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Ex-SpaceX engineer leads Stratolaunch to major rocket engine test milestone
Led by rocket propulsion expert Jeff Thornburg, Stratolaunch – famous for owning the largest fixed-wing aircraft ever built – has completed the first hot-fire test of a full-scale rocket engine component known as the preburner, a major milestone in the development of any launch vehicle or propulsion system.
Despite the significant size and power of the component, destined to support an engine that will generate 200,000 pounds (~900 kN) of thrust, Thornburg and his team of engineers and technicians have managed to go from designing the preburner to successfully hot-firing a full-scale test article, an extraordinary achievement by any measure.
The team made amazing progress this week! Check out the #PGAEngine preburner’s first hot-fire test at @NASAStennis. #NewUSEngine pic.twitter.com/kKTnf0bj1S
— Stratolaunch (@Stratolaunch) November 6, 2018
Aside from SpaceX, Blue Origin, and Aerojet-Rocketdyne, Stratolaunch is the only private entity developing – let alone testing full-scale parts for – a liquid-fueled rocket engine as large as PGA. Shorthand for the Stratolaunch’s late founder and bankroller Paul G. Allen, PGA is a fuel-rich staged combustion cycle engine that uses liquid hydrogen and oxygen (hydrolox) fuel and oxidizer, typically resulting in high efficiency. In terms of scale and thrust, PGA is very closely comparable to SpaceX’s Merlin 1D engine, which uses kerosene instead of hydrogen but produces roughly 190,000 lbf (850 kN) of thrust and stands 4 feet (1.2m) wide and ~10 feet (~3m) tall.
Another major difference between PGA and Merlin 1D is the fact Merlin 1D’s nozzle is largely optimized for sea level while PGA is being built for a rocket that will be “launched” from a massive plane flying around 35,000 feet (~10.5 km), ultimately resulting in a nozzle that is much wider and longer, featuring nearly the same proportions as fully vacuum-optimized engines like SpaceX’s MVac. By widening the nozzle relative to the rest of the engine, rocket engines are able to operate far more efficiently at higher altitudes, where Earth’s atmosphere thins and exerts less pressure on the escaping exhaust gases. This is visualized well by the visible expansion of rocket exhausts during launches, morphing from a straight cylinder to a massive teardrop-shaped plume. At lower altitudes (and thus higher atmospheric pressures), wider nozzles can produce extreme turbulence and will ultimately shake themselves to destruction, preventing their usage on ground-launched rocket boosters.
Judging from official renders of the engine, PGA’s in-atmosphere variant appears to utilize a form of regenerative nozzle cooling very similar to that used on M1D, where liquid propellant flows through thin capillaries sandwiched between two or more layers of metal to cool the nozzle much like cold water chills the skin of an uninsulated water bottle.
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- A to-scale comparison of Falcon 1, Pegasus XL, MLV, and Falcon 9. (Teslarati/Stratolaunch/Wikipedia)
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- A render of Stratolaunch’s impressive PGA engine. Note the giant nozzle relative to the throat. (Stratolaunch)
Testing rocket engine preburners
In the case of staged combustion cycle hydrolox rocket engines, a small portion of liquid oxygen and all of the liquid hydrogen (hence “fuel-rich”) are mixed and combusted to generate hot gas that then spools up the engine’s primary turbopump(s), ultimately drawing fuel and oxidizer into the combustion quickly enough to ignite the engine and generate sustained thrust. The components that get those main turbopumps started are known collectively as the preburner, which is what Stratolaunch successfully tested – at full-scale – for the first time ever last week. For any liquid rocket engine that cannot solely rely on propellant tank pressure to deliver fuel to the combustion chamber, full-scale tests of preburners or gas-generators effectively mark the moment that engines truly become real.
“This is the first step in proving the performance and highly efficient design of the PGA engine. The hot-fire test is an incredible milestone for both the propulsion team and Stratolaunch.” – Jeff Thornburg, VP of Propulsion, Stratolaunch
Stratolaunch’s propulsion team will continue to test the preburner for longer durations and at higher power levels over the next several months, likely optimizing operations and tweaking or upgrading the preburner’s hardware as real tests produce valuable lessons-learned. Built entirely with additive manufacturing (3D printing), the team should be able to rapidly iterate on the physical design of the engine, a rarity in a field where traditional fabrication methods can take weeks or months to produce complex turbomachinery components with mercilessly strict tolerances.
According to Thornburg, the ultimate goal is to continue that additive-manufacturing-only strategy throughout the development of this rocket engine, theoretically enabling unprecedented design flexibility while also slashing production time throughout. PGA will ultimately power the creatively-named Medium Launch Vehicle (MLV), a small-ish air-launched rocket designed to place a respectable 3400 kg into low Earth orbit (LEO) as early as 2022, as well as a Heavy version of MLV and, potentially, a reusable spaceplane somewhere down the line.
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- PGA’s first full-scale preburner seen during assembly. (Stratolaunch)
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- PGA’s first full-scale preburner seen during assembly. (Stratolaunch)
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- Jeff Thornburg stands in front of Stratolaunch’s NASA Stennis Space Center test stand. (Stratolaunch)
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- The PGA preburner seen after installation at Stennis. (Stratolaunch)
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- The control center. (Stratolaunch)
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- MLV is released from Stratolauncher. (Stratolaunch)
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- A concept video produced by Stratolaunch shows the Roc launching a Kraken rocket. (Stratolaunch, via Wired)
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Tesla VP explains latest updates in trade secret theft case
Tesla reportedly caught Matthews copying the tech into machines that were sold to competitors, claiming they lied about doing so for three years, and continued to ship it. That is when Tesla chose to sue Matthews in July 2024 in Federal court, demanding over $1 billion in damages due to trade secret theft.
Tesla Vice President Bonne Eggleston explained the latest updates in a trade secret theft case the company has against a former manufacturing equipment supplier, Matthews International.
Back in 2024, Tesla had filed a lawsuit against Matthews International, alleging that the firm stole trade secrets about battery manufacturing and shared those details with some of Tesla’s competitors.
Early last year, a U.S. District Court Judge denied Tesla’s request to block Matthews International from selling its dry battery electrode (DBE) technology across the world. The judge, Edward Davila, said that the patent for the tech was due to Matthews’ “extensive research and development.”
The two companies’ relationship began back in 2019, as Tesla hired Matthews to help build the equipment for its 4680 battery cell. Tesla shared confidential software, designs, and know-how under strict secrecy rules.
Fast forward a few years, and Tesla reportedly caught Matthews copying the tech into machines that were sold to competitors, claiming they lied about doing so for three years, and continued to ship it. That is when Tesla chose to sue Matthews in July 2024 in Federal court, demanding over $1 billion in damages due to trade secret theft.
Now, the latest twist, as this month, a Judge issued a permanent injunction—a court order banning Matthews from using certain stolen Tesla parts or designs in their machines. Matthews is also officially “liable” for damages. The exact amount would still to be calculated later.
Bonne Eggleston, a VP for Tesla, said on X today that Matthews is a supplier who “exploited customer IP through theft or deception,” and has no place in Tesla’s ecosystem:
Buyer beware: Matthews International stole Tesla’s DBE technology and is now subject to an injunction and liable for damages.
During our work with Matthews, we caught them red-handed copying our technology—including proprietary software and sensitive mechanical designs—into… https://t.co/Toc8ilakeM
— Bonne Eggleston (@BonneEggleston) March 10, 2026
Tesla calls this a big win and warns other companies: “Buyer beware—don’t buy from thieves.”
Matthews hit back with a press release claiming victory. They say an arbitrator ruled they can keep selling their own DBE equipment to anyone and rejected Tesla’s request for a total sales ban. They call Tesla’s claims “nonsense” and insist their 20-year-old tech is independent. Both sides are spinning the same narrow ruling: Matthews can sell their version, but they’re blocked from using Tesla’s specific secrets.
What are Tesla’s Current Legal Options
The case isn’t over—it’s moving to the damages phase. Tesla can:
- Push forward in court or arbitration to calculate and collect huge financial penalties (potentially $1 billion+ if willful theft is proven).
- Enforce the permanent injunction with contempt charges, fines, or even jail time if Matthews violates it.
- Challenge Matthews’ new patents that allegedly copy Tesla’s work, asking courts to invalidate them or add Tesla as co-inventor.
- Seek extra damages, lawyer fees, and possibly punitive awards under the federal Defend Trade Secrets Act and California law.
Tesla could also refer evidence to federal prosecutors for possible criminal trade-secret charges (rare but serious). Settlement is always possible, but Tesla’s fiery public response suggests they want full accountability.
This isn’t just corporate drama. It shows why trade secrets matter even when Tesla open-sources some patents, confidential know-how shared in trust must stay protected. For the EV industry, it’s a reminder: steal from your biggest customer, and you risk losing everything.
News
Tesla Cybercab includes this small but significant feature
The Cybercab is Tesla’s big plan to introduce fully autonomous ride-sharing in a seamless fashion. In fact, the Full Self-Driving suite was geared toward alleviating the need to manually drive vehicles.
Tesla Cybercab manufacturing is strikingly close, as the company is still aiming for an April start date. But small and significant features are still being identified for the first time as production units appear all over the country for testing and for regulatory events, like one yesterday in Washington, D.C.
The Cybercab is Tesla’s big plan to introduce fully autonomous ride-sharing in a seamless fashion. In fact, the Full Self-Driving suite was geared toward alleviating the need to manually drive vehicles.
This was for everyone, including the disabled, who are widely reliant on ride-sharing platforms, family members, and medical shuttles for transportation of any kind. Cybercab aims to change that, and Tesla evidently put a focus on those riders while developing the vehicle, evident in a small but significant feature revealed during its appearance in the Nation’s Capital.
Tesla Cybercab display highlights interior wizardry in the small two-seater
Tesla has implemented Braille within the Cybercab to make it easier for blind passengers to utilize the vehicle. On both the ‘Stop/Hazard Lights’ button and the Door Releases, Tesla has placed Braille so that blind passengers can navigate their way through the vehicle:
The hazard lights button will be used as an emergency stop. Smart pic.twitter.com/vkYBioqmKm
— Whole Mars Catalog (@wholemars) March 10, 2026
We have braille on the interior door releases as well
— Eric (@EricETesla) March 11, 2026
This is a great addition to the Cybercab, especially as Full Self-Driving has been partially pointed at as a solution for those with disabilities that would keep them from driving themselves from place to place.
It truly is a great addition and just another way that Tesla is showing they are making this massive product inclusive for everyone out there, including those who have not been able to drive due to not having vision.
The Cybercab is set to enter mass production sometime in April, and it will be responsible for launching Tesla’s massive plans for an autonomous ride-sharing program.
Elon Musk
Tesla and xAI team up on massive new project
It is the latest move by a Musk company to automate, streamline, and reduce the manual, monotonous, and tedious work currently performed by humans through AI and robotics development. Digital Optimus will be capable of processing and actioning the past five seconds of a real-time computer screen video and keyboard and mouse actions.
Elon Musk teased a massive new project, to be developed jointly by Tesla and xAI, called “Digital Optimus” or “Macrohard,” the first development under Tesla’s investment agreement with xAI.
Musk announced on X that Digital Optimus will “be capable of emulating the function of entire companies.”
Macrohard or Digital Optimus is a joint xAI-Tesla project, coming as part of Tesla’s investment agreement with xAI.
Grok is the master conductor/navigator with deep understanding of the world to direct digital Optimus, which is processing and actioning the past 5 secs of…
— Elon Musk (@elonmusk) March 11, 2026
It is the latest move by a Musk company to automate, streamline, and reduce the manual, monotonous, and tedious work currently performed by humans through AI and robotics development. Digital Optimus will be capable of processing and actioning the past five seconds of a real-time computer screen video and keyboard and mouse actions.
Essentially, it will be an AI version of a desk worker in many capacities, including accounting, HR tasks, and others.
Musk said:
“Grok is the master conductor/navigator with deep understanding of the world to direct digital Optimus, which is processing and actioning the past 5 secs of real-time computer screen video and keyboard/mouse actions. Grok is like a much more advanced and sophisticated version of turn-by-turn navigation software. You can think of it as Digital Optimus AI being System 1 (instinctive part of the mind) and Grok being System 2. (thinking part of the mind).”
Its key applications would be used for enterprise automation, simulating entire companies, high-volume repetitive tasks, and potentially, future hybrid use with the Optimus robot, which would handle physical tasks, while Digital Optimus would handle the clerical work.
The creation of a digital AI suite like Digital Optimus would help companies save time and money, as well as become more efficient in their operations through massive scalability. However, there will undoubtedly be concerns from people who are skeptical of a fully-integrated AI workhorse like this one.
From an energy consumption perspective and just a general concern for the human workforce, these types of AI projects are polarizing in nature.
However, Digital Optimus would be a great digital counterpart to Tesla’s physical Optimus robot, as it would be a hyper-efficient addition to any company that is looking for more production for less cost.
Musk maintains that there is no other company on Earth that will be able to do this.
Tesla VP explains latest updates in trade secret theft case
Tesla Cybercab includes this small but significant feature
