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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Cybertruck
Tesla Cybertruck’s newest trim will undergo massive change in ten days, Musk says
It appears as if the new All-Wheel-Drive trim of Cybertruck won’t be around for too long, however. Elon Musk revealed this morning that it will be around “only for the next 10 days.”
Tesla’s new Cybertruck trim has already gotten the axe from CEO Elon Musk, who said the All-Wheel-Drive configuration of the all-electric pickup will only be available “for the next ten days.”
Musk could mean the price, which is $59,990, or the availability of the trim altogether.
Last night, Tesla launched the All-Wheel-Drive configuration of the Cybertruck, a pickup that comes in at less than $60,000 and features a competitive range and features that are not far off from the offerings of the premium trim.
Tesla launches new Cybertruck trim with more features than ever for a low price
It was a nice surprise from Tesla, considering that last year, it offered a Rear-Wheel-Drive trim of the Cybertruck that only lasted a few months. It had extremely underwhelming demand because it was only $10,000 cheaper than the next trim level up, and it was missing a significant number of premium features.
Simply put, it was not worth the money. Tesla killed the RWD Cybertruck just a few months after offering it.
With the news that Tesla was offering this All-Wheel-Drive configuration of the Cybertruck, many fans and consumers were encouraged. The Cybertruck has been an underwhelming seller, and this seemed to be a lot of truck for the price when looking at its features:
- Dual Motor AWD w/ est. 325 mi of range
- Powered tonneau cover
- Bed outlets (2x 120V + 1x 240V) & Powershare capability
- Coil springs w/ adaptive damping
- Heated first-row seats w/ textile material that is easy to clean
- Steer-by-wire & Four Wheel Steering
- 6’ x 4’ composite bed
- Towing capacity of up to 7,500 lbs
- Powered frunk
It appears as if this trim of Cybertruck won’t be around for too long, however. Musk revealed this morning that it will be around “only for the next 10 days.”
Only for the next 10 days https://t.co/82JnvZQGh2
— Elon Musk (@elonmusk) February 20, 2026
Musk could mean the price of the truck and not necessarily the ability to order it. However, most are taking it as a cancellation.
If it is, in fact, a short-term availability decision, it is baffling, especially as Tesla fans and analysts claim that metrics like quarterly deliveries are no longer important. This seems like a way to boost sales short-term, and if so many people are encouraged about this offering, why would it be kept around for such a short period of time?
Some are even considering the potential that Tesla axes the Cybertruck program as a whole. Although Musk said during the recent Q4 Earnings Call that Cybertruck would still be produced, the end of the Model S and Model X programs indicates Tesla might be prepared to do away with any low-volume vehicles that do not contribute to the company’s future visions of autonomy.
The decision to axe the car just ten days after making it available seems like a true head-scratcher.
Elon Musk
Elon Musk’s Neuralink sparks BCI race in China
One of the most prominent is NeuroXess, which launched in 2021 and is already testing implants in patients.
Neuralink, founded by Elon Musk, is helping spark a surge of brain-computer interface (BCI) development in China, where startups are moving quickly into human trials with strong state backing.
One of the most prominent is NeuroXess, which launched in 2021 and is already testing implants in patients.
Neuralink’s clinical work and public demonstrations have drawn worldwide attention to invasive brain implants that allow patients to control digital devices using their minds. The company is currently running a global clinical trial and is also busy preparing for its next product, Blindsight, which would restore vision to people with visual impairments.
Neuralink’s visibility has helped accelerate similar efforts in China. Beijing last year classified brain-computer interfaces as a strategic sector and issued a roadmap calling for two or three globally competitive companies by 2030, as per the Financial Times. Since February last year, at least 10 clinical trials for invasive brain chips have launched in the country.
NeuroXess recently reported that a paralyzed patient was able to control a computer cursor within five days of implantation. Founder Tiger Tao credited government support for helping shorten the path from research to trials.
Investment activity has followed the policy push. Industry data show dozens of financing rounds for Chinese BCI startups over the past year, reflecting rising capital interest in the field. Ultimately, while Neuralink remains one of the most closely watched players globally, its momentum has clearly energized competitors abroad.
News
Tesla Supercharger vandalized with frozen cables and anti-Musk imagery amid Sweden union dispute
The incident comes amid Tesla’s ongoing labor dispute with IF Metall.
Tesla’s Supercharger site in Vansbro, Sweden, was vandalized during peak winter travel weeks. Images shared to local media showed frozen charging cables and a banner reading “Go home Elon,” which was complete with a graphic of Musk’s controversial gesture.
The incident comes amid Tesla’s ongoing labor dispute with IF Metall, which has been striking against the company for more than two years over collective bargaining agreements, as noted in a report from Expressen.
Local resident Stefan Jakobsson said he arrived at the Vansbro charging station to find a board criticizing Elon Musk and accusing Tesla of strikebreaking. He also found the charging cables frozen after someone seemingly poured water over them.
“I laughed a little and it was pretty nicely drawn. But it was a bit unnecessary,” Jakobsson said. “They don’t have to do vandalism because they’re angry at Elon Musk.”
The site has seen heavy traffic during Sweden’s winter sports holidays, with travelers heading toward Sälen and other mountain destinations. Jakobsson said long lines formed last weekend, with roughly 50 Teslas and other EVs waiting to charge.
Tesla Superchargers in Sweden are typically open to other electric vehicle brands, making them a reliable option for all EV owners.
Tesla installed a generator at the location after sympathy strikes from other unions disrupted power supply to some stations. The generator itself was reportedly not working on the morning of the incident, though it is unclear whether that was connected to the protest.
The dispute between Tesla and IF Metall centers on the company’s refusal to sign a collective agreement covering Swedish workers. The strike has drawn support from other unions, including Seko, which has taken steps affecting electricity supply to certain Tesla facilities. Tesla Sweden, for its part, has insisted that its workers are already fairly compensated and it does not need a collective agreement,
Jesper Pettersson, press spokesperson for IF Metall, criticized Tesla’s use of generators to keep charging stations running. Still, IF Metall emphasized that it strongly distances itself from the vandalism incident at the Vansbro Supercharger.
“We think it is remarkable that instead of taking the easy route and signing a collective agreement for our members, they are choosing to use every possible means to get around the strike,” Pettersson said.
Tesla Cybertruck’s newest trim will undergo massive change in ten days, Musk says
Elon Musk’s Neuralink sparks BCI race in China
