12 thoughts on “Launch Failure”

  1. … or at least not to orbit.
    That latter part is very ominous even without having read the article…

  4. Either the “four minutes into the mission” was a mistake, or the actual failure occurred about two minutes prior to thrust termination. Scott Manley’s video shows thrust levels dropping for a couple seconds before the thrust completely stopped. The only reasons I can think of for thrust to start dropping off like that are if the pumps started slowing down, perhaps because a battery/electric motor issue, or perhaps a gradual but rather rapid loss of stage pressurization, leading to cavitation on the inlet side and the eventual triggering of various pump shutdown conditions.

  5. Someone in the Ars article mentioned it seemed to happen at the battery hot swap on the second stage which might make sense.

    1. I was thinking the thrust drop off approximately coincided with the drop-out of the video signal, which was about 30 seconds prior to the hot swap. One possibility is that the batteries depleted somewhat prematurely, leading to a voltage drop.

      Note that the hot swap was a precisely scheduled flight event. At something like +06:30.00 the hot swap would occur. Well, what if the batteries run down at 6:10.50? That’s 95% of the run-time they expected, which is probably within the margin of error of a battery considering batch variations, prior test drains (which decrease battery life), ambient temperature, and variations in pump performance and bearing lubrication.

      Given those variables, it would make more sense to do the hot swap based on voltage and current, not time, and make sure the total battery capacity has enough margin to cover variations in pump and battery performance. But since the batteries are so heavy, which is why they hot swap and drop the depleted ones, they might well be running the batteries with very little electrical performance margin. If that’s the case, the decision to hot-swap based on time instead of performance meant the difference between a slightly premature termination of second-stage thrust, resulting in a slightly lower final orbit, and a very premature termination of second-stage thrust, resulting in a mission failure.

      1. George in a sense you are describing a dual fuel rocket. Where propulsion relies on both RP-1 and the life of the Lithium Polymer batteries.

        The one reference paper I found off Wikipedia
        https://www.aacademica.org/hernan.emilio.tacca/9.pdf

        Seems to focus primarily on mass and battery efficiency translated strictly into estimates of time rather than performance. So you may be onto something here. I’m sure Electron has taken this difference into account. But if the engine power had to be tweaked for this mission that would also be an indicator that fuel consumption was higher than they estimated. Or the fuel “density” wasn’t as expected.

        2. And exactly what is powering the stage’s TVC system? No matter how you arrange things, I think the answer is the turbopump batteries because there’s no other big power source to use. So if the control system is seeking more than normal, that’s an extra drain on the battery system. And from the onboard video, there was quite a bit of continues steering taking place.

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