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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.
The Tesla Semi is entering a new Pilot Program with Paper Transport, LLC (PTI), a Wisconsin-based transportation provider. The company will test the Semi’s Long Range configuration through “dedicated operations within the Chicago market.”
Chicago presents an interesting challenge for the Semi, as it will be a colder-weather climate that will test the Semi’s ability to operate in lower temperatures and in potentially large accumulations of snow. This is something Tesla has been testing with the Semi in Alaska and even in Northern California during the colder months, but Chicago will present a truly tough midwestern winter.
Tesla Semi spotted on journey home after winter performance testing
PTI says it is using the Semi to evaluate its strategy of reducing transportation emissions while maintaining performance, reliability, and cost efficiency. These are major arguments for the Semi being introduced into new fleets.
CEO of PTI Tyler Ellison said:
“PTI has been a leader in sustainable transportation solutions for over 15 years. We take a consultative approach to helping customers identify and implement the right transportation solution for their network. Our partnership with Tesla expands our portfolio alongside renewable natural gas and intermodal, giving customers more ways to reduce Scope 3 emissions without compromising service or economics.”
PTI is far from the first company to adopt the Semi within a fleet, as Tesla entered strategic agreements with PepsiCo. and its subsidiary Frito-Lay for a Pilot Program that extended throughout the California region.
Tesla has let companies like those utilize the Semi to determine whether it would be suitable for their operations. Additionally, Tesla gets valuable information regarding the Semi’s performance, knowing what to improve and what is ideal for companies that will utilize the all-electric truck for regional and nationwide logistics.
PTI plans to utilize the Long Range configuration, which is priced at $290,000 and features a range of approximately 500 miles, a three-motor powertrain, up to 800 kW of drive power, and consumption of just 1.7 kWh per mile.
Tesla Semi pricing revealed after company uncovers trim levels
VP of Maintenance at PTI, Bryan Ellen, added:
“We are excited to partner with Tesla, leveraging their ever-evolving technology. We are bullish in our estimation of the parallels available between our dedicated model and the efficiency of their fully electric Class 8 tractor. We anticipate a growing synergy between our businesses as we work to facilitate this sustainable solution for our customers.”
PTI has logged more than 87 million miles using sources like compressed and renewable gas, but now is looking to take it a step further with fully electric operations.
Tesla revealed on Monday that it is building a new autonomous vehicle at Gigafactory Texas, its plant just outside of the City of Austin. This particular vehicle will be geared toward those who are in need of a wheelchair-accessible car that would require no human driver for operation.
According to a new report from Wired, Tesla’s Senior Policy Advisor, India Herdman, told members of the Washington D.C. City Council on Monday:
“We are in development for a purpose-built, wheelchair-accessible autonomous vehicle. We know that paratransit can be very difficult, and people who are confined to wheelchairs permanently should still be able to move around freely, so that is an active product being built by Tesla in Texas.”
This builds upon what CEO Elon Musk said last year on X, which confirmed the company was working on accessible rides within its Robotaxi platform, which currently is confined to the Model Y.
Absolutely
— Elon Musk (@elonmusk) September 19, 2025
Tesla is also developing the Cybercab, which started employee rides last week. However, this vehicle is not necessarily geared toward wheelchair accessibility.
That leaves a major gap in the autonomous ride-sharing program that Tesla is attempting to build; the company has been pretty clear that it does not want to complicate its manufacturing lines by bringing in a wide array of body styles.
However, it seems necessary to have something larger that could help transport people to appointments when they cannot drive. For wheelchair accessibility, the Robovan, which was unveiled at the “We, Robot” event in October 2024, seems to be the most ideal solution:
Herdman did not indicate whether she was referring to the Robovan or if Tesla is building yet another body style that is geared toward full autonomy but also caters to the handicapped.
Tesla might need to develop something specifically for the handicapped in order to align with the Americans with Disabilities Act, which prevents discrimination against people with disabilities in transportation services. Uber was hit with a lawsuit late last year for “refusing to reasonably modify its policies, practices, or procedures where necessary to avoid discriminating against riders with disabilities.”
Tesla would obviously like to avoid this.
It will be interesting to see what Tesla will do with this project, and whether it will introduce something new to the market or just continue with the Robovan.
Tesla weirdly confirmed that its steering wheel-less and pedal-less Cybercab vehicle is now in the process of giving employees rides, a huge milestone for the vehicle program.
But the entire thing was super strange. On Friday, Tesla released a video stating that there was “Cool news from Giga Texas” and that employees were now taking rides in Cybercabs that have no manual controls. The units seen on public roads are engineering vehicles that have manual controls inside, a necessity as Tesla moved through the testing phase.
However, Tesla removed the video and reposted it shortly after with a more vague title. It seems like the employee rides are still going, but the video was adjusted slightly. The initial upload showed employees doing things like watching movies and adjusting the climate, but these snippets were removed in the second upload.
Cool news from Giga Texas pic.twitter.com/gvbG456Tzw
— Tesla Robotaxi (@robotaxi) July 11, 2026
Both images below were uploaded with the first video, but were removed after Tesla re-uploaded the announcement. These are not available in the second upload
Credit: Tesla
Credit: Tesla
Nevertheless, the announcement from Tesla is that the Cybercab is operating with employees inside who can control the vehicle’s audio, video, climate, and destination settings through their smartphone app.
Tesla has already been testing Cybercab engineering units, but last month, it was able to self-certify for SAE Level 4, which would enable unsupervised self-driving in Texas. The company is moving toward that, and the plans have always been to launch Cybercab rides this year.
The Cybercab is potentially looked at as the next generation of Tesla’s mobility leg. For the past 15 years, the company has been known as somewhat of an automaker, among many other things. However, these passenger vehicles that Tesla has manufactured are now moving into a new realm, as they will eventually drive themselves with no supervision thanks to the Full Self-Driving suite.
The Cybercab is just the next step of that: a true vehicle developed for the sole purpose of ride-hailing. It has no human controls, it has only two seats, and it will get passengers from Point A to Point B with no awkward driver, no need for manual inputs, and with no stress.
Tesla is moving forward with other developments related to the Cybercab project as well. However, the big announcement will come when Tesla finally announces that it is launching Cybercab rides to the general public, something that it plans to launch either late this year or early 2027.
Tesla Semi enters new Pilot Program with interesting challenge
Tesla is building a wheelchair-accessible Robotaxi
