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
Tesla launches 200mph Model S “Gold” Signature in invite-only purchase
Tesla’s final 350-unit Signature Edition closes the book on two cars that changed everything.
Tesla has announced a super limited Signature Edition run of 250 Model S Plaid and 100 Model X Plaid units as an invite only purchase in a bid to give its original flagship vehicles a proper send-off.
When the Model S first launched in 2012, the first 1,000 units sold were “Signature” editions that required a $40,000 deposit and cost nearly $100,000 each. Those early buyers were Tesla’s first real believers. This new Signature Edition deliberately echoes that moment, bookending a 14-year run with numbered collector hardware.
Both models are finished in an exclusive Garnet Red paint not available on any current Tesla production vehicle, with gold Tesla T badges up front, a gold Plaid badge and Signature badge at the rear, and a white Alcantara interior featuring gold Plaid seat badges, gold piping, Signature-marked door sills, and a numbered dash plate. The Model S adds carbon ceramic brakes with gold calipers. Every unit ships with Tesla’s Luxe Package, bundling Full Self-Driving (Supervised), four years of Premium Service, free lifetime Supercharging, and a Signature Edition key fob. Both are priced at $159,420, a roughly $35,000 premium over standard Plaid inventory.
The discontinuation is part of a broader strategic shift. At Tesla’s Q4 2025 earnings call, Musk described the decision as “slightly sad” but necessary, saying: “It’s time to basically bring the Model S and X programs to an end with an honorable discharge, because we’re really moving into a future that is based on autonomy.”
The Fremont factory floor that built these cars is being converted to manufacture Optimus humanoid robots, with a target of one million units annually.
Elon Musk
Tesla FSD in Europe vs. US: It’s not what you think
Tesla FSD is approved in the Netherlands, but the European version differs from what US drivers use.
On April 10, 2026, the Dutch vehicle authority RDW granted Tesla the first European type approval for Full Self-Driving Supervised, making the Netherlands the first country on the continent to authorize Tesla’s semi-autonomous system for customer use on public roads.
As Teslarati reported, the RDW approval followed 18 months of testing, more than 1.6 million kilometers driven on EU roads, 13,000 customer ride-alongs, and documentation covering over 400 compliance requirements. Tesla Europe had been running public demo drives through cities like Amsterdam and Eindhoven since early 2026, giving passengers their first experience of the system on European streets.
The European version of FSD is not the same software US drivers use. The RDW’s own statement is direct, noting that the software versions and functionalities in the US and Europe “are therefore not comparable one-to-one.” We’ve compile a table below that captures the most significant differences between US-based Tesla FSD vs. European Tesla FSD that’s based on what regulators and Tesla have publicly confirmed.
| Feature | FSD US | FSD Europe (Netherlands) |
| Regulatory framework | Self-certification, post-market oversight | Pre-market type approval required (UN R-171 + Article 39) |
| Hands requirement | Hands-off permitted on highway | Hands must be available to take over immediately |
| Auto turning from stop lights | Available — navigates intersections, turns, and traffic signals autonomously | Available in EU build — confirmed in Amsterdam demo footage handling unprotected turns and signalized intersections |
| Driving modes | Multiple profiles including a more aggressive “Mad Max” mode | EU build is more conservative by default and errs on the side of restraint when it cannot confirm the limit |
| Summon | Available — Smart Summon navigates parking lots to driver | Status unclear — not confirmed as part of the RDW-approved feature set; urban FSD approval targeted separately for 2027 |
| Driver monitoring | Camera-based eye tracking | Stricter continuous monitoring with more frequent intervention alerts |
| Software version | FSD v14.3 | EU-specific builds that must be separately validated by RDW |
| Geographic restriction | US, Canada, China, Mexico, Australia, NZ, South Korea | Netherlands only; EU-wide vote pending summer 2026 |
| Subscription price | $99/month | €99/month |
| Full urban FSD scope | Available | Partial — separate urban application planned for 2027 |
The approval comes as Tesla is under real pressure to grow FSD subscriptions globally. Musk’s 2025 CEO compensation package, approved by shareholders, includes a milestone requiring 10 million active FSD subscriptions as one condition for his stock awards to vest. Tesla hit one million subscriptions during its Q4 2025 earnings call, which is a meaningful start, but still a long way from the target. Opening Europe as a market for subscriptions, rather than just hardware sales, directly accelerates that number.
Tesla has said it anticipates EU-wide recognition of the Dutch approval during summer 2026, which would extend FSD access to Germany, France, and other major markets through a mutual recognition process without each country repeating the full 18-month review. That timeline is Tesla’s projection, not a confirmed regulatory outcome. As Musk acknowledged at Davos in January 2026, “We hope to get Supervised Full Self-Driving approval in Europe, hopefully next month.”
News
Tesla’s troublesome Auto Wipers get a major upgrade
Tesla has quietly deployed a major over-the-air (OTA) update across its entire fleet, implementing a new patent that could finally solve one of the most complained-about features in its vehicles: the Auto Wipers.
One of Tesla’s most complained-about features is that of the Auto Wipers, but they have recently received a major upgrade that impacts every vehicle in the company’s fleet, a company executive confirmed.
Tesla has quietly deployed a major over-the-air (OTA) update across its entire fleet, implementing a new patent that could finally solve one of the most complained-about features in its vehicles: the Auto Wipers.
Confirmed by senior Tesla AI engineer Yun-Ta Tsai on April 10, the improvement is based on patent US 20260097742 A1. It introduces an “energy balance model” that adds a tactile, physics-driven layer to the existing camera-based system—without requiring any new hardware.
🚨 Tesla has already implemented a new patent that improves the accuracy of the Auto Wiper system https://t.co/QjjKHKxSNv pic.twitter.com/mEbd04oJAu
— TESLARATI (@Teslarati) April 10, 2026
Tesla drivers have griped about auto wipers since the company ditched traditional rain sensors in favor of Tesla Vision around 2018.
Owners routinely report the wipers failing to activate in light drizzle or mist, leaving windshields streaked and visibility dangerously reduced. Just as often, they formerly blasted into high-speed mode on dry, sunny days, screeching across glass and risking scratches or premature blade wear.
This is a rare occurrence anymore, but many owners still report the feature having the wipers perform at the incorrect speed or frequency when precipitation is falling.
Tesla has tried repeatedly to fix the problem through software alone.
Early “Deep Rain” initiatives and the 2023 Autowiper v4 update used multi-camera video and refined neural networks, with Elon Musk promising “super good” performance. The 2024.14 update added manual sensitivity boosts, and later FSD versions claimed further gains. Yet complaints persisted.
Elon Musk apologizes for Tesla’s quirky auto wipers, hints at improvements
Vision systems struggle with edge cases—glare, bugs, reflections, or faint mist—because they rely purely on visual inference rather than physical detection
The new patent takes a different approach. The car’s computer constantly measures electrical power delivered to the wiper motor. It subtracts predictable losses—internal motor friction, linkage drag, and aerodynamic resistance—leaving only the friction force between the rubber blade and windshield glass.
Water lubricates the glass, sharply reducing friction; dry or icy surfaces increase it dramatically. This real-time “tactile” data acts as an independent check on the camera’s visual cues, instantly shutting down false triggers on dry glass and fine-tuning speed for actual rain.
The system can also detect ice and auto-activate defrost heaters, while long-term friction trends alert drivers when blades need replacing.
By fusing vision with precise motor-load physics, Tesla has created a hybrid sensor that is both elegant and cost-free. Owners have waited years for reliable auto wipers; this OTA rollout may finally deliver them.
Tesla launches 200mph Model S “Gold” Signature in invite-only purchase
Tesla FSD in Europe vs. US: It’s not what you think
