(For those who don't know, Cameron County is around Brownsville, at the southern tip of Texas. I happen to know that off the top of my head because there's a rocket research center there.)
(I selected Language English when posting this, but there's "Warning: If you deselect Undetermined, you will not see most content." above that. Did I do a bad thing?)...
Quarter-sized hail in Northwest Hills, and it was really loud against my garage door and on my roof.. My new glass skylights did not have obvious cracks, but I'll look in the morning. Lost both U-verse to my home and cell access via the nearby tower (T-Mobile, I think), but that didn't last more than 10 minutes or so.
It was nice to have heavy rain to wash crud off the roads, and I'm grateful for any rain, but a few hours of gentler rain would have been more useful.
So, the instance I joined Lemmy on last week largely to participate here defederated from lemmy.world an hour ago. It's early post-Reddit days, which is the only reason I'm posting a general tech tip in /r/!austin, but it's a previously impossible inconvenience that isn't theoretical. Choose wisely or start your collection of...
In a Twitter Space with @ashleevance, @elonmusk shares that Starship will hot-stage during the next flight, lighting engines on the ship with some engines still running on the booster, as to Never Stop Thrusting!™️
"Hot staging" is firing the upper stage engines while it's still nominally attached to the lower stage (like resting on or loosely attached). The advantages that I gather exist: It's fast. It takes care of stage separation without needing springs or little rockets or a flip or anything. Before firing a liquid-fueled stage that may have gases in a tank ("ullage"), you have to settle the contents so that the engine intakes suck only liquid (maybe using "ullage rockets"), but if you're still accelerating at separation, that's automatically taken care of.
But if you intend to reuse the first stage, well, I wonder whether six engines igniting will be too hard on it.
Apparently U.S. Titan rockets, a lot of Soviet / Russian ones (Soyuz, Progress, N-1), and (some?) Chinese Long March rockets were designed with hot staging.
Joe Barnard @joebarnard replies: "'okay so when I hot stage it’s “an anomaly” and I’ve “torched another flight computer” but when SpaceX does it it’s fine???'
"We made sort of a late-breaking change that’s really quite significant to the way that stage separation works," Musk said, describing the switch to hot staging. "There’s a meaningful payload-to-orbit advantage with hot-staging that is conservatively about a 10% increase."...
Musk said that, for Starship, most of the 33 Raptor engines on the Super Heavy booster would be turned off, but a few still firing, when the engines on the Starship upper stage are ignited. Doing so, he said, avoids the loss of thrust during traditional stage separation, where the lower stage shuts down first.
Doing so requires some modifications to the Super Heavy booster. Musk said SpaceX is working on an extension to the top of the booster “that is almost all vents” to allow the exhaust from the upper stage to escape while still attached to the booster. SpaceX will also add shielding to the top of the booster to protect it from the exhaust.
“This is the most risky thing, I think, for the next flight,” he said of the new stage separation technique.
Besides the change in stage separation, Musk said SpaceX made a “tremendous number” of other changes to the vehicle, “well over a thousand.” He didn’t go into details about the changes, ...
SpaceX also made improvements to the Raptor engines, with Musk describing the vehicle launching in April as using a “hodgepodge” of engines built over time. The Raptors on the new vehicles include changes to the hot gas manifold in the engine to reduce fuel leakage.
Those changes, he said, gave him more confidence in the success of the next launch. “I think the probability this next flight working, getting to orbit, is much higher than the last one. Maybe it’s like 60%.” In an online conversation in late April, he estimated a “better than 50% chance” of success on the next launch.
In another note, Musk finally learned some caution!
Musk, asked about any plans for a Starlink IPO, declined to comment. “It would not be legal for me to speculate about a Starlink IPO,” he claimed. “I think it’s against regulations to talk with any kinds of specifics about a future public offering.”
Edit: Peter Hague PhD @peterrhague: Thus far Musk estimates $2-3bn invested by SpaceX so far in Starship. The price of a single SLS launch
TheSpaceEngineer @mcrs987 has a thread on Twitter about hot-staging. A lot of people have been assuming that the lacy structure in his second picture will be the interstage that lets the exhaust out. He argues that it's unlikely, because (1) it doesn't look structurally sound, (2) it has been marked for scrap and no others have been seen, (3) the stringer pattern doesn't match the booster.
He advocates for another ring, which looks much more solid but has some reinforced holes. There have been two of them so far. He also says it resembles the hot-stage interstage of the Titan 2.
The best part is no part. The next-best part is a part somewhere else.
I started out making a silly joke, but ... hmm, actually, there's something there. Starting your booster? Mostly stage 0. Flipping? Stage 2. Decelerating? Atmosphere, mostly. Landing? Ha ha, get this: stage 0 again.
Looks like the segments are around 400mm thick and constructed from 40mm (38mm=1.5"?) steel plate The overall shape is a hexagon about 10m across the flats with each corner notched out.
They also speculated on how to weld the edges together: maybe put them on a stand above the final location, weld them from above and below, attach cranes and remove the stand, lower into place.
[Meta] Twitter is now throwing up a nag screen to force users to log in to view content, supposedly on a temporary basis. Since a lot of the content here links to Twitter, this could be inconvenient to those without an account.
A simple solution is to link to the embedded version of the Tweet, like so. Simply type:
So the big news of the day and night was what is believed to be the center plate of the water deluge system. It is thought that it will be placed directly under the Orbital Launch Mount.
CSI Starbase SPMT Tracker @SpmtTracker posted a tweet with a picture of what is very likely to be a vertical stand for the center plate. The image is on Imgur.The tweet is here. Ryan Hansen Space @RyanHansenSpacetweeted a rendering of how it might look under the OLM. This should be the image:
@LettuceTurnipTheBeet posted below (if sorted by new) a link to a 13-minute video by Starship Gazer, of people working in the tent on the center plate. https://lemm.ee/comment/534238 . Someone commented that, from 4 minutes on, it's comedy gold. People were grinning around them. I'm told that someone is standing on top of the cheater pipe at one point.
NASASpaceflight posted a video of the rollout of the center. It's about 1 hour 26 minutes long. The stand / jig was on the first truck; the center plate with some people on it was on the next truck. The clearest views are about 17 minutes on.
Same to you, bud! I figure I’ll keep blowing on the embers. Either the flame will catch (& I get to boast “I was into Lemmy before it really took off”), or my lungs will get too tired.
Christian Schiffer - schiffer-soft @schiffer_softtweeted a diagram of Super Heavy and Starship. It’s for something for @Senkrechtstart3; “Senkrechtstarter is the biggest german YouTube-Channel about spaceflight, rockets and newspace.” They asked for corrections. Errors have been noted: “Why did you keep the CH4 header tank on the common dome?”, and the shapes of the header tanks. But it looks like a good start.
More pour info, this time from tweets from Zack Golden @CSI_Starbase. The truck counts basically match those from @LettuceTurnipTheBeet’s post earlier.
SpaceX has received their final load of concrete for today’s Orbital Launch Mount foundation work. Here are the totals after the 15.3 hour marathon:
June 25th - 132 Truck loads
July 3rd - 171 Truck loads
Total Volume = 2,302 m^3 = 3030 yd^3
Total Weight = 5,411 Tons
For reference, a Fully loaded Starship ~ 5,000 Tons
Note: There were 4 additional trucks that showed up but were turned back around without offloading.
Shoutout to agents @VickiCocks15 and @SpmtTracker for keeping track of all these.
4:11 PM · Jul 3, 2023
and
Obviously this number is significantly greater than we predicted. For those who asked, that previous number was not considering the area in yellow, which were also completed today. This area is technically outside of the true foundation of the OLM
Unrolled tweet thread at threadreaderapp.com by Ryan Hansen Space @RyanHansenSpace. It’s a look at the details of the steel plate parts and assembly under the Orbital Launch Mount.
Much lifting and lowering and all sorts of craney stuff, but it’s believed that all the manifolds are in place by now. A nice Imgur picture of a manifold being craned.
Musk has repeatedly said he’d like to try to launch Starship again as soon as this summer, but the FAA said in a statement to CNN that SpaceX has yet to take public safety actions or submit a mishap report with corrective actions for FAA review and approval.
Opinions about the fireworks at Q2 tonight?
I saw the fireworks at the Q2 stadium tonight, but from a building nearby....
Dispelling the myth of the Proton rocket crash of 2 July 2013 (twitter.com)
I hope spaceflight posts are welcome for now....
APH monitoring malaria situation following a locally-acquired infection in Texas (www.kxan.com)
Travis County jury duty notice
(I selected Language English when posting this, but there's "Warning: If you deselect Undetermined, you will not see most content." above that. Did I do a bad thing?)...
Eric Berger in ArsTechnica: Weirdly, a NASA official says fixed-price contracts do the agency “no good” (arstechnica.com)
NASA official Jim Free testifying to Congress about Artemis....
Hail
Sounds like a war zone above my house. Golfball sized for sure. Hope y’all are safe!
Defederation is a thing ... anyone for whom this community is a main draw and not yet committed to a Lemmy instance would do well to pitch their tent on lemmy.world
So, the instance I joined Lemmy on last week largely to participate here defederated from lemmy.world an hour ago. It's early post-Reddit days, which is the only reason I'm posting a general tech tip in /r/!austin, but it's a previously impossible inconvenience that isn't theoretical. Choose wisely or start your collection of...
Going to heb... (lemm.ee)
deleted_by_author
This community has really gone downhill since it was created.
It's for Austin, so it had to be posted. The meta must flow....