Color-coding the engine config according to startup/shutdown sequences REALLY shows the impact of that single engine on the entire booster. 3 other engines failed to fully light before the energetic event.

Shielding wouldn’t help here (unlike what others are saying). Much better to solve the cause of the issue. Engines shouldn’t be exploding. Boosters shouldn’t have flow issues whether it’s the rate of propellant flow or a hammer effect etc. It’s good that this failure happened early into V3 testing so they can solve for it. Upper stage raptor failing is much more interesting to me. Was it blow back from hot staging? Something else?

I do agree and have said in other replies that I do not believe shielding would have contained this. It would have probably prevented the entire booster from getting immediately crippled but yes it wouldn't have prevented the entire incident

@Lunnzies Realistically this is an easy fix. They had the same volatility with Raptor version 1/2. Once they get the flight cadence up, engine reliability will follow quickly.

@mcrs987 Raptor 3 is a little more complicated than 1/2 which isn’t great

@JoeTegtmeyer The fix which I’m sure you will agree is quite simple. Make them more reliable so this doesn’t happen. Honestly my guess is it has something to do with the downcomer and engine start up. They will work it out. It might just all be software related.

I agree. It's more of a figuring out how to make it more reliable which isn't a simple task This is the first time they've flown a cluster of these new engines together so I was expecting issues anyway but it's really just this one single engine that appears to have not had a good day out of chance, it doesn't seem to be correlated with anything wrong on the vehicle

@JoeTegtmeyer Time to do more Masseys testing 😅 although not sure if that would help in this situation. I’m sure they received the data they need or at least enough to diagnose what happened.

@JoeTegtmeyer Yes. Would be surprised if the next one goes awry. They typically just need that data from the first one to really get it going and from then on that issue doesn't crop up again especially if it's something stupid like here with just probability

@OverlyTrev @JoeTegtmeyer Has Spacex confirmed that a Raptor exploded? Do they release such information as they go through their investigation? I know they are pretty open about failures and fixes, but I’m curious if it’s also their opinion that it’s the engine and not something else.

They typically release that information months later in detail when the next flight is up-coming. It's never specific but it does say what happened from a basic perspective . Currently their wording on the website is "It was unable to light all planned engines and performed a partial boostback burn that ended early." That said, you don't really need spacex explicitly saying it to see that an engine had a rather spicy failure here

So could it be -> violent flip -> more slosh -> starved engine -> RUD -> nearby engines affected?

So they can add more shielding or make Raptor 3 more reliable. Ig theyll do the second option

@Starship_block3 I don't believe shielding is the move here. It would have helped for sure but would not contain it

@Starship_block3 Booster 9 also died due to a raptor failure despite extra shielding right? Unless I’m mischaracterizing it

@Starship_block3 that's just what happens when you throw debris at a rotating assembly moving at 36,000rpm and not really the fault of the engine

Very cool but I think the other engines would have died soon after because the ullage had to be crazy during this flip it looked way more energetic then the ones before

That doesn't cause an entire bank of engines to fail in fractions of a second

Dang, love this visualization. So close despite the unexpected flip dir. Awesome for a first flight of so much new hardware

It's not only one raptor mulfunction, looks like 2 engines were extra lit during shut down sequence comared to flight 11.

Yup, that was intentional

oo, I didnt know, assuming that always 3 engines stay lit after shutdown.

Yeah changed to 5 now on V3 Boostback sequence goes 33->5 MECO, 5->33->13 boostback, 13->3->0 boostback shutdown. Same with landing burn, 0->13->5->3->0

I wonder why they tried at all to ignite the outer ring of Raptors. AFAIR this was never necessary with V2 boosters, the 13 inner engines provide plenty of thrust. In fact I thought you can not ignite the outer engines during flight, the hardware for that is in the launch pad.

That hardware on the pad-side no longer exists and the booster is capable of starting all engines in flight if it wishes to

@Intotron So they are capable to relight all the engines

@Intotron Yes

@Mookafish It could just be a fuel rich plume but it looks like there was a fire near the engine that blew?

Am I correct in saying the rotation of the ring of 13 raptors in your diagram is a tad clockwise compared to the real thing?

My diagram is accurate to the real thing. The SpaceX stream graphic has the middle bank rotated wrong by 18 degrees counterclockwise, they forgot to change it from V1 but kept the E# mapping

@ConanToole The center three are a bit off. They should be 120 degrees apart, and E2 should be in line with E4 and E9.

@ConanToole No. This changed on V3. Centers are 108-144-108 degrees apart and the entire middle ring has been rotated 18 degrees

@ConanToole So the diagram on the right is wrong, again?

@ConanToole The center engines being not precisely oriented I can live with. They at least rotated them 180 so the centerline engine would be on the bottom not the top and that's fine. But yes, technically speaking

My bet is on fuel over-supply during the highest energy moment during the flip. Might be due to some new calculations to do with R3 and the new tanks.

I would be surprised if they were not able to successfully account for any 'new calculations' regarding the engine interacting with the vehicle

I would be surprised if they were able, each additional change compounds complexity in a cascading calculation. Reduced aft + new methane downcomer + longer main tanks + much higher energy (33 engine re-light + R3 vacuum) + off centre lox tank + new staging ring + grid fins.

Removing the shielding was a mistake?

I don't think this is the type of failure that the shielding would have been able to contain. It would have certainly helped... this feels like some extremely improbable anomaly that ended up occurring by sheer bad luck. It's only the one engine and I don't see any clear pattern or correlation to any of the external conditions of the booster such as its attitude. Genuinely just Did That and it sucks

@Vantadaga Do you see any debris?

@Vantadaga There are definitely a couple moments of debris being ejected a few frames after the energetic event

Can sorta be interpreted from the video but just the plain grey is off, the orange is engine failure (up to the energetic event), the red is engines that shut down / fail immediately after the energetic event, pink is fuel preburner ignition, light blue is oxygen preburner ignition, and white is a healthy(ish), running engine.

@AleSh09758566 @amechi_nwandu Impressive work, thanks. I had to run it at 25% of 25% to have any hope of following along! How do you spot the preburner ignitions? Also, is there an "energetic event" early on at 8secs right before your indicated E4/E8 fuel preburner ignition?

The preburner ignitions are on a known timing, but you can also see it in the jets of gas before the engines light as two distinct stages. There's also spinup before that but it's not a visible effect while in vacuum. I have previously timed these for convenience as well: I don't see any events before or at E4 ignition consistent with anything anomalous. Are you referring to the flame on the booster tank caused by the ship engine exhaust?

did it flip the way they wanted at stage sep? it looked odd

They flipped the wrong way. It is supposed to flip up and away (in the direction of the heatshield-side of the ship. IE, the side of the booster without a gridfin should be facing the ship's engines as it flips) and it went completely sideways

I thought as much. It defiantly seemed to have been an odd "choice" while watching. I wonder if that could also explain the angry engine.

I'm not certain as to why it flipped that direction yet. The direction is mainly influenced by the ship's engines the integrity of whom is also in question. Number of things could've done it

The Rvac that was shut down later on ship is the one that would have had influence in that push up. So if it was under performing then the symmetrical nature of the thrust from the other 4 engines would have made it a game of chance to the lateral direction it flipped. one idea..

The thing is if it was *just* that engine causing the flip to go awry it would have flipped in the OTHER direction, towards Z+, not mostly off to the side

Definatly more than one thing, flipped in the wrong direction and off to the side which could have been from any variation of the thrust or TVC position in the other engines would upset it into an odd flip but it will be interesting to hear exactly what happened if SpaceX share.

Perhaps they need to slow the flip so the engines are not exposed the Ship’s exhaust for another couple of seconds?

did the adjacent engines shutdown or blow up after that one engine popped how did the booster didn’t just explode lol. it just continued on until the gridfin could have control

@Erdayastronaut Lots of speculation and assumption here. I don't see any debris. I'm gonna wait to see what SpaceX says.

I'm just scrolling through my notifications watching you repeatedly reply "where are the debris" under a dozen posts like a parrot when there's very clearly debris

It doesn't seem like it's enough debris for an engine exploding violently enough to destroy a bunch of others. The groups of engines starting and stopping looks like the fight computer trying to find engines that will stay lit. SpaceX has the data to show if the groups of engines were under computer control not.

The camera cannot resolve every single tiny fragment Also, that's not how the guidance logic works

Flight control computer probably was the wrong term, whatever computer controls the engines starting and stopping.

I made some fenders for a go-kart I'm building yesterday and then read about engineering like this here. Now I feel like Fred Flintstone. 🤦‍♂️

@JoeTegtmeyer I love the term energetic event in this context

@JoeTegtmeyer Not sure what else to call it lol

@caviterginsoy @JoeTegtmeyer It aspires to be a RUD when it grows up. ;o)

@mcrs987 @JoeTegtmeyer Hopefully grows up to do better

I'm not ruling out the possibility of that being the case, but I still suspect that issues with the flip maneuver itself were already setting up the engines on that side to shut down anyway. Maybe that one engine RUDing just shook things enough to shut them down faster

Contrary to many I don't think adding shielding back is the right move here, its just a reliability issue they'll solve by testing the engine and the vehicle more

@NASASpaceflight I’ll wait for the geniuses at @SpaceX to figure out the issue(s) and come up with a solution for the next test launch. 🚀

Initially thought this was due to an energetic flip but clearly most engines managed to relight for BB. Left a few unlit prob due to high engine out margins. Imo with shielding most of the gimballing engines necessary for landing would've died anyways. Really energetic.

someone pressed the wrong action groups button. toggled all the engines back on

This is from the video stream. Ship ignition sequence. 1 lazy RVAC ignited late, pushing the top of the booster to the left instead of up. Note that the central engine (that should have nudged it up) is already on.

The orientation would be flipped. The graphic is illustrated as if viewing from below

Wtf they can ignite external ring now?

Yup. Perks of redesigning the spinup sequence such that it doesn't require nearly as much gaseous propellant , all supporting hardware can be placed on the booster instead of having to rely on ground connections to start up the outer engines

Do you think this was a Raptor-specific issue, or something in the booster’s plumbing caused by the extreme forces from 32 engines firing on a mostly empty booster during the flip?

@Mookafish Do you think the ship rocket exhaust hitting the booster engines could have helped mess things up and caused them to shut down?

"it’s like having a box of grenades, really big grenades.”

I wonder if it wasn’t a fuel supply issue

@JoeTegtmeyer I doubt it, more likely the aborted boost back burn was slosh enduced because the flip was way more aggressive than V2 probably because the 6 ship engines have more power now. The single engine out wasn’t a violent let go.

I think you're missing the forest for the trees. To me it looks like the flip was the problem. Those other engines were going to go out regardless. Anyway, SpaceX will tell us at some point.

Engineering stupidity to the core! If they hadn’t just removed the shielding for the engines, this might not have happened!

@Blobifie Good job man! Great work.