SpaceX has identified the source of the problem that caused the loss of the Starship SN11 prototype.
We didn’t see it, but we heard it: the flight of the SN11 prototype which took place at the end of March ended badly. Still, SpaceX’s attempt was off to a good start, despite really bad weather conditions, with fog on the launch pad. The Starship rocket passed all of the first stages of flight without apparent difficulty. It was at the end that there was a problem.
While righting the launcher to prepare for a vertical landing, a Raptor engine malfunction occurred. ” It appears that Engine 2 had some issues during the ascent and did not reach the operating pressure level of the chamber during combustion on landing, but in theory this was not necessary », Explained Elon Musk.
It should in fact be understood that after takeoff and the ascent phase, the rocket, once at the desired altitude, tilts on its side and descends to Earth more or less horizontally. Even if it is on the side, the machine can control its return thanks to the four fins along the cabin and adjust its aerodynamic profile. Obviously, he cannot keep this position indefinitely: at some point, you have to switch back.
A motorization problem
Although the founder of SpaceX indicated at the end of March that one of the three Raptor engines encountered difficulties from the outset, the circumstances of the failure were not yet identified. Things are now clearer today. On April 5, Elon Musk took to Twitter again to provide clarification. We now know that the problem stems from a methane leak.
Ascent phase, transition to horizontal & control during free fall were good.
A (relatively) small CH4 leak led to fire on engine 2 & fried part of avionics, causing hard start attempting landing burn in CH4 turbopump.
This is getting fixed 6 ways to Sunday.
— Elon Musk (@elonmusk) April 5, 2021
« A (relatively) small methane leak led to a fire on engine 2 and fry some of the avionics », Wrote the American entrepreneur to an Internet user who asked him for news of the investigations on SN11. The methane is used by SpaceX for rocket propulsion. It is a highly flammable chemical, which can be available as a gas or in a liquid state.
The ” difficult start Which is mentioned by Elon Musk suggests a delay in the ignition of engine 2. The Space.com site adds that this occurs when there is too much fuel in the combustion chamber and the pressure is too high – which could damage the engine. The difficult start occurred in the methane turbopump while preparing to reignite for landing.
SN11 is the fourth prototype in a row that is destroyed during the return phase, after a high altitude flight. The causes which led to the loss of four pitchers are different each time. The next test will be with the SN15 model. SpaceX has plans to scrap the SN12, SN13 and SN14 models, after performing some engineering tests on them.
According to Elon Musk, SN15 – whose assembly is complete and which will soon be leaving its assembly bay for testing – represents a significant leap forward in terms of design: “ It benefits from hundreds of structural, avionics, software and engine improvements », he indicated end of March. The flight test date has not yet been set.
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