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In Boca, they still haven't started construction of their next 'Mark 3' prototype. Instead, they have been devoting all of their attention to improving their facilities and manufacturing methods. Apart from lots of earth-grading work and what appear to be new building foundations appearing, the biggest event has been the appearance of a giant tent currently under construction. (SpaceX has a demonstrated fondness for giant tents. Cheap and easy to erect and take down.)

Photo by SpacePadreIsle:



Edit: The contractor putting up the giant tents in Boca is Sprung Structures. (It's a Canadian company, from Calgary! They are all over the world now.) This is the same company that put up the giant tent that Tesla called upon to house the additional Model 3 assembly line that they constructed outside their huge Fremont California factory, in order to boost production to meet demand. So Elon is familiar with these people, with their products and with the speed with which they can erect structures. Relatively inexpensive too, compared to conventional factory buildings. The one in Boca looks like it will be shorter but taller and wider than the one in Fremont. (But longer than in the photo, they are still adding arches to it.) Everyone calls these structures "tents" (even Elon does) and they are that: tough waterproof fabric over frames. But they are built to potentially be permanent structures. Tesla needed a fast solution and the Tesla tent was completed in 19 days. Tesla was setting up the assembly line as the tent was being erected around it and new cars were rolling off three weeks after the project started.

https://www.sprung.com/case-study/tesla/

Sprung photo:

NSF story about recent test-stand upgrades at McGregor and about SpaceX's busy upcoming 2020 manifest of rocket engine tests. Lots of acceptance/check-out tests for the many Falcon 9 Merlins, as well as continuing development tests for the new Raptors. Hopefully the Raptors will also be well into quantity production by later in the coming year.

https://www.nasaspaceflight.com/2019/12/...busy-2020/

Video of a rocket engine test-fire at McGregor. Unclear whether this is Merlins or a Raptor. (Consensus seems to be Merlins.) It was an extended burn. (Don't know how much was omitted at the beginning.) Every second these things run, the SX engineers get more of their beloved data. (Engineers love data.)

https://twitter.com/bluemoondance74/stat...5263448070

Here's Labpadre's video flyover of the Boca Chica shipyard and launch areas, filmed Friday in a Cessna. The video starts in a room with a very cool glass table built atop an old aircraft radial engine (it's at a small general aviation airport). Lab goes outside and gets in the plane with the pilot, they take off and fly over the shipyard and launch area repeatedly with closeups. You see the vertical building with a newly constructed fuel tank bulkhead inside, the still-under-construction giant tent with what look like numerous rolls of something at one end. A large graded area to the west between the other end of the giant tent and Stargate that's seemingly being prepped for something, the smaller ring machine tent with some rings nearby (I'm guessing that they are test rings as they perfect their process) and more. 

https://twitter.com/LabPadre/status/1210966541249974274

Regarding the giant tent, it may be near its final size, but now they are installing insulation on its inner surface. I think that's what the rolls might be, insulation. It looks like they are planning to construct a whole climate-controlled manufacturing area in there. The newest upcoming Starship is no longer being referred to as "Mark 3" but as "SN 1" (serial number 1, like the Raptors). If a rocket doesn't perform (like Mark 1 didn't) it's simply erased from history like it never existed. More seriously, it does indicate that there may have been some kind of reset in SpaceX thinking. That much is obvious frm how they more or less shut down Cocoa and how they are behaving at Boca. Lots more emphasis on infrastructure and fabrication methods.

Elon's still issuing his time-dilated "Elon time" projections about when "SN 1" will be completed and flying. He says 2 to 3 months. Construction of the vehicle hasn't even started yet!

https://twitter.com/elonmusk/status/1210756057791729665

There's also some speculation that SN1 might be built horizontally this time, on its side in the giant tent. More like the Falcons are manufactured.

Today (Saturday) there are cement trucks pouring cement, perhaps to replace the dirt with a concrete floor surface.

It looks like Elon may be there in person, since he posted this. It sounds like he pulled an all-nighter with his guys as they constructed a fuel tank bulkhead. You can see the walls of the container fort, perhaps to reduce wind for better welding.

https://twitter.com/elonmusk/status/1210649166407438336

It appears that there's a road closure scheduled for Jan 6. Seeing as how they haven't even started construction of SN1 yet, there's speculation that they might be planning to slap together a small tank out of their test rings with top and bottom bulkheads, put it on a stand at the launch area, and intentionally pressurize it to the point where it explodes. Just to see what their improved welds and manufacturing techniques can withstand.

Or (less exciting) they might just be planning to move some heavy equipment or something, and need the road clear for that.

There's additional speculation that they might be planning to construct a second giant tent beside the one they are completing now. LabPadre's flyover video seems to suggest that they are preparing an area next to the giant tent about the same size.

Sad that the "starship welded together out in the open of a hillbilly junkyard" look seems to be fading for the usual, obscuring, big assembly edifice. The former was so Zefram Cochrane -ish.

Elon's just let loose an absolute tweet-storm of information about Starship and SpaceX's plans.

First, he posted another video of tank bulkhead manufacturing. Definitely not a clean-room environment. (More on that below.):

https://twitter.com/elonmusk/status/1211531714633314304

At least one of the dome bulkhead has been joined to its ring

https://twitter.com/elonmusk/status/1211577293296087041

Tim Dodd asked, "Is there any substantial difference in welding/manufacturing techniques between these bulk heads and MK-1/MK-2?"

Elon replies, "Almost everything is different. These parts are stamped vs manually bump-formed & TIP TIG welded vs flux core. Higher precision, stronger joints & 20% mass reduction.

Best would probably be an autogenous laser weld, but we need more precise parts & fixtures. Hopefully get that done in 2020."

Tim Dodd again, "Speaking of autogenous, when will we see autogenous pressurization on Starship? I assume the first couple will still utilize helium COPVs like StarHopper?"

Elon: "No, will be autogenous from the start, tapping hot CH4 & O2 from Raptor"

Tesla Owners Silicon Valley ask: "Is the team going to be working through the night to complete?"

Elon: "Yeah"

Somebody asked: "Have you heard of solid-state ultrasonic welding?"

Elon: "Tesla uses that to wirebond cells to module current collectors. Is there a commercially available machine that can weld ~4mm full hard 301 stainless barrels & domes?"

Somebody else asked the question we've been wondering: "Will SpaceX keep manufacturing Starship (and, presumably Super Heavy too) out in the open, or do you foresee eventually moving production into (the industry norm) cleanrooms?"

Elon: "Moving to an enclosed (fairly) clean room environment for SN2 in Jan, although, unlike aluminum, stainless steel welding is not super sensitive. Our main issue here in Boca is that it can get very windy, which affects weld arc & steel melt pool."

Somebody asks, "Texas, Florida, ... do you have the next Starship sites picked out?"

Elon: "We're focusing on Boca right now for Starship & Cape is focused on Falcon/Dragon"

Tim Dodd again: "Have you moved onto direct drive / electromechanical on the body flaps with motors yet or still spinning a pump for SN1?"

Elon: "Direct drive using several Tesla Plaid motors in parallel for SN1. Simpler, lighter & more fault tolerant. Rear flaps each need ~1.5 megawatts. It's like moving the entire wing of an aircraft!"

Somebody asks: "So we're gonna see the plaid power train in action in a spacecraft before we see it in a production Tesla?"

Elon: "Building prototypes is relatively easy, volume production is hard"

Somebody suggests: "How about worm gears for the rear flaps like the jack screws in planes with an upper rear elevator on their tails? Could you make them strong enough because getting enough torque to drive them at such a high gear ratio wouldn't be an issue."

Elon responds: "Many ways to solve this problem, but the power requirements are much higher than aircraft control surfaces. When moving giant body flaps rapidly, achieving high power is much harder than high torque."

***********************************

One of the NSF engineers exclaims, "Holy cow..."

(Dec 30, 2019 02:59 AM)C C Wrote: [ -> ]Sad that the "starship welded together out in the open of a hillbilly junkyard" look seems to be fading for the usual, obscuring, big assembly edifice. The former was so Zefram Cochrane -ish.

There's still an element of that. The tank bulkheads that they've been working on day and night are still being completed outside in fairly rough conditions.

Elon says that they will be be constructing SN 2 (their second new-era 'serial number' Starship) indoors. I'm assuming that the indoors that he's talking about is the new Giant Tent, which should have a concrete floor and insulation by then. Keeping the howling Boca Chica winds out suggests that the ends will get walls (otherwise the tent could become a wind tunnel). The Giant Tent is impressively tall, but not tall enough to house a vertical Starship. So they must be planning to build it horizontally, on its side.

Which still leaves us with the question of SN 1. Will it be constructed outdoors?

Another Elon tweet that I missed yesterday:

Scott Manley asks: "Really curious as to what you think of the explosive hydro forming process that was used for the Saturn V bulkheads."

Elon: "We use that process for the Raptor nozzle jacket. The knuckles of this dome were stamped in Michigan with a 4000 ton car body press, which costs much less for the same outcome."

https://twitter.com/elonmusk/status/1211539123758141445

And some explanation for "Tesla Plaid motors" and "Plaid power train" from earlier tweets, from Road and Track:

"If you've seen Mel Brooks's Star Wars parody, Spaceballs, you know that after Ludicrous Speed, you go Plaid. Four years ago, Tesla launched the Ludicrous Speed upgrade for the Model S sedan, and promised that "Maximum Plaid" would be the next thing to come."

As illustration of how quickly the Giant Tent has appeared, here's a undated photo (by local pilot Sam Sun) believed to have been taken around the middle of December. The location where the Giant Tent is to go is below and to the right of Poppy's forgotten nose. But people are pointing out that there's a similar sized space cleared just to the left of this location and there's speculation that a second giant tent might be planned there. And there's the area closer to the camera that's been getting lots of attention from the earth movers and graders, so something is expected to happen there too.



And here's a photo taken Dec 30 by Mary:

Today Friday January 3, there are lots of cement trucks lined up to get in. Pouring more concrete flooring is my guess.

In addition to that, more trucks are arriving carrying what some observers believe are parts of the structural framework for a second giant tent. That would confirm the speculations that another giant tent is to be erected right next to the one now being completed. Combined, two Giant Tents would total a truly huge enclosed work area. We've seen that Sprung Structures can build these things in as little as 3 weeks. (Their company impresses me. Impressed Elon too apparently, since he's giving them so much business.)

Other trucks seen arriving in the last few days were carrying girth-welding machines and ring-making machines from IMCAR, an Italian metal fabrication machinery company. (The labels on crates can tell engineering sleuths a lot.) So I'm guessing that the test-runs in the smaller ring-making tent have told SpaceX what they wanted to know. They have good idea of how they are going to do this and are now outfitting the Giant Tents with metal fabrication machines.

There was a Boca Chica road closure today, but they cancelled it.

https://twitter.com/BocaChicaGal/status/...6285515776

(Originally for the 6th, then for the 8th, now (maybe) for next Monday the 13th. (Still nothing on the official county road closure webpage though.)

Question is... why?

We know that they have been making difficult to construct pressure bulkheads. Then they mated the bulkheads with rings. Then they flipped one of these ringed bulkheads upside down and placed it in one of the stands.

Now they seem to have placed another ringed bulkhead on top and are welding them together to create a pressure tank.

So the speculations are that they will transport one of these new pressure tanks down to the launch area, pressurize it and see if all the welds hold.

There's still lots of questions about whether this tank is a flight article, or just a test article. If it's the former, they might want to use it on their coming SN1 Starship and just figured that given what happened to Poppy, they probably should pressure test it before it has a whole spaceship built  around it. If it's the latter, just a test of their manufacturing techniques, there's the possibility that they might test it to destruction to determine precisely what its limits are.

The engineers are busy calculating its volume to see if it corresponds to the known size of either the Starship O2 or CH4 tanks. It may need additional rings.

But before they can pressurize it, it still needs the necessary plumbing. So they need time to complete it. (Whatever it is.)