“it goes to 11”. Eleven has been one of Elon”s favorite numbers. Hope it truly does this time!
So I read in Liftoff THE reason why 11 is an important number for SpaceX in particular. For the second launch of Falcon 1, they hadn't yet had their second stage light, so they really didn't know how it was going to work, and they had a long laundry list of possible ways it could fail. Number 11 was LOX tank slosh. They had computer simulations and on some small number of simulation runs, the liquid in the tanks would slosh around so much that it would destabilize the second stage enough to cause it to tumble out of control. But they had characterized the risk as number 11 on their list of things that could go wrong, so they made the decision to not address it (among other things, they were battling weight penalties AND they were worried about structural integrity, so welding baffles inside the tank also seemed risky).
Well, Falcon 1 makes her second flight and sure enough, slosh in the second stage caused it to spiral out of control soon after stage separation.
So now, SpaceX works through all possible issues up to number 11 on the list!