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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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Tesla Semi is already winning over truck drivers
The consensus among participants is clear: the Semi feels quieter, quicker, and far less physically demanding than diesel rigs while delivering three times the power and dramatically lower operating costs.
Tesla’s all-electric Semi is proving more than just a flashy concept as it is winning converts among the professionals who know trucks best.
As fleets roll out Pilot Programs for Tesla across North America, drivers are raving about the Class 8 electric truck’s unique features, including a centered driver’s seat, massive touchscreen visibility, instant torque, and absence of gear-shifting fatigue.
These features are transforming long days behind the wheel into noticeably easier, less stressful shifts.
Tesla Semi pricing revealed after company uncovers trim levels
In a recent Wall Street Journal profile of early pilots, Dakota Shearer of IMC Logistics described backing out of a tight spot he had mistakenly entered:
“I backed right out of there, no problem. It’s like I’d never done it in the first place. That right there showed me that the technology the Tesla has makes a big difference.”
His colleague Angel Rodriguez of Hight Logistics, who switched from a 13-speed diesel, agreed:
“It’s just easier on your body. It’s less stressful because you’re not really having to engage the clutch and the stick shift.”
Veteran drivers in other tests echo the same enthusiasm. Tom Sterba, a Senior Driver at Saia, spent days testing the Semi and came away impressed with the navigation and overall feel:
“The navigation systems in these trucks are just unbelievable. That’s what I love about it.”
Sterba summed up the experience with a line that has since gone viral among trucking circles:
“I hope I retire in this truck.”
Pilot programs with ArcBest, thyssenkrupp Supply Chain Services, and Mone Transport delivered similar feedback. Drivers consistently praised the center-seat layout for eliminating blind spots, the smooth acceleration, and the overall comfort and safety.
Real-world data backed the hype, as ArcBest logged thousands of miles at efficient consumption rates, even over the challenging routes, like Donner Pass, while other fleets beat Tesla’s own efficiency targets.
The consensus among participants is clear: the Semi feels quieter, quicker, and far less physically demanding than diesel rigs while delivering three times the power and dramatically lower operating costs.
The latest chapter in the Semi’s story arrived just days ago on Jay Leno’s Garage, as Leno became the first outsider to drive the updated long-range production model, joined by Tesla Chief Designer Franz von Holzhausen, and Semi Program Director Dan Priestley.
Tesla reveals various improvements to the Semi in new piece with Jay Leno
The episode revealed major upgrades heading to volume production this year: the truck sheds roughly 1,000 pounds, adopts a 48-volt architecture, switches to fully electric steering with Cybertruck-derived actuators, and uses 4680 battery cells engineered for an over-one-million-mile lifespan.
Aerodynamics improved, enabling a 500-mile range on the long-haul version, and about 325 miles on the shorter-wheelbase standard-range model. Megachargers can now deliver up to 1.2 megawatts, adding roughly 300 miles in about 30 minutes.
Leno hauled heavy loads and marveled at the turning radius and effortless power delivery. “I don’t feel like I’m pulling anything,” he said during the episode.
With hundreds of Semis already accumulating over 13.5 million fleet miles and high uptime, the future of heavy-duty trucking looks electric. Drivers are giving raving reviews, and they’re ready to climb aboard the electric trucking industry for good.
Investor's Corner
Tesla and SpaceX to merge in 2027, Wall Street analyst predicts
The move, Ives argues, is no longer a distant possibility but a logical next step, fueled by deepening operational ties, shared AI ambitions, and Elon Musk’s vision for dominating the next era of technology.
Tesla and SpaceX are two of Elon Musk’s most popular and notable companies, but a new note from one Wall Street analyst claims the two companies will become one sometime next year, as 2027 could see the dawn of a new horizon.
In a bold new research note, Wedbush analyst Dan Ives has reaffirmed his long-standing prediction: Tesla and SpaceX will merge in 2027.
The move, Ives argues, is no longer a distant possibility but a logical next step, fueled by deepening operational ties, shared AI ambitions, and Elon Musk’s vision for dominating the next era of technology.
He writes:
“Still Expect Tesla and SpaceX to Merge in 2027. We continue to believe that SpaceX and Tesla will eventually merge into one company in 2027 with the groundwork already in place for both operations to become one organization. Tesla already owns a stake in SpaceX after the company’s $2 billion investment in xAI got converted to SpaceX shares following SpaceX’s acquisition of xAI earlier this year initially tying both of Musk’s ventures closer together but still represents <1% of SpaceX’s expected valuation. The recent announcement of a joint Terafab facility between SpaceX and Tesla further ties both operations together making it more feasible to merge operations given the now existing overlap being built out across the two with this the first step.”
The groundwork is already being laid. Earlier this year, SpaceX acquired xAI, converting Tesla’s $2 billion investment in the AI startup into a small equity stake, less than 1 percent, in SpaceX.
Regulatory filings cleared the transaction in March 2026, formally linking the two Musk-led companies financially for the first time. Then came the announcement of a joint TERAFAB facility in Austin, Texas: two advanced chip factories, one dedicated to Tesla’s AI needs for vehicles and Optimus robots, the other targeting space-based data centers.
Elon Musk launches TERAFAB: The $25B Tesla-SpaceXAI chip factory that will rewire the AI industry
Ives calls Terafab the “first step” toward full operational integration.
SpaceX’s impending IPO, expected as soon as mid-June 2026, will turbocharge these plans. The company aims to raise approximately $75 billion at a roughly $1.75 trillion valuation, far exceeding earlier estimates.
Proceeds will fund Starship rocket flights, a NASA-contracted lunar base, expanded Starlink services across maritime, aviation, and direct-to-mobile applications, and crucially, orbital AI infrastructure
A major driver is the exploding demand for AI compute. U.S. data centers are projected to consume 470 TWh of electricity by 2030, constrained by power grids and land.
🚨 Wedbush’s Dan Ives says that Tesla and SpaceX will merge in 2027. SpaceX will IPO soon, his new note says:
“According to media reports, SpaceX could file a prospectus for an IPO imminently with the goal of raising ~$75 billion above the prior expectation of ~$50 billion…
— TESLARATI (@Teslarati) March 27, 2026
SpaceX’s strategy, launching millions of solar-powered satellites to host data centers in orbit, bypasses Earth’s energy bottlenecks. Solar energy captured in space avoids atmospheric losses and day-night cycles, offering a scalable solution for AI training and inference.
The xAI acquisition ties directly into this vision, positioning the combined entity as a leader in extraterrestrial computing.
The merger would create a formidable conglomerate spanning electric vehicles, robotics, satellite communications, human spaceflight, and defense.
Ives highlights SpaceX’s role in the Trump administration’s “Golden Dome” missile defense shield, which would leverage Starlink satellites for tracking.
For Tesla, access to SpaceX’s launch cadence and orbital assets could accelerate autonomous driving, Robotaxi fleets, and Optimus deployment.
Musk, who has signaled his desire to own roughly 25 percent of Tesla to steer its AI future, views the combination as essential to overcoming fragmented regulatory scrutiny from the FTC and DOJ.
Challenges remain. Antitrust hurdles could delay or reshape the deal, and shareholder approvals on both sides would be required. Yet Ives remains bullish, maintaining an Outperform rating on Tesla with a $600 price target, implying substantial upside from current levels. The analyst sees the merger as the “holy grail” for consolidating Musk’s disruptive tech empire.
If realized, a 2027 Tesla-SpaceX union would not only reshape corporate boundaries but redefine humanity’s trajectory in AI and space exploration. It would mark the moment two pioneering companies become one unstoppable force, pushing the limits of what’s possible on Earth and beyond.
News
Tesla ‘Killer’ heads to the graveyard as AFEELA taps out
SHM has officially discontinued development of its highly anticipated AFEELA electric vehicles. On March 25, the joint venture between Sony and Honda announced it would halt the AFEELA 1 luxury sedan and a planned SUV model.
There have been many Tesla “Killers” over the years, all of which have either failed to dethrone the automaker from its dominance in the United States, or even make it to the market altogether.
The Sony Honda Mobility (SHM) project, known as AFEELA, is the latest to make it to the grave, as the company announced its intentions to abandon the project earlier this week, Bloomberg reported.
SHM has officially discontinued development of its highly anticipated AFEELA electric vehicles. On March 25, the joint venture between Sony and Honda announced it would halt the AFEELA 1 luxury sedan and a planned SUV model.
🚗 Tesla Killers Graveyard:
Sony-Honda AFEELA
The sleek, AI-packed luxury sedan with PlayStation integration. Officially cancelled in March 2026 after Honda scaled back its EV plans.Fisker Ocean
Stylish SUV with solar roof promises. Company filed for bankruptcy in 2024 amid… https://t.co/Om14UhISOy— TESLARATI (@Teslarati) March 26, 2026
The decision follows Honda’s March 12 reassessment of its electrification strategy, which scrapped several upcoming EV programs amid slowing demand, high costs, and shifting market conditions.
SHM stated that it could no longer rely on key Honda technologies and manufacturing assets, leaving “no viable path forward.” Reservation fees for early buyers in California are being fully refunded, and the joint venture’s future is now under review.
Launched with fanfare in 2022, the AFEELA was positioned as a tech-forward premium EV blending Honda’s engineering reliability with Sony’s entertainment and AI expertise.
Prototypes featured advanced autonomous driving systems, immersive in-cabin displays, and even PlayStation integration, earning it early media labels as a potential “Tesla Killer.”
Priced around $90,000, the sedan was slated for limited production at Honda’s Ohio plant with deliveries targeted for late 2026. Industry watchers saw it as a serious challenger to Tesla’s dominance in software, connectivity, and premium appeal.
Yet, like many ambitious EV projects, it fell victim to broader industry headwinds: softening consumer demand, persistent high interest rates, and intense competition from established players.
The AFEELA joins a long list of vehicles once hyped as “Tesla Killers” that failed to deliver. In the late 2010s, Fisker’s second act, the Ocean SUV, promised stylish design and solid-state battery tech but collapsed into bankruptcy in 2024 after production delays, quality issues, and financial shortfalls.
Faraday Future poured billions into the FF 91 luxury sedan, touting it as a hyper-tech rival with unmatched performance and features; the company delivered fewer than 100 vehicles before fading into obscurity.
Lordstown Motors’ Endurance electric pickup generated massive pre-order buzz and Wall Street excitement but imploded after exaggerated range claims, a factory sale, and eventual bankruptcy.
Even Lucid Motors’ Air sedan, frequently called a Tesla slayer for its superior range and luxury, has struggled with sluggish sales and missed growth targets despite strong reviews.
Rivian’s R1T and R1S trucks enjoyed similar early acclaim and a blockbuster IPO, yet production ramp-up challenges and profitability woes have prevented it from dethroning Tesla.
The AFEELA’s quiet demise underscores a harsh reality in the EV sector. While Tesla’s first-mover advantage in software, charging infrastructure, and brand loyalty remains formidable, legacy automakers and tech newcomers alike continue to underestimate the complexities of scaling affordable, desirable electric vehicles.
As market realities force tough choices, the graveyard of “Tesla Killers” grows longer, another reminder that innovation alone is rarely enough to topple an established leader.








