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Stoke Space to build SpaceX Raptor engine’s first real competitor
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.
The update that's rolling out to the fleet makes full use of the front and rear steering travel to minimize turning circle. In this case a reduction of 1.6 feet just over the air— Wes (@wmorrill3) April 16, 2024
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.
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.
Elon Musk
Elon Musk drops a surprise update on Boring Company’s next big dig
Musk says Boring Company could shrink the Austin to San Antonio drive to just minutes.
Elon Musk says The Boring Company is working on what he called “a simple, precursor Hyperloop” tunnel connecting Austin and San Antonio, targeting speeds above 200 mph and cutting a drive that can take up to two and a half hours down to a consistent under 30 minutes. Musk posted the idea on X Sunday, in a reply to a repost of an AI generated video imagining a science fiction future with human colonies on other worlds, which he shared with the line “This is the future we shall bring into being.”
This is the future we shall bring into being pic.twitter.com/8aD0w8MDVc
— Elon Musk (@elonmusk) September 20, 2026
The Boring Company’s own account picked up the idea in the same thread, adding a detail about how the trip would actually work: “Because Loop/Hyperloop is express (i.e. no intermediate stops), one could travel from an Austin parking lot to a favorite San Antonio restaurant in about 30 minutes. As long as they both have Loop stations.” That framing ties the proposed intercity link to the same station model the company already runs in Las Vegas, where riders enter the tunnel network through small, garage style stops rather than one central terminal.
This is not the company’s first run at the Austin to San Antonio corridor. Boring Company floated tunnels between the two cities as far back as 2021, and later competed for a separate San Antonio Loop project tied to the airport before that specific bid stalled. Pitches for tunnels in Chicago, Los Angeles, and a New York to Washington corridor have followed a similar pattern of big announcement without a shovel in the ground.
What is different this time is the balance sheet, especially since The Boring Company closed a 3 billion dollar funding round led by investors in the United Arab Emirates earlier this month at a valuation near 23 billion dollars, giving the tunneling company more capital to chase speculative projects than it had during its earlier Texas pitches. The company is also mid-build on two other intercity systems it has actually broken ground on, inc;luding a Nashville tunnel linking downtown to the airport, where a second boring machine finished commissioning in June, and its Las Vegas network, where the station count keeps climbing on paper faster than tunnels get dug.
That gap between announcement and execution is the reason to treat Sunday’s post as an opening bid rather than a project. A tunnel spanning roughly 80 miles between two metro areas, running at speeds Boring Company has not demonstrated over any real distance, would dwarf anything the company has built. For now, the Austin to San Antonio Hyperloop exists as a caption under an AI generated space video.
Elon Musk
Tesla eyes supply partners for Optimus mass production
Tesla certified three Chinese suppliers for Optimus mass production, signaling its robot timeline is accelerating.
Tesla’s robotics team traveled to Ningbo, in China’s Zhejiang province, on September 16 and spent the following day auditing component suppliers for Optimus, according to a Bloomberg report cited by RobotAIGeek. The visit moved three manufacturers from provisional status to certified mass production partners: Tuopu Group, which handles actuators and chassis components, Ningbo Joyson Electronic, a sensor supplier, and Zhejiang Sanhua Intelligent Controls, which builds thermal management systems. All three already supply parts to Tesla’s electric vehicles, and the audit reportedly came with fresh orders that supply chain reports put at an initial batch of roughly 5,000 units.
Tuopu, Joyson, and Sanhua built their manufacturing base serving the automotive industry, where tolerances and volume requirements are already close to what a mass produced humanoid robot demands. Sanhua in particular has history here. Teslarati reported last October that the company had received a roughly $685 million order for linear actuators tied to Optimus, a volume industry watchers estimated could cover around 180,000 robots once production ramped.
Supply chain reports tied to this week’s audit put Tesla’s near term production goal at about 1,000 Optimus units a week by late September, rising to 2,000 to 2,500 units a week by the end of the year. That pace would put real weight behind the timeline Tesla has been building toward since May, when it wound down Model S and Model X production at Fremont to convert that floor space into a dedicated Optimus line targeting one million units annually. JPMorgan analysts who toured the factory in August confirmed the conversion took roughly four months, a pace Musk has called unprecedented for a facility that size.
New drone video shows Tesla’s Optimus Factory reaching a turning point
Fremont is only the first phase. A second, larger Optimus plant is rising at Gigafactory Texas, where drone footage shared by Joe Tegtmeyer last week showed the structural steel nearing completion on the north end of the building. Tesla has said that facility is meant to eventually support production of up to 10 million units a year, though volume output there is not expected before 2027.
Commercial sales of Optimus are still targeted for the second half of 2027, but production is expected to start well before then. JPMorgan analyst Rajat Gupta has said Tesla’s “Optimus Academy” program, which uses early units to collect real world training data inside Tesla’s own facilities, is expected to be running later this year. Bloomberg Intelligence analyst Ian Ma described the Ningbo audits as “a positive commercialization signal for China’s humanoid supply chain,” noting that sentiment could improve further if the visit leads to confirmed supplier nominations and larger orders. The Solactive China Humanoid Robotics Index rose about 1.4% on the news, though it remains down roughly 30% for the year.
Elon Musk
Elon Musk’s next Uranium in Uranus merch is Boring Company’s weirdest tease yet
Elon Musk teased a glowing new Boring Company merch idea, complete with a Geiger counter.
Elon Musk teased the next piece of Boring Company merchandise on X Saturday, and it is exactly as unserious as fans of the company’s product history have come to expect. “The next @boringcompany merch will put Uranium in Uranus,” Musk wrote in a thread posted early Saturday morning. He followed up by explaining that the item would glow in the dark, “because otherwise how could you find it,” and that a Geiger counter would be sold separately as “an optional strap-on.”
Musk closed the thread with a line that doubles as a mission statement for the tunneling company’s merchandise arm: “It’s not easy coming up with something that is both outrageously unsellable and yet extremely popular.”
The Boring Company has built a small but consistent side business out of novelty items that start as jokes and end up selling out. The company’s Not-a-Flamethrower raised roughly $10 million in a few days back in 2018, moving all 20,000 units it produced. Its Burnt Hair perfume, priced around $100 a bottle, sold out fast enough that scalpers were flipping units on eBay for ten times the retail price. Boring Bricks, made from tunneling spoil, followed the same playbook of teasing a product on X months before it became real.
Musk has not said what the actual item will be, only that it involves uranium and glows in the dark. Given the pattern, that vagueness is probably intentional. Past merch announcements have started as one-line jokes and taken weeks or months to turn into an actual product listing on the company’s site, and there is no guarantee this one follows through at all.
The timing lines up with a period of real momentum for the Boring Company outside of the joke merchandise. The company said last week it plans to double the number of operational stations on its Vegas Loop by the end of the year, a target tied to a hiring push for drivers and operations managers. Prufrock-5, one of the company’s tunnel boring machines, also just wrapped a test tunnel in Bastrop, Texas, and is expected to relaunch on its next assignment in November.
Whether the uranium joke turns into an actual product remains to be seen. Musk’s post did not include a price, a shipping date, or even a name for the item, which has historically meant a Boring Company website page goes up quietly, password protected, sometime before an announcement.