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SpaceX begins stress-testing upgraded Super Heavy booster
In a what is likely a prelude to engine installation, SpaceX has begun stress-testing an upgraded Super Heavy booster prototype.
Known as Super Heavy Booster 7 or B7, the prototype is the first of its kind designed to support up to 33 new Raptor V2 engines – each potentially capable of producing up to 230 tons (~510,000 lbf) of thrust at liftoff. Even with just 20 such engines installed, Super Heavy – measuring around 69 meters (~225 ft) tall and nine meters (~30 ft) wide – will be the largest and most powerful rocket stage ever tested. That potentially unprecedented power is why SpaceX has custom-built a complex structural test stand to explore Super Heavy’s true performance envelope in a slightly less risky manner.
In the second half of 2021, that structural test stand briefly tested an unusual half-Starship, half-Super Heavy test tank with a nine-engine thrust section (‘puck’) and later compressed a different test tank until its reinforced steel skin buckled. In the interim, SpaceX removed its nine-ram setup and modified the stand to support 13 rams, guaranteeing that its new purpose was to test Super Heavy’s new 13-engine thrust section. Prior to Booster 7, all Super Heavy prototypes have had a similar nine-engine puck and an outer ring of 20 engines that would attach directly to the rim of each booster’s cylindrical body.
Increasing the central engine count from 9 to 13 was already certain to up the amount of stress future Super Heavy thrust pucks would need to survive by almost 45%. But combined with Raptor V2’s thrust increases, Super Heavy Booster 7’s thrust puck could actually be subjected to at least 80% more thrust at liftoff. Altogether, Super Heavy B7’s 33 engines should be able to produce ~7600 tons (~16.8M lbf) of thrust compared to Super Heavy B4’s ~5400 tons (~11.9M lbf). As a result, though it’s odd that SpaceX never did significantly test Booster 4, it’s no surprise that the company chose to give Booster 7 priority as soon it was ready.
After a few false starts and at least one ‘pneumatic proof test’ that likely saw Booster 7 pressurized with benign nitrogen gas, SpaceX began stress-testing the upgraded Super Heavy in earnest on April 14th. First, the booster was filled about a third of the way with roughly 1000 tons (~2.2M lb) of liquid nitrogen (LN2) or a combination of liquid oxygen (LOx) and LN2. Once the rocket was fully chilled, there were clear signs of some kind of added stress as large sheets of ice that had formed on the side of B7’s skin broke apart and fell off.
Only ice close to Super Heavy’s base was visibly disturbed, increasing the odds that the behavior was a sign of some or all of the structural test stand’s hydraulic rams simulating Raptor engines. It’s also possible that the stress was caused by pressurizing Super Heavy’s tanks to the point that they began to appreciably deform, though that type of testing is far harder to differentiate. Without official comments, it’s unfortunately impossible to ever know what exactly SpaceX is testing or how successful those tests are when the structural test stand is involved.
Nonetheless, it’s likely that Booster 7 isn’t done with the stand just yet. SpaceX could benefit from just about any data gathered about the performance of Super Heavy’s new thrust puck during simulated Raptor startup, throttling, and shutdown both at liftoff and during boostback and landing burns. SpaceX might also want to simulate engine-out scenarios that would result in asymmetric thrust.
Assuming Booster 7 survives this particular series of tests and SpaceX is happy with its performance on the structural test stand, the upgraded Super Heavy could be ready for Raptor installation and integrated wet dress rehearsal and static fire testing in the near future. SpaceX began delivering upgraded Raptors V2 engines to Starbase in late March.
Tesla confirmed this morning that it has sent the first production units, manufactured with no steering wheel or pedals, to on-road testing in Austin, sharing video of the first rides with no human controls.
The lack of steering wheels and pedals in the Cybercab aligns with Tesla’s self-certification of Robotaxi as Level 4 SAE, a platform it plans to make widespread through internal vehicles and customer-owned cars that will operate and generate revenue for individuals.
The start of these engineering tests is a major signal for Tesla, which plans to bring driverless, wheel-less, and pedal-less Cybercabs to market in the coming months. With production already well underway at Gigafactory Texas, where the Cybercab is built, there is some inclination to believe the first public rides could happen sooner rather than later.
Engineering tests of the first production Cybercab have begun in Austin pic.twitter.com/fk3KQvcE8a
— Tesla (@Tesla) June 30, 2026
Tesla’s engineering tests will put the Cybercab in real-world scenarios, testing not only the hardware, but more importantly, the software that drives the car around Austin with nobody supervising it within the car.
This is perhaps the biggest part of the internal testing process, especially prior to allowing regular, everyday people to hail the Cybercab for an autonomous ride. These early rides serve as a true benchmark for Tesla: How many rides can it achieve safely? How many miles did it travel consecutively without needing an intervention? What scenarios challenge the Full Self-Driving suite the most?
The proper precautions have already been put into place as well, as Tesla released the First Responders Guide to Cybercab over the weekend, ensuring that emergency services have 24/7 access to Robotaxi Assistance, as well as other boundaries, such as Geofencing features that can be used to redirect autonomous vehicle traffic due to accidents, road closures, construction, or maintenance.
Cybercab seems genuinely close to being added to the Robotaxi fleet in Austin, but Tesla has prioritized safety throughout this entire process. Therefore, we think it could be months before it truly starts giving rides to the public. People have been frustrated with this, but Robotaxi in Austin has a tremendous safety record so far, so the slow rollout has kept people safe and accidents to a minimum.
The most important thing is that Tesla continues to show consistent progress in the Cybercab’s ramp-up toward fleet addition. A few weeks back, we saw the EPA reward the Cybercab a Certificate of Conformity, allowing it to enter the stream of commerce. Then, we saw Tesla add decals, signaling that it was likely about to start testing it publicly. That has now happened.
The next big move will be the announcement of the first rides, so this Summer should be filled with anticipation.
For years, there have been images and videos across social media platforms that have reminded me of when I was a 15-year-old kid teased by “Xbox 720” videos on YouTube. These videos are of the supposed “Tesla Phone” that Elon Musk was secretly developing in between leading Tesla with its electric cars and SpaceX with its reusable rockets.
Would you buy a Tesla phone ? pic.twitter.com/aaTwvvIJit
— Tesla Owners Silicon Valley (@teslaownersSV) October 6, 2023
Although Musk has put those rumors to bed several times, it was never completely out of the realm that he could get involved in cell phones in some capacity. Think outside the box and more macro-level, though. Instead of reinventing the computer, Musk reinvented connectivity by developing Starlink with SpaceX.
It could be something similar, TD Cowen analyst Gregory Williams said in a note last week, where he hinted SpaceX could be gathering some steam to acquire T-Mobile.
Williams said it would be the “clear choice” for SpaceX if it decided to go through with a network acquisition. He also suggested AT&T.
The move would be possible through selling more of its own stock, which would help SpaceX raise the money to purchase T-Mobile, which would cost roughly $300 billion. It could be one of the moves SpaceX makes post-IPO in terms of an acquisition: it already acquired Cursor AI for $60 billion.
Other analysts, like Dan Ives of Wedbush, believe SpaceX and Tesla will eventually merge into one anyway, and that conglomeration could come as soon as this year, some have said.
The implications of SpaceX purchasing T-Mobile are massive. A combined entity would create a truly ubiquitous network: T-Mobile’s terrestrial 5G towers and Starlink’s growing constellation of Direct-to-Cell satellites. This would essentially eliminate dead zones across the U.S. and potentially globally.
SpaceX would instantly become a full-scale facilities-based carrier with satellite differentiation; a huge advantage. This would pressure AT&T and Verizon heavily.
There are also concerns like a potential reduction in long-term competition, and of course, a deal of that size would face intense scrutiny from government agencies.
The strategic fit is compelling due to the existing Starlink–T-Mobile partnership and complementary technologies (space + terrestrial). It could create a dominant integrated communications player. However, the regulatory, financial, and execution hurdles are enormous — this remains highly speculative with no indication SpaceX is actively pursuing it right now.
Tesla revealed a major new Cybercab detail in a guide it released for First Responders, showing new territory in its beliefs and intentions for the ride-hailing-focused vehicle that entered production in April.
The First Responders Guide is released to give fire departments, paramedics, and other emergency personnel the proper guidance on what to do in the event of an accident, entrapment, or other situation that would require immediate attention.
On one of the pages of the First Responders Guide, Tesla revealed a stark detail about the Cybercab, which could help personnel enter the vehicle more easily in case of an emergency.
Tesla Cybercab has one important piece that AI4 cars might need for FSD
It shows Tesla has no intention of releasing any Cybercab units that were initially proposed for ride-hailing services for the general public with any manual controls, meaning a steering wheel or pedals:
“A Cybercab equipped with steering wheel, brake pedal, and an acceleration pedal is typically an engineering or test vehicle, and operates at SAE Level 2 autonomy. Cybercab is not typically equipped with a steering wheel or acceleration and brake pedals.”
New official Cybercab documentation from Tesla:
“A Cybercab equipped with steering wheel, brake pedal, and an acceleration pedal is typically an engineering or test vehicle, and operates at SAE Level 2 autonomy. Cybercab is not typically equipped with a steering wheel or… https://t.co/P6ut1mZyzr pic.twitter.com/yq6skl9s2J
— Sawyer Merritt (@SawyerMerritt) June 27, 2026
This is a major development for those who continue to believe Tesla planned to release the Cybercab with any sort of manual controls so that passengers could take over if needed. However, when Tesla started manufacturing production versions of the Cybercab in Giga Texas earlier this year, they were spotted without a steering wheel or pedals.
It essentially confirms the company has no intentions of bringing manual controls to the car’s production versions. Some have argued that the likelihood of Tesla having something
There still are some Cybercab units out there with a steering wheel and pedals, and as Tesla said, these cars are engineering or test vehicles, which have Safety Monitors on board to help the car out of a precarious situation or emergency.
Tesla sends production Cybercab with no steering wheel, pedals to on-road testing
Tesla Phone? Not quite, but close: analyst
