Although all three Sea-Level Raptor engines on SN15 were supposed to start up for the landing burn, only two did. Let's Discuss! 🚀🤓

Analysis of Starship SN15s’ Landing Burn - (1/10)
When landing, the Raptor engines at the base of Starship are sent commands from the flight computer to startup, reorient the vehicle, and slow it down for a soft touchdown...(2/10)
The two Raptor engines that have the biggest lever arm (leverage) to reorient the vehicle are those that are towards the windward side of the ship. These engines are theoretically going to try to start (or “relight”) first...(3/10)
If you take a gander at the SpaceX official feed for SN15s’ flight (which is quite jumpy) you can see that when the engine cluster starts to gimble towards the top of the engine housing (to perform the flip) one windward-side engine is already not following the other two...(4/10)
Eventually, this engine completely breaks off to the side, a gimbal position that is furthest away from the other two engines in the center cluster, which allows other engines enhanced freedom of movement...(5/10)
The past four high-altitude flights of the Starship vehicle show that when a Raptor engine gimbals towards the edge of its’ range / edge of the Starship, the engine is doing so because it will not be starting up for the foreseeable future...(6/10)
This indicates, that even before a single Raptor engine relit, a decision was made, by either the flight computer or SpaceX [email protected], to not include this particular raptor engine for the landing flip maneuver...(7/10)
It is quite possible flight computer, as it was checking for engine performance, saw that this particular Raptor engine was not performing up to par for pre-startup tasks or it may have eliminated it from the landing flip altogether after non-ideal performance on ascent...(8/10)
There are definitely a lot of variables in play, but with @jinsprucker confirmation pre-flight of the 3 Raptor Engine Landing Flip maneuver, the timeline of events (and Elon tweets) leading up to the new version of the landing flip (Post-SN9), and SN10s' landing...(9/10)
...We know for a fact that there was a decision made by the flight computer, or ground, to not include an engine for the landing burn sequence, and it may have occurred at some point during the flight.

That being said, SN15 was still able to perform a soft landing on the pad!
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