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Elon Musk gives a tutorial on the Raptor-2 engine

Tim Dodd of Everyday Astronaut on Friday released another video from his most recent tour of Starbase at Boca Chica with Elon Musk. I have embedded it below.

Essentially, this 41 minute video is Elon Musk giving us a tutorial on how SpaceX simplified and improved its Raptor engines from its first iteration to the present Raptor-2. He does this while standing in front of a long row of finished Raptor-2s, all meant for installation in the seventh prototype of Superheavy, the booster now on the launchpad with those engines installed and being prepared for its first static fire test prior to the orbital flight.

Musk revealed two interesting factoids during this video. First SpaceX blew up approximately 20 to 30 Raptor engines during the development phase, and melted the chambers on another 50. All of this was perfectly acceptable, because they designed engine manufacture so that a high production rate was built in. As Musk noted, “A high production rate solves many ills.” Losing engines during testing and development was no big deal because they were able to quickly replace them, with revisions and upgrades.

Secondly, Musk claimed that the Raptor-2 engine has a 99% efficiency, a level of efficiency that is unheard of in any engine for any purpose ever. I wonder if that claim will hold up as new companies and engineers work to beat SpaceX in the coming centuries.


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13 comments

  • Ian C.

    “as new companies and engineers work to beat SpaceX in the coming centuries.”

    Delicious.

  • Edward

    There are a lot of excellent tidbits in that interview. Deleting and combining parts (simplification) was another important point. “The single biggest mistake made by smart engineers is optimizing a thing that should not exist.” Twenty-one minutes into the video he gives five things to do while designing. I wish I had known that mantra during my life as a design engineer. I didn’t often oversimplify so much that I had to put things back into the design. Clearly, I was not simplifying enough. Rats. Now I find out.

    Just as Alfred Hitchcock would tell everyone his secrets to making amazing movies, Musk is telling everyone how to do rapid development to create an inexpensive rocket (or anything else, for that matter). Although efficient rockets and their engines are new, rapid development isn’t new, so it isn’t like Ford inventing the moving assembly line; Musk is not inventing rapid development. The U.S. did this kind of thing on rockets in the 1950s, and it is one of the reasons why ‘our rockets always blew up,’ to paraphrase Tom Wolf’s The Right Stuff. NASA’s contractors have either forgotten this methodology or have different goals in mind.

    Another reason why SpaceX was able to quickly replace engines, with revisions and upgrades, is that they are inexpensive to make — it is more than just the high production rate, it is the inexpensive nature of this testing. Testing is quick and cheap, and pushing the limits costs little but comes with great rewards, as the limits are quickly found (in time, not in number of engines destroyed). SpaceX could afford to destroy 20 or 50 or 80 engines, but could Rocketdyne afford to lose that many RS-25 SLS main engines? Not at $100 million each.

    “Any given technology development is how many iterations you have and what’s your time and progress between iterations.” To paraphrase Musk’s next sentence: ‘a high production rate allows for a lot of iterations and trying different things,’ thus the ability to solve so many ills. No wonder they are able to reach such good combustion efficiency. (A slight correction, Robert, Musk said “We should be able to get 99% [of theoretical] combustion efficiency,” which means they aren’t quite there, yet. See time mark 14:40) Using methane probably helps, too, as they don’t have to break apart carbon-carbon bonds.

    SpaceX is serious about advancing the technology and reaching its goals sooner rather than later. This seems to be another advantage to having commercial space operations rather than government as a monopsony.

  • Edward: FYI, that mantra of Musk, always worth repeating as he says, was first outlined in great detail by Musk in a previous Tim Dodd tour.

  • Ray Van Dune

    I would like to remind Tim that although his knowledge of rocket engines is impressive, he needs always to remember that we are there to hear primarily Elon’s words, not his. Hint, hint Tim.

  • Jay

    Great video! This was a nice rocket engine 101 video and a motivator for best engineering practices. Development, testing, production, and go back to step 1- continuous improvement.

    After listening to him talk actual physics and engineering on this video, Musk does deserve the title Chief Designer.

  • sippin_bourbon

    I watched this video over the weekend, just after it was posted.
    Going to watch the one on Merlin engines as well.
    I do not know how Tim gets these inside tracks, but good on him. He has great content.

    As for Elon, you can tell his brain is just going so fast, his mouth cannot keep up.

    It is great to see and hear this kind of stuff, as opposed to board room presentations, or PR-generated boasting.

    I do also love Tim’s enthusiasm. I had watched his previous content on aerospikes, which is a topic I had also been fascinated with.
    I know he had mentioned it previously with Elon.
    When he says “I know I mention this every time I interview you” and Elon is like “Yeah…”
    Unintentional comedy at it’s best.

    I laughed pretty hard. My wife came in asking what was so funny. (She entertains my geek side.).

  • pzatchok

    Musk may never go to Mars himself but he knows one thing.

    Set the goal high and watch the young people strive to reach it.

    Help them to reach that goal by keeping them fed with funding and the visible use of the results of their work.

  • Jeff Wright

    Thing is, hydrogen engines run cooler-and fly-back reduces the wear. Ironically-an engine that burns that efficent has to be hot-and that might be best for RS-68 expendable ablative nozzles. I wish he had done channel wall-and made that reusable. Now had it been old space doing fail fast, libertarians would attack that too.

  • wayne

    Elon Musk & Akira The Don
    “Optimistic And Wrong”
    (2018)
    https://youtu.be/7ypJ5ByaYbg
    6:01

    “I’d rather be optimistic and wrong… than pessimistic and right…”
    Elon Musk

  • James Street

    Starship Booster Explodes Unexpectedly During SpaceX Ground Test [Updated]
    https://gizmodo.com/starship-booster-explodes-unexpectedly-during-test-1849166744

  • Jay

    James,
    Thanks for that piece of news.
    Looking at the video, the booster did not blow up. SpaceX is saying there was an explosion under the booster from the methane during engine spin-up. I am sure they pulling all the engines for inspection.

  • I have posted the video of the explosion in a more recent post. Take a look. I’d love to hear opinions from the engineers in my readership.

  • John Wittenberg

    The Raptor 2 is in development, but as it is improved and better versions emerge, will Elon ever sell the older version engines to other companies or institutions, whether US or foreign?

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