10% relative to the wonky IFT1-style flip maneuver, but for a droneship landing scenario they could probably do a Falcon-type separation while flying faster and more horizontally, so presumably the penalty would be a lot less than 10%. By also eliminating the mass of the hot-staging ring, maybe it could be a net positive.
The original separation method involved a flip release (like Starlink deploy). Hot staging keeps the Ship going straight.
Thank you for that reality check. Some random person on X tweeting what they think will get attention is not the best way to get information.
I recall that not too long ago SpaceX sold the two oil platforms they had purchased years ago?
As I understand it, the IFT-1 flip maneuver was primarily required to keep Booster's propellant settled (by centrifugal force) while it separated from Starship, so it could safely start up its boostback burn a few seconds later. In the droneship scenario, with a Falcon-like separation, there is no boostack burn (or reentry burn) to worry about, so the booster propellant doesn't need to stay settled after separation. Gravity+drag will settle it during atmospheric descent, so it will be settled for the landing burn. And even though Starship will have a few seconds of non-spinning weightlessness before lighting its engines, it doesn't matter because its tanks are full at that point, so there's no sloshing to worry about. The 10% reduction in payload efficiency was more due to the rotation than the coasting, IIRC. Also, in the droneship scenario the separation will be faster/higher/more horizontal than in the RTLS scenario, so gravity losses should be even less of a factor.
Yes that's what I was getting at - hot staging improves overall performance even considering carrying the extra mass of the hot staging ring. I can't seem to find where I read that. If that increase in performance still holds on the longer boost, I expect they would not remove the hot staging ring if they were to try a drone ship booster landing.
As I recall, it was primarily to get maximum performance out of the stack. Being able to keep the propellant settled was obviously a big win, but the name of the game is payload to orbit, and the flip was superior to traditional staging in that respect. I'm sure they considered hot staging from the start, and thought that they had come up with a simpler solution. It's curious that they made the attempt, then discarded it immediately. Perhaps it was an Elonism that his guys didn't like, he pushed for it anyway, then abandoned it when it didn't immediately work. Or telemetry disproved it as a useful technique.
spacenews.com
I assume that it's to ensure that the pins haven't been bent during the tile removal process, and that they'll line up properly for tile installation.
It could be a waterproofing spray. Scotchguard. They used to do that in the early days, but it wasn't very effective, so they changed to a different treatment that was more toxic to the workers. If these are the new tiles, they may be designed to either be less hydrophilic, absorbing less moisture, or more easily capable of shedding moisture without shattering.
That comment about cork inspired some google searches which led me to an excellent NASA slide deck: Fundamentals of Launch Vehicle Ablative Thermal Protection System (TPS) Materials. It briefly covers lots of things I didn't know existed. Heat resistant spackle (my term) for last minute patches. Heat resistant rubber for joints that flex (e.g. Shuttle SRBs). "Fundamentals" is correct, you won't learn details about anything, but you'll learn lots of things. And lots of pictures, too
