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SpaceX delays Starhopper’s first flight a few days despite Raptor preburner test success
SpaceX has (partially) ignited Starhopper’s freshly-installed Raptor engine, successfully verifying that the engine is ready for its next major test: a full ignition and static firing. Although successful, SpaceX still has some work to do before the vehicle is ready for its first untethered flight(s).
July 15th’s progress is just the latest in a several day-series of preflight tests designed to reduce the likelihood that Starhopper is destroyed over the coming days and (hopefully) weeks. If all goes planned during the awkward Starship prototype’s first foray into hover tests, SpaceX CEO Elon Musk has stated that he will provide an official presentation updating the public on the status of the company’s ever-changing next-generation rocket.
The past week or so of Starhopper preflight testing began with Raptor serial number 6 (SN06) completing the last of a series of acceptance test fires in McGregor, Texas on June 10th. Even on its own, this was a major milestone for the new SpaceX engine: Raptor SN06 was the first of the new, full-scale engines to pass the acceptance test program with flying colors. According to Musk, for the engine to complete those tests so successfully, SpaceX had to solve a challenging bug in which some sort of mechanical resonance (i.e. vibration) damaged or destroyed Raptors SN01-05.
Hours later, the engine began a short ~450 mi (720 km) journey south to Starhopper, located in Boca Chica, Texas. The engine arrived on July 11th and was fully installed on Starhopper by the following evening (July 12th), at which point SpaceX put Starhopper and Raptor through some mild but valuable thrust vector controller (TVC) tests, wiggling the car-sized engine to ensure it can accurately steer the prototype rocket.
Around two days after the above ‘wiggle’ test was successfully completed, SpaceX moved into the next stage, partially fueling Starhopper with liquid methane and oxygen propellant and helium pressurant in what is known in rocketry as a wet dress rehearsal (WDR). The (implicitly) successful WDR was capped off with a duo of what can now safely be concluded were some sort of Raptor test preceding even pre-ignition operations. Whatever the tests were, they appear to have been completed successfully.
That appears to be the case because less than 24 hours after their completion, on July 15th, SpaceX once again began loading Starhopper with propellant and pressurant for a second round of wet testing. This time around, SpaceX got right into more critical Raptor tests once enough propellant was loaded, igniting the engine’s interwoven oxygen and methane preburners.
Previously discussed 24 hours ago in a Teslarati article focused on Raptor wiggles and other miscellaneous tests, Raptor is an extremely advanced rocket engine based on a cycle (i.e. how propellant is turned into thrust) known as full-flow staged combustion.
“In a staged-combustion engine like Raptor, getting from the supercool liquid oxygen and methane propellant to 200+ tons of thrust is quite literally staged, meaning that the ignition doesn’t happen all at once. Rather, the preburners – essentially their own, unique combustion chambers – ignite an oxygen- or methane-rich mixture, the burning of which produces the gas and pressure that powers the turbines that bring fuel into the main combustion chamber. That fuel then ignites, producing thrust as they exit the engine’s bell-shaped nozzle.
Unintuitively, conditions inside the preburner – hidden away from view – are actually far more intense than the iconic blue, purple, and pink flame that visibly exists Raptor’s nozzle. Much like hot water will cool while traveling through pipes, the superheated gaseous propellant that Raptor ignites to produce thrust will also cool (and thus lose pressure) as it travels from Raptor’s preburner to its main combustion chamber. If the pressure produced in the preburners is too low, Raptor’s thrust will be (roughly speaking) proportionally limited at best. At worst, low pressure in the preburners can trigger a “hard start” or shutdown that could destroy the engine. According to Elon Musk, Raptor’s oxygen preburner thus has the worst of it, operating at pressures as high or higher than 800 bar (11,600 psi, 80 megapascals).”
In full-flow staged combustion (FFSC), even more complexity is added as all propellant that touches the engine must necessarily end up traveling through the main combustion chamber to eke every last ounce of thrust out of the finite propellant a rocket lifts off with. As such, FFSC engines can be about as efficient as the laws of physics allow any given chemical rocket engine to be, at the cost of exceptional complexity and brutally difficult development.
Additionally, FFSC physically requires two separate preburners and then makes things even harder by making each separate preburner (methane and oxygen) depend on each other’s operation for the engine to fully ignite. This means that no individual preburner can be used to kickstart Raptor – instead, SpaceX must somehow spin the turbopumps that feed propellant into each preburner with some separate system. This is all just to emphasize the fact that Raptor’s ignition sequence is a spectacularly complex orchestra of valves, spark plugs, sensors, and magic. This is why it’s valuable for Raptor to test its preburner system independently of an actual ignition test, at least as long as the engine is still in the development stages.
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According to NASASpaceflight.com managing editor Chris Bergin, what this practically translates to is a minor Starhopper hover test delay of 1-2 days, while the static fire has also been pushed roughly 24 hours from July 15th to July 16th. If that full static fire produces lots of happy data, Starhopper could be cleared for a hover test debut attempt as early as Wednesday or Thursday (July 17/18).
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Tesla Model Y is still China’s best-selling premium EV through October
The premium-priced SUV outpaced rivals despite a competitive field, while the Model 3 also secured an impressive position.
The Tesla Model Y led China’s top-selling pure electric vehicles in the 200,000–300,000 RMB segment through October 2025, as per Yiche data compiled from China Passenger Car Association (CPCA) figures.
The premium-priced SUV outpaced rivals despite a competitive field, while the Model 3 also secured an impressive position.
The Model Y is still unrivaled
The Model Y’s dominance shines in Yiche’s October report, topping the chart for vehicles priced between 200,000 and 300,000 RMB. With 312,331 units retailed from January through October, the all-electric crossover was China’s best-selling EV in the 200,000–300,000 RMB segment.
The Xiaomi SU7 is a strong challenger at No. 2 with 234,521 units, followed by the Tesla Model 3, which achieved 146,379 retail sales through October. The Model Y’s potentially biggest rival, the Xiaomi YU7, is currently at No. 4 with 80,855 retail units sold.
Efficiency kings
The Model 3 and Model Y recently claimed the top two spots in Autohome’s latest real-world energy-consumption test, outperforming a broad field of Chinese-market EVs under identical 120 km/h cruising conditions with 375 kg payload and fixed 24 °C cabin temperature. The Model 3 achieved 20.8 kWh/100 km while the Model Y recorded 21.8 kWh/100 km, reaffirming Tesla’s efficiency lead.
The results drew immediate attention from Xiaomi CEO Lei Jun, who publicly recognized Tesla’s advantage while pledging continued refinement for his brand’s lineup.
-->“The Xiaomi SU7’s energy consumption performance is also very good; you can take a closer look. The fact that its test results are weaker than Tesla’s is partly due to objective reasons: the Xiaomi SU7 is a C-segment car, larger and with higher specifications, making it heavier and naturally increasing energy consumption. Of course, we will continue to learn from Tesla and further optimize its energy consumption performance!” Lei Jun wrote in a post on Weibo.
Elon Musk
SpaceX’s Starship program is already bouncing back from Booster 18 fiasco
Just over a week since Booster 18 met its untimely end, SpaceX is now busy stacking Booster 19, and at a very rapid pace, too.
SpaceX is already bouncing back from the fiasco that it experienced during Starship Booster 18’s initial tests earlier this month.
Just over a week since Booster 18 met its untimely end, SpaceX is now busy stacking Booster 19, and at a very rapid pace, too.
Starship V3 Booster 19 is rising
As per Starbase watchers on X, SpaceX rolled out the fourth aft section of Booster 19 to Starbase’s MegaBay this weekend, stacking it to reach 15 rings tall with just a few sections remaining. This marks the fastest booster assembly to date at four sections in five days. This is quite impressive, and it bodes well for SpaceX’s Starship V3 program, which is expected to be a notable step up from the V2 program, which was retired after a flawless Flight 11.
Starship watcher TankWatchers noted the tempo on X, stating, “During the night the A4 section of Booster 19 rolled out to the MegaBay. With 4 sections in just 5 days, this is shaping up to be the fastest booster stack ever.” Fellow Starbase watcher TestFlight echoed the same sentiments. “Booster 19 is now 15 rings tall, with 3 aft sections remaining!” the space enthusiast wrote.
Aggressive targets despite Booster 18 fiasco
SpaceX’s V3 program encountered a speed bump earlier this month when Booster 18, just one day after rolling out into the factory, experienced a major anomaly during gas system pressure testing at SpaceX’s Massey facility in Starbase, Texas. While no propellant was loaded, no engines were installed, and no one was injured in the incident, the unexpected end of Booster 18 sparked speculation that the Starship V3 program could face delays.
-->Despite the Booster 18 fiasco, however, SpaceX announced that “Starship’s twelfth flight test remains targeted for the first quarter of 2026.” Elon Musk shared a similar timeline on X earlier this year, with the CEO stating that “ V3 is a massive upgrade from the current V2 and should be through production and testing by end of year, with heavy flight activity next year.”
Considering that Booster 19 seems to be moving through its production phases quickly, perhaps SpaceX’s Q1 2026 target for Flight 12 might indeed be more than feasible.
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Elon Musk makes a key Tesla Optimus detail official
“Since we are naming the singular, we will also name the plural, so Optimi it is,” Musk wrote on X.
Tesla CEO Elon Musk just made a key detail about Optimus official. In a post on X, the CEO clarified some key wording about Optimus, which should help the media and the public become more familiar with the humanoid robot.
Elon Musk makes Optimus’ plural term official
Elon Musk posted a number of Optimus-related posts on X this weekend. On Saturday, he stated that Optimus would be the Von Neumann probe, a machine that could eventually be capable of replicating itself. This capability, it seems, would be the key to Tesla achieving Elon Musk’s ambitious Optimus production targets.
Amidst the conversations about Optimus on X, a user of the social media platform asked the CEO what the plural term for the humanoid robot will be. As per Musk, Tesla will be setting the plural term for Optimus since the company also decided on the robot’s singular term. “Since we are naming the singular, we will also name the plural, so Optimi it is,” Musk wrote in his reply on X.
This makes it official. For media outlets such as Teslarati, numerous Optimus bots are now called Optimi. It rolls off the tongue pretty well, too.
Optimi will be a common sight worldwide
While Musk’s comment may seem pretty mundane to some, it is actually very important. Optimus is intended to be Tesla’s highest volume product, with the CEO estimating that the humanoid robot could eventually see annual production rates in the hundreds of millions, perhaps even more. Since Optimi will be a very common sight worldwide, it is good that people can now get used to terms describing the humanoid robot.
-->During the Tesla 2025 Annual Shareholder Meeting, Musk stated that the humanoid robot will see “the fastest production ramp of any product of any large complex manufactured product ever,” starting with a one-million-Optimi-per-year production line at the Fremont Factory. Giga Texas would get an even bigger Optimus production line, which should be capable of producing tens of millions of Optimi per year.
Tesla Model Y is still China’s best-selling premium EV through October
SpaceX’s Starship program is already bouncing back from Booster 18 fiasco
