17 thoughts on “Raptor Update”

  1. “Metric tons of force”? Don’t you mean maganewtons?

    Only if the prefix “maga” means 9800. Reminds me of the good old days of pounds, slugs and poundals. I guess you could base SI on a force unit of a “kg”, but the mass unit wound be the “Musk”, which “weighs” 9.8 kg. So a kg of force would be 9.8 Newtons and would have the unit of Musk x m x s^(-1). Hey, it could happen.

  2. I think the thrust is 168 gigadynes.

    A dyne, which is 10 microNewtons, is a handy unit for the measurement of both thrust and experimental error in reactionless drive tests.

  3. It’s just Elon doing a metricization of the lbs-force thing. He said the newest Raptor is to produce 200 metric tons of force (440,000 lbs.) at sea level. So it’s at 86% with “warm” propellant.

    These tests seem much more like what one would expect for acceptance of a production item than they do like development tests. I think the former is exactly what they are. Raptors are going to go to McGregor as fast as Hawthorne can turn them out for a slam-bam-thank-you-ma’am set of acceptance firings and then on to Boca Chica. The first three go into Star Hopper. The next seven into the full prototype Starship. After that, SpaceX starts saving them up for the first prototype Super Heavy.

    As for the “crazy pace,” you’ve nailed that. As soon as the switch to stainless for SH-Starship and the in-situ construction of StarHopper were announced I started referring to SpaceX as having shifted over to what I call a “war footing.”

    In retrospect, the first major visible part of this shift was the decapitation strike on the Starlink management some months ago – pour encourager les autres as the French say.

    The second part – or it might have been first – was the invisible and unannounced at the time clean-sheet-of-paper reconsideration of the BFR design trades with much heavier emphasis on reducing total development project duration and cost. The “liquid silver” bird was the result.

    The recently announced layoff is also part of this – stripping down to fighting weight.

    So was the trucking to CA of the first Block 5 1st stage that had flown twice out of FL so it could fly a third time out of Vandy and be inspected promptly at Hawthorne. I suspect when wear and tear after zero, one, two and three flights, respectively, were graphed, the curve was essentially flat. That allowed even more Falcon production staff to be let go in the layoff and even more people staying on to be assigned to Raptor-SH-Starship work.

    Then there was the decision to abandon the San Pedro BFS factory in favor of an almost literally next-to-the-pad site at Boca Chica.

    Add it all up and you have SpaceX doing what Ford did to get B-24 production going or what Boeing did to stand up the B-29. SH-Starship and Starlink are now jointly top priority.

    Everything else is in second place or lower, including Dragon 2.

    1. Yup. Exciting though all this is, this is the early phase of Elon’s next great near-death experience.

      SpaceX is under-capitalized, and has committed to two high-risk projects that are completely interdependent: Starlink can’t make its FCC deadlines without SH/SS and BC creating some new launch capacity, and SH/SS can’t get through the “huh, they really can throw 100 t to LEO–what should we build?” doldrums without the Starlink revenue stream.

      I do think it’s interesting how “Moon” got put into all the PR to replace “Mars” recently. If Starlink weren’t urgent enough, I suspect that SpaceX has finally hoisted the Jolly Roger on SLS, after pretending for years to be above it all.

      Cockeyed optimist that I am, I’m going to give them a 75% chance of pulling it off. But if they don’t, it’s gonna be ugly. I can see why they’re siccing their pet congresscritters on LSA and EELV2. They can’t afford to leave any F9 or FH orders on the table if they want to stay solvent.

      1. If it is like other constellations in the past SpaceX only needs to put a test satellite on the frequency to get their slot. They can easily launch that on a Falcon 9.

        It was a good idea to market it as a Moon launcher because it means they are downscaling the launcher. I still think it is too large however.

        1. I’m skeptical that the FCC is going to be very forgiving of blown deadlines. There are too many interests that view SpaceX as an existential threat, and they all have way, way deeper lobbying benches than SpaceX does.

      2. Cislunar space is where the near term government money is. That doesn’t mean SH/SS isn’t Mars capable but that they make sure they can go where the customers are and let everyone know it.

      3. I don’t think SpaceX actually is undercapitalized, though I suspect Elon Musk isn’t averse to having that notion gain some currency until he’s too far along to be effectively jammed up by people hoping he just goes conveniently broke in the meantime. The SH-Starlink redesign not only shortens the time to first flight, it takes a lot of expensive capex, testing and even materials costs off the table as well.

        There’s no real need for Elon to formally raise the Jolly Roger on SLS. SLS is going to be merely incidental roadkill as the SH-Starship juggernaut goes pelting down the road at a breakneck pace.

        The recent emphasis on the Moon, as opposed to Mars, is for two reasons:

        1) SpaceX has already booked one paying Moon mission for SH-Starship.

        2) The Trump administration’s NASA, under Bridenstine, has already indicated a desire to go back to the Moon for keeps and to do so ASAP. SH-Starship fits perfectly into such plans.

        1. When a company as hot as SpaceX puts out another round of venture stock and it comes back under-subscribed, there’s something going on. We know they’re selling through on the F9 and FH missions, or close enough, so that’s not the problem. Either there’s something hinky with Starlink, or the balance sheet was too ugly even for a bunch of go-go tech investors. Under-capitalization fits the facts pretty well.

    2. Well I told you guys I thought the carbon filament wound tanks were a boondoggle. Particularly once you take into consideration that SpaceX had a lot more experience in house with metal construction.

      I still remember when the large composite tank was made. A lot of people claimed it was a success. Yet if you read the news releases, like I noted back then, the “success” was a water pressure test on which the tank did not reach design specification. It passed the in-flight pressure requirement but did not have enough design margin to be safe. I also noted back then that LOX was not the same as water and that the test was thus not only a failure but insufficient. I guess Elon eventually came to the same conclusions.

      If there is one thing which should have used carbon-filament wound tanks should be the hypergolic fuel tanks in the Dragon 2. I think.
      Those are both small and on the upper stage. Besides the fuel is not cryogenic so there should be less issues with expansion. Also the molecules are larger so infiltration on the tanks should be less of an issue. I know composite tanks are used on the second stage of the hypergolic Ariane 5 for example.

      I do wonder if they would not be better off with Al-Li on the first stage instead of using stainless steel on everything however. The first stage should have a less demanding reentry heat environment and they already got it working on the Falcon 9 with LOX.

      1. I don’t share your dim view of the ITS tank test, but whether it was a failure or success is kind of beside the point now. Personally, I think it was the necessity to get SH-Starship producible much faster and at much lower cost that drove the decision to abandon carbon fiber composite as primary structural material. Carbon fiber structures pretty much have to be monolithic for maximum strength. This requires huge molds/mandrels which are long lead-time items and don’t easily accommodate late-stage design changes. Carbon fiber is also more difficult and expensive to QC than metal.

        Switching to a combined structure-is-also-TPS approach also eliminated the need to be able to crank out acres of PICA-X to cover the “windward” side of the vehicle which would have necessitated an expensive and lengthy process of multiplying SpaceX’s in-house production capacity for PICA-X.

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