While the Booster 7 / Starship 24 stack has been in place on the Orbital Launch Mount since last week, and was cryo-tested last Friday, it's not the only thing going on at Starbase. It appears that Starship 25 was rolled out to the launch area and placed on the Starship test stand on the 14th.
It's not the first time that S25 has been to the test area; that was back in October. After a pressurization proof test, multiple cryogenic proof tests, and likely a few simulated thrust tests using six hydraulic rams, she was rolled back to the shipyard on November 8.
An interesting second thing on Saturday was that when S25 went back to the test area Musk was asked how many Starships SpaceX is looking to build this year and he replied "about five full stacks."
Full stacks, of course, means that S25 needs a booster, and B9 has been associated with B9 in the same way as B7 and S24; everyone seems to refer to them as a pair. Like S25, B9 has also been to the test area and proof tested before, more recently than S25.
About two months behind Ship 25, Booster 9 rolled out of its Starbase assembly bay and headed to the launch site on December 15th, 2022. The Super Heavy prototype ultimately completed two partial cryogenic proof tests on December 21st and 29th, during which it was likely loaded with around a thousand tons of liquid nitrogen to simulate explosive liquid oxygen and methane propellant. Booster 9 then returned to Starbase’s factory on January 10th, 2023.
B9 returned to the shipyard to get its new Raptor engines installed and these are expected to be the latest version engines, not compatible with B7. Instead of the hydraulic thrust vector control (gimballing the engines), the latest Raptors use electric TVC. SpaceX has been testing the TVC design at their McGregor, Texas engine testing facility (that linked video has some interesting aspects to watch but only until about 1 minute 40 seconds). The only question is if there are enough of them on hand to fully outfit B9, which probably depends on when they want to start testing B9 out at the pad. There's only one pad out there big enough to handle B9 and that's occupied by the B7/S24 stack. Which Elon says is likely to launch before the end of March. I imagine that some delay between launching B7/S24 and testing B9 is inevitable.
There's a road closure from 8AM to 8PM (central time, of course) at Boca Chica, with Thursday as the backup (alternate) day, same hours. They're getting close to the point where they could do a full Wet Dress Rehearsal - everything except firing the 33 engines.
Let's gooooooooooo! Light that candle!
ReplyDelete"This electric stuff is getting out of hand" B. Franklin. This is new to me. What is the advantage or necessity? Some of those excursions look like they could collapse a stack in flight. Wait, will that be on a test flight?
ReplyDeleteThe advantages are saving space and weight around the engines. The Teslarati article says:
DeleteInstead of using a complex web of plumbing and hydraulic power units bolted to the side of Super Heavy, Booster 9’s 13 central Raptors will be electrically steered. That has allowed SpaceX to remove those power units (streamlining Booster 9’s exterior) and reduce the already rats nest of plumbing required to fuel, control, power, and steer dozens of high-performance rocket engines on one booster.
I don't think the fast or far-ranging excursions are likely to be used, but they're testing to far more than just their requirements to ensure they have margin. That's pretty common.
When I was watching the video, I remember thinking that the test stand was pretty impressive. The engine is dancing around while throwing half a million pounds of thrust. That's changing the forces on the structure, too.