YazataApr 30, 2023 02:36 AM (This post was last modified: Apr 30, 2023 04:24 PM by Yazata.)
Elon just did a live Starship Q & A with his subscribers on Twitter Spaces.
I didn't listen to it since I'm not one of Elon's subscribers (maybe I should be, it only costs $4/mo). But Michael Sheetz has a good summary of the Elon-nuggets here:
Edit: I subsequently did get a chance to hear a recording of it after it was concluded.
Elon says that the pad damage is actually not nearly as bad as some of the photos suggest and should be quite repairable. He estimates it will take 6-8 weeks to repair the pad. (That's almost certainly Elon-time and I'd guess 6 months.)
Elon: "The vehicle's structural margins appear to be better than we expected, as we can tell from the vehicle actually doing somersaults towards the end and still staying intact."
He says that he anticipates 4 to 5 more flights this year! (Probably ambitious.)
"The longest item on that is probably requalification of the flight termination system ... it took way too long to rupture the tanks." Elon talked about putting more det-cord around the tanks to better 'unzip' them.
Elon said that 3 of the 33 engines didn't start properly and were immediately shut down by computer autoabort. Starship launched with 30 engines which is the minimum that they were prepared to go with.
The odd looking slide up off the pad was due to the missing engines. They don't intend for it to happen again.
At T + 27 seconds there was some kind of "energy event" that took out their telemetry communications with one of the engines on the vehicle. Suggestion is that an engine blew up and its explosion damaged several additional engines.
But the ship powered on!
Then in Elon's words All hell broke loose as they lost thrust vector control at T + 85 seconds and the vehicle lost control.
A big item for the next booster is to ensure they don't lose thrust vector control. That involves reducing failure points that can take out all of the TVC for all of the steering engines at once. The follow-on boosters have replaced booster 7's hydraulic TVC with electric TVC, and they think they have a good handle on that issue.
When asked about the crater under the pad, Elon says they are going to "put down a lot of steel" under the pad before the next flight. This will be a sort of water-cooled steel sandwich with water flowing between two armor plates. The top one will have holes and will be in effect the worlds largest shower head. So it should be able to at least somewhat attenuate both heat and accoustic energy. The plates will be tied in with the OLM's legs to transmit mechanical force to the piers sunk deep in the ground. SpaceX engineers seem pretty confident about it. The goal is a launch pad that can be used over and over without major refurbishment.
"Got pretty close to stage separation ... if we had maintained thrust vector control and throttled up, which we should have ... then we would have made it to staging. Our goal for the next flight is to make it to staging and hopefully succeed."
Elon says the flight plan for the next flight will be a repeat of this first one. Booster to make a controlled landing in the Gulf, the Ship to attempt hypersonic reentry near Hawaii.
"The goal of these missions is just information. Like, we don't have any payload or anything -- it's just learning as much as possible."
Elon says he estimates maybe an 80% probability or reaching orbit this year, and close to 100% in 12 month.
He says that they will be ready with HLS when Artemis needs it (2025).
SpaceX expects to spend ~ $2 billion on Starship this year and doesn't expect to need to raise funding.
And Elon said that they are going to pull out the vertical tanks in the orbital tank farm and replace them with horizontal tanks that Elon called "double walled hotdog tanks". He says they already planned to do that before the launch damaged a couple of the vertical tanks.
The rocket didn't exactly explode, it was intentionally terminated on command after its steering control was lost.
The "explosion" took place far out over the Gulf of Mexico in an area that had been cleared of marine traffic and didn't result in any injuries or known dmage.
"Devastated a town"?? There weren't any towns close to the launch, apart from Starbase. The workers and residents there were evacuated before the launch and they didn't find any damage when they returned. (What damage there was, was limited to the launch area a mile away.)
Apart from that, the closest towns outside the exclusion zone were South Padre Island and Port Isabel. They suffered no damage, not even a broken window. South Padre Island is a resort and I'm sure its hotels and restaurants were thrilled by the crowds of rocket nuts that arrived to watch the launch. Local establishments courted them and the community has visions of the struggling south Texas coast achieving the prosperity enjoyed by the famous "Florida Space Coast".
"Devastated" the surrounding wildlife refuge? The biggest impact was probably the huge cloud of dust that Starship kicked up. This was mostly sandy dirt from beneath the Orbital Launch Mount and it wasn't toxic.
There's the economic impacts to consider as well. Before SpaceX arrived, Brownsville Texas was very likely the poorest metropolitan area in the United States. 90% Hispanic, home prices averaging $80k. Today SpaceX is probably Cameron County's largest employer, certainly in terms of payroll if not numbers. They employ thousands of locals in high paying skilled construction type jobs, and that no doubt has ripple effects as those workers spend money in local stores and businesses. Elon has personally donated millions to the Brownsville schools and Starbase often welcomes their field-trips. SpaceX has internship arrangements with the U. of Texas. Doesn't sound like "devastation" to me. Probably one of the best things that's happened to the Rio Grande Valley in its history.
Certainly average home prices are now in the $200K range now and some locals are claiming that Brownsville has become unaffordable. I expect that there are ethnic militants who aren't pleased by white anglos moving into "their" town. And there are no doubt activists at the U. of Texas Rio Grande Valley who will protest anything and everything.
But my understanding is that SpaceX receives widespread popular support in Brownsville and the other south Texas communities. It's not only raised their standard of living away from Mexican levels to more typical American levels, it's also made their communities cool, exciting and desirable places to live. People from all around the world, of many ethnicities, speaking many languages, are tuned in and watching them, wishing they lived there too. All sharing a common fascination with this extraordinary sci-fi vision.
Last night, a tornado struck Port Isabel Texas, one of the closest towns to Starbase (along with South Padre Island), both about 5 miles away. Port Isabel is where many of the former Boca Chica residents moved after SpaceX bought them out.
Several dozen homes were damaged, some severely. Initial reports said there was one death and 10 hospitalized, two in critical condition. But later reports say two dead, so apparently one of the critical cases didn't make it.
Late last night after midnight, Ship 25 which was at Massey's getting pressure tested, rolled out atop SPMTs, proceeded past the Build Area and ended up at the Launch Area, some five miles from Massey's.
SpaceX says that it is slated to undergo a full 6-engine static-fire on one of the suborbital test stands. It's still unknown (to those of us outside SX) whether they plan to fly 25, or whether it is just a test object.
YazataMay 19, 2023 07:39 PM (This post was last modified: May 20, 2023 05:14 AM by Yazata.)
After the first full-stack Starship test flight, the launch pad was pretty torn up by the force of some 30 Raptors at ~90% thrust. In particular the concrete surface under the pad had been turned into a deep crater. The large volume of ejecta (including large concrete chunks) flew everywhere around the launch site and caused quite a bit of damage.
It seems that SpaceX already had a solution in work, but not yet ready by the first launch date. Their mistake was believing that the concrete surface would survive one launch. (It had already survived static fires.)
Elon revealed that the new solution would be a water-cooled steel plate under the launch mount, with water-spray holes that Elon described as an upside down shower-head.
And opinion among the space-nuts was widespread "Yeah right, that'll work!" skepticism. The cooling water would supposedly just turn to steam, blowing the whole thing apart.
Well, it looks like the SpaceX engineers really did the math. Here's video of a proof-of-concept test at McGregor with a full-bore Raptor firing directly at a small test model of Elon's shower-head. The shower-head not only survived, it was still defiantly spraying water when the rocket engine shut down!
The new space-nut opinion is that heat transfer through the steel would be sufficiently low if the other side of the plate was continuously cooled by a high enough flow rate of cold water. What's more, water boiling point is a function of water pressure. The higher the pressure, the higher the boiling point, which is why steam engine boilers don't explode, but will explode if they are ruptured and the pressure in them is released. The cooling water in this thing will be pressurized at something approaching 30 bar. (Water boils at about 230C at 30 bar.) And if the water spray has higher pressure than the rocket exhaust plume, estimated at ~15 bar at that distance from the engine nozzle, the hot rocket exhaust should never actually contact the steel plate.
Ryan Hansen did an extraordinarily good Twitter thread on how he thinks it will fit together and work.
^ ^ ^ ^ ^
It's kind of surprising that apparently(?) no one in the 70 years beforehand ever considered how a super-duper powerful rocket launch would require something more innovative than the traditional limitations of a concrete foundation. "Nah, no collection of engines would ever have destructive effects of significant magnitude on the surface below."
(May 19, 2023 11:24 PM)C C Wrote: ^ ^ ^ ^ ^
It's kind of surprising that apparently(?) no one in the 70 years beforehand ever considered how a super-duper powerful rocket launch would require something more innovative than the traditional limitations of a concrete foundation. "Nah, no collection of engines would ever have destructive effects of significant magnitude on the surface below."
They were using Fondag, perhaps the strongest refractory concrete available on the market. It's specially formulated for strength at high temperatures and pressures. NASA uses it (along with big blast diverters) and it's common in many industrial applications.
The static fires did create some erosion (and fragmentation) of the concrete surface and they decided that it wasn't going to be satisfactory for a launch pad that is intended for repeated use. So Elon and his engineers invented the shower-head. But the big 33 engine static fire only caused limited damage to the concrete surface, which they promptly patched up. So they figured it should be good for the first launch, while they were still busy constructing the pieces of the shower-head.
YazataMay 23, 2023 12:02 AM (This post was last modified: May 23, 2023 12:53 AM by Yazata.)
Tony Bela does infographics on space subjects. Here's his truly extraordinary Orbital Flight Test One infographic. Read his numbered description of what was happening second by second, and it appears to have been a total cascade of problems.
Apart from the pad damage, successive loss of way too many engines and the failure of both hydraulic power units doomed the mission. Right off the pad the thing was accelerating too slowly due to lost engines. Loss of more on the way up probably eliminated any chance it could achieve orbit. And loss of both supposedly redundant hydraulic power units (HPUs) led to loss of steering control. That led to activation of the FTS flight termination system.
But both the pad and the thrust vector control had improvements for subsequent flights already planned and in work before this first flight, so OFT-1 will be the last with the problematic HPUs and the last with the Fondag concrete blast surface.
I'm reasonably confident about solutions to the pad and steering problems. The more difficult problem will be improving raptor engine reliability. They just can't keep losing engines one after another like they did this first time.
One bright spot was the surprisingly good structural strength of the design. There had been some concern about that before the flight, but it held together through Max-Q and then through some crazy corkscrewing (due to loss of steering control, rolling and assymetric thrust) and then actually flipping end to end repeatedly at supersonic velocity. Any normal rocket would have been ripped apart.
YazataMay 24, 2023 07:52 AM (This post was last modified: May 24, 2023 03:09 PM by Yazata.)
Big changes coming at the Starbase build area!
The photo below is by Mauricio of RGV Aerial Photography. The red and green marks are by Zack Golden.
Just to the left of the green rectangle is a grey rectangle. This is the existing factory building. To its left, behind and to the right of the newest "Mega-bay" is a grey rectangle on the ground. This is the foundation of another new vertical assembly bay.
The green rectangle is an extension to the existing grey building that will double the size of the factory. That's phase-1 of expansion and it's already underway with foundation work.
But that's nothing compared to what's coming. The red X's mark existing buildings that are expected to be torn down in the near future. (Their contents are already being cleared out of them.) The whole square space from the green factory expansion to the road will be a phase-2 factory expansion.
Then ultimately, it's believed that the three giant tents will go as well, and phase-3 will engulf that area as well, resulting in a single super-huge square building similar in size to a Tesla giga-factory. To get an idea of the scale, compare its outsize footprint to the cars parked along the road!
This expansion isn't unexpected but it's about twice as large as expected. What we all believed would happen would be tearing out the three tents and expanding the new factory building to the road. That's still probably going to happen, but it will come last instead of being first. Presumably the motivation for leaving it for last is that the three giant tents currently contain too many vital functions, so the tents can't go until the things taking place in them can move into new factory areas that have to be built first.
The ambition seems to be to create a series-production factory capable of churning out three giant spaceships a week! (150 a year!) Elon wants a whole fleet of those babies! Look out solar system! Here comes humanity!!
Apr 30, 2023 02:36 AM
(This post was last modified: Apr 30, 2023 04:24 PM by Yazata.)
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