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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.
News
Tesla Sweden maintains Trelleborg port deal despite union blockade
As noted in a report from Dagens Arbete (DA), Tesla was able to maintain its storage agreement with the Port of Trelleborg.
Tesla Sweden is still storing vehicles at the Port of Trelleborg despite the ongoing blockades against the company from the country’s labor unions.
Tesla still at Port of Trelleborg
As noted in a report from Dagens Arbete (DA), Tesla was able to maintain its storage agreement with the Port of Trelleborg. This allows the company to keep vehicles at the port while imports into Sweden continue. This was despite a Transport Workers’ Union blockade aimed at halting the loading and unloading of Tesla vehicles in the area.
Local union leader Jörgen Wärja, chairman of Transport and an employee representative on the port company’s board, confirmed that the agreement was still active. “The agreement has not been terminated. You want to have the money instead of having empty warehouses. I understand the reason, but I do not support it,” Wärja said
The local union leader also noted that he visited Tesla’s storage area earlier this week. “There were a lot of cars. I was surprised that there were so many, actually,” he said.
Tesla had been able to bring vehicles into Sweden via passenger ferries at Trelleborg, a method that unions said allowed the company to bypass the blockade. According to estimates from IF Metall, the workaround enabled Tesla to deliver thousands of cars to Sweden each year.
Port defends decision
The Port of Trelleborg did not issue a comment on its current agreement with Tesla, but said it had complied with union sympathy measures. Documents reviewed by Swedish media showed that the contract with Tesla was being extended in six-month intervals. Port CEO Malin Collin noted that the port would not discuss individual customer arrangements.
“We do not go into details regarding any customer agreements. We have continuous dialogue with potential tenants, and this is not unique to any location,” Collin wrote in an email.
The CEO added that the port was following legal requirements related to the labor dispute. “We have taken note of the Transport Workers’ Union’s decision on sympathy measures and are of course following applicable legislation and the requirements placed on us as employers,” Collin said.
Jörgen Wärja, for his part, noted that the issue was not whether Tesla’s imports into Sweden could be fully stopped, but whether the port should provide logistical support to the electric vehicle maker during an active conflict. “The port shouldn’t have anything to do with Tesla at all, we believe,” he said. “It’s purely moral. Whether you honor a conflict or not. If you say you support Transport’s sympathetic actions against Tesla, it becomes a double standard.”
Elon Musk
Elon Musk shares insights on SpaceX and Tesla’s potential scale
In a pair of recent posts on X, Musk argued that both companies operate in domains where growth is not linear, but exponential.
Elon Musk outlined why he believes Tesla and SpaceX ultimately dwarf their competitors, pointing to autonomy, robotics, and space-based energy as forces that fundamentally reshape economic scale.
In a pair of recent posts on X, Musk argued that both companies operate in domains where growth is not linear, but exponential.
Space-based energy
In a response to a user on X who observed that SpaceX has a larger valuation than all six US defense companies combined, Musk explained that space-based industries will eventually surpass the total economic value of Earth. He noted that space allows humanity to harness roughly 100,000 times more energy than Earth currently uses, while still consuming less than a millionth of the Sun’s total energy output.
That level of available energy should enable the emergence and development of industries that are simply not possible within Earth’s physical and environmental constraints. Continuous solar exposure in space, as per Musk’s comment, removes limitations imposed by atmosphere, weather, and land availability.
Autonomy and robots
In a follow-up post, Elon Musk explaned that “due to autonomy, Tesla is worth more than the rest of the auto industry.” Musk added that this assessment does not yet account for Optimus, Tesla’s humanoid robot. As per the CEO, once Optimus reaches scaled production, it could increase Earth’s gross domestic product by an order of magnitude, ultimately paving the way for sustainable abundance.
Even before the advent of Optimus, however, Tesla’s autonomous driving system already gives vehicles the option to become revenue-generating assets through services like the Tesla Robotaxi network. Tesla’s autonomous efforts seem to be on the verge of paying off, as services like the Robotaxi network have already been launched in its initial stages in Austin and the Bay Area.
News
Tesla Cybercab undergoes winter testing as Elon Musk reiterates production start date
CEO Elon Musk confirmed the timeline in a recent post on X, while Tesla’s official social media accounts separately revealed that Cybercab prototypes are now undergoing winter testing in Alaska.
Tesla has reiterated that production of its fully autonomous Cybercab is set to begin in April, even as the company continues expanding real-world testing of the vehicle.
CEO Elon Musk confirmed the timeline in a recent post on X, while Tesla’s official social media accounts separately revealed that Cybercab prototypes are now undergoing winter testing in Alaska.
Musk confirms April Cybercab initial production
In a post on X, Musk reiterated that Cybercab production is scheduled to begin in April, reiterating his guidance about the vehicle’s manufacturing timeline. Around the same time, Tesla shared images showing the Cybercab undergoing cold-weather testing in Alaska. Interestingly enough, the Cybercab prototypes being tested in Alaska seemed to be equipped with snow tires.
Winter testing in Alaska suggests Tesla is preparing the Cybercab for deployment across a wide range of climates in the United States. Cold temperatures, snow, ice, and reduced traction present some of the most demanding scenarios for autonomous systems, making Alaska a logical proving ground for a vehicle designed to operate without a human driver.
Taken together, Musk’s production update and Tesla’s testing post indicate that while the Cybercab is nearing the start of manufacturing, validation efforts are still actively ramping to ensure reliability in real-world environments.
What early Cybercab production might look like
Musk has previously cautioned that the start of Cybercab manufacturing will be slow, reflecting the challenges of launching an all-new vehicle platform. In a recent comment, Musk said initial production typically follows an S-curve, with early output constrained by how many new parts and processes are involved.
According to Musk, both Cybercab and Optimus fall into this category, as “almost everything is new.” As a result, early production rates are expected to be very deliberate before eventually accelerating rapidly as manufacturing processes mature.
“Initial production is always very slow and follows an S-curve. The speed of production ramp is inversely proportionate to how many new parts and steps there are. For Cybercab and Optimus, almost everything is new, so the early production rate will be agonizingly slow, but eventually end up being insanely fast,” Musk wrote in a post on X.
Tesla Sweden maintains Trelleborg port deal despite union blockade
Elon Musk shares insights on SpaceX and Tesla’s potential scale
