SpaceX ramps up Raptor engine tests

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Capitalism in space: SpaceX has conducted another Raptor engine test, this time running the engine at full power.

“Raptor just achieved power level needed for Starship [and] Super Heavy,” Musk tweeted just after 3 a.m. EST (08:00 GMT) Feb. 7.

Musk did not say how long the test was or if it was at full power. The Feb. 3 burn was only about two seconds and at about 60 percent power. However, he said the latter test reached a chamber pressure of 257 bar, or about 3,700 pounds per square inch, and an estimated force of about 172 metric tons with “warm propellant.”

Musk has said that they will be doing hopper test flights with their Starship prototype this spring, but they can’t do that until they have three working Raptor engines. It seems to me that it will be at least a few months before this engine is tested sufficiently to be ready for flight. Then they need two more finished engines.

Don’t expect the first Starship hopper flights for at least six more months, if that soon.



  • Diane Wilson

    Word on NSF yesterday centered around 90% power for less than 10 seconds, probably around 6. Also, shock and awe that this test followed the first by only two days. Musk says it will be a while (Musk time?) for full power. But this is sufficient for the hopper and apparently the first prototypes.

    No speculation yet on “full duration” firing, whatever that might mean for hopper engines. And no word on the overall test plan, but noting that this is a full-scale Raptor fresh off the production line. (I don’t think I’d call serial number one a “production model,” though. Close.) Depending on results, this engine may get more testing than hopper engines two and three, and maybe a spare for the hopper. I don’t expect a test-to-destruction until after the hopper has its engines. The hopper engines will get some restart testing, but again I expect that engines for prototypes will get a lot more of that.

    By way of comparison, Boeing sets aside two airframes for static testing of new airliners, one for wing deflection (usually to destruction, although they didn’t do that for the composite wings of the 787), and one for fatigue testing, with simulated take-off and landing cycles in excess of expected airframe life. That seems a prudent approach for high reliability and reuse.

  • Edward

    Diane Wilson wrote: “I don’t expect a test-to-destruction until after the hopper has its engines.

    I don’t expect any intentional tests to destruction on rocket engines. It tends to be hard on the test equipment, and it does not reassure customers. (9 minutes: “Test firing a new rocket engine (and watching it explode)”)

    I once tested some standoffs for a spacecraft instrument, and we decided that while we were on the shake table and finished with the planned test, we would test to destruction just to see how well we had designed our standoffs, but it gave no necessary engineering information. When NASA heard that the standoffs had broken, they were upset, and we had to calm them down, because they hadn’t realized that we had deviated from the test plan.

    I have stuck to test plans ever since, and made sure to design the plans to test only what was necessary. This is a case where going above and beyond is not such a good idea.

    Boeing testing wings and airframes to destruction may have given them important engineering feedback and reassured customers that their purchases would last longer than the designed economic lifetime.

  • Diane Wilson

    Test-until-destruction and fatigue testing are done with aircraft because aircraft are reused. That hasn’t been done with rockets because rockets didn’t get reused, until SpaceX. And New Shepard, which takes months between re-use; Musk certainly plans faster turn-around than that.

    We’ll see. SpaceX seems intent to shake up the rocketry industry with more than just pricing.

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