BFR Developments

[Yazata]

There was supposed to be something happening tonight, but the road closure was cancelled. Road closures are on for all day tomorrow and throughout next week, probably for additional Sn8 static fires from the header tanks, proving out lots of new plumbing and valves and stuff.

In other Boca news, they have installed tail fins on Sn 9, assembled the tank section of Sn 10 and have Sn 11 underway stacking its barrels. So even if Sn8 craters on its first flight (I think that Elon considers it at least a 50% probability) there are three more in the pipeline at various stages of completion. And parts accumulating for still more. SpaceX has established a cycle: test, fail (more or less expected at first), improve, test... rapid prototyping. Routine in the software industry, but not in aerospace.

And in bigger and more portentous news, they have started stacking Lox tank ring barrels in the new High Bay for the first Superheavy.

Mass producing spaceships! 

In addition to the three Raptor engines on Sn8, this morning Mary spotted another engine on a forklift at the build site and identified it as engine Sn 42. Unknown how many engines are lurking around Boca, but McGregor is busy testing them with static fires.

Plus lots of concrete being poured at the launch site. Probably in preparation for launching the first Superheavys.

Weekly update video

https://www.youtube-nocookie.com/embed/JrWnJzmo8jI

[Yazata]

11-10 -- They just performed a static fire.

Good news: Sn8 is still standing and looks fine

Bad news: The static fire didn't appear satisfactory. First, all kind of spark like debris flew out of the exhaust plume. Lots of internet theories about what it was, ranging from a Raptor engine tearing itself apart (bad) through launch pad concrete ablating (not good) to ice from the abundant pre-fire Lox vents being propelled away by engine exhaust (no biggie). Ianars, so I don't know. SpaceX might not even know themselves until they get up close to examine it.

More bad news: There was the now-familiar loud metallic honk at shutdown, which indicates vibration in an engine and isn't good either.  

https://twitter.com/NASASpaceflight/stat...3162385410

https://twitter.com/austinbarnard45/stat...6301457414

[C C]

Sheesh. I was at least expecting a mid-air explosion or a fiery crash from Sn8. Not that familiar whimper exit of many before it.

[Yazata]

Sheesh. I was at least expecting a mid-air explosion or a fiery crash from Sn8. Not that familiar whimper exit of many before it.

Don't worry, CC. Sn8's still likely to crash very spectacularly at the end of its planned 15 km flight. Big fireballs and everything. Elon seems to expect that something will go wrong on the first try. (And everyone expects the media to run with joyous "Elon's ridiculous rocket fails!" headlines if/when it craters.)

But Sn9 is in the final stages of completion, Sn10's tank section is largely complete, and Sn 11 is already being stacked. Mary's spotted parts of 12, 13 and 14 too. If one fails, just wait a couple of weeks for the next one to roll out. The beauty of rapid prototyping.

Yesterday's static fire doesn't seem to have damaged Sn8 itself. It's still very much alive. Everyone was watching this morning to see that the crews did at sunrise. And everyone was surprised that nobody did much of anything. If an engine needed to be swapped out, we would expect workers to be swarming. If the launch pad was damaged, we'd expect activity too.

Right now, the most popular theories about what happened seem to be that the sparks were either ice or launch pad concrete spalling. Doesn't seem to have been engine bits, which was an early favorite.

Tomorrow's all-day road closure is still on. Probably for more static fires. They have to get where they can just turn the engines on and off if they expect to relight them in flight in order to land (like they do with the Merlins on the Falcons). Since they haven't removed an engine, I assume they think the engines are good to go tomorrow.

The 15 km flight isn't really expected until after Crew-1 on Saturday. Maybe next week if everything goes right.

[Yazata]

Drama in Boca!

They performed what looked like a good static fire (it did release more sparks, foreign object debris, what the aerospace engineers call FOD)

but... appeared that something liquid on fire was flowing from the engine bay. Then a long period without any visible detanking. Then Elon tweeted:

https://twitter.com/elonmusk/status/1327070929868914689

We lost vehicle pneumatics. Reason unknown at present. Liquid oxygen header tank pressure is rising. Hopefully triggers burst disk to relieve pressure, otherwise it's going to pop the cork.

https://twitter.com/elonmusk/status/1327073241693765633

Maybe melted an engine preburner or fuel hot gas manifold. Whatever it is caused pneumatics loss. We need to design out this problem.

Edit: relatively small plume of vapor from the nose. Appears the burst-disc performed as designed and prevented an overpressure in the lox header.

Edit 2: video

https://www.youtube-nocookie.com/embed/gUAj7UdDqfI

[Yazata]

Another Elon tweet from last night

Burst disk worked, so vehicle appears to be ok. We'll have to swap out at least one of the engines.

https://twitter.com/elonmusk/status/1327090548478414850

[Yazata]

Austin Barnard?
@austinbarnard45
·
14 Nov
Raptor Serial #32 after being removed from StarShip SN8.

https://twitter.com/austinbarnard45/stat...73/photo/1

I can't see anything wrong with it - there again I can't see anything right about these engines - but not blown to smithereens.

Mary has some super close-ups of it from all around it and I couldn't see any visible signs of damage either. I guess that the rotor/stator blades in the turbo pumps might still be totalled. That might be where the molten-blob is that I expected to see externally.

Elon's given some more explanation of what happened.

"About 2 secs after starting engines, martyte covering concrete below shattered, sending blades of hardened rock into engine bay. One rock blade severed avionics cable, causing bad shutdown of Raptor."

What the rocket engineers call "FOD", foreign object debris. So I guess that the "sparks" seen flying away from the exhaust plume were a worse problem than thought.

https://twitter.com/elonmusk/status/1328742122107904000

Explanation of what "martyte" is in nasa link below. It's a combination of ceramic and epoxy used in high-heat applications like rocket launch pads. Didn't work so well this time. (Elon's really gonna have to start thinking about Cape Canaveral-style flame ducts. Having the rocket-blast hit the ground and bounce back up is proving to be problematic. I know that a launch on Mars will have to do it that way, but...)

https://ntrs.nasa.gov/citations/20130014277

Elon's apparently going to go with hardening the bottom of the Starship and a cooling system for the pad.

https://twitter.com/elonmusk/status/1328743239327866881

"Avionics cables moving to steel pipe shields & adding water-cooled steel pipes to test pad."

[Yazata]

Cameron County has just (only a few minutes ago) announced new road closures for Sn8 testing.

One for next Monday, presumably for another static fire.

Then one for seven days after, on Monday 11-30, for the 15km flight!

https://www.cameroncounty.us/wp-content/....30.20.pdf

In other news, the Sn9 nose has received its flipper-flappers and will be stacked atop its barrel section at any time. (The cone and the barrel have been moved into position and the crane is there.) The tank section of Sn9 already appears to be more or less completed, so 9 is almost ready to go. Sn10's tank section is structurally complete, but doesn't have its rear flipper-flappers yet. Sn 11's tank section is in the midbay being stacked. Plus assorted parts (rings, barrels, domes, plumbing, manifolds, headers...) for 12, 13, 14 and 15 have been identified but have yet to be stacked.

Plus, the Superheavy being stacked in the highbay.

Strangely, there's been little obvious work on Sn8. All three engines (including a new one to replace the one removed) are installed. Today there's several lifts under Sn8, so they may be rerouting cabling in steel pipes to harden them against FOD as Elon said they would.

But I haven't seen any work taking place repairing the surface of the test pad after the three engine tests the last couple of times tore it up. I expected to see lots of work being done down there resurfacing it.

That being said, there's massive work being done around the Superheavy launch site. A whole parade of cement trucks and lots of graders pushing dirt around. But none of that work has been building a platform atop the big concrete legs they built months ago. Those legs seem forgotten and planning might have moved on to a different launch pad concept. (SpaceX is famous for making it up as they go.) There's been some speculation that they might be building a new higher capacity tank farm to serve the Superheavys.

[Yazata]

They just conducted a static fire of Sn8 that went well this time. Elon seems pleased and says,

"Good Starship Sn8 static fire! Aiming for first 15km / ~50k ft altitude flight next week. Goals are to test 3 engine ascent, body flaps, transition from main to header tanks & landing flip."

https://twitter.com/elonmusk/status/1331386982296145922

Excitement and anticipation are building around the world.

I personally think that the odds of everything going right are < 50%. And unless everything goes right, Sn8 will be lost, probably in spectacular fashion. Of course if even part of the flight plan is successful, they can check those goals off the list and move on to Sn9 which is more or less complete. So the likelihood of initial failure is built into the test campaign which will probably be like early tries to land the Falcon 9's. Multiple failures before they finally stuck a landing.

[Yazata]

They just conducted a static fire of Sn8 that went well this time. Elon seems pleased and says,

"Good Starship Sn8 static fire! Aiming for first 15km / ~50k ft altitude flight next week. Goals are to test 3 engine ascent, body flaps, transition from main to header tanks & landing flip."

https://twitter.com/elonmusk/status/1331386982296145922

Excitement and anticipation are building around the world.

I personally think that the odds of everything going right are < 50%. And unless everything goes right, Sn8 will be lost, probably in spectacular fashion. Of course if even part of the flight plan is successful, they can check those goals off the list and move on to Sn9 which is more or less complete. So the likelihood of initial failure is built into the test campaign which will probably be like early tries to land the Falcon 9's. Multiple failures before they finally stuck a landing.

Elon was asked what he thinks the chances are that Sn8 lands in one piece.

"Lots of things need to go right, so maybe 1/3 chance."

https://twitter.com/elonmusk/status/1331388984023461888

"But that's why we have Sn9 and Sn10"

https://twitter.com/elonmusk/status/1331389134624219136

There are rumors in Boca Chica village that residents might be required to leave entirely for up to three days for the test flight. I guess that there isn't only the now familiar explosion risk, but also some risk that all or parts of this huge thing might crash down on their heads if the landing attempt goes seriously awry. My understanding is that they plan to keep most of the flight plan out over the Gulf to minimize that risk. But it will still have to steer onshore to land, which is likely to go wrong and result in a big fireball and lots of shrapnel.