This is the finest FAQ in the fediverse. I come back to it, just to appreciate just how much data you fit in it, so easily accessible and concise for the experienced and inexperienced alike. It makes up for so many poorly written, ugly, inhuman FAQs across the years.

John Kraus @johnkrausphotos:

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???’

Edit: There’s now an article up at SpaceNews, “SpaceX changing Starship stage separation ahead of next launch”, which includes

“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

What about it!? @FelixSchlang tweet from 3:03 PM - Jun 29, 2023:

It happened!!!

SpaceX opened the wall to the inventory tent and revealed one of the water deluge plates to us up close and countless other things in there!

High res pictures for supporters on all platforms coming soon!

The image alone.

In a reply, they said it looks to be upside down.

In The Other Place, u/warp99 wrote,

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.

Starship Gazer (as seen on Nitter) had more pictures.

More pour info, this time from tweets from Zack Golden @CSI_Starbase. The truck counts basically match those from @LettuceTurnipTheBeet@lemm.ee’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

with a picture by RGV Aerial Photography.

Starbase live-

9:15am cdt- 11 more loads of rebar have been lifted over to the OLM since midnight. LR11000 still holding the deluge pipe in position to be welded.

Edit-

10:48am- Deluge pipe is moved to the side of the underground pipe bunker and laid down on the ground.

11:50am- 8 more bundles of rebar have been lifted over to the OLM. Some presumably extra bent pieces have been lifted away as well.

1:11pm- Deluge pipe raised again and moved back to join the pipe that goes underground.

5:00pm- Since noon there has been 15 more loads of rebar craned over to the OLM. Most loads appear to be multiple pieces but there are several large bent pieces that have been moved one at a time.

9:00pm- 10 more loads of rebar have been moved over. (44 for the day so far and 56 in the last 40 hours)

Ship 25 completed a flight-like chill and spin of the Raptor engine pumps, stopping just before engine ignition. As a result of the test, cryogenic liquid oxygen formed a visible cloud beneath the ship. This checked out vital systems in advance of the upcoming static fire.

source

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.

@LettuceTurnipTheBeet@lemm.ee already posted (at top level) “CSI Starbase video on new Deluge system”, a deep dive part 1. The URL I see for the post is https://lemmy.world/post/879748 , because that’s how I access this. The canonical one is https://lemm.ee/post/530280 .

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 @RyanHansenSpace tweeted a rendering of how it might look under the OLM. This should be the image:

@LettuceTurnipTheBeet@lemm.ee 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.

RGV Sneak Peek shows some nice shots of the steel plates, as well as the pour under the OLM. Looks like a lot more concrete is needed though, wonder when that’ll happen.

The steel plates look ready for transport, so I bet this next pour will be soon — it seems to be the main hold up.

Yooooo

Road closure is now scheduled for tomorrow!

Exciting stuff happening right now (See Starbase Live).

• Launch site movement with the SPMT that transported the steel plate for the water deluge system and the SPMT with the Jig!
• Jig is being moved into position and now a crane is being raised! Things are getting exciting this morning.
• At the same time S28 is getting a payload door.

edit: And here’s the latest RGV Flyover video, which is the flyover from last week. Interesting content, but already heavily out of date.

This is great thank you, I started following spacex Reddit in the echologic (was that his name?) Days, but the sub got a bit, I dunno, it started to lack a certain something. Just got too big maybe.

I’m happy to see this here! Thanks for starting it, sorry for the off topic 😂

Looks like the Ship Quick-Disconnect is back!

I’m leaving reddit permanently, so thanks for maintaining this!

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.

SpaceX @SpaceX on Twitter

Ship 25 completes a six-engine static fire test at Starbase in Texas

11 seconds. In the audio, only a little bit of HONK at the end.

Someone pointed out that the flames start out as a triangle, but then switch rotated 60 degrees when the vacuum engines start - V to ^.

A comment in The Other Place mentioned that it looks like a little spalled concrete at 4 seconds in.

In a later tweet, Musk called it a “Key milestone completed for flight 2”.