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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News
Tesla Semi gets new product launch as mass manufacturing hits Plaid Mode
While the 1.2 MW Megacharger handles quick 30-minute en-route boosts, the Basecharger serves as a reliable overnight solution for longer dwell times at warehouses, distribution centers, fleet yards, and even, potentially, homes.
The Tesla Semi is getting a new production launch as mass manufacturing on the all-electric truck is gearing up to hit Plaid Mode.
Tesla has introduced a game-changing addition to its commercial charging lineup with the new 125 kW Basecharger for Semi. Launched this week as part of the new “Semi Charging for Business” program, this compact unit is purpose-built for depot and overnight charging of Tesla Semi trucks.
While the 1.2 MW Megacharger handles quick 30-minute en-route boosts, the Basecharger serves as a reliable overnight solution for longer dwell times at warehouses, distribution centers, fleet yards, and even, potentially, homes.
Our new 125 kW Basecharger is designed for longer dwell times and overnight charging of Semis. It’s the “home charging” for heavy-duty fleets.
It features a fully integrated design that eliminates the need for a separate AC-to-DC cabinet, simplifying installation. The 6 meter… https://t.co/ovy1C4PsRW pic.twitter.com/vBUCNMzs57
— Tesla Charging (@TeslaCharging) May 1, 2026
Delivering up to 60 percent of the Semi’s range in roughly four hours, perfect for overnight top-ups during mandated driver rest periods or while trucks are loaded or unloaded. Its fully integrated design eliminates the need for bulky separate AC-to-DC cabinets.
Tesla engineers tucked one of the power modules from a V4 Supercharger Cabinet directly inside the sleek post, resulting in a compact footprint. It also features a six-meter cable for layout flexibility. This is one thing that must have been learned through the V4 Supercharger rollout.
Installation and operating costs drop dramatically thanks to daisy-chaining. Up to three Basechargers can share a single 125 kVA breaker, slashing electrical infrastructure requirements. The unit outputs 150 amps continuous across an 180–1,000 VDC range, matching the Semi’s high-voltage architecture while supporting the MCS 3.2 standard.
Tesla Semi sends clear message to Diesel rivals with latest move
Priced from $40,000 for a minimum order of two units, the Basecharger is far more affordable than the $188,000 Megacharger setup for two posts. Deliveries begin in early 2027. Buyers also receive Tesla’s full network-level software, remote monitoring, maintenance, and a guaranteed 97 percent or higher uptime—critical for fleet reliability.
This launch arrives as Tesla accelerates high-volume Semi production at its Nevada factory, targeting 50,000 units annually. By pairing affordable depot charging with ultra-fast highway options, Tesla removes one of the biggest obstacles to electrifying Class 8 trucking: infrastructure cost and complexity.
Fleet operators stand to gain lower electricity rates during off-peak hours, dramatically reduced maintenance compared to diesel, and quieter yards at night. The Basecharger isn’t just another charger—it’s the practical bridge that makes large-scale electric semi adoption economically viable.
With the Basecharger handling “home” duties and Megachargers powering the road, Tesla is delivering a complete ecosystem that could finally tip the scales toward zero-emission freight. For trucking companies ready to go electric, the future just got a whole lot more charger-friendly.
News
Tesla revises new Intervention Reporting system with Full Self-Driving
It is the second revision to the program as Tesla is trying to make it easier to decipher driver and owner complaints, but also to make it easier to report issues within the suite for them.
Tesla has revised its new Intervention Reporting system within the Full Self-Driving suite that now categorizes reasons that drivers take over when the semi-autonomous driving functionality is active.
It is the second revision to the program as Tesla is trying to make it easier to decipher driver and owner complaints, but also to make it easier to report issues within the suite for them.
With the initial rollout of Full Self-Driving v14.3.2, Tesla included a new reporting menu that gave four options for an intervention: Preference, Comfort, Critical, and Other. A slightly revised version of Full Self-Driving with the same ID number then came out a few days later, changing the “Other” option to “Navigation” after numerous complaints from owners.
It appears Tesla has listened to those owners once again and has not only made it smaller and more compact, but also easier to report the issues than previously.
The new menu is now embedded within the request for a Voice Memo from Tesla, and does not block the entire screen, as the second rollout of the menu was:
Thank you Tesla! The new intervention screen is much better! @Tesla_AI pic.twitter.com/1lea9G27N1
— Dirty Tesla (@DirtyTesLa) May 1, 2026
There will likely be one additional revision to the Interventions Menu, as we have coined it here at Teslarati.
Unfortunately, at times, there are no reasons for an intervention at all, but the menu does not give an option to simply disregard the reporting and forces the driver to choose one of the options. We, as well as other notable Tesla influencers, indicated that there is not always a reason for an intervention.
For example, I choose to back into my parking spot in my neighborhood at least some of the time for the reason of charging. I usually hit “Preference” for this, but it sends a false positive to Tesla that there was a reason I took over that I was unhappy with.
Tesla begins probing owners on FSD’s navigation errors with small but mighty change
Instead, I’m simply performing a maneuver that is not yet available to us. When Tesla allows drivers to choose the orientation at which their car enters a parking spot, I and many others won’t have to deal with this menu.
Others are still skeptical that it will help resolve any issues whatsoever and prefer to disregard the menu altogether. It does seem as if Tesla will issue another revision in the coming days to allow this to happen.
Lifestyle
California hits Tesla Cybercab and Robotaxi driverless cars with new law
California just gave police power to ticket driverless cars, including Tesla’s Cybercab fleet.
California DMV formally adopted new rules on April 29, 2026 that allow law enforcement to issue “notices of noncompliance”, or in other words ticket autonomous vehicle companies when their cars commit moving violations. The rules take effect July 1, 2026 and officially closes a regulatory gap that previously let driverless cars operate on public roads with nearly no traffic enforcement consequences.
Until now, state traffic laws only applied to human “drivers,” which meant that when no person was behind the wheel, police had no mechanism to issue a ticket. Officers were limited to citing driverless vehicles for parking violations only. A well-known example came in September 2025, when a San Bruno officer watched a Waymo robotaxi execute an illegal U-turn and could do nothing but notify the company.
Under the new framework, when an officer observes a violation, the autonomous vehicle company is effectively treated as the driver. Companies must report each incident to the DMV within 72 hours, or 24 hours if a collision is involved. Repeated violations can result in fleet size restrictions, operational suspensions, or full permit revocation. Local officials also gained new authority to geofence driverless vehicles out of active emergency zones within two minutes and require a live emergency response line answered within 30 seconds.
Tesla Cybercab ramps Robotaxi public street testing as vehicle enters mass production queue
California’s new enforcement rules arrive at a pivotal moment for Tesla. The company is ramping Cybercab production at Giga Texas toward hundreds of units per week, targeting at least 2 million units annually at full capacity, while simultaneously pushing to expand its Robotaxi service to dozens of U.S. cities by end of 2026. Unsupervised FSD for consumer vehicles is currently targeted for Q4 2026, and when it arrives, Tesla’s fleet may not have a human to absorb legal accountability, under the July 1 rules.
Tesla has confirmed plans to expand its Robotaxi service to seven new cities in the first half of 2026, including Dallas, Houston, Phoenix, Miami, Orlando, Tampa, and Las Vegas, with the service already running without safety drivers in Austin. Musk has said he expects robotaxis to cover between a quarter and half of the United States by end of year.
Tesla Semi gets new product launch as mass manufacturing hits Plaid Mode
Tesla revises new Intervention Reporting system with Full Self-Driving
