16 votes

SpaceX - Initial results from investigation into Crew Dragon explosion during engine tests on April 20, 2019

6 comments

  1. [2]
    Neverland
    (edited )
    Link
    Obligatory video on this topic from Scott Manley. Under 7 minutes in length yet goes into pretty great detail, while still being approachable.

    Obligatory video on this topic from Scott Manley. Under 7 minutes in length yet goes into pretty great detail, while still being approachable.

    5 votes
    1. blitz
      (edited )
      Link Parent
      As soon as the report was posted I was eagerly awaiting his video.

      As soon as the report was posted I was eagerly awaiting his video.

      4 votes
  2. [2]
    blitz
    Link
    It's so lucky that this failure happened on this test firing. I think it was the last test firing scheduled before they started flying people on Crew Dragon. They've test fired the launch escape...

    It's so lucky that this failure happened on this test firing. I think it was the last test firing scheduled before they started flying people on Crew Dragon. They've test fired the launch escape system several times without this sort of failure, so if the failure hadn't happened on this test firing then this failure mode would still exist on the capsule while people were flying on it.

    From my understanding, the launch escape system needs to be the most reliable system on the entire rocket. It needs to work even when everything else has gone wrong. They're replacing reusable check valves for fuel/oxy tanks that supply the superdraco thrusters with one-time use burst caps. This means that they can't test the exact hardware that will fly, they just have to trust the manufacturing process. It also means that the capsule will need more service if the escape system is ever fired (this is probably the case already).

    Crew Dragon will splash down in the ocean, so they won't be flying reused capsules for crewed missions anyway.

    2 votes
    1. zlsa
      Link Parent
      This was (as far as we know) the second-to-last SuperDraco test firing before crew. If the capsule had not exploded, it would have been used for the in-flight abort test, where they try to...

      This was (as far as we know) the second-to-last SuperDraco test firing before crew. If the capsule had not exploded, it would have been used for the in-flight abort test, where they try to activate the launch abort system while in-flight.

      2 votes
  3. [2]
    AugustusFerdinand
    Link
    If they replace the pre-fuel/oxidizer check valves with burst discs then the fuel/oxidizer tanks can't be unpressurized. However this being the emergency abort system I think that's the least of...

    If they replace the pre-fuel/oxidizer check valves with burst discs then the fuel/oxidizer tanks can't be unpressurized. However this being the emergency abort system I think that's the least of the worries at that point and use of all of the fuel during abort is more likely than needing to deal with pressurized fuel upon landing. Just happy this was found out prior to their being astronauts on board.

    2 votes
    1. blitz
      Link Parent
      This is a good point that I hadn't considered. I agree with you that during a launch abort they're likely to want to use all of the fuel. I wonder if the check valves were a holdover from the...

      If they replace the pre-fuel/oxidizer check valves with burst discs then the fuel/oxidizer tanks can't be unpressurized.

      This is a good point that I hadn't considered. I agree with you that during a launch abort they're likely to want to use all of the fuel. I wonder if the check valves were a holdover from the initial design of wanting to be able to use superdraco for landing, which might require such an ability.

      2 votes