Sunday, April 30, 2023

Elon Musk Restates He Expects the Next Starship Test in About 2 Months

In a private chat for subscribers only held on April 29th, Elon Musk predicted that the company would be ready to make another launch attempt in about two months with a greater chance of reaching space. 

“The outcome was roughly sort of what I expected and maybe slightly exceeded my expectations,” he said. Those expectations, he said, were that the vehicle would get clear of the pad and get “significant” data during the flight, including through maximum dynamic pressure or max-Q. “Overall, I actually feel like that was a great flight.”

Musk gives a good, detailed account of the flight and it's captured at that link to SpaceNews.com.  He says that at launch three engines out of 33 either failed to start or were shut down by the controlling systems.  Musk added, “Those engines did not explode, but the system didn’t think they were healthy enough to bring them to full thrust.” 

Still, the 30 engines running at that point are the minimum number required for liftoff.  This was the cause of the Starship stack leaning away from the Tower as it cleared the pad that many people had noted. 

At T+27 seconds, a Raptor designated engine 19 lost communications at the same time that “some kind of energetic event” broke off part of the heat shield around that engine and three others. At that point there were “visible fires” coming from the aft end of the rocket, he said.

At T+62 seconds, there was additional heat shield damage around another Raptor, engine 30, although that engine continued to operate. At T+85 seconds, “things really hit the fan,” he said, with the loss of communication with another engine. “Roughly from this point onwards, we lose thrust vector control of the rocket,” he said, meaning it could no longer steer.

Interestingly, Musk said that they don't conclusively know what caused the engines to fail, but feels that they have no specific evidence that the failures were caused by the “rock tornado” of debris from the concrete pad created by the thrust of the engines at liftoff. 

“Weirdly, we do not see evidence of the rock tornado actually damaging engines or heat shields in a material way,” he said. “It may have, but we have not yet seen evidence of that.”

One would think that sort of evidence would be most easily observed on the wreckage, but there's no specific mention of them having recovered the wreckage for failure analysis (autopsy).  The area where the wreckage fell into the Gulf should be known accurately enough to make search and recovery fairly straightforward.  Or as straightforward as recovering tens of thousands of pounds of steel and wreckage ever gets.

Another oddity was that they had difficulty terminating the flight.  This seems like it could have been related to the hydraulic systems being damaged early in the flight. 

SpaceX made no attempt to separate the Starship upper stage from the Super Heavy vehicle as it tumbled in later stages of flight. Musk said while controllers initiated the flight termination system, it took much longer than expected, about 40 seconds, for explosives to rupture the vehicle’s tanks.

Requalifying that flight termination system will be the long-lead item for the next launch, he predicted, with the next vehicle and a repaired pad likely ready in six to eight weeks. “Hopefully, we’ll be ready to fly again in a couple months.”

Musk played down damage to the pad, including the concrete debris scattered for 400 acres around the pad and the concrete dust that fell over 6 miles away.   “The debris was basically sand and rocks,” he said, “but we don’t want to do that again.”    

Changes to the pad include placing a water-jacketed “steel sandwich” below the launch mount. “You have what’s basically a massive super strong steel showerhead pointing up,” he said, with that water deluge system mitigating dust and debris.
...
He said SpaceX will also be replacing damaged tanks in the tank farm at the pad that were already set to be swapped out with vacuum-jacketed versions. The launch tower itself suffered no “meaningful” damage, he added.
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The next launch will use a Super Heavy booster called Booster 9, but he said the company had not decided which of the Starship upper stages will fly. “The engines on Booster 9, which is next, are much newer and more consistent, and with significant reliability improvements,” he said, along with improved shielding. “I think we’ll see a much more robust engine situation with Booster 9.”

Unlike before this launch, Musk said he thought there was a “better than 50% chance of reaching orbit” on the next launch.  More surprisingly (to me), he said he expected SpaceX to attempt four to five Starship launches this year.

“I would be surprised if we exit this year without getting to orbit,” he said, giving the company an “80%-plus probability” of doing so, increasing to nearly 100% within 12 months.

He said the company will spend about $2 billion this year on Starship, which he argued the company can support without raising outside funding.

“Once again, excitement is guaranteed,” Musk said of the next launch. “Success is not.”

Starship test flight, April 20th. SpaceX photo



12 comments:

  1. Good synopsis. Good engineers learn as much or more from failures than successes.

    Still waiting to find out if they turn The Hole into a flame diverter,

    And two months? No other aerospace company, let alone Legacy Aerospace, could bounce back these days so quickly from such a large oops. This really reminds me of the days of the early ICBM race. Of course, the rockets that were blowing up weren't as powerful as Starship/Booster. Of course, there was the series of rocket failures that nuked Johnston Atoll twice (admittedly, indirectly, but still waaaaay too close to a huge nuke.)

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  2. Again, I'm pleased, and I thought it was going to fail. SpaceX is awesome at learning from failure.

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  3. Beans, they'll fill in the hole, ten put the flat-plate "Flame Diverter" on top of it. It should do the job, the guy that designed it has already had other installations work just fine.

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  4. Sure would be nice if they were to put the entire US Congress (House AND Senate) on the next launch!

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    1. Why? The next launch might work. Not good enough odds.

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    2. Because - Taking Off is Required, but Landing is Optional

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    3. Ensure proper effect by not making Starship fully sealed. "Oops, seems we have no cabin pressurization, nor any O2 stats..."

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  5. 'Good analysis' my arse. Elon speaks in platitudes.
    Now please explain, 'Starship didn't destroy the pad'.

    I'm a go for launch but I don't have stars in my eyes. Given the curious way Elon speaks here (as reported in this blog), its either Elon concealing something concerning the mission or something concerning the funding.

    With the intense oversight of the FAA (which I hate with the burning of a thousand suns) I too might speak as such. And guess who else spent Billions all the while declaring no need for additional funding?
    However, what look like, what is, not same.
    Time will show.

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    1. Why don't you just come out and say whatever it is you want to say without beating around the bush, Anonymous C.? As it is, I don't understand half your points, if indeed you have any other than to be catty.

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  6. The FTS anomaly has to be fixed, and to the FAA’s satisfaction, and rightfully so. You cannot wait 40s if, say, the rocket starts heading for a nearby town.

    It is an interesting problem, because virtually every other rocket is built with minimal margins, and the explosives don’t have to do much.

    Starship OTOH is built extraordinarily strong because it is lifting millions of tons at multiple Gee, has multiple load paths to support engine out contingencies, and is designed to land and be reused and, I believe, fly sideways at speed during the recovery phase.

    A handful of quarter pound C4 charges placed here and there probably won’t cut it (heh).

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  7. The solid-fueled Minuteman tests that were out of Vandenberg had to have a linear-shaped charge installed to insure the rocket body was opened up like a zipper to kill the thrust. They might have to do the same with Starship since it's so bloody sturdy!

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    1. Step back a second. How many times in history has the problem been that the rocket was too sturdy?

      While I'm here it's looking like they've started excavating under the launch mount to install the "turbo power sprinkler" and steel plate system that has been talked about. NASA Spaceflight had it in update video yesterday.
      https://youtu.be/zfptugkdH0c
      Usual warning about it being 15 minutes long with one or two minutes at the pad. The pad itself doesn't look that bad to me. As someone said, it has looked visually that way after much less severe testing. It looks like the only problem with the OLM was that concrete.

      Disclaimers about not being a civil engineer or experienced contractor, yada yada.

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