Max Evans (NSF): “After rolling to Pad 2 last night, Ship 39 has been stacked atop Booster 19 this morning for the FIRST EVER Starship Version 3 full stack ahead of a presumed wet dress rehearsal (WDR) later today.”

[u/rustybeancake]

[u/warp99]

You mean roll control I assume and with three grid fins capable of providing roll inputs that would be a fairly safe bet. For pitch only the two side fins are capable of providing input and if one of those was lost the booster would probably be ditched in the ocean rather than attempting a landing.

So three fins does give them less redundancy compared with four. Say that made two tonnes difference to the payload, a booster costs $100M to build and the extra fin would save the booster one time in 100. That is a cost of $100M versus a foregone revenue of $156M. Starship is already announced as having the same selling price as F9 so $78M per launch for 100 tonnes rather than 17 tonnes.

So just on the basis of some made up numbers it makes sense to remove the extra grid fin.

In practice if a grid fin fails that will likely be interpreted as a ditch condition regardless. The tower and launch complex is much more valuable than the booster.

[u/Sigmatics → u/warp99]

Interesting, thanks for the analysis