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SpaceX Starship test tank survives first two nights of stress testing

SpaceX's newest Starship test tank has survived the first round of stress testing. SN2 - very similar to SN7.1 - is pictured here in March 2020. (NASASpaceflight - bocachicagal)

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SpaceX’s newest Starship test tank has survived the first two nights of stress testing, pushing the steel tank one step closer to a destructive finale.

Known as Starship SN7.1, the new tank – aside from one critical difference – is similar to Starship SN2 (pictured above), a full-scale prototype SpaceX repurposed into a test tank in March 2020. SN2 served to test improvements made to the design of Starship’s “thrust puck,” a dense steel cone that must transmit the thrust of three Raptor engines through the rest of the rocket. Much like SN2, SN7.1 is a test tank with a focus on the behavior of Starship’s engine section under extreme loads at cryogenic temperatures.

Unlike SN2, however, SN7.1 is built almost entirely out of a new steel alloy – closer to 304L than the 301 stainless used on all previous prototypes.

SN2, July 2020. (NASASpaceflight – bocachicagal)
Design-wise, SN7.1 is almost identical to SN2. (NASASpaceflight – bocachicagal)

SpaceX rolled the tank to the launch site and pressurized it with cryogenic liquid nitrogen on September 10th as part of a routine “cryo proof” acceptance test. SN7.1 appeared to complete that proof without issue, exhibiting no leaks or unusual behavior, and likely reached pressures of 7.5-8 bar (~110-120 psi) before detanking.

Over the next three days, SpaceX inspected the test tank, relocated it to a more capable (and expensive) test stand, and connected hydraulic rams (used to mechanically simulate engine thrust) to its thrust puck.

While SpaceX never confirmed results, Starship test tank SN7 is believed to have broken pressure records before it burst, a strong sign that the new steel alloy is the superior choice for future prototypes. (NASASpaceflight – bocachicagal

Around midnight on September 15th, SpaceX kicked off the first round of SN7.1 stress testing, repeatedly loading and unloading the tank with liquid nitrogen. While it’s impossible to visually confirm the use of the stand’s hydraulic rams, it’s safe to assume that SpaceX used them to stress SN7.1’s thrust puck while chilled to cryogenic temperatures. The new steel alloy SpaceX is using on SN7.x and prototypes SN8 and beyond is designed to be less brittle at cryogenic temperatures, nominally ensuring that flawed or aged Starship tanks leak before they burst or explode.

Aside from the obvious triple-Raptor thrust simulation, SpaceX likely also simulated thrust from one or two Raptors to verify the new design’s ability to survive asymmetric thrust in engine-out scenarios. Ultimately, SN7.1 made it through the night without obvious issues and there have been no signs of leak-fixing today, suggesting that the tank performed well. SpaceX has a second SN7.1 test period scheduled to begin on September 17th, as well as backups on the 15th, 16th, 20th, and 21st. More likely than not, SN7.1’s next test will end when the tank is intentionally pressurized to failure.

Update: SpaceX has kicked off another night of SN7.1 stress testing, beginning almost as soon as the nine-hour window opened (9pm CDT (UTC-5) on September 15th). As of midnight, the company has already put the test tank through one cycle, rapidly filling and pressurizing it with liquid nitrogen before detanking. It remains to be seen if the company will continue testing this window, which closes at 6am on Wednesday. There is also a chance that SpaceX will intentionally pressurize SN7.1 to failure tonight, although it’s much more likely that the tank will be returned to a cheaper, simpler transport stand rather than risking damage to a new launch mount.

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Eric Ralph is Teslarati's senior spaceflight reporter and has been covering the industry in some capacity for almost half a decade, largely spurred in 2016 by a trip to Mexico to watch Elon Musk reveal SpaceX's plans for Mars in person. Aside from spreading interest and excitement about spaceflight far and wide, his primary goal is to cover humanity's ongoing efforts to expand beyond Earth to the Moon, Mars, and elsewhere.

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Tesla has a Cybercab problem nobody saw coming

Tesla’s Cybercab line now builds robotaxis faster than Tesla can deploy them, Lars Moravy says.

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Tesla’s Cybercab line in Texas can now build the two seat robotaxi faster than the company can put it into service, according to Lars Moravy, Tesla’s Vice President of Vehicle Engineering. “We don’t run every day because the line can run so fast. It’s currently outpacing our deployments,” Moravy said in a new Cybercab deep dive from Munro Live. “So, it’s a bit of a race right now. Who’s going to go faster? Right now the manufacturing line’s ahead.”

Tesla’s official Robotaxi account shared a Cybercab analysis video on X on Monday, calling it a “Cybercab engineering deep dive.” Moravy’s comments go further than what he told analysts on the Q3 earnings call last week, when he said the Cybercab line’s listed capacity of more than 125,000 units a year undersells what it can actually run.

The tour shows where that speed comes from. Tesla’s unboxed process splits the Cybercab into front, rear, side and center modules that are built and tested on their own before they meet on a short final line. That final line has just 25 fully automated stations, which Tesla’s team estimated is a fifth to a tenth of what a Model Y needs. The full line is about 78% automated, the framing line is already at 100%, and the layout uses roughly 50% less floor space per vehicle. The stated goal is “100% automation in 10 second cycle time,” or one finished Cybercab every 10 seconds.

Tesla also deleted the paint shop. Only the side modules are coated, and the exterior panels get their color inside the molding machine. Engineers said the car is designed to run at least 500,000 miles, which matters for a vehicle that will spend most of its day carrying riders.

The battery got the same treatment. The Cybercab uses an 88S6P pack of 4680 cells in a steel enclosure, a first for Tesla, with each module potted separately so a single failed module can be swapped instead of the whole pack. Wireless battery management boards replace a wiring harness, and new contactors are fast enough to drop the pyro fuse entirely. Tesla’s battery director graded the pack an A minus, compared with a D for the Model Y structural pack and a B minus for Cybertruck. Up front, the drive unit runs an 11:1 gear ratio versus roughly 9:1 on most Teslas, since the Cybercab does not need a high top speed.

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The deployment side is now the bottleneck Moravy described. Tesla had more than 50 Cybercabs working the Formula 1 weekend in Austin, and Texas records show 463 Cybercabs registered. Tesla said on its earnings call that Cybercab service will launch in Dallas next month, and Moravy said the company is aiming to get Cybercabs to customers by the end of 2026. Every unit built so far has gone into Tesla’s own fleet since the line moved into volume production in April.

Munro Live also asked when it could get a Cybercab to tear down. Tesla’s answer: “Not yet.”

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How SpaceX Is raising Raptor’s sea-level thrust while holding engine mass steady

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Credit: SpaceX

SpaceX’s Raptor engine family has steadily increased sea-level thrust while simultaneously reducing mass, turning iterative engineering gains into substantially higher performance for the Super Heavy booster. CEO Elon Musk shed more light on how powerful Raptor 4 will be, and it’s pretty crazy.

Raptor 1 delivered 185 metric tons of thrust at roughly 2,080 kilograms, while Raptor 2 raised that to 230 tons while cutting mass to about 1,630 kilograms. SpaceX data for Raptor 3 lists a target of 280 tons at 1,525 kilograms (with further reductions in associated vehicle hardware), while operational flight ratings have been cited near 250 tons.

This morning, Elon Musk stated that Raptor 4 is expected to reach 300 tons of sea-level thrust at roughly the same mass as Raptor 3. Across these versions, thrust has risen by more than 60 percent from the first engines while engine mass has fallen, producing a sharp improvement in thrust-to-weight ratio. This is a true testament to how great SpaceX engineering has been:

With 33 engines on SuperHeavy, the jump from earlier versions to a 300-ton Raptor 4 would produce roughly 9,900 metric tons of total liftoff thrust, nearly three times the Saturn V’s approximately 3,400 metric tons from its five F-1 engines.

This is not just a larger number on a data sheet, either, as sea-level thrust is the force available the moment the vehicle leaves the pad. This is when it is heaviest and still deep in Earth’s gravity well and dense atmosphere.

Higher levels of sea-level thrust directly improves the initial thrust-to-weight ratio of the full stack. A higher ratio produces faster acceleration off the pad, which shortens the time the rocket has to spend fighting gravity, and gravity losses during the first minute or two of the flight are a major drain on total available delta-v. Every second shaved off of that early climb preserves more propellant energy for reaching orbital velocity or for carrying extra payload.

Because Super Heavy’s engine count is constrained by vehicle diameter and packing density, increasing thrust per engine is the most straightforward way to raise total liftoff performance without redesigning the booster structure or design.

The same-mass target for Raptor 4 is equally important. Holding engine mass roughly constant while raising thrust improves the engine’s own thrust-to-weight ratio and reduces the structural and propellant mass fraction that must be carried solely to support the engines.

Earlier Raptor iterations also simplified or eliminated extensive vehicle-side hardware such as heat shields. These gains compound: more force for less installed mass leaves additional capacity for propellant, payload, or operational margins such as engine-out capability.

For Starship’s architecture, the practical effects are large. Greater liftoff thrust supports heavier vehicles, larger propellant loads, and higher payloads to low Earth orbit, figures SpaceX has targeted in the 100-plus-ton reusable range. That capacity underpins orbital refueling, lunar missions, and eventual Mars cargo and crew flights.

Continued growth in sea-level thrust therefore tightens the gap between theoretical rocket performance and the high flight rates and reusability needed to make large-scale space transport practical.

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Tesla Assisted Driving expands to tenth EU country

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Tesla has expanded its Tesla Assisted Driving (TAD) suite to its tenth European country, as Latvia joined a growing list of European Union member states authorizing the company’s advanced driver assistance technology.

Tesla Europe announced this morning that the system is now approved in Latvia, with a software rollout to begin soon.

The approval and rollout follow recognition of a provisional European type approval originally granted by the Netherlands’ RDW authority on April 10.

Latvia’s Road Traffic Safety Directorate (CSDD) evaluated the Dutch documentation, coordinated with the other national authorities, and reviewed updates from Tesla. These included tightened limits on speed offsets, automatic resets of any manual speed adjustments after each trip, and stronger driver monitoring.

In Europe, the feature is marketed as Tesla Assisted Driving after a recent rule change that labeled the name “Full Self-Driving” as misleading.

Tesla starts showing how FSD will change lives in Europe

The system remains an SAE Level 2 driver assistance tool, not unsupervised autonomy. It can control speed, steering, braking, lane changes, and intersections while following a navigation route. Drivers need not keep their hands on the wheel at all times, yet they must continuously monitor the road and be prepared to intervene immediately.

The sequence of EU recognitions began with the Netherlands in April and continued through Lithuania, Estonia, Denmark, Belgium, Slovenia, Czechia, Croatia, and Slovakia. Most have relied on mutual recognition of the single Dutch provisional approval rather than independent national testing.

These national clearances do not yet constitute bloc-wide authorization. An EU-wide decision requires a qualified majority in the Technical Committee on Motor Vehicles: at least 15 of 27 member states representing 65 percent of the EU population. Larger markets, like Germany, France, and Italy, remain under review, and a vote is expected this December.

However, for Latvian Tesla owners with compatible vehicles and software, the imminent rollout expands access to the supervised system while underscoring that attentive human oversight remains essential.

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