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.
- A to-scale comparison of Falcon 1, Pegasus XL, MLV, and Falcon 9. (Teslarati/Stratolaunch/Wikipedia)
- 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.
- PGA’s first full-scale preburner seen during assembly. (Stratolaunch)
- PGA’s first full-scale preburner seen during assembly. (Stratolaunch)
- Jeff Thornburg stands in front of Stratolaunch’s NASA Stennis Space Center test stand. (Stratolaunch)
- The PGA preburner seen after installation at Stennis. (Stratolaunch)
- The control center. (Stratolaunch)
- MLV is released from Stratolauncher. (Stratolaunch)
- A concept video produced by Stratolaunch shows the Roc launching a Kraken rocket. (Stratolaunch, via Wired)
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Elon Musk
Delta Airlines rejects Starlink, and the reason will probably shock you
In a pointed exchange on X, Elon Musk defended SpaceX’s uncompromising approach to Starlink’s in-flight internet service, explaining why Delta Air Lines walked away from a deal.
SpaceX frontman Elon Musk explained on Wednesday why commercial airline Delta got cold feet over offering Starlink for stable internet on its flights — and the reason will probably shock you.
In a pointed exchange on X, Elon Musk defended SpaceX’s uncompromising approach to Starlink’s in-flight internet service, explaining why Delta Air Lines walked away from a deal.
Delta rejected Starlink because it insisted on routing all connectivity through its branded “Delta Sync” portal rather than allowing a simple Starlink experience.
Instead, the airline partnered with Amazon’s Project Kuiper—rebranded as Amazon Leo—for high-speed Wi-Fi on up to 500 aircraft, with rollout targeted for 2028. At the time of the announcement, Kuiper had roughly 300 satellites in orbit, while Starlink operated more than 10,400.
The use of the “Delta Sync” portal would not work for SpaceX, as Musk went on to say that:
“SpaceX requires that there be no annoying ‘portal’ to use Starlink. Starlink WiFi must just work effortlessly every time, as though you were at home. Delta wanted to make it painful, difficult and expensive for their customers. Hard to see how that is a winning strategy.”
Musk doubled down in a follow-up post:
“Yes, SpaceX deliberately accepted lower revenue deals with airlines in exchange for making Starlink super easy to use and available to all passengers.”
Not exactly. SpaceX requires that there be no annoying “portal” to use Starlink.
Starlink WiFi must just work effortlessly every time, as though you were at home.
Delta wanted to make it painful, difficult and expensive for their customers. Hard to see how that is a winning…
— Elon Musk (@elonmusk) May 13, 2026
SpaceX has structured its airline agreements to prioritize zero-friction access—no captive portals, no SkyMiles logins, no paywalls or ads blocking basic connectivity.
While this means forgoing higher-margin deals that would let carriers monetize the service more aggressively, it ensures Starlink feels like home broadband at 35,000 feet. Passengers on partner airlines such as United, Qatar Airways, and Air France have already praised the service for enabling seamless video calls, streaming, and work mid-flight without interruptions.
Delta’s choice reflects a different philosophy. By keeping Wi-Fi behind its Delta Sync ecosystem, the airline aims to drive loyalty program engagement and control the digital passenger journey. Yet, critics argue this short-term control comes at the expense of immediate competitiveness.
Airlines already installing Starlink are pulling ahead in customer satisfaction surveys, while Delta passengers face years of reliance on slower, legacy systems until Leo launches.
SpaceX’s decision to trade revenue for simplicity will pay off in the longer term, as Starlink is already positioning itself as the default high-speed option for carriers that value passenger satisfaction over incremental fees.
Musk’s focus on creating not only a great service but also a reasonable user experience highlights SpaceX’s prowess with Starlink as it continues to expand across new partners and regions.
News
Tesla gathers 93,000 FSD miles in a country where FSD isn’t approved – here’s how
Tesla has quietly logged an impressive 93,000 miles (roughly 150,000 km) of autonomous driving at its Giga Berlin factory—using Full Self-Driving (FSD) in a country where the technology remains unavailable to consumers on public roads.
Tesla has gathered 93,000 Full Self-Driving miles in a country where Full Self-Driving is not even approved. Here’s how.
Tesla has quietly logged an impressive 93,000 miles (roughly 150,000 km) of autonomous driving at its Giga Berlin factory—using Full Self-Driving (FSD) in a country where the technology remains unavailable to consumers on public roads.
The milestone, revealed alongside news that Giga Berlin has now built 750,000 Model Y vehicles, highlights how Tesla is putting its AI to work in one of the most controlled environments imaginable: it’s own factory floor.
Every Model Y that rolls off the final assembly line at Giga Berlin doesn’t need a human driver to reach the outbound lot. Instead, the freshly built vehicles engage FSD and navigate themselves across the factory campus.
The Tesla Model Ys rolling off the production line at Giga Berlin have now driven themselves on FSD a combined 93,000 miles from the end of the production line to the outbound lot. https://t.co/6RhL3W4q4p pic.twitter.com/DOKKHUcSSL
— Sawyer Merritt (@SawyerMerritt) May 11, 2026
The route—from the end of the production line through marked internal pathways to the staging area where cars await delivery or export—is entirely on private property. No public roads, no mixed traffic, and no regulatory hurdles for on-road autonomous operation.
It’s a closed-loop system: wide lanes, predictable layouts, minimal pedestrians, and consistent conditions that make it one of the simplest proving grounds for the software.
A short factory tour video shared by Tesla Manufacturing shows General Assembly team member Jan explaining the process. Gesturing beside a glossy black Model Y still wearing its protective wrap, he notes the cumulative distance the fleet has covered autonomously.
Tesla Giga Berlin seems to be using FSD Unsupervised to move Model Y units
The cars handle the short drive flawlessly, freeing up workers who would otherwise spend hours shuttling vehicles manually. For a high-volume plant like Giga Berlin, the time and labor savings add up quickly. Even small gains in cycle time per car can reclaim valuable space in the outbound lot and streamline logistics.
This internal deployment serves multiple purposes. First, it delivers zero-cost validation data. Each factory run exposes FSD to real-world physics—acceleration, steering precision, obstacle avoidance—in a repeatable setting far safer than public testing.
Second, it demonstrates the system’s readiness at scale. If FSD can reliably move thousands of brand-new cars without intervention inside a busy factory, it underscores the robustness of the vision-based, end-to-end neural network Tesla has been refining.
Critics often point to Europe’s cautious regulatory stance on unsupervised autonomy, yet Tesla has turned that limitation into an advantage. While owners in Germany still cannot activate consumer FSD on highways or city streets, the software is already proving its worth behind the factory gates.
The 93,000 miles represent not just internal efficiency gains but a subtle flex: the cars are manufactured ready to navigate autonomously, at least in the bounds of the factory. It’s a big feather in the cap of FSD, even if regulators have yet to green-light broader use.
As Giga Berlin continues ramping output, expect this autonomous logistics loop to grow. What began as a practical workaround for moving finished vehicles has quietly become one of the most compelling real-world showcases of FSD’s potential—right in the heart of regulated Europe. Tesla isn’t waiting for approval to perfect its autonomy; it’s already driving the future, one factory mile at a time.
Elon Musk
Elon Musk reveals how SpaceX is always on board Air Force One
Musk confirmed Tuesday that Starlink internet is live and kicking on Air Force One. Responding with a simple “Yup!” to a post showing him and Nvidia CEO Jensen Huang aboard the presidential jet en route to Beijing with President Trump, Musk proved the point: America’s most important aircraft now has seamless, high-speed satellite connectivity—even over the middle of the Pacific.
Air Force One, the official call sign for a U.S. Air Force aircraft carrying the President, now runs on SpaceX Starlink, CEO Elon Musk revealed.
Musk confirmed Tuesday that Starlink internet is live and kicking on Air Force One. Responding with a simple “Yup!” to a post showing him and Nvidia CEO Jensen Huang aboard the presidential jet en route to Beijing with President Trump, Musk proved the point: America’s most important aircraft now has seamless, high-speed satellite connectivity—even over the middle of the Pacific.
Yup!
— Elon Musk (@elonmusk) May 13, 2026
The timing couldn’t be more symbolic. With trillion-dollar CEOs and the President sharing the cabin, Starlink wasn’t just a nice-to-have—it was mission-critical. No more spotty signals or dropped calls. Instead, real-time video conferences, secure data transfers, and global coordination at Mach speed.
Starlink’s aviation push has already transformed commercial and private flying. Dozens of major airlines have signed on or begun rollouts.
Hawaiian Airlines, United Airlines, Qatar Airways, Air France, SAS, WestJet, airBaltic, and Emirates (now equipping its Boeing 777 and A380 fleets) offer Starlink Wi-Fi to passengers. Lufthansa plans to follow in late 2026.
On private jets, the upgrade is even hotter: owners and charter companies report skyrocketing demand because Starlink turns cabins into flying boardrooms.
Starlink gets its latest airline adoptee for stable and reliable internet access
The advantages are massive. Traditional in-flight Wi-Fi relied on slow, high-latency geostationary satellites or ground-based systems that cut out over oceans and remote areas. Starlink’s low-Earth-orbit constellation delivers blazing speeds—often exceeding 200 Mbps download with latency as low as 25-60 milliseconds—gate-to-gate, from takeoff to landing.
Passengers stream 4K video, join Zoom calls, or work in the cloud without buffering. Pilots get real-time weather, NOTAM updates, and live ATC data. Even private-jet travelers get the benefits, as it means productivity that rivals the office.
On Air Force One, those benefits become strategic superpowers. The presidential aircraft demands unbreakable communications for national security, diplomacy, and crisis response. Starlink provides global coverage with no dead zones, offering redundancy against traditional systems that could fail in contested airspace or during long-haul flights.
It enables the President and staff to maintain secure links with the Pentagon, allies, or business leaders anywhere on Earth. During the Beijing trip, it likely facilitated direct coordination on trade, tech, and AI—proving the system’s reliability for the highest-stakes missions.
Critics once dismissed Starlink as a rich-person toy or military experiment. Now, it’s the backbone of commercial fleets, private aviation, and the world’s most visible symbol of American power, and it is providing stable internet to travelers.
With over 2,000 commercial aircraft committed and private-jet installations booming, Starlink is rewriting the rules of connected flight, and it seems like each week, a new airline is choosing to use it for on-flight connectivity.
For Air Force One, it’s more than faster Wi-Fi. It’s uninterrupted command-and-control in an increasingly connected world—ensuring the President never has to go dark at altitude. Elon Musk just made sure of it.








