Hmm, yes, normally one would consider an object in free fall when gravity is the only force acting on it (or following Einstein, no force is acting on it). This is what led me to my initial reply about the booster hardly (if ever) being in free fall during its flight.

But your point was about the relevance of gravity on the settling of the debris in the LOX tank in which case one can ignore most forces on the booster and still observe it as free falling.

The why is not easy to wrap my head around, so I understand why Zack and his team made the mistake, but I do get that it is the case. Thanks again!

I had a feeling I was stretching into territory where I don’t know enough, thank you for the clarification.

Following that, and I hope you don’t mind me asking instead of following up myself, would I be correct to conclude that the vehicle technically is in free fall while going up? Just about everything to do with spaceflight can be so unintuitive, which is simultaneously what makes it interesting as well as frustrating at times :)

There was a lot to digest, so I might be wrong, but I was under the impression that he was referring to the boost back phase, so not in free fall. I’m not smart enough to figure out if the gravity vector plays any significant role compared to the one from the engines in that situation :) Neither during the landing burn. There is a huge amount of deceleration which would be a vector straight through the booster? There is a slight tilt to the booster most of the way down, but I don’t know if that could make the debris settle unevenly.

In between those burns nothing can settle as you say. If Zac was referring to that phase than that was indeed an oversight.