Why Did so Many Engines Fail on Super Heavy?

if you saw the Starship orbital launch attempt of April 20th 2023 then you might have seen a lot of things didn't go right on that and if you've also seen my last video you'll note that there were a lot of engines that failed on that launch a lot of engines the super heavy booster has 33 engines on it and they lost probably eight it's hard to get the exact account especially later into the flight as the booster is getting further away it's harder to see every individual engine SpaceX had a small infographic at the bottom left which showed which engines were still running however as it got further along into the flight that seemed to become unreliable because there were distinctly more engines not running than were shown on that graphic but you might be wondering why did those engines die we've seen them work pretty well on the smaller Starship suborbital test flights so what did they like about this Mission specifically and there's a couple of reasons I was able to come up with for why this might happen so let's start it off with reason number one which is just in that first second or so of launch the super heavy booster is very very close to the ground and the concrete base of the orbital launch pad now while concrete is obviously very strong the world's most powerful rocket was a little too much for it and SpaceX you see they decided to not use a flame diverter or a water sound suppression system at the launch pad all they had were some little sprayers on the pad itself which could shoot Jets of nitrogen and water to do their best to at least stop detonations like what happens to booster 7 a couple months ago but it just didn't do the trick in this case and when they lit the engines it just started boring down into the ground beneath the launch pad and there's some spectacular pictures showing a 10 or 20 foot deep hole drilled by those engines and when it was doing all that digging not all of the concrete was being reduced to dust in some launch footage you can actually see debris being launched all the way out to the ocean and I'm sure some of that debris probably got kicked back up into the engine compartment of the booster a similar thing happened way back in 2020 there was a static fire test of Starship sn8 which kicked up a lot of concrete debris and a piece of that debris got kicks into a Pneumatic line which uh controlled the pressurization systems of the ship and without those lines it wasn't able to regulate pressure and the header tank started over pressurizing and it nearly blew up sn8 except for a burst disc which saved it now that same sort of issue could happen with booster 7 but in that tightly packed Center it could just be that debris got kicked into an engine and severely damaged something because we saw as soon as the SpaceX infographic popped up it showed that three engines weren't operating so those engines could very well have been knocked out by concrete debris our next possibility is that say those engines those first few engines were downed by uh debris then it could be that if they violently failed well each Raptor has a flash Shield surrounding it which ideally keeps any debris from an exploding engine contained if one of those shields were to fail debris could have gotten kicked out and damaged another engine alongside it and you can see that a lot of the damaged engines had another engine fail right next to them so it's entirely possible that those engines failed because of a chain reaction from that first one going out our next possibility is overheating now my reason for thinking this is if we look back at the Saturn V rocket all five engines had insulation around them now if you see a Saturn V's F1 engine in a museum it won't have that insulation it would have bare metal but for the flights they realized that the engines need to be insulated because with them so tightly packed together just the heat that the metal of the engine would be radiating outwards that could start to build up and actually begin damaging engines as the temperature approaches the melting points of various parts in the engine now while I'm super heavy none of the individual engines are more powerful than the f1s on the Saturn V they're so tightly packed together that it could be that the inner engines started to overheat and failed in some way due to that it could crack metal it could make pieces expand to be too large to properly move or it could just downright melt apart or two but a Counterpoint to this is that the middle ring of 10 engines and the booster seem to perform very well compared to the outermost engines which we would expect to be the least likely to fail from overheating as the inner engines would begin more heat because of those outboard ones surrounding them so that one it's possible but unlikely now another problem that these engines could run into is something that we saw on Starship sn11's flight one of the three Raptor engines it developed a leak in a methane line and that produced a small fire which start burning through the engine's Avionics while somehow that engine kept firing for the duration it needed to during the ascent when it attempted to re-light the engine for landing that Raptor just exploded and destroyed sn11 completely so if any of the engines on booster 7 developed a leak like that that could pretty easily destroy the engine and now for our last potential failure point we're once again going to look back to the Saturn V the Saturn V rocket and the Apollo 6 Mission encountered something that's called Pogo oscillation basically the vehicle can start to develop a vibration which can shake across the whole vehicle and as the vehicle starts to shake like that it causes the fuel in the fuel lines to slosh around and it makes the engines start to almost pulse producing more thrust then less thrust and that keeps shaking the rocket more and more and in some extreme cases that can completely destroy engines in the case of Apollo 6 all five of the first stage F1 engines kept working but the shaking from that oscillation damaged uh engines on the second stage and then the third stage the Saturn 4be actually failed to re-light after they'd achieved orbit to send the Apollo capsule out to the Moon now this sort of thing is primarily an issue with how the engines handle these oscillations and then also it's an issue of properly simulating the structure of the Racket and seeing if there's a harmonic resonance point which if that's something the engines can produce that can start Poco oscillation but it can be weird sometimes just different conditions on launch day or just one engine doing something weird can completely change the vibrations produced by the engines firing because the first flight of the Saturn V didn't see that problem but Apollo 6 did so maybe just in this specific case those oscillations started and started damaging engines we could see Raptors dropping out through the whole flight they didn't seem to stop failing and that would tend to indicate that through the whole flight there was just something going on that SpaceX wasn't expecting because a lot of these Raptor engines actually probably all of them have gone through thorough testing at spacex's engine testing facility in McGregor Texas where they're they're testing engines a couple times a day and running them through their full flight duration testing to make sure that nothing like this would happen so it seems like something was going on during the orbital flight that they just didn't expect to see or couldn't simulate using ground testing now once again like in my first video I could be entirely wrong on all of these these are just possibilities for what could have happened and as SpaceX goes through the data I'm sure they will be able to figure out what happened and do their best to prevent it from happening in the future and I'm excited to see what they find out how they fix it and what happens when they fly again

Channel: LZ-1

Views: 133,182

Keywords: SpaceX, Starship, Super Heavy, Elon Musk, Explosion, space, rocketry, science, orbit, OFT, IFT, Orbital Flight Test, Integrated Flight Test, physics, technology, spaceship, NASA, raptor, engine, failure

Id: LxhqFVfgbMo

Length: 11min 22sec (682 seconds)

Published: Fri Apr 21 2023