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 Board has set a Mars bonus for Elon Musk
SpaceX has given Elon Musk the goal to put one million people on Mars.
SpaceX’s board approved a compensation plan for Elon Musk that ties his pay directly to colonizing Mars and building data centers in outer space. The details surfaced this week after Reuters reviewed SpaceX’s confidential registration statement filed with the Securities and Exchange Commission, making it one of the first concrete looks inside the company’s financials ahead of a public offering.
The pay package will reportedly award Musk 200 million super-voting restricted shares if the company hits a market valuation milestone, with the most ambitious targets going further. To unlock the full award, SpaceX would need to reach a $7.5 trillion valuation and help establish a permanent human settlement on Mars with at least one million residents. Additional incentives are tied to developing space-based computing infrastructure capable of delivering at least 100 terawatts of processing power.
SpaceX wins its first MARS contract but it comes with a catch
Long before SpaceX filed anything with the SEC, Elon Musk had already spent years framing Mars colonization as an insurance policy against human extinction. The philosophy traces back to at least 2001, when Musk first began researching Mars missions independently, before SpaceX even existed. By 2002 he had founded the company with Mars as the stated long-term goal.
In a 2017 presentation at the International Astronautical Congress, Musk outlined the specific vision that still underpins SpaceX’s architecture today. He described a self-sustaining city on Mars requiring roughly one million people to become viable, the same number now written into his compensation package.
SpaceX’s Starship, still in active development, was designed from the ground up to support the eventual colonization of Mars. Musk has stated publicly that getting the cost per ton to Mars below $100,000 is necessary to make mass migration economically feasible. Everything from Starship’s payload capacity to its full reusability targets flows from that single constraint. One can say that Musk’s latest compensation package has put a formal valuation on Mars for the first time.
SpaceX is targeting an IPO around June 28, Musk’s birthday, at a valuation of approximately $1.75 trillion. Between the Mars rover contract, the Golden Dome software group, Space Force satellite launches, and now a pay structure built around interplanetary colonization, SpaceX has become the single most consequential contractor in American space and defense. The IPO will put a public price tag on all of it for the first time.
Earlier this week, we wrote a story on how Tesla is launching a new Supercharging Queue system to mitigate problems between drivers when there is a wait to charge.
Rather than potentially having people end up in a physical conflict, Tesla’s approach is to determine who is next to charge based on geographic data.
Tesla launches solution to end Supercharger fights once and for all
But some companies, notably Tesla’s biggest rival in China, BYD, are taking a different approach, focusing on charging speeds rather than how they will manage delays.
BYD’s approach, especially with its tests of ultra-fast “Flash Charging” technology, is to eliminate the length of a charging session. At the heart of this strategy is BYD’s second-generation Blade Battery paired with 1,500-kW Flash Chargers.
Real-world FLASH Charging in action.
⚡ 10% → 70% in 5 minutes
⚡ 10% → 97% in 9 minutesIntroducing BYD’s 2nd Generation Blade Battery + FLASH Charging Technology.
20,000 stations will bring faster, safer, and smarter EV charging across China by the end of 2026. pic.twitter.com/uzQC8q1xGf
— BYD (@BYDCompany) March 9, 2026
Unveiled earlier this year, the system charges compatible vehicles from 10 percent to 70 percent state of charge in just five minutes and from 10 percent to 97 percent in nine minutes.
Real-world demonstrations on models like the Yangwang U7 and Denza Z9 GT have shown the tech delivering roughly 250 miles (400 kilometers) of range in just five minutes. This would essentially match or beat the time it takes to fill a gas tank.
Sometimes, gas pumps get congested, and there are lines. You rarely see conflicts at pumps because filling up a tank rarely takes more than five minutes.
Tesla’s fastest Supercharger build currently is the v4, which can deliver up to 325 kW for Cybertruck and 250 kW for other models, but there are “true” sites that are capable of up to 500 kW. This enables speeds of up to 1,000 miles per hour, or 1,400 miles for 350 kW-capable vehicles.
The breakthrough stems from BYD’s vertically integrated ecosystem: a new 1,000-volt architecture, 10C charging rates, and proprietary silicon-carbide chips that minimize internal resistance while protecting battery health.
The company plans to install 20,000 Flash Charging stations across China by the end of 2026, with thousands already operational and global expansion eyed for Europe and beyond later this year.
Early rollout targets popular models, including upgrades to high-volume sellers like the Seal and Sealion series, bringing five-minute charging to mainstream prices around 100,000 yuan (about $14,000).
This approach contrasts sharply with Tesla’s software solution. Tesla’s Virtual Queue uses geofencing and the app to assign turns at crowded sites, addressing driver disputes and idle time. It’s a clever fix for today’s network realities.
Yet, BYD’s philosophy is simpler: make charging so fast that waits barely exist. A five-minute stop becomes as convenient as a gas-station visit, reducing station dwell time, easing grid strain, and lowering range anxiety for long trips.
For consumers, the difference is potentially tangible. They’ll spend more time driving and less time parked. It is just another way Tesla and BYD are pushing one another to improve the overall experience of EV ownership.
News
Tesla wins big as NHTSA drops three-year, 120k unit probe against Model Y
In all, 120,089 Model Ys were impacted, but in two cases, drivers reported the complete detachment of the steering wheel from the steering column while the vehicle was in motion. NHTSA’s initial review revealed that the vehicles had been delivered without the critical retaining bolt that secures the steering wheel to the splined steering column.
A probe into over 120,000 2023 Tesla Model Y units has been closed by the National Highway Traffic Safety Administration (NHTSA). The probe ends without the agency requiring any action from Tesla.
The probe, designated PE23-003, opened in March 2023 and stemmed from just two consumer complaints involving low-mileage Model Y SUVs.
In all, 120,089 Model Ys were impacted, but in two cases, drivers reported the complete detachment of the steering wheel from the steering column while the vehicle was in motion. NHTSA’s initial review revealed that the vehicles had been delivered without the critical retaining bolt that secures the steering wheel to the splined steering column.
NHTSA has ended a probe into over 120,000 Tesla Model Y vehicles after claims that the steering wheel could detach from the steering column due to a missing retaining bolt
There is no action needed by Tesla pic.twitter.com/YpAO3bKugA
— TESLARATI (@Teslarati) April 28, 2026
Factory records showed each car had undergone an “end-of-line” repair at Tesla’s facility, during which the steering wheel was removed and reinstalled. The bolt was apparently omitted after the repair, leaving only a friction fit between the wheel and column to hold it in place temporarily.
According to NHTSA documents, this friction fit maintained the connection during initial low-mileage driving until forces during normal operation caused the wheel to detach. Both vehicles that were impacted were repaired under warranty with no injuries reported, and no additional incidents surfaced during the agency’s three-year review.
After analyzing manufacturing processes, complaint data, and field reports, NHTSA concluded the issue was isolated to those two post-repair vehicles rather than indicative of a systemic defect in Tesla’s production or quality control.
The closure means the agency has determined no recall or further enforcement is warranted for this specific missing-bolt condition.
This outcome marks the second NHTSA investigation into Tesla closed without action this month, as a recent probe into the company’s “Actually Smart Summon” feature was also resolved in April.
The two resolutions provide some relief for Tesla amid the continuous and somewhat unfair regulatory scrutiny of its vehicles, including open inquiries into driver assistance systems.
Importantly, the closed probe does not involve or affect Tesla’s separate May 2023 voluntary recall of certain 2022-2023 Model Y vehicles. That recall addressed a different issue—steering-wheel fasteners that were installed but not torqued to specification—prompted by a service technician’s observation of a loose wheel during unrelated repairs.
Tesla identified a small number of related warranty claims and proactively addressed the matter without NHTSA mandate.
The Model Y remains one of the world’s best-selling vehicles, and Tesla continues to refine its lineup, including the recent “Juniper” refresh. While federal oversight of the electric vehicle pioneer remains intense, this decision underscores that isolated manufacturing anomalies do not always translate into broader safety defects requiring recalls.
SpaceX Board has set a Mars bonus for Elon Musk
Tesla’s biggest rivals fights charging wait times with a modern approach
