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Stoke Space to build SpaceX Raptor engine’s first real competitor

Stoke Space has begun testing parts of an engine similar to SpaceX's famous Raptor.

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Seattle startup Stoke Space has revealed plans to develop an efficient rocket engine similar to the Raptors that power SpaceX’s Starship.

Formed in October 2019, Stoke Space secured its first significant round of funding – $9.1 million – less than three years ago. At that time, CEO and co-founder Andy Lapsa says that the startup had just five employees, no permanent workspace, and a “barren field” for a test site. Within 18 months, Stoke Space had turned that empty field into an impressive test facility, conducted numerous component tests, and assembled its first full-scale rocket engine – an exotic UFO-like device unlike any seen before.

It also raised another $65 million – enough funding to begin earnestly developing a potentially revolutionary rocket capable of launching more than 1.65 tons (~3600 lb) into orbit for less than half a million dollars. To realize that extremely ambitious goal, Stoke Space has taken the even more ambitious step of attempting to make the first rocket it develops fully reusable. Simultaneously, the company has incorporated several exotic technologies into that rocket, recently culminating in a surprise announcement that it will attempt to develop one of the most difficult types of engines to power that rocket’s booster stage.

Full-flow staged combustion

At the end of an extended interview and tour with YouTuber Tim Dodd (The Everyday Astronaut), CEO Andy Lapsa revealed that Stoke Space has decided to build a full-flow staged combustion (FFSC) engine for the first stage of its reusable rocket. FFSC is the most efficient type of combustion cycle available for a chemical bipropellant rocket engine, but it’s also the most difficult to develop.

A full-flow engine attempts to squeeze every possible ounce of performance out of the propellant it consumes. The most powerful and efficient chemical rocket engines must consume huge volumes of propellant in a short amount of time without destroying the launch vehicle they’re attached to. To create pressure and spin the pumps that are needed to feed that propellant into their main combustion chamber, engines often burn a small amount of propellant in a separate gas generator or preburner. Gas-generator engines vent that exhaust overboard, reducing efficiency but making for a much simpler design. Staged-combustion engines use preburners to create gas that pumps liquid propellant, and that exhaust gas is eventually injected into the main combustion chamber.

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Full-flow staged combustion sets itself apart by having two separate pumps and preburners for oxidizer and fuel. Unlike simpler variants of staged combustion, FFSC engines turn all of their propellant into gas before injecting it into the combustion chamber. That hot gas increases the heat of combustion and the pressure inside the combustion chamber, ensuring that virtually all of the propellant that flows through the engine is combusted and turned into thrust as efficiently as possible. FFSC is exceptionally difficult because of the extra-high temperatures and pressures it requires, as well as the need for an oxygen-rich preburner and pump. In a high-pressure, hot-oxygen environment, virtually anything imaginable – including most metals – will spontaneously combust.

Only complex custom-designed alloys can survive those conditions. SpaceX’s Raptor, the only FFSC engine that has ever flown, is especially difficult because it’s meant to be highly reusable. To be successful, Raptor will have to survive those conditions dozens or even hundreds of times in a row with little to no maintenance in between.

The first booster engine Stoke Space ever attempts to build will be a reusable full-flow staged combustion engine powered by liquid methane and liquid oxygen – essentially a smaller version of SpaceX’s Raptor. Stoke’s booster is otherwise familiar and features deployable landing legs like SpaceX’s Falcon boosters. Lapsa says it will likely also have grid fins.

Reusing the upper stage

In some ways, the upper stage of Stoke’s first rocket is even more ambitious. Powered by hydrogen and oxygen propellant, Stoke has designed a conical capsule-like upper stage with an integral fairing. The upper stage’s propulsion is exotic and unique. A large pump will feed propellant to up to 30 combustion chambers distributed around the rim of its heat shield. The exhaust coming from those 30 chambers will expand and partially push against the upper stage’s equally exotic metallic, liquid-cooled heat shield. That expansion against the heat shield improves the efficiency of the upper stage and means that its engine will technically be an aerospike.

Stoke has already begun testing a full-scale version of the upper stage’s UFO-like rocket engine with 15 combustion chambers. Since testing began in the second half of 2022, Stoke has completed dozens of static fires. Everyday Astronaut’s tour also revealed that the startup has made significant progress fabricating and assembling its first full-scale upper stage prototype – tanks, nosecone, heat shield, engine, and all.

Reminiscent of SpaceX’s Grasshopper and Starhopper campaigns, Stoke plans to conduct hop tests with that prototype if it makes it through qualification testing. On February 7th, Stoke also revealed that it’s begun testing a crucial component of its full-flow booster engine. All told, Stoke Space is making progress at a remarkable pace and continues to tackle the hardest problems. The startup has also avoided widely publicizing any specific deadlines, instead choosing to let hardware and tangible results speak for themselves. Only time will tell if that approach pays off, but Stoke is off to an exceptionally impressive start in an industry full of impressive rocket startups.

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Eric Ralph is Teslarati's senior spaceflight reporter and has been covering the industry in some capacity for almost half a decade, largely spurred in 2016 by a trip to Mexico to watch Elon Musk reveal SpaceX's plans for Mars in person. Aside from spreading interest and excitement about spaceflight far and wide, his primary goal is to cover humanity's ongoing efforts to expand beyond Earth to the Moon, Mars, and elsewhere.

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Tesla ‘Mad Max’ gets its first bit of regulatory attention

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Credit: Teslarati

Tesla “Mad Max” mode has gotten its first bit of regulatory attention, as the National Highway Traffic Safety Administration (NHTSA) has asked for additional information on the Speed Profile.

A few weeks ago, Tesla officially launched a new Speed Profile for Full Self-Driving (Supervised) known as “Mad Max,” which overtook the “Hurry” mode for the fastest setting FSD offers.

Tesla launches ‘Mad Max’ Full Self-Driving Speed Profile, its fastest yet

It launched with Full Self-Driving v14.1.2, and it was no secret that the company was looking for a new mode that would cater to more aggressive driving styles.

The release notes showed the description of the Speed Profile as:

“Introduced new speed profile MAD MAX, which comes with higher speeds and more frequent lane changes than Hurry.”

It certainly lived up to its description. In our testing, it was aggressive, fast, and drove similarly to some of the more challenging traffic patterns I’ve come across.

In normal highway driving, it was one of the quicker cars on the road, while other applications saw it be a suitable version for navigating things like rush-hour traffic.

Here’s what my experience with it was:

While Tesla owners have certainly enjoyed the feature and the behaviors of Mad Max, the NHTSA said it is in contact with Tesla about it, looking to gather additional information. Additionally, it said:

“The human behind the wheel is fully responsible for driving the vehicle and complying with all traffic safety laws.”

The important thing to note with Mad Max mode, along with the other Speed Profiles, is that the driver can choose whichever one they’d like, and they all cater to different driving styles.

While Mad Max is more aggressive, modes like “Sloth” and “Standard” are significantly more conservative and can be more suitable for those who are not comfortable with the faster, more spirited versions.

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Tesla shares AI5 chip’s ambitious production roadmap details

Tesla CEO Elon Musk has revealed new details about the company’s next-generation AI5 chip, describing it as “an amazing design.”

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Image used with permission for Teslarati. (Credit: Tom Cross)

Tesla CEO Elon Musk has revealed new details about the company’s next-generation AI5 chip, describing it as “an amazing design” that could outperform its predecessor by a notable margin. Speaking during Tesla’s Q3 2025 earnings call, Musk outlined how the chip will be manufactured in partnership with both Samsung and TSMC, with production based entirely in the United States.

What makes AI5 special

According to Musk, the AI5 represents a complete evolution of Tesla’s in-house AI hardware, building on lessons learned from the AI4 system currently used in its vehicles and data centers. “By some metrics, the AI5 chip will be 40x better than the AI4 chip, not 40%, 40x,” Musk said during the Q3 2025 earnings call. He credited Tesla’s unique vertical integration for the breakthrough, noting that the company designs both the software and hardware stack for its self-driving systems.

To streamline the new chip, Tesla eliminated several traditional components, including the legacy GPU and image signal processor, since the AI5 architecture already incorporates those capabilities. Musk explained that these deletions allow the chip to fit within a half-reticle design, improving efficiency and power management. 

“This is a beautiful chip,” Musk said. “I’ve poured so much life energy into this chip personally, and I’m confident this is going to be a winner.”

Tesla’s dual manufacturing strategy for AI5

Musk confirmed that both Samsung’s Texas facility and TSMC’s Arizona plant will fabricate AI5 chips, with each partner contributing to early production. “It makes sense to have both Samsung and TSMC focus on AI5,” the CEO said, adding that while Samsung has slightly more advanced equipment, both fabs will support Tesla’s U.S.-based production goals.

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Tesla’s explicit objective, according to Musk, is to create an oversupply of AI5 chips. The surplus units could be used in Tesla’s vehicles, humanoid robots, or data centers, which already use a mix of AI4 and NVIDIA hardware for training. “We’re not about to replace NVIDIA,” Musk clarified. “But if we have too many AI5 chips, we can always put them in the data center.”

Musk emphasized that Tesla’s focus on designing for a single customer gives it a massive advantage in simplicity and optimization. “NVIDIA… (has to) satisfy a large range of requirements from many customers. Tesla only has to satisfy one customer, Tesla,” he said. This, Musk stressed, allows Tesla to delete unnecessary complexity and deliver what could be the best performance per watt and per dollar in the industry once AI5 production scales.

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Tesla VP hints at Solar Roof comeback with Giga New York push

The comments hint at possible renewed life for the Solar Roof program, which has seen years of slow growth since its 2016 unveiling.

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Image Credit: Tesla/Twitter

Tesla’s long-awaited and way underrated Solar Roof may finally be getting its moment. During the company’s Q3 2025 earnings call, Vice President of Energy Engineering Michael Snyder revealed that production of a new residential solar panel has started at Tesla’s Buffalo, New York facility, with shipments to customers beginning in the first quarter of 2026. 

The comments hint at possible renewed life for the Solar Roof program, which has seen years of slow growth since its 2016 unveiling.

Tesla Energy’s strong demand

Responding to an investor question about Tesla’s energy backlog, Snyder said demand for Megapack and Powerwall continues to be “really strong” into next year. He also noted positive customer feedback for the company’s new Megablock product, which is expected to start shipping from Houston in 2026.

“We’re seeing remarkable growth in the demand for AI and data center applications as hyperscalers and utilities have seen the versatility of the Megapack product. It increases reliability and relieves grid constraints,” he said.

Snyder also highlighted a “surge in residential solar demand in the US,” attributing the spike to recent policy changes that incentivize home installations. Tesla expects this trend to continue into 2026, helped by the rollout of a new solar lease product that makes adoption more affordable for homeowners.

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Possible Solar Roof revival?

Perhaps the most intriguing part of Snyder’s remarks, however, was Tesla’s move to begin production of its “residential solar panel” in Buffalo, New York. He described the new panels as having “industry-leading aesthetics” and shape performance, language Tesla has used to market its Solar Roof tiles in the past.

“We also began production of our Tesla residential solar panel in our Buffalo factory, and we will be shipping that to customers starting Q1. The panel has industry-leading aesthetics and shape performance and demonstrates our continued commitment to US manufacturing,” Snyder said during the Q3 2025 earnings call.

Snyder did not explicitly name the product, though his reference to aesthetics has fueled speculation that Tesla may finally be preparing a large-scale and serious rollout of its Solar Roof line.

Originally unveiled in 2016, the Solar Roof was intended to transform rooftops into clean energy generators without compromising on design. However, despite early enthusiasm, production and installation volumes have remained limited for years. In 2023, a report from Wood Mackenzie claimed that there were only 3,000 operational Solar Roof installations across the United States at the time, far below forecasts. In response, the official Tesla Energy account on X stated that the report was “incorrect by a large margin.”

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