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
SpaceX (SPCX) IPO is live today at $135: Here’s exactly what you need to know
SpaceX priced its historic IPO at $135 per share today, raising a record $75 billion.
SpaceX officially priced its initial public offering at $135 per share, offering 555,555,555 shares of Class A common stock and raising $75 billion in what is the largest IPO in stock market history. Shares are set to begin trading on the Nasdaq Global Select Market on Friday, June 12, under the ticker symbol SPCX. The previous record holder was Saudi Aramco’s 2019 offering at $29 billion, followed by Alibaba’s $22 billion offering in 2014.
At $135 per share and roughly 555.6 million shares, the implied valuation sits near $1.75 trillion, which would make SpaceX roughly the seventh largest company in the United States, just above Tesla’s current market cap. Regular investors can request shares at the IPO price through Robinhood, Fidelity, Charles Schwab, SoFi, and E*TRADE, though the deal is heavily oversubscribed and most retail allocations will be partial or unfilled. Once trading opens June 12, anyone with a brokerage account can buy SPCX on the open market.
SpaceX’s amended S-1 is sparking a major Tesla merger conversation
The valuation is anchored primarily by Starlink. Starlink crossed 10 million subscribers as of February 2026 and is adding 750,000 to 1.5 million new users per month, with the connectivity segment already posting a $1.19 billion profit last quarter. The offering also bundles in xAI following SpaceX’s all-stock merger earlier this year, adding Grok and the Colossus supercomputer to the investment thesis. As Teslarati reported, Starlink ended 2025 with $10 billion in revenue, a figure analysts project could reach $24 billion by end of 2026.
Wedbush analyst Dan Ives has been vocal in his support. “I think the time is right,” Ives said, adding that the offering expands the Elon Musk ecosystem rather than competing with Tesla. An average 12-month price target of $165 per share represents roughly 22% upside from the IPO price. Not everyone agrees – Motley Fool noted xAI is spending $1 billion per month playing catch-up to OpenAI and Anthropic.
Musk founded SpaceX in 2002 with a single stated purpose. “Elon founded SpaceX with a goal to change humanity, to make us a multi-planet species,” CFO Bret Johnsen said in the company’s retail roadshow video this week. Musk himself has been more direct: “We are building the systems and technologies necessary to provide global connectivity on Earth and beyond, to understand the true nature of the universe, and to extend the light of consciousness to the stars.”
Investor's Corner
Tesla unfolded its first European “folding Supercharger”
Tesla’s folding Supercharger just arrived in Europe and it changes how fast charging expands.
Tesla’s Folding Unit Supercharger has officially landed in Europe, with the company teasing a new installation in its effort for a broader rollout targeting major motorway rest stops across the European continent in Q3 2026. The arrival marks a notable shift in how Tesla is thinking about network expansion, moving from hardware performance alone to engineering the logistics chain itself.
While Tesla did not reveal the exact location for the new folding Supercharger in Europe, the photo shared on X heavily suggests that this maybe somewhere in Norway. Historically, whenever Tesla rolls out an entirely new infrastructure architecture in Europe, whether it was the original Supercharger stalls years ago or these brand-new modular V4 “Folding Units”, Norway is almost always the designated launch pad because of its unmatched EV adoption rate and supportive infrastructure
The Folding Unit, introduced in March 2026, is a factory pre-assembled V4 charging station built on an industrial hinge system mounted to a heavy-duty concrete base. The entire assembly arrives on site ready to unfold and connect. Tesla confirmed the units feature telescopic light poles specifically designed for easy transportation and fast on-site deployment, a detail that signals how carefully the logistics chain has been engineered alongside the hardware itself. The design allows 33% more stalls per delivery truck, cuts installation time roughly in half, and reduces overall deployment costs by more than 20% compared to traditional installations.
Tesla’s newest “Folding V4 Superchargers” are key to its most aggressive expansion yet
Tesla also noted telescopic light poles which provide benefits over traditional Supercharger installations that require fixed-height poles that are awkward to ship, slow to position on site, and often require separate crews and equipment to erect before charging hardware can even be staged. By engineering poles that compress for transit and extend on arrival, Tesla has removed one of the quieter bottlenecks in the physical deployment process. Every hour saved on a light pole installation is an hour redirected toward getting stalls energized. At scale, across dozens of new sites per quarter, those hours add up to a meaningful acceleration in how quickly a location goes from approved permit to serving its first customer.
Each Folding Unit pairs a single V4 power cabinet with eight charging posts. The V4 cabinet delivers up to 500 kW per stall for passenger vehicles and up to 1.2 MW for the Tesla Semi, supporting twice the stalls per cabinet at three times the power density of its predecessor. Longer cables make every new station immediately usable by non-Tesla vehicles, a priority as Tesla continues opening its network to Ford, GM, Rivian, Hyundai, Stellantis, and others.
As Teslarati reported when the Folding Unit was first unveiled, Tesla’s Gigafactory New York produced its final V3 Supercharger cabinet in March 2026 after more than seven years and 15,000 units, completing a full pivot to V4 production. The European arrival of the folding design is the next chapter in that transition.
Faster and cheaper deployment means Tesla can justify building in markets and corridors that were previously too expensive to serve, filling the coverage gaps that have slowed EV adoption outside major urban centers.
First Folding Unit Superchargers in Europe 🇪🇺 https://t.co/KNfYWJukkL pic.twitter.com/YR1udIpH1i
— Tesla Charging (@TeslaCharging) June 10, 2026
Tesla has stunned by gaining yet another approval for its Full Self-Driving suite in Europe, its second in two days and its fifth overall.
Belgium will be the latest country to allow Tesla owners to utilize FSD on public roads in Europe, joining a quickly growing list that started with the Netherlands, Lithuania, and Estonia.
On Tuesday, Denmark announced its approval of the FSD suite, which has now been followed by Belgium just one day later.
The country’s Minister of Mobility, Annick De Ridder, announced the approval on her X account, stating that she had just signed the approval of Tesla FSD. It now goes to the country’s homologation department for the last step of the approval process.
De @Tesla community houdt hier al geruime tijd de vinger aan de pols over de toelating voor de FSD-technologie op onze Vlaamse en Belgische wegen.
Uit waardering voor jullie niet-aflatende interesse (en aanmoediging 😉), krijgen jullie hierbij de primeur: ik heb net de toelating… pic.twitter.com/Yrps4OHTj8— Annick De Ridder (@AnnickDeRidder) June 10, 2026
The Belgian approval is one of mighty importance because it truly shows how quickly countries in Europe could greenlight the FSD suite consecutively. Approvals are already coming in relatively quickly, which is a great sign.
Perhaps the next big development that could come from FSD approvals in Europe is an approval from a country like England, Italy, France, Spain, or Germany. It would be something to see how FSD would perform in a major European metro, such as London, Barcelona, Madrid, Paris, Rome, or Berlin.
Getting Full Self-Driving in Spain and England will be such huge milestones for Tesla. I am so excited to see how FSD performs in Madrid, Barcelona, and London, specifically.
The ultimate test will always be Mumbai or New Delhi. Excited for India’s eventual approval! https://t.co/paw9Ch1qmL pic.twitter.com/9RdDERVSSJ
— TESLARATI (@Teslarati) June 9, 2026
Full Self-Driving does an excellent job of roaming around major U.S. cities like New York and Los Angeles, but other high-profile international cities of significance would truly mark a line in the sand for Tesla, which can simply enable any vehicle in its customer-owned fleet to run FSD with the correct approvals.
SpaceX (SPCX) IPO is live today at $135: Here’s exactly what you need to know
Tesla unfolded its first European “folding Supercharger”
