News
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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Elon Musk said in late November that he’s “tried to warn” legacy automakers and “even offered to license Tesla Full Self-Driving, but they don’t want it,” expressing frustration with companies that refuse to adopt the company’s suite, which will eventually be autonomous.
Tesla has long established itself as the leader in self-driving technology, especially in the United States. Although there are formidable competitors, Tesla’s FSD suite is the most robust and is not limited to certain areas or roadways. It operates anywhere and everywhere.
The company’s current position as the leader in self-driving tech is being ignored by legacy automakers, a parallel to what Tesla’s position was with EV development over a decade ago, which was also ignored by competitors.
The reluctance mirrors how legacy automakers initially dismissed EVs, only to scramble in catch-up mode years later–a pattern that highlights their historical underestimation of disruptive innovations from Tesla.
Elon Musk’s Self-Driving Licensing Attempts
Musk and Tesla have tried to push Full Self-Driving to other car companies, with no true suitors, despite ongoing conversations for years. Tesla’s FSD is aiming to become more robust through comprehensive data collection and a larger fleet, something the company has tried to establish through a subscription program, free trials, and other strategies.
-->Tesla CEO Elon Musk sends rivals dire warning about Full Self-Driving
However, competing companies have not wanted to license FSD for a handful of speculative reasons: competitive pride, regulatory concerns, high costs, or preference for in-house development.
Déjà vu All Over Again
Tesla tried to portray the importance of EVs long ago, as in the 2010s, executives from companies like Ford and GM downplayed the importance of sustainable powertrains as niche or unprofitable.
Musk once said in a 2014 interview that rivals woke up to electric powertrains when the Model S started to disrupt things and gained some market share. Things got really serious upon the launch of the Model 3 in 2017, as a mass-market vehicle was what Tesla was missing from its lineup.
This caused legacy companies to truly wake up; they were losing market share to Tesla’s new and exciting tech that offered less maintenance, a fresh take on passenger auto, and other advantages. They were late to the party, and although they have all launched vehicles of their own, they still lag in two major areas: sales and infrastructure, leaning on Tesla for the latter.
-->I’ve tried to warn them and even offered to license Tesla FSD, but they don’t want it! Crazy …
When legacy auto does occasionally reach out, they tepidly discuss implementing FSD for a tiny program in 5 years with unworkable requirements for Tesla, so pointless. 🤷♂️
🦕 🦕
— Elon Musk (@elonmusk) November 24, 2025
Musk’s past warnings have been plentiful. In 2017, he responded to critics who stated Tesla was chasing subsidies. He responded, “Few people know that we started Tesla when GM forcibly recalled all electric cars from customers in 2003 and then crushed them in a junkyard,” adding that “they would be doing nothing” on EVs without Tesla’s efforts.
-->Companies laughed off Tesla’s prowess with EVs, only to realize they had made a grave mistake later on.
It looks to be happening once again.
A Pattern of Underestimation
Both EVs and self-driving tech represent major paradigm shifts that legacy players view as threats to their established business models; it’s hard to change. However, these early push-aways from new tech only result in reactive strategies later on, usually resulting in what pains they are facing now.
Ford is scaling back its EV efforts, and GM’s projects are hurting. Although they both have in-house self-driving projects, they are falling well behind the progress of Tesla and even other competitors.
It is getting to a point where short-term risk will become a long-term setback, and they may have to rely on a company to pull them out of a tough situation later on, just as it did with Tesla and EV charging infrastructure.
-->Tesla has continued to innovate, while legacy automakers have lagged behind, and it has cost them dearly.
Implications and Future Outlook
Moving forward, Tesla’s progress will continue to accelerate, while a dismissive attitude by other companies will continue to penalize them, especially as time goes on. Falling further behind in self-driving could eventually lead to market share erosion, as autonomy could be a crucial part of vehicle marketing within the next few years.
Eventually, companies could be forced into joint partnerships as economic pressures mount. Some companies did this with EVs, but it has not resulted in very much.
Self-driving efforts are not only a strength for companies themselves, but they also contribute to other things, like affordability and safety.
Tesla has exhibited data that specifically shows its self-driving tech is safer than human drivers, most recently by a considerable margin. This would help with eliminating accidents and making roads safer.
-->Tesla’s new Safety Report shows Autopilot is nine times safer than humans
Additionally, competition in the market is a good thing, as it drives costs down and helps innovation continue on an upward trend.
Conclusion
The parallels are unmistakable: a decade ago, legacy automakers laughed off electric vehicles as toys for tree-huggers, crushed their own EV programs, and bet everything on the internal-combustion status quo–only to watch Tesla redefine the industry while they scrambled for billions in catch-up capital.
Today, the same companies are turning down repeated offers to license Tesla’s Full Self-Driving technology, insisting they can build better autonomy in-house, even as their own programs stumble through recalls, layoffs, and missed milestones. History is not merely rhyming; it is repeating almost note-for-note.
Elon Musk has spent twenty years warning that the auto industry’s bureaucratic inertia and short-term thinking will leave it stranded on the wrong side of technological revolutions. The question is no longer whether Tesla is ahead–it is whether the giants of Detroit, Stuttgart, and Toyota will finally listen before the next wave leaves them watching another leader pull away in the rear-view mirror.
-->This time, the stakes are not just market share; they are the very definition of what a car will be in the decades ahead.
News
Waymo driverless taxi drives directly into active LAPD standoff
No injuries occurred, and the passengers inside the vehicle were safely transported to their destination, as per a Waymo representative.
A video posted on social media has shown an occupied Waymo driverless taxi driving directly into the middle of an active LAPD standoff in downtown Los Angeles.
As could be seen in the short video, which was initially posted on Instagram by user Alex Choi, a Waymo driverless taxi drove directly into the middle of an active LAPD standoff in downtown Los Angeles.
The driverless taxi made an unprotected left turn despite what appeared to be a red light, briefly entering a police perimeter. At the time, officers seemed to be giving commands to a prone suspect on the ground, who looked quite surprised at the sudden presence of the driverless vehicle.
People on the sidewalk, including the person who was filming the video, could be heard chuckling at the Waymo’s strange behavior.
The Waymo reportedly cleared the area within seconds. No injuries occurred, and the passengers inside the vehicle were safely transported to their destination, as per a Waymo representative. Still, the video spread across social media, with numerous netizens poking fun at the gaffe.
-->Others also pointed out that such a gaffe would have resulted in widespread controversy had the vehicle involved been a Tesla on FSD. Tesla is constantly under scrutiny, with TSLA shorts and similar groups actively trying to put down the company’s FSD program.
A Tesla on FSD or Robotaxi accidentally driving into an active police standoff would likely cause lawsuits, nonstop media coverage, and calls for a worldwide ban, at the least.
This was one of the reasons why even minor traffic infractions committed by the company’s Robotaxis during their initial rollout in Austin received nationwide media attention. This particular Waymo incident, however, will likely not receive as much coverage.
Tesla Model Y demand in China is through the roof, and new delivery dates show the company has already sold out its allocation of the all-electric crossover for 2025.
The Model Y has been the most popular vehicle in the world in both of the last two years, outpacing incredibly popular vehicles like the Toyota RAV 4. In China, the EV market is substantially more saturated, with more competitors than in any other market.
However, Tesla has been kind to the Chinese market, as it has launched trim levels for the Model Y in the country that are not available anywhere else. Demand has been strong for the Model Y in China; it ranks in the top 5 of all EVs in the country, trailing the BYD Seagull, Wuling Hongguang Mini EV, and the Geely Galaxy Xingyuan.
The other three models ahead of the Model Y are priced substantially lower.
Tesla is still dealing with strong demand for the Model Y, and the company is now pushing delivery dates to early 2026, meaning the vehicle is sold out for the year:
NEWS: New orders for all four Tesla Model Y trims in China are now officially sold out for 2025, as the factory’s remaining production capacity for the year has been fully allocated.
Estimated delivery dates for new orders now show January-February 2026. pic.twitter.com/Dfnu7yY58N
— Sawyer Merritt (@SawyerMerritt) December 1, 2025
Tesla experienced a 9.9 percent year-over-year rise in its China-made EV sales for November, meaning there is some serious potential for the automaker moving into next year despite increased competition.
There have been a lot of questions surrounding how Tesla would perform globally with more competition, but it seems to have a good grasp of various markets because of its vehicles, its charging infrastructure, and its Full Self-Driving (FSD) suite, which has been expanding to more countries as of late.
Tesla Model Y is still China’s best-selling premium EV through October
Tesla holds a dominating lead in the United States with EV registrations, and performs incredibly well in several European countries.
With demand in China looking strong, it will be interesting to see how the company ends the year in terms of global deliveries.
Elon Musk and Tesla try to save legacy automakers from Déjà vu
Waymo driverless taxi drives directly into active LAPD standoff
