Great engineering breakdown of why SpaceX’s new rocket engineer, Raptor 3, is likely more of an explosive dud than the engine it is replacing. And why SpaceX is trapped in an engineering Catch-22 that probably makes the entire Starship project a flop that simply cannot succeed:

https://www.planetearthandbeyond.co/p/spacex-has-finally-figured-out-why-63b

At the time of writing, SpaceX has already spent approximately $10 billion on Starship and hasn’t even managed to reach proper orbit, let alone deliver any payload to space. For comparison, NASA’s Saturn V rocket, which was designed and built using more expensive and less accurate old-school analogue technology, cost roughly $6.4 billion to develop, and the launch costs were approximately $1.4 billion in today’s dollars. In other words, for the same amount of cash that Musk has splashed on creating a rocket that doesn’t work, NASA was able to send astronauts to lunar orbit using technology from the 1960s. And, even more embarrassingly for Musk, this sorry saga is only going to get worse.

… how did test flight 7 fail? Well, excessive harmonic vibrations ruptured the fuel lines, creating a gigantic fire that destroyed the entire upper stage mid-flight. This occurred despite the reduced stress placed on the engines and structure itself. Even worse, test flights 7 and 8 were launched using an improved version of Starship, featuring redesigned and strengthened fuel lines to prevent these failures from occurring.

So, why did this solution not work? Well, Starship has a huge thrust problem. Musk and his engineers overestimated the amount of thrust their Raptor engine could produce while designing the Starship. Even Musk himself has publicly stated that Starship can only take less than 50% of its promised payload to orbit, which is likely an overestimate. This means they are forced to cut down on as much of the craft’s weight as possible and push the engines to the limit during launches. Unfortunately, this makes the rocket more fragile and means the engines generate excessive heat and vibrations — which is a perfect recipe for guaranteed failure.

At the time, the cause of this failure was apparent to me and many others. It’s obvious SpaceX can’t make Starship robust enough to survive the thrust required for a fraction of its payload without dramatically increasing its weight and, therefore, reducing its payload to nothing.

On the eve of Starship’s 9th test flight, SpaceX finally revealed what happened during flight 8. A “flash” event occurred in one of the rocket’s engines, causing it to fail (or, more accurately, explode) and take out the other engines in the process. This led to the rocket tumbling uncontrollably and disintegrating in the atmosphere.

A flash is when a rocket’s propellant ignites when it shouldn’t, creating a sudden explosion. This can be caused by many things: a fuel leak igniting; an incomplete fuel and oxidiser mix that removed the engine; rapid pressure changes that disrupt the correct flow of fuel and propellant; or even overheating, causing combustion in the wrong places. However, SpaceX has stated that “the most probable root cause for the loss of Starship was identified as a hardware failure in one of the upper stage’s center Raptor engines.” This heavily suggests a fuel leak or an overheating problem, which can be caused by building these engines too light and fragile or pushing them too hard — which all but confirms my and many others’ speculations.

Flight 8 is damning evidence that these engines are being exerted beyond their natural limits and are still incapable of producing enough thrust, as well as that Starship is simultaneously far too heavy and far too fragile to actually function. This is a fatal catch-22 that is baked into the core design of Starship.

So, how does SpaceX address this issue? Well, with an updated engine: the Raptor 3. This engine is simpler, 7% lighter and has 21% more thrust than the current Raptor 2. Surely, that should solve all these problems, right?

Well, no. First of all, Musk has lied about Raptor’s thrust before, meaning that his claim of “21% more thrust” is seriously dubious. But also, the engine being 7% lighter and having a 21% increase in thrust isn’t nearly enough to increase Starship’s payload to usable levels.

What is more concerning is the method SpaceX used to made this engine so light and powerful. By modifying how the fuel flows, they have improved the engine’s internal cooling needs and supposedly eliminated the requirement for external heat shields and a fire suppression system. As a result, they have elected to remove these components, which has made it possible to save this amount of weight. Furthermore, the improved cooling will supposedly enable them to push the engine harder, creating the aforementioned 21% increase in thrust.

In other words, the current engines are being pushed too hard, causing them to fail from fuel leak fires and excessive heat, which has happened so consistently that no Starship has even survived a trip to space with a fraction of its proposed payload onboard. Yet somehow, the natural solution is to ditch the engine’s heat shields and fire suppression systems? That decision alone would be silly, but to then also push these engines 21% harder makes this entire proposal utterly moronic.

More thrust will create more vibrations and stress, causing fuel leaks (especially if the lines aren’t further enforced), incorrect fuel mixing, and unstable internal pressure. All of these factors can then create flashes, which overheat the engines and quickly develop into huge explosive fires, which will be even more catastrophic than before, as these engines have no heat shields or fire suppression systems.