Why would dropping the fairings earlier mean more heating? Isn’t that a lower velocity and closer to shore?
Quote from: Norm38 on 06/20/2022 02:39 amWhy would dropping the fairings earlier mean more heating? Isn’t that a lower velocity and closer to shore?More heating of the uncovered payload on Stage 2
It’s so good to see how well Gerst appears to have adapted to SpaceX culture, and fascinating how frustrated he had become with the NASA way.
Quote from: ThatOldJanxSpirit on 06/11/2022 02:50 pmIt’s so good to see how well Gerst appears to have adapted to SpaceX culture, and fascinating how frustrated he had become with the NASA way.He was the reason for the "NASA" way and was in position to affect it.
They are now aiming at 15 flights per booster. They do this vibrating, heating, etc. each component to 4x the expected time of exposure at 15 flights.
Static fires used to be run after an engine was pulled or a turbine wheel changed. Now only if 3 engines are pulled; turbine wheels are now monitored by accelerometers during startup, and don't force a static fire.
Even Block 5 is still evolving; examples include better thermal shields and a way to drain the second stage tanks even if the QD pops off (which would otherwise be fatal). For most changes they identify the potential improvement, then test it on the bench, then on a StarLink launch, then it becomes general.
They keep tweaking the time interval between MECO and second stage start. The smaller the delay, the better the performance, but the more wear on the first stage.
They have two software systems tuned for re-use. One called Hyperion looks at the telemetry and points out areas that need a closer look. Warp, their production system, also has modifications for re-use such as pointing out similar problems that have occured on prior flights.
IOW into 10s of reuses of a first stage to M6, but nowhere near the 100's (1000s?) Musk thought was possible. That suggests the booster takes a hell of a beating
100s of reuses requires 100s of flights. I think SpaceX have just been taking a cautious / methodical approach as they’re not sure where the weak links might be and at what point they’ll hit a limitation (at least without significant refurbishment). So they’ve built up a reasonably sized fleet of boosters to support many flights even if 10 - 15 per booster proves a limit.
100s of flights may be possible but with Elon switching SpaceX’s focus to Starship, I don’t think he’s particularly interested in finding out any more (for F9, Starship is a whole other issue).
Now this is surprising. I'd have guessed a longer coast would have given them more altitude and be beneficial. OTOH more booster damage due to earlier sustainer ignition makes perfect sense due to greater exposure to engine plume.
Quote from: Norm38 on 06/20/2022 02:39 amWhy would dropping the fairings earlier mean more heating? Isn’t that a lower velocity and closer to shore?Lower velocity, but also a lower altitude so more atmospheric drag. The threshold for dropping the fairing is the amount of heat generated by drag.
In another description of the article it's stated that 15 is the limit as they want to phase out F9 launches and that in fact the real limit is higher. That may be true, but given that Starship hasn't reached orbit yet that is a very bold plan, never mind going to Mars (still 130 days to go to 2023).I wonder if someone who's been tracking number of launches across the 21 booster fleet can say how many of those 315 possible launches (15*21) the fleet has left in total? That's basically how long SX has to get SS orbit capable. Once that happens they can fix any outstanding issues with the design. Obviously SX could use the last flight of each as a "special" with maximum payload due to no landing gear (even for the fairings, as they are phasing out the whole vehicle). Really crank up the payload. Outer planets probe? I don't think Neptune or Uranus has had a visit since Voyager.
How do you know that they won’t build any more boosters beyond the current 21? Every additional booster gives them 15 more launches as may be needed.
I agree it’d be smart to prepare a much bigger buffer of F9 capacity than Elon would probably prefer, but…
Docking Starship to ISS is not very different from docking Shuttle to ISS.