if that was a win mass-wise, but it sure was complexity-wise.
At any rate, there’s lots of good material in the walkaround. The new facility is impressive in size (it’s the one I photographed in this post).
It’s funny to see Raptor 2 engines packed in like Christmas trees, while Tory Bruno is posting things like “Thanks to Blue Origin for sending one of your engines. Now please send the second one” (I’m paraphrasing a bit).
Well, the Raptor is deliberately designed to be simple and require a bunch of them. Blue Origin is building massive rocket engines but doesn’t need as many. I think the jury is close to a verdict on which approach works better. Traditional government builds are dead men walking (propped up by taxpayer dollars).
The current cadence on builds (let alone what they’re planning for) is so far ahead of the rest of the field, it’s hard to imagine SpaceX getting caught by anybody at this point. SpaceX is building more rockets (all stages) and engines than the rest of the world combined by a significant factor.
Fun video!
The cool thing I learned is that they’re using Tesla electric motors to drive the fins and flaps! Zero hydraulics on Starship!
That’s true but mostly a function of rocket size. The BE-4 and Raptor 2 have very similar thrust: 2.45 MN vs. 2.26 MN. Most likely, Raptor 3 will easily exceed this. Raptor is also more efficient due to the full-flow cycle.
Blue Origin said that their plan for BE-4 was to be a “medium-performing version of a high-performance architecture”… which is a little weird since although oxygen-rich staged combustion is better than a gas generator, it’s still not as good as full-flow.
So their engine seems to be more expensive, less efficient, harder to produce, physically larger, and probably less powerful in the long run. Well, at least it’s not Aerojet Rocketdyne. And the BE-4 isn’t a bad engine by any stretch. Just unimpressive in comparison.
There is an interesting video exploring the issue on rocket engine size versus many rocket engines that you may find interesting (this came out a few days ago):
Your engines have a sufficiently high reliability in the first place
There was really only one reason why the Saturn V had 5 engines, though (aside from the name): the F-1 was the engine they had. It had been developed by the Air Force since 1955 and so was already in a pretty advanced state when the Apollo program started. There wasn’t enough time to develop anything else. They picked five engines because they wanted a single rocket and that’s how big it had to be.
Indeed. As noted in the video the Soviets saw the problems with massive rocket engines so opted for lots of smaller engines and those rockets (the whole system, not just a given engine type) were a failure. The idea was sound but the ability to pull it off was too much for the Soviets (maybe anyone) at the time.
But the tech is there now. It is still incredibly complex rocket science but, clearly, doable. Although it is interesting in the Everyday Astronaut video (and one he did some time ago) the engines are getting refined over and over again and each iteration is less complex (read less expensive) than the last one while still getting the job done.
That was great. That guy said so many things I’ve been thinking for years, it’s not even funny. Thanks for sharing!
It’s not a pure analogy, but when I ship something, I don’t ask what equipment is going to be used. I say “I need this moved from here to there. What’s your price?” Then I pick the cheapest reliable one. NASA needs to start thinking that way (with obvious caveats - but “you did something cool for us 50 years ago” shouldn’t be one of them.) The old ‘design, design, design, design, then build, and it better work’ is NOT how to do things in the modern world. By the time you’ve finished the second or third design phase SpaceX is has already accomplished your mission, by doing ‘design, build, refine, refine, refine’ at high cadence. They changed the game and the dinosaurs will either adapt or die. My money is on die unless we keep propping them up with tax dollars so that Congresspeople can keep their jobs.
Also, as noted in the first video tour of SpaceX, a large engine precludes reusability unless it has an ability to throttle down to absurdly low thrust rates.
The build quality is going to be so much better in the new factory compared to the tents, which was already passable. They actually seem to have proper workstation tooling/structure and climate control now which is going to do wonders for speeding up production.
Yeah, and that was a major factor in its reliability. Some engines went through thousands of seconds of testing.
The NK-15 engines of Russia’s N1 rocket in comparison could not be tested at all, as they could only be fired exactly once. So they could only test fire one engine out of a batch, and install the remaining ones on the rocket–hoping that if anything was wrong, it would apply to all engines in the batch. It was an impressive engine in many ways but the reliability was not great.
IMO BE’s statement “medium-performing version of a high-performance architecture” should be read as “A functionally derated version of a high performance design that will buy high reliability by staying well back from the redlines of anything.”
Which is not a crazy way to “buy” (in the engineering tradeoff sense) high reliability, but may be becoming an uneconomical way to buy (in the accounting sense) high reliability in the face of the ever-improving competition from Falcon.
We shall see.
But overall I lean towards the opinion that SpaceX is so much farther down the learning curve and the volume curve that no one from any nation can possibly catch up organically. The way SpaceX gets passed is they do something real stupid on a sustained basis or they get real unlucky.
SpaceX seems to be iterating their design much, much faster than Blue Origin. SpaceX seems to be on a rocket ride of development while Blue Origin barely muddles forward.
The nature of rocket flight, and apparently rocket development, is that acceleration runs on a square law or maybe even exponential curve, which means velocity builds up ever faster, and distance really builds faster yet.
Once you’re just a bit ahead the opposition quickly dwindles to a dot in your rear view telemetry camera.
Oh, sure–mainly I’m just poking at the “high-performance” aspect. Largely true in 2016 when they said it. Less true today when we have a flying full-flow staged combustion engine.
And the BE-4 is more than a little derated. Chamber pressure is a pretty good proxy for overall engine performance. The RD-180 is a good comparison here since ULA wanted to replace a single RD-180 (with two nozzles) with a pair of BE-4s for a similar sized rocket. The RD-180 runs at 267 bar pressure. The BE-4 is just 134 bar. That seems extreme to me. Yeah, it makes sense to back off from “war emergency power” levels, but we’re typically only talking the last 10-20% here, where the wear curve really starts to go vertical. And besides, the RD-180 was a reliable engine.
Meanwhile, the Raptor is running at >300 bar, and they keep pushing this higher (350 bar in tests). Arguably, it’s also well back from the redlines–the full-flow architecture means they don’t have to run their turbines as hard as the RD-180 even with increased chamber pressure. Though I think we can expect them to keep pushing that.
BE has been moving at oldspace speed where 8 years of effort is but an eyeblink along the long road leading eventually towards a flying product.
Conversely, at newspace speeds 8 years is forever; time for basic designs to have evolved, had a full lifecycle of operations, and then been replaced by yet newer basic designs better in every way.
When you are launching twice a year at best and your competition is launching 140 times a year, you’re not just not keeping up, you’re irrelevant to the discussion.
I’m not a giant fan of Elon Musk (I am a fan of the company he built), but he said it best in the video above (paraphrased) - “If you’re building a rocket that isn’t partially or fully reusable, you’re wasting your time.” He said the 3 Rs “rapid, reusable, reliable”. Boeing has clearly demonstrated that they and their partners lack all 3.
Now, now, they’re batting 2 for 3 with their airplanes. That ought to count for something.
Seriously, I could not agree more with what you’ve said. Newspace really is different. It’s as different as assembling CPUs with discrete 7400-series TTL DIP chips on wirewrap boards versus VLSI and all the rest of the exponential improvement since then. The old way is an oxcart versus a modern dump truck or highway tractor + semi-trailer rig.
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