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Friday, April 21, 2023

I'm Leaning Toward a Simple Explanation

I think everything that went wrong with Starship's first Flight Test can be traced to the OLM and especially the concrete underneath it disintegrating in the eight to ten seconds that the first stage built up enough thrust to lift off.  Flying debris took out engines, and damaged the Hydraulic Power Units (HPUs) that power the engines to gimbal.  A system that's going away on the next generation Raptor engines, to be replaced with some batteries they got from a Tesla.  

Earlier today, I added to the comments on yesterday's post a link to a photograph that showed up today in the NASASpaceflight.com thread devoted to the mission.  Later on, I edited the post to include the photograph and edited the comment to tell the story.  This link will take you directly to the photograph.  It shows the damage to the OLM was far worse than we saw yesterday.

It's also worth watching Scott Manley, as usual, who has some good observations and points out things to notice.  At just over 10 minutes, there's a lot of information in it.  This picture is a freeze-frame from T+07 seconds, and I've circled what appears to be a flying L-shaped chunk of concrete.  There are at least two other enormous pieces of debris flying up around the same time in the video (14 to 17 seconds from the start), both to the left and right of this one. Starship is 9 meters diameter (nearly 30feet); that makes the concrete chunk look at least 20 feet long and 5 ft vertically.

Screen capture from Scott's video, processed to enhance contrast and visibility of that chunk by me.

There have been reports of the hydraulic power units (HPUs) failing early, possibly due to chunks like this.  There are reports of damage all around the launch complex.  This video shows a NASA Spaceflight van getting pounded by debris, and smashed up badly, along with a lot of other things being damaged. Cameras, perhaps telescopes, lots of thing get knocked over.

In the early days of building up the "stage zero" launch infrastructure there was talk about building a flame trench or a water deluge system like we typically see at the major launch facilities (KSC, Vandenberg SFB, and so on).  There was a quote going around that Musk had said he had hoped it wouldn't be needed because a water deluge wasn't doable on Mars and I think the trench didn't seem likely, either.  I think the reasons are more mundane.  Starbase Boca Chica is in the middle of miles of federally-controlled wetlands.  The water table is very close to the surface, and any water collected probably would need to be purified in some way, approved by the EPA or both. 

I may be totally off base here, but it seems to me that at Boca Chica they have the boosters and ships for the next few missions queued up.  They will need testing and won't be able to get tested.  The Starship pad and facilities at the Kennedy Space Center are a lot closer to being able to support new tests than Boca Chica, and will be for months.   Another deluge system to add to the wetlands on Cape Canaveral doesn't sound anywhere near as threatening, specifically because it will be "another" water deluge or flame trench, rather than the only one within 500 miles.  They should move those next couple of Starships over here for testing, even to launch the next Starship. 



9 comments:

  1. So, this suggests many things, not the least of which is how old or not adequate was the concrete on the base pad, and why did no one consider the launch location, or was this dis-regarded? We now have more questions than answers.

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    1. The concrete used was Fondag, calcium aluminate, which is supposed to be better in this use. I recall problems with it during a static firing in the last year, but it was supposedly fixed and all better.

      Since posting this, I ran across a tweet from Musk saying,

      "3 months ago, we started building a massive water-cooled, steel plate to go under the launch mount.

      Wasn’t ready in time & we wrongly thought, based on static fire data, that Fondag would make it through 1 launch.

      Looks like we can be ready to launch again in 1 to 2 months."

      We now have more questions than answers. Pretty much always that way.

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    2. 3 months, tops. SpaceX doesn't screw around and are not hobbled by Big Gubmint-itis. They want to get moving, and methinks launch #2 is going to go a LOT better!

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  2. I don't think the OLM was designed with more than a few launches in mind. Hence, they threw the dice that things would be "good enough" for the first test flight, and they almost were. I'm sure this thing was sending a staggering amount of telemetry back in real-time, and it all gets recorded down to a gnat's behind for later use. If it hadn't lost all those engines, and the gimballing ability, it might very well have made it to Stage Separation. From there it's all speculation. I almost feel like I'm watching Robert Goddard do his pioneering experiments, but in "4K Ultra-HD!".

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  3. You know, SpaceX probably couldn't get the permissions, because of wetlands and other bullscat, to build a flame trench or diverter system once it was known to them that anything over 20 engines firing was going to totally thrash the concrete and parts of the mount.

    But they now have that huge arse hole already dug that follows the flow of the exhaust perfectly. Hmmmm... Gosh.... Intended consequences possibly?

    The whole launch was a combination of two things to me. First, what to do with S24B7? Gotta get rid of them anyways, so...

    Second, it was mostly a test of the OLM and surrounding facilities. Which proved again that just concrete wasn't going to stand up to what they were doing. And proved they needed a water deluge system. And proved their little blast-walls protecting the tank farm was woefully inadequate, well, somewhat inadequate as if the concrete held, the tank farm probably wouldn't have been damaged.

    Though the tank farm damage mostly seemed, to what I saw, to be on the external jackets and caused by huge chunks of concrete achieving orbital speed in a horizontal direction.

    Watching the videos of close-by cameras and seeing all the chunks of concrete was kind of scary. Oops.

    Still...

    SpaceX has this huge hole now... What to do... What to do...

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    1. I'm reasonably sure you got it right, Beans.
      Now let's build a flame diverter trench, already!!

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  4. I tear my hair out at the "Mars won't have a prepared surface" argument. The boosters will only ever launch from Earth. Starship will launch from Mars with only six engines (some concepts say nine) which is a completely different level of boom than 33 engines!

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    1. Right. For other readers, I can see I kind of implied that, but didn't mean to.

      It's not safe to say super heavy boosters will never get to Mars - I've heard of refueling them and sending them to Mars to be a fuel depot, but have no idea if that's serious or idle speculation. Even if there's one there, Mars' gravity is around 1/3 of Earth's, so something the power of super heavy is absolutely not needed.

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  5. I surprised that they don't use a flame trench. Tried and true. Even with water deluge and intumescent paint NASA had stuff destroyed by the F1 engines

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