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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.
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 already has a complete Robotaxi model, and it doesn’t depend on passenger count
That scenario was discussed during the company’s Q4 and FY 2025 earnings call, when executives explained why the majority of Robotaxi rides will only involve one or two people.
Tesla already has the pieces in place for a full Robotaxi service that works regardless of passenger count, even if the backbone of the program is a small autonomous two-seater.
That scenario was discussed during the company’s Q4 and FY 2025 earnings call, when executives explained why the majority of Robotaxi rides will only involve one or two people.
Two-seat Cybercabs make perfect sense
During the Q&A portion of the call, Tesla Vice President of Vehicle Engineering Lars Moravy pointed out that more than 90% of vehicle miles traveled today involve two or fewer passengers. This, the executive noted, directly informed the design of the Cybercab.
“Autonomy and Cybercab are going to change the global market size and mix quite significantly. I think that’s quite obvious. General transportation is going to be better served by autonomy as it will be safer and cheaper. Over 90% of vehicle miles traveled are with two or fewer passengers now. This is why we designed Cybercab that way,” Moravy said.
Elon Musk expanded on the point, emphasizing that there is no fallback for Tesla’s bet on the Cybercab’s autonomous design. He reiterated that the autonomous two seater’s production is expected to start in April and noted that, over time, Tesla expects to produce far more Cybercabs than all of its other vehicles combined.
“Just to add to what Lars said there. The point that Lars made, which is that 90% of miles driven are with one or two passengers or one or two occupants, essentially, is a very important one… So this is clearly, there’s no fallback mechanism here. It’s like this car either drives itself or it does not drive… We would expect over time to make far more CyberCabs than all of our other vehicles combined. Given that 90% of distance driven or distance being distance traveled exactly, no longer driving, is one or two people,” Musk said.
Tesla’s robotaxi lineup is already here
The more interesting takeaway from the Q4 and FY 2025 earnings call is the fact that Tesla does not need the Cybercab to serve every possible passenger scenario, simply because the company already has a functional Robotaxi model that scales by vehicle type.
The Cybercab will handle the bulk of the Robotaxi network’s trips, but for groups that need three or four seats, the Model Y fills that role. For higher-end or larger-family use cases, the extended-wheelbase Model Y L could cover five or six occupants, provided that Elon Musk greenlights the vehicle for North America. And for even larger groups or commercial transport, Tesla has already unveiled the Robovan, which could seat over ten people.
Rather than forcing one vehicle to satisfy every use case, Tesla’s approach mirrors how transportation works today. Different vehicles will be used for different needs, while unifying everything under a single autonomous software and fleet platform.
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Tesla Cybercab spotted with interesting charging solution, stimulating discussion
The port is located in the rear of the vehicle and features a manual door and latch for plug-in, and the video shows an employee connecting to a Tesla Supercharger.
Tesla Cybercab units are being tested publicly on roads throughout various areas of the United States, and a recent sighting of the vehicle’s charging port has certainly stimulated some discussions throughout the community.
The Cybercab is geared toward being a fully-autonomous vehicle, void of a steering wheel or pedals, only operating with the use of the Full Self-Driving suite. Everything from the driving itself to the charging to the cleaning is intended to be operated autonomously.
But a recent sighting of the vehicle has incited some speculation as to whether the vehicle might have some manual features, which would make sense, but let’s take a look:
🚨 Tesla Cybercab charging port is in the rear of the vehicle!
Here’s a great look at plugging it in!!
— TESLARATI (@Teslarati) January 29, 2026
The port is located in the rear of the vehicle and features a manual door and latch for plug-in, and the video shows an employee connecting to a Tesla Supercharger.
Now, it is important to remember these are prototype vehicles, and not the final product. Additionally, Tesla has said it plans to introduce wireless induction charging in the future, but it is not currently available, so these units need to have some ability to charge.
However, there are some arguments for a charging system like this, especially as the operation of the Cybercab begins after production starts, which is scheduled for April.
Wireless for Operation, Wired for Downtime
It seems ideal to use induction charging when the Cybercab is in operation. As it is for most Tesla owners taking roadtrips, Supercharging stops are only a few minutes long for the most part.
The Cybercab would benefit from more frequent Supercharging stops in between rides while it is operating a ride-sharing program.
Tesla wireless charging patent revealed ahead of Robotaxi unveiling event
However, when the vehicle rolls back to its hub for cleaning and maintenance, standard charging, where it is plugged into a charger of some kind, seems more ideal.
In the 45-minutes that the car is being cleaned and is having maintenance, it could be fully charged and ready for another full shift of rides, grabbing a few miles of range with induction charging when it’s out and about.
Induction Charging Challenges
Induction charging is still something that presents many challenges for companies that use it for anything, including things as trivial as charging cell phones.
While it is convenient, a lot of the charge is lost during heat transfer, which is something that is common with wireless charging solutions. Even in Teslas, the wireless charging mat present in its vehicles has been a common complaint among owners, so much so that the company recently included a feature to turn them off.
Production Timing and Potential Challenges
With Tesla planning to begin Cybercab production in April, the real challenge with the induction charging is whether the company can develop an effective wireless apparatus in that short time frame.
It has been in development for several years, but solving the issue with heat and energy loss is something that is not an easy task.
In the short-term, Tesla could utilize this port for normal Supercharging operation on the Cybercab. Eventually, it could be phased out as induction charging proves to be a more effective and convenient option.
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Tesla confirms that it finally solved its 4680 battery’s dry cathode process
The suggests the company has finally resolved one of the most challenging aspects of its next-generation battery cells.
Tesla has confirmed that it is now producing both the anode and cathode of its 4680 battery cells using a dry-electrode process, marking a key breakthrough in a technology the company has been working to industrialize for years.
The update, disclosed in Tesla’s Q4 and FY 2025 update letter, suggests the company has finally resolved one of the most challenging aspects of its next-generation battery cells.
Dry cathode 4680 cells
In its Q4 and FY 2025 update letter, Tesla stated that it is now producing 4680 cells whose anode and cathode were produced during the dry electrode process. The confirmation addresses long-standing questions around whether Tesla could bring its dry cathode process into sustained production.
The disclosure was highlighted on X by Bonne Eggleston, Tesla’s Vice President of 4680 batteries, who wrote that “both electrodes use our dry process.”
Tesla first introduced the dry-electrode concept during its Battery Day presentation in 2020, pitching it as a way to simplify production, reduce factory footprint, lower costs, and improve energy density. While Tesla has been producing 4680 cells for some time, the company had previously relied on more conventional approaches for parts of the process, leading to questions about whether a full dry-electrode process could even be achieved.
4680 packs for Model Y
Tesla also revealed in its Q4 and FY 2025 Update Letter that it has begun producing battery packs for certain Model Y vehicles using its in-house 4680 cells. As per Tesla:
“We have begun to produce battery packs for certain Model Ys with our 4680 cells, unlocking an additional vector of supply to help navigate increasingly complex supply chain challenges caused by trade barriers and tariff risks.”
The timing is notable. With Tesla preparing to wind down Model S and Model X production, the Model Y and Model 3 are expected to account for an even larger share of the company’s vehicle output. Ensuring that the Model Y can be equipped with domestically produced 4680 battery packs gives Tesla greater flexibility to maintain production volumes in the United States, even as global battery supply chains face increasing complexity.
Tesla already has a complete Robotaxi model, and it doesn’t depend on passenger count
Tesla Cybercab spotted with interesting charging solution, stimulating discussion
