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SpaceX wiggles Starhopper’s Raptor engine, tests parts ahead of hover test debut

Repeating a test conducted in June with Raptor SN04, SpaceX tested Starhopper and Raptor SN06's thrust vectoring capabilities on July 12th. (NASASpaceflight - bocachicagal)

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6 years ago

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On the evening of July 12th, SpaceX technicians put Starhopper’s freshly-installed Raptor – serial number 06 (SN06) – through a simple but decidedly entertaining test, effectively wiggling the engine in circles.

Designed to verify that Raptor’s thrust vectoring capabilities are in order and ensure that Starhopper and the engine are properly communicating, the wiggle test is a small but critical part of pre-flight acceptance and a good indicator that the low-fidelity Starship prototype is nearing its first hover test(s). Roughly 48 hours after a successful series of wiggles, Starhopper and Raptor proceeded into the next stage of pre-flight acceptance, likely the final more step before a tethered static fire.

Routine for all Falcon rockets, SpaceX’s exceptionally rigorous practice of static firing all hardware at least once (and often several times) before launch has unsurprisingly held firm as the company proceeds towards integrated Starhopper and Starship flight tests. Despite the fact that Raptor SN06 completed a static fire as recently July 10th, SpaceX will very likely put Starhopper and its newly-installed Raptor through yet another pre-flight static fire, perhaps its fourth or fifth test this month.

Although it would undoubtedly be easier, cheaper, and faster to skip that post-delivery static fire, it will simultaneously lower the risk of Raptor failing mid-flight and verify that Starhopper itself is healthy and ready for untethered hovering. Although SpaceX could likely live without Starhopper in the event that it’s lost during flight-testing, any failure capable of destroying the vehicle itself is at least as capable of severely damaging or completely destroying the spartan but still expansive test and launch facilities the company built over the course of several months.

SpaceX has been hard at work gradually building, expanding, and upgrading its South Texas launch facilities since December 2018. (NASASpaceflight – bocachicagal, 04/27/2019)

Would you like some testing with your testing?

Follow July 12th’s nighttime Raptor wiggle test, July 13th was mainly quiet and filled with inspections of Starhopper, Raptor, and other various work. The day after, however, SpaceX proceeded through several hours of propellant loading, ending with what looked like less energetic versions of the Raptor preburner ignition tests Starhopper previously performed with Raptor SN02.

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.

The first obvious test occurred around 7:30pm CT, July 14th. (LabPadre)
The second obvious test followed around 8:50 pm CT. (LabPadre)

Although the fireworks are so subtle that they are easily missed, the conditions inside the preburner – hidden away from view – are actually far more intense than the iconic blue, purple, and pink flame that exists Raptor’s nozzle. This is because the preburners have to nurture the conditions necessary for the pumps they power to fuel the main combustion chamber. 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 the main combustion chamber.

Thus, if the head 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 completely prevent Raptor from starting and running stably and can even trigger a “hard start” or shutdown that could damage or destroy the engine. As such, to preburners fundamentally have to operate at higher chamber pressures (and thus higher temperatures) than the main combustion chamber (the big firey bit at the end). According to Elon Musk, Raptor’s oxygen preburner has the worst of it, operating at pressures as high or higher than 800 bar (11,600 psi, 80 megapascals).

Coincidentally, this is roughly equivalent to the pressure at the bottom of the Pacific Ocean.

Starhopper and Raptor seen on the afternoon of July 14th, preparing for an evening of testing. (NASASpaceflight – bocachicagal)

In short, preburner testing is no less critical than full-on static fire testing with an engine like Raptor. July 14th’s test was also made doubly efficient due to the fact that preburner testing requires liquid propellant, which effectively makes the whole test a wet dress rehearsal (WDR) even before any engine ignition or partial ignition is involved. Per SpaceX moving from propellant loading to preburner/turbine testing, Starhopper is almost certainly healthy and operating as expected, an excellent sign that the ungainly vessel may be ready for a static fire of Raptor as early as 2pm CT, July 15th.

The memes, oh, the memes.

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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 CEO Elon Musk confirms Robotaxi is opening to the public: here’s when

Anyone will be able to request a Tesla Robotaxi in September, Elon Musk said this morning.

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1 hour ago

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August 11, 2025

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Credit: Joe Tegtmeyer | X

Tesla CEO Elon Musk has confirmed that the company’s Robotaxi platform is opening to the public, and he even gave a timeline for when anyone will be able to access one for a ride.

Tesla’s Robotaxi platform launched to a small group on June 22 in Austin, Texas. The company has continued to expand the number of riders and its geofence over the past month and a half.

Tesla officially launches Robotaxi service with no driver

Additionally, it launched rides in the Bay Area of California, but it differs slightly, as the Texas Robotaxi platform does not utilize a Safety Monitor in the driver’s seat. In California, the monitor sits in the driver’s seat.

As the geofence, service areas, and testing populations expand, Tesla fans are awaiting their elusive emails that enable their ability to use the Robotaxi platform. It now seems that the email will come soon, as Musk said Tesla will open up public access to Robotaxi next month:

Tesla has been prioritizing safety over anything else with the launch of the Robotaxi platform, which is why it has been slow to push invitations to new riders. It is confident in the abilities of the platform and its Full Self-Driving suite, which has been proven with data.

However, even a single accident could set Tesla back years in terms of its development of self-driving cars. It is not a risk it is willing to take.

Musk said during the recent Q2 Earnings Call:

“We need to make sure it works when the vehicles are fully under our control. It’s kind of one step at a time here. We don’t want to jump the gun. As I said, we’re being paranoid about safety. But I guess next year is I’d say confidently next year. I’m not sure when next year, but confidently next year, people would be able to add or subtract their car to the Tesla, Inc. fleet.”

As the platform will expand in Austin and the Bay Area for anyone, Tesla still continues to reiterate that Robotaxi will be available for everyone sometime next year, as Musk said in the quote above.

Things will continue to improve over time, and Tesla will likely expand its geofence in both regions in the coming weeks. It has already done that in Austin twice, with about a doubling in size occurring both times.

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Elon Musk

Tesla warns consumers of huge, time-sensitive change coming soon

Tesla is urging customers to take delivery of their new EV by September 30 in order to take advantage of the $7,500 tax credit.

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2 hours ago

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August 11, 2025

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(Credit: Tesla)

Tesla is continuing to warn consumers of a huge, time-sensitive change that is coming soon, as the end of the EV tax credit is less than two months away.

The EV tax credit has offered $7,500 off new EVs and $4,000 off used EVs for certain individuals who qualify due to income. For years, it has been a great incentive for consumers, and it has improved further as car companies were able to apply the credit at the point of sale starting in 2023.

Tesla is ready with a perfect counter to the end of US EV tax credits

However, with the Trump Administration, it always seemed as if the EV tax credit was in jeopardy. Earlier this year, the White House officially announced that it would do away with it completely.

On September 30, the tax credit will be abolished. In order to utilize it, customers will have to take delivery of their vehicle by that date. Orders placed before September 30 without delivery by that day will not be able to utilize the credit.

Tesla is truly pushing this point incredibly hard: the sooner an order gets in, the more likely you are to take delivery of the car by September 30.

The end of the EV tax credit is something that has been looming on the minds of electric carmakers, consumers, and investors.

The $7,500 discount for buying a clean energy vehicle truly puts many of the cars in a much more affordable price range. Without it, the least expensive Tesla model will be the Model 3 Rear-Wheel-Drive, which starts at $42,490.

That price comes down to $34,990 with the tax credit, and brings the monthly payment down about $130, depending on how much money is put down.

Despite the change, CEO Elon Musk does not believe it will impact Tesla negatively. In fact, he has been in favor of getting rid of the EV tax credit for several years, believing it will actually work to Tesla’s advantage.

Perhaps the most interesting thing that will come of this is how all EV makers will be impacted by the loss of credit. Musk believes Tesla will come out as the big winner here, especially as it plans to roll out new affordable models sometime this year.

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Tesla FSD V14 gets tentative release date

The update will feature a 10X higher parameter count, among other improvements.

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3 hours ago

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August 11, 2025

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Credit: Whole Mars Catalog/YouTube

Tesla is not releasing Unsupervised FSD to regular customers yet, but the company seems to be preparing something special for its FSD users nonetheless. 

This was, at least, according to Elon Musk in a recent post on X.

Tesla FSD V14

Tesla’s FSD program has been deemed by Elon Musk as one of the key factors that would determine the company’s long term success. Over the past months, however, Tesla has mostly been focusing on the rollout and ramp of its Robotaxi program in Austin and the Bay Area. Tesla’s Robotaxi service uses Unsupervised FSD, which is not yet released to customers.

However, in a post on X, Musk stated that Tesla is preparing its next big update for its consumer-grade FSD system—V14. Musk did not provide a lot of details about FSD V14’s capabilities, but the CEO did state that the update will feature a 10X higher parameter count, among other improvements.

“The FSD release in about 6 weeks will be a dramatic gain with a 10X higher parameter count and many other improvements. It’s going through training & testing now. Once we confirm real-world safety of FSD 14, which we think will be amazing, the car will nag you much less,” Musk wrote in his post.

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Tesla Unsupervised FSD Rollout

During the second quarter earnings call, Tesla executives were asked for a timeline on the rollout of Unsupervised FSD to consumer vehicles. In his reply, Musk stated that he believes Unsupervised FSD will be available for consumers in certain geographies. He did explain that Tesla will be extra careful with the system’s release. 

“We are getting there. I think it will be available for unsupervised personal use by the end of this year in certain geographies. We are just being very careful about it. This is not something we should rush,” Musk said, adding that “I am confident that by this year, within a number of cities in the US, it will be available to end users.

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