SpaceX Starship SN11 Fails After Landing Engine Start

SpaceX Starship SN11 had a test flight and had an engine problem.

Written by Brian Wang,

67 thoughts on “SpaceX Starship SN11 Fails After Landing Engine Start”

  1. Good point. That could explain the fuel feed problems they have experienced.

    Isn't the flip eventually supposed to be done by other motors mounted higher up? That could solve the problem.

  2. What are you even talking about?
    Musk is now the richest man on the planet, who has proven wrong most of his naysayers and gobbled up the lion's share of the global launch industry in like 8 years.
    Forgive us for having a little faith in the guy's abilities and taking a grain of salt in what some guy from the internet said.

  3. Ironically, NASA actually did build a methane rocket engine, but never followed up on the tests, probably because they'd used a mixture of oxygen and fluorine as the oxidizer, and the use of fluorine scared them off.

  4. Remember, Musk's philosophy is, "The best part is no part, the best system is no system."

    He will not add subsystems unless it is absolutely proven they're unavoidable, because subsystems that aren't present have no weight, cost, or chance of malfunctioning.

    At this point, it looks to me like they have a leak problem, not a pressurization problem.

  5. Thanks, I didn't run across that.

    Though given problems they seem to be having with their turbopumps, maybe they could consider an electric pump stage to keep lower-pressure "buffer" tanks filled to feed into the turbopumps.

  6. Well, consider how many F-1 engines were chewed through, this isn't unprecedented. Though the lack of a triple engine stand at McGregor to test the engines together as a set seems to be a bit of problem in my opinion. This will only get worse when they start BN2 testing with that monster engine set.

  7. Can you cite a source? Not questioning your accuracy, I just always wonder where people find technical specifics like this about SpaceX stuff. Or is it more that you accumulate tidbits a tweet here, video there, etc?

  8. for the last 40years all the focus on rocket fuels has focused on RP1, Hydrogen, hypergolic (self igniting) propellants. So no one built or test Methane rocket engines. Only in the last 15 years have researchers looked into it. and now blue origin and Space X are going to it. Methane has advantages over RP1 and performed fairly well when compared to hydrogen.

  9. Yep. Thankfully he who pays the piper calls the tune. This program will remain testing and ongoing as long as Musk wishes it to.

    By comparison: any public program with so many test failures would be dead on the water. That's why they avoid launching as much as possible .

  10. Yeah, at the speeds they're running the precession forces must be fierce – and if their bearings spall because of it… hmm. That might explain why they're having a bit of trouble during the relight. There'd be a lot of resistance to changing the plane of rotation of the pumps and if for whatever reason they can't get up to speed (bearing bind, impellers brushing against housings…) then there wouldn't be sufficient flow…

  11. Holy camoly! 100 000 HP! Are you sure?

    And, of course, if it's really 100 000 HP per engine then you are right that this would absolutely be to much power and weight. That would be at least 10 tons of batteries per engine (and that is assuming 10 kW per kilo of batteries, which by itself is quite a lot).

    I guess that settles it then…

  12. You can buy stock in Tesla, but not in SpaceX. It is privately held. Dollars to donuts that Elon has read Heinlein's "The Man Who Sold the Moon."

  13. Not that it matters to SpaceX but I would have loved to have seen the launch. Next time I hope they don't launch into a fog.

  14. Methane is problematic. As I understand it, it is OK in liquid form, but as a gas it is pretty flammable and explosive. Of course makes sense if you can make it on Mars, but they are having many problems with it. Perhaps because Methane engines are extremely rare and were not studied as much as standard kerosene or hydrogen ones. As they say, not best at anything, but you can make it on Mars.
    Seems pretty complex design.

    If they say engines are not the cause, why are they changing them so often?
    I hope they will manage to get 3 intact engines for detailed review.

    If anyone can do it, I am positive Musk won't give up and they'll do it.

  15. Each Raptor engine has 100,000 HP worth of turbopumps.

    This is a 44,000 HP electric motor, so imagine each Raptor having two of these mounted to it:

  16. Well, if it's "25-year old", then it happened a quarter century ago, and this IS "NextBigFuture", after all.

    OK, seriously, this is a technology and science site, not politics.

  17. If there isn't enough pressure in the header tank to sustain the needed flow rate into the turbo pump, you'll just get cavitation. Doesn't really matter what is powering the pump, it can't pull in fuel, the fuel has to be pushed in by tank pressure.

    And I think you're underestimating how heavy your electrical turbo pump would be; The turbopumps on a Raptor are 100,000 HP. Got any idea how heavy and electric motor and battery set capable of that would be? Bye bye payload!

  18. You got to be joking. If they take the NASA approach, then they will be stuck in power-point presentations for decades.

  19. I wonder if there is a point to making an electrically powered turbo pump of the raptor engine? Sure, the weight would increase, but by how much? And how much of the problems starting the engine is based on the fact that you need a combustion in a small chamber to power the turbo pump, which to me seems a bit like trying to lift yourself by your boot-straps.

    Previously, they have had problems with insufficient "header pressure" and I wonder if the pressure requirement of the fuel/oxygen tanks is reduced when using an electrical turbo pump? I.e. even if the pressure would be really low, you could still "suck" out the methane and oxygen with the electrical turbo pump?

  20. I think you're safe. Chances of getting blown to bits are high, but chances of winning the lottery, and of rocket flight being affordable even then, are much lower. Try a ride in a sailplane instead – slow doesn't have to mean boring.

  21. Yeah – I don't recall Shuttle or Saturn V catching fire like this.
    Delta IV Heavy, on the other hand…

  22. Why should they care about demoralizing the public? Is the public paying for this development effort? They launched during fog, not worrying about whether the public could see this flight or not — tough luck for the public, who are just gawkers anyway.

  23. The price of taking on something complex, never tried before and experimenting on close to real life model without fully understanding it.
    They need to take a step back and try the more of the Nasa approach, computer modeling, more partial physical models. No one design method is perfect.

  24. Electric pumps? A la RocketLab?
    Possibly generating electricity in the rocket exhaust (magneto-hydrodynamics) after start-up, to avoid lots of battery mass?

  25. Be patient people, it takes time to work all the problems out. If at first you don't succeed try try again! I could suggest some more plumbers tape on those leaky engines.

  26. I am just wondering why Brian is writing not a thing about the 25-year old pact between Iran and China which is a huge defeat for the USA?

  27. Musk is a stubborn dude, they saw one kinda successful landing and they are certainty fixing to see another.

  28. Rockets go boom all the time. We know it can work and if you were thinking that this would all be solved by SN11 your sorely mistaken.

  29. Yes, I hope they're building these engines with little margin so they can figure out all the failure points more quickly now than you would later along the line, at far greater cost. Seems like something you'd expect from them at this point.

  30. If there's a problem with fuel leaks, perhaps the overhaul for the next 'block' of prototypes( SN 15-19) will address the root cause.

    If they have two or three flights of the next block with the same issue, I'll start worrying then.

  31. It's becoming clear what the Great Filter is: turbopump rocket engines. They will probably never work the way we hope. And there are no alternatives.

  32. Try several miles. But that's why their site is next to the ocean, and in the middle of a wildlife refuge, with a tiny beach community as its only neighbor; Not a lot of people to evacuate. As they go up higher, they can go out over the ocean. I gather there's actually some science to determining how big the area has to be for a given altitude, it's not just a WAG.

    Yes, I think there's some flaw in the engine. I'm not sure how major, but basically every flight with a Raptor, you've been able to see one or more of the engines leaking flames off and on. And NOT in what looks like an exhaust port!

    And then there's the fact that they're installing tested engines, and still having to replace them on a frequent basis after test firing. That's not good. Either the testing is hit or miss, or is actually occasionally damaging an engine on shutdown.

    At the engine failure rate they're exhibiting right how, I don't see how they test the booster, as it requires enough engines that they'd be forever getting a complete set of working ones, and would likely have to fly with several failed engines even if they all had passed the last test fire.

    They need to resolve this engine problem, or Starship is never flying.

  33. yes, I know that there are not people standing exactly below and even few 100's of meters next to the launch place, but in case when rocket would have failure say 5km above the ground with still a lot of fuel aboard and due to malfunction change its path, moving few km west or east, where civilization exists, it could do a lot of damage. They would probably blow it up in the air in such case but still debris would fall and fly in all directions. But what in case if remote detonation would not work? In good visibility( like in all previous launch attemps before) all those fans and locals watching from their balconies could probably see it or see the boom above their heads and have time to hide.

    Back to the main issue
    You think there is major flaw in the design of rocket/engine and it need to be redesigned?

  34. The concern on the Moon is that the exhaust velocity is higher than lunar escape velocity. So, in theory, you could be throwing debris into orbit. At the very least, a long distance, and a threat to anything you nearby on the surface. Not an issue on Mars.

    I agree the need to swap out engines after test firings doesn't look like a good sign at all. They should, after all, be installing known good engines. It suggests that the qualification tests are actually, themselves, damaging some fraction of the engines that pass, or that the installation process is hit or miss.

    I *think* what may be going on is that the engines are built with very little margin, intentionally, and each engine failure is viewed as a learning experience. 

    But if the engine learning experiences interfere with the rocket learning experiences, you've got a problem.

    Look at this: Looks like a leaky connection. I think they're having trouble sealing the plumbing, given the extreme conditions.

  35. I certainly would not turn down any launch, but would work extra extra to be able to stay long enuf to do things productive. I suppose I just would rather see someone else do the tourist "overview effect" enlightenment. I think/hope/imagine I already think that way. And I would NOT want to come back so soon! One more point, they say it takes several days to get comfortable with 0 g, so that would be a bummer to feel really bad the whole short time.

  36. I hope they've got really durable black boxes on those rockets, and more cameras running than they showed us the feed from. 

    Ideally they'd be running enough cameras at high resolution and frame rate, to reconstruct everything going on inside the engine bay.

  37. Gotta break it to you, but even with perfect visibility, your odds of dodging anything like that would be poor.

    Which is why nobody is permitted to be in a range where they might have to dodge anything.

    Some remote controlled cameras got hit, no human was anywhere near enough to be at risk.

  38. I had a young childhood at my grandfather's small airport, saw Sputnik 3rd stage thru Apollo, loved astronomy, studied Physics, even dreamt of having a telescope in Space, in a glass sphere. Then, when I was mid 20s, saw Timothy Leary SMI2LE show, read O'Neill, totally changed my outlook about Space. Had no clue before O'Neill.

  39. You'll have to wait a decade or two, it seems. If current plans stay on course, I'd enjoy the launch and a couple of weeks in microgravity, or a trip to the moon for a week (plus a week in transits) and that's not so far away.
    Edit: I'd also have to hit the lottery. And I don't play.

  40. It should be able to take off without a flame diverter, the whole Mars scenario seems off the cards otherwise.

    The Raptors don't seem reliable. What surprises me the most is needing to swap them out after testing at McGregor.

  41. I got my first pair of glasses when I was in elementary school, went out that night, and actually saw stars for the very first time in my life. I've been space mad ever since.

  42. Seeing those constant problems with engines it's hard to believe in all those plans like Earth people transport system or even cargo system competing with planes, with those frequency of failures.

    Hard to believe, that in near future reliability will be as good as in plane engines.
    Tens of thousands of man hours devoted to figuring out this one engine and the same problems appear launch after launch, what are they doing all that time between launches?

    Also, why they launched in complete fog, literally 0 visibility. It is extremely dangerous for all those people below, huge rocket with tons of fuel(basically a bomb) falling at you and if you're for example cameraman, photographer or someone living nearby, you can not see the path of falling and have any chance and time to ran away

  43. I'm just not into fast cars or stuff, don't like the Physics! So the rocket ride is not at all attractive to me, personally. I know others differ on this. I want to be in Space.

  44. I start seeing a risk of demoralizing the public and their own engineers with continuing on this route.

    They're really paying a high price for starting with the hardest part first.

    Had they focused on, you know, launching something to space first like they did with F9, they would have probably already succeeded a couple of times. Even if the return part equally ended up in a RUD for both Starship and Superheavy.

    Engineers as the public do get wary of failure and start making a worse job.

    Beatings from management continuing until morale improves only can do so much.

  45. I'd probably be one of those daredevils if I hit the lottery. If I explode, I explode. At least my headstone can read, "Hey, y'all, watch this!"

  46. The video froze (but not the audio feed) and there was a loud BOOM shortly thereafter. So yes, "something significant".

  47. I'm the guy who kept praying to win the lottery, until God(s) finally told me I would at least have to buy a ticket!

  48. Well, yes, they've had other fires, too. But basically every launch has seemed to include at least one engine catching fire.

  49. Well, a flame diverter wouldn't be all that hard for them to add. A few thousand dollars of welded up steel plate, and they'd be good to go.

    I know they're concerned enough about flying debris that the Moon landing version has a second set of thrusters at the top for landing and takeoff, to allow the exhaust to diffuse before it hits dirt.

    But here they're launching off of concrete, and I assume at least a steel plate on top immediately under the launch pad. Or else they'd get explosive spalling, and that would be bad.

  50. My personal rule is that I'm only going to launch if I hit the lottery. But if I do, I'm going up, and I don't care much about the conditions.

  51. I remember different fires, some not even on engine??? If the same exact fire keeps happening, should have been easy to fix.

  52. Not my idea, Musk talked about it, but perhaps not for these launch stands(?). My *good* idea is that one engine acts as you say, but two or more next to each other will throw stuff directly *up* between the exhausts, rather than the expected down and out. Where else could something directly between the plumes go? Unless it is on a slope of a diverter, that is.

  53. You can actually see the side of the engine on fire, in video on multiple test flights. See Brian's still photo at the top of the post, for instance.

  54. Hadn't thought about that.

    The rockets launch from an elevated structure, though, so that shouldn't directly be an issue. I suppose you could get some kind of resonant feedback into the engine, though, firing in close proximity to a blunt obstacle. Not directly through the exhaust, (It's moving away from the engine at well over the speed of sound, no disturbance could propagate backwards through it.) but back up along side it.

    It's an interesting idea.

  55. Do we know if it is the engines catching fire and not the stuff in the bay? That happens with F9's alot on landing.

  56. My personal *rule* is I'm only going to launch one time and have a place to stay, for a while at least, before coming back down. Too expensive in many ways otherwise.

  57. Perhaps all of this is lack of flame diverter, and engines are damaged during static fire, OR worse, liftoff?

  58. Only real daredevils will be riding on the starship for some years yet, by the time they're launching manned flights on them, these tests will be long forgotten.

    I assume that tourist trip around the Moon will involve launching the vehicle unmanned, and sending the people on a Falcon launch after it has been fueled.

  59. I've been suspecting all along that the turbopumps probably do not 'like' high rate gimballing while running. But the engine swaps after the test fires are presumably before they've been exposed to such, and must be QC related.

    You would think every engine would get a static test fire before being shipped, though.

  60. I have this fear that, the longer it takes for Starship to have a perfect run during development, the longer it'll take for the public to be willing to board them, even after they're ready and have been launching and landing smoothly. Though, I know launching humans in one is quite a ways off.

  61. Those Raptor methane engines look a lot more complex than the very reliable Merlin engines used on the Falcon 9.
    Maybe SpaceX needs to build somethin akin to an amusement park ride at their Texas facility that will subject the Raptor engines to the forces experienced during the flip–> belly flop maneuver.

  62. I find it troubling that, after all this time, they're still routinely having engines catch fire during the ascent. I've never seen them even discuss that, but it stands out like a sore thumb. And the high rate of swap-outs after the test firing suggests that they've got a serious QC issue with the engines.

    Now, granted, I suppose it's parallel development, and they're working out engine issues at the same time as rocket issues. But "Don't catch fire while running" seems to me to be a fairly early engine development goal which they should already have nailed.

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