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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.
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Tesla Giga Berlin makes a statement of solidarity amid IG Metall conflict
The display comes as tensions between Tesla and IG Metall continue to escalate.
Tesla Giga Berlin is sending a strong message of solidarity amid its ongoing legal dispute with German union IG Metall.
In a post on social media platform X, Giga Berlin plant manager André Thierig shared an image of the facility’s lobby covered with a large banner that reads: “Progress. Innovation. Success.” He added that the slogan reflects what the facility has stood for since Day One.
“Our lobby at Giga Berlin covered in a huge banner these days. Progress. Innovation. Success – this is what we stand for since we started production in 2022 and how we will go into our future!” Thierig wrote in his post on X.
The display comes as tensions between Tesla and IG Metall continue to escalate.
The dispute began after Tesla accused a union representative of secretly recording a works council meeting at Giga Berlin. Tesla stated that it filed a criminal complaint after the alleged incident. Police later confirmed they had seized a computer belonging to an IG Metall member as part of their investigation.
“What has happened today at Giga Berlin is truly beyond words! An external union representative from IG Metall attended a works council meeting. For unknown reasons he recorded the internal meeting and was caught in action! We obviously called police and filed a criminal complaint!” Thierig wrote on X at the time.
IG Metall denied the accusation and characterized Tesla’s move as an election tactic ahead of upcoming works council elections. The union subsequently filed a defamation complaint against Thierig. Authorities later confirmed that an investigation had been opened in connection with the matter.
Giga Berlin began production in 2022 and has since become one of Tesla’s key European manufacturing hubs, producing the Model Y for regional markets. The facility has expanded capacity over the past years despite environmental protests, labor disputes, and regulatory scrutiny.
Energy
Tesla Megapack Megafactory in Texas advances with major property sale
Stream Realty Partners announced the sale of Buildings 9 and 10 at the Empire West industrial park, which total 1,655,523 square feet.
Tesla’s planned Megapack factory in Brookshire, Texas has taken a significant step forward, as two massive industrial buildings fully leased to the company were sold to an institutional investor.
In a press release, Stream Realty Partners announced the sale of Buildings 9 and 10 at the Empire West industrial park, which total 1,655,523 square feet. The properties are 100% leased to Tesla under a long-term agreement and were acquired by BGO on behalf of an institutional investor.
The two facilities, located at 100 Empire Boulevard in Brookshire, Texas, will serve as Tesla’s new Megafactory dedicated to manufacturing Megapack battery systems.
According to local filings previously reported, Tesla plans to invest nearly $200 million into the site. The investment includes approximately $44 million in facility upgrades such as electrical, utility, and HVAC improvements, along with roughly $150 million in manufacturing equipment.
Building 9, spanning roughly 1 million square feet, will function as the primary manufacturing floor where Megapacks are assembled. Building 10, covering approximately 600,000 square feet, will be dedicated to warehousing and logistics operations, supporting storage and distribution of completed battery systems.
Waller County Commissioners have approved a 10-year tax abatement agreement with Tesla, offering up to a 60% property-tax reduction if the company meets hiring and investment targets. Tesla has committed to employing at least 375 people by the end of 2026, increasing to 1,500 by the end of 2028, as noted in an Austin County News Online report.
The Brookshire Megafactory will complement Tesla’s Lathrop Megafactory in California and expand U.S. production capacity for the utility-scale energy storage unit. Megapacks are designed to support grid stabilization and renewable-energy integration, a segment that has become one of Tesla’s fastest-growing businesses.
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Tesla Sweden strikers see tax issues over IF Metall union error
To address the issue, IF Metall is encouraging Tesla strikers to return the refunded tax amounts to the union.
A tax correction is set to return two years of income tax payments to Tesla strikers in Sweden, after authorities determined that conflict compensation during a labor dispute should not have been taxed.
The issue is caused by a decision by IF Metall to treat strike compensation for Tesla workers as taxable income during the ongoing labor dispute with Tesla Sweden. That approach has now been reversed following guidance from the Swedish Tax Agency.
Strike compensation is typically tax-free under Sweden’s Income Tax Act, as noted in a report from Dagens Arbete (DA). However, two years ago, IF Metall’s board decided to classify payments to Tesla strikers as taxable.
“We did it to secure SGI, unemployment insurance and public pension. Those were the risks we saw when the strike had already dragged on,” Kent Bursjöö, financial manager at IF Metall, stated.
According to Bursjöö, the union wanted to ensure that members continued to register earned income with the tax agency, protecting benefits tied to income history. At the end of January, however, the Swedish Tax Agency informed the union that compensation during a labor dispute must be tax-free.
“Of course, we knew that it could be tax-free. But we clearly didn’t know that it couldn’t be taxable,” Bursjöö said.
Following discussions with auditors and tax authorities, IF Metall began correcting the payments. As a result, two years of paid income tax will now be credited back to the affected strikers’ tax accounts. The union will also recover previously paid employer contributions.
However, the correction creates secondary effects. Since the payments will now be treated as tax-free, pension contributions tied to those earnings will be withdrawn, potentially affecting state pension accrual and income-based benefits such as parental or sickness benefits.
To address this, IF Metall is encouraging members to return the refunded tax amounts to the union. In exchange, the union plans to pay 18.5% into occupational pensions on their behalf. “Otherwise, it will be a form of overcompensation when they get the tax paid back,” Bursjöö said.
That being said, the IF Metall officer acknowledged that the union’s legal ability to reclaim the funds from its improperly paid Tesla Sweden strikers is limited. “The legal possibilities are probably limited, from what we can see. But we assume that most people see the value of securing their pension,” Bursjöö said.
Tesla Giga Berlin makes a statement of solidarity amid IG Metall conflict
Tesla Megapack Megafactory in Texas advances with major property sale
