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SpaceX sends “radically redesigned” Starship engine to Texas for hot-fire tests

As of September 2017, subscale Raptor engines had been cumulatively fired for more than 1200 seconds in just 12 months of testing. (SpaceX)

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SpaceX has shipped one of the first of a group of Starship engines known as Raptor, described last month by CEO Elon Musk as “radically redesigned”. A culmination of more than 24 months of prototype testing, the first flight-worthy Raptor could be ignited for the first time as early as February.

According to Musk, three of these redesigned Raptors will power the first full-scale BFR prototype, a Starship (upper stage) test article meant to conduct relatively low-altitude, low-velocity hop tests over the southern tip of Texas. Those tests could also begin next month, although a debut sometime in March or April is increasingly likely.

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Effectively designed on a blank slate, Raptor began full-scale component-level tests in 2014 at NASA’s Mississippi-based Stennis Space Center, evolving from main injector development to oxygen preburner hot-fires in 2015. Soon after Raptor’s prototype preburner design was validated at Stennis, SpaceX moved testing to its privately-owned and operated facilities in McGregor, Texas, where Raptor static fire testing has remained since.

Just days before CEO Elon Musk was scheduled to reveal SpaceX’s next-generation rocket (BFR, formerly known as the Interplanetary Transport System or ITS) in September 2016, he announced in a tweet that propulsion engineers and technicians had successful hot-fired an integrated Raptor prototype – albeit subscale – for the first time ever. Just 12 months later, Musk once again took to the stage to announce an update to BFR’s design, while also revealing that prototype Raptor engines had already completed more than 1200 seconds (20 minutes) of cumulative hot-fire tests, an extremely aggressive and encouraging rate of progress for such a new engine.

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Although Raptor undoubtedly borrows heavily from much of the same expertise that designed Merlin 1 and operated and improved it for years, that is roughly where the similarities between Raptor and M1D end. M1D, powered by refined kerosene (RP-1) and liquid oxygen, uses a combustion cycle (gas-generator) that is relatively simple and reliable at the cost of engine efficiency, although SpaceX propulsion expertise still managed to give M1D the highest thrust-to-weight ratio of any liquid rocket engine ever flown. Still, measured by ISP (instantaneous specific impulse), M1D’s inefficient kerolox gas-generator cycle ultimately means that the engine simply can’t compete with the performance of engines with more efficient propellants and combustion cycles.

While SpaceX’s Falcon 9 and Heavy rockets – powered by Merlin 1D and Merlin Vacuum – are more than adequate in and around Earth orbit, a far more efficient engine was needed for the company to enable the sort of interplanetary colonization Musk had in mind when he created SpaceX. Raptor was the answer. Ultimately settling on liquid methane and oxygen (methalox) as the propellant and a full-flow staged-combustion (FFSC) cycle, Raptor was designed to be extraordinarily reliable and efficient in order to safely power a spacecraft (BFS/Starship) meant to ferry dozens or hundreds of people to and from Mars.

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An excellent NASASpaceflight article explores the engine’s journey from a blank sheet to integrated static-fire tests and offers a deeper explanation of the technical details.

Raptor enters a new era

For all the extensive and invaluable testing SpaceX has done with a series of prototype Raptor engines, the engines tested were subscale versions with around 30% the thrust of the c. 2016 Raptor and around 40-50% of the updated c. 2017 iteration, producing almost the same amount of thrust as Merlin 1D (914 kN to Raptor’s ~1000 kN). In September 2018, Musk described Raptor as an “approximately…200-ton (~2000 kN) thrust engine” that would eventually operate with a chamber pressure as high as 300 bar (an extraordinary ~4400 psi), requiring at least one of the FFSC engine’s two preburners (used to power separate turbopumps) to operate at a truly terrifying ~810 bar (nearly 12,000 psi).

Conveniently stood beside a Merlin 1D engine also ready for hot-fire acceptance testing, the Raptor engine spotted departing SpaceX’s Hawthorne, CA factory last week was reportedly immense in person, towering over an M1D engine. Raptor also featured a mass of spaghetti-like plumbing (complexity necessary for its advanced combustion cycle), with a significant fraction of the metallic pipes and tubes displaying mirror-like finishes. Most notable was an obvious secondary preburner/turbopump stack and the lack of any exhaust port, whereas M1D relies on a single turbopump and exhausts the gases used to power it. Raptor’s full-flow staged-combustion cycle uses separate oxygen and methane preburners to power separate turbopumps, significantly improving mass flow rate and smoothing out combustion mixing.

 

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Unlike all previous hot-fired Raptors, those shipping now to McGregor, Texas are expected to be the first completed engines with a finalized design, arrived at only after a period of extensive testing and iterative improvement. They also appear to be full-scale, meaning that the test bays dedicated to Raptor will likely need to be upgraded (if they haven’t been already) to support a two- or threefold increase in maximum thrust.

SpaceX’s Starship hopper will need three finalized engines, meaning that the Raptor now in McGregor, Texas may not have been the first to arrive. Nevertheless, the shipment of full-scale hardware is always an extremely encouraging milestone for any advanced technology development program, while also foreshadowing the first imminent static-fires of the “radcally redesigned” rocket engine. With hardware now at the test site before January is out, a February test debut – one month behind a January debut teased by Elon Musk last December – is not out of the question.

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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 Sweden appeals after grid company refuses to restore existing Supercharger due to union strike

The charging site was previously functioning before it was temporarily disconnected in April last year for electrical safety reasons.

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Credit: Tesla Charging

Tesla Sweden is seeking regulatory intervention after a Swedish power grid company refused to reconnect an already operational Supercharger station in Åre due to ongoing union sympathy actions.

The charging site was previously functioning before it was temporarily disconnected in April last year for electrical safety reasons. A temporary construction power cabinet supplying the station had fallen over, described by Tesla as occurring “under unclear circumstances.” The power was then cut at the request of Tesla’s installation contractor to allow safe repair work.

While the safety issue was resolved, the station has not been brought back online. Stefan Sedin, CEO of Jämtkraft elnät, told Dagens Arbete (DA) that power will not be restored to the existing Supercharger station as long as the electric vehicle maker’s union issues are ongoing. 

“One of our installers noticed that the construction power had been backed up and was on the ground. We asked Tesla to fix the system, and their installation company in turn asked us to cut the power so that they could do the work safely. 

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“When everything was restored, the question arose: ‘Wait a minute, can we reconnect the station to the electricity grid? Or what does the notice actually say?’ We consulted with our employer organization, who were clear that as long as sympathy measures are in place, we cannot reconnect this facility,” Sedin said. 

The union’s sympathy actions, which began in March 2024, apply to work involving “planning, preparation, new connections, grid expansion, service, maintenance and repairs” of Tesla’s charging infrastructure in Sweden.

Tesla Sweden has argued that reconnecting an existing facility is not equivalent to establishing a new grid connection. In a filing to the Swedish Energy Market Inspectorate, the company stated that reconnecting the installation “is therefore not covered by the sympathy measures and cannot therefore constitute a reason for not reconnecting the facility to the electricity grid.”

Sedin, for his part, noted that Tesla’s issue with the Supercharger is quite unique. And while Jämtkraft elnät itself has no issue with Tesla, its actions are based on the unions’ sympathy measures against the electric vehicle maker. 

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“This is absolutely the first time that I have been involved in matters relating to union conflicts or sympathy measures. That is why we have relied entirely on the assessment of our employer organization. This is not something that we have made any decisions about ourselves at all. 

“It is not that Jämtkraft elnät has a conflict with Tesla, but our actions are based on these sympathy measures. Should it turn out that we have made an incorrect assessment, we will correct ourselves. It is no more difficult than that for us,” the executive said. 

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Music City Loop could highlight The Boring Company’s real disruption

The real story behind the tunneling startup’s Nashville tunnel project is the company’s targeted $25 million per mile construction cost.

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Credit: The Boring Company/X

Recent commentary on social media has highlighted what could very well prove to be The Boring Company’s real disruption.

The analysis was shared by tech watcher Aakash Gupta on social media platform X, where he argued that the real story behind the tunneling startup’s Nashville tunnel project is the company’s targeted $25 million per mile construction cost.

According to Gupta’s breakdown, Nashville’s 2018 light rail proposal was priced at roughly $200 million per mile. New York’s East Side Access project reportedly cost about $3.5 billion per mile, while Los Angeles Metro expansion projects have approached $1 billion per mile.

By comparison, The Boring Company has stated it can construct 13 miles of twin tunnels in the Music City Loop for between $240 million and $300 million total. That implies a cost near $25 million per mile, or roughly a 95% reduction from industry averages cited in the post.

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Several technical departures from conventional tunneling allow the Boring Company to lower its costs, from its smaller 12-foot diameter tunnels to its fully electric Prufrock machines that are designed to mine continuously with no personnel inside the tunnel and their capability to “porpoise” for easy launch and retrieval.

Tesla and Space CEO Elon Musk responded to the post on X, stating simply that “Tunnels are so underrated.”

The Boring Company has seen some momentum as of late, with the company recently signing a construction contract in Dubai and the Universal Orlando Loop progressing. Recent reports have also pointed to tunnels potentially being constructed to solve traffic congestion issues near the Giga Nevada area. 

While The Boring Company’s tunnels have so far been used for Loop systems publicly for now, Elon Musk recently noted that the tunneling startup’s underground passages would not be limited only to ride-hailing vehicles. 

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In a reply to a post on X which discussed the specifications of the Music City Loop, Musk clarified that “any fully autonomous electric cars can use the tunnels.” This suggests that vehicles potentially running systems like FSD Supervised, even if they are not Teslas, could be used in systems like the Music City Loop in the future.

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SpaceX IPO could push Elon Musk’s net worth past $1 trillion: Polymarket

The estimates were shared by the official Polymarket Money account on social media platform X.

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Gage Skidmore, CC BY-SA 4.0 , via Wikimedia Commons

Recent projections have outlined how a potential $1.75 trillion SpaceX IPO could generate historic returns for early investors. The projections suggest the offering would not only become the largest IPO in history but could also result in unprecedented windfalls for some of the company’s key investors.

The estimates were shared by the official Polymarket Money account on social media platform X.

As noted in a Polymarket Money analysis, Elon Musk invested $100 million into SpaceX in 2002 and currently owns approximately 42% of the company. At a $1.75 trillion valuation following SpaceX’s potential $1.75 trillion IPO, that stake would be worth roughly $735 billion.

Such a figure would dramatically expand Musk’s net worth. When combined with his holdings in Tesla Inc. and other ventures, a public debut at that level could position him as the world’s first trillionaire, depending on market conditions at the time of listing.

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The Bloomberg Billionaires Index currently lists Elon Musk with a net worth of $666 billion, though a notable portion of this is tied to his TSLA stock. Tesla currently holds a market cap of $1.51 trillion, and Elon Musk’s currently holds about 13% to 15% of the company’s outstanding common stock.

Founders Fund, co-founded by Peter Thiel, invested $20 million in SpaceX in 2008. Polymarket Money estimates the firm owns between 1.5% and 3% of the private space company. At a $1.75 trillion valuation, that range would translate to approximately $26.25 billion to $52.5 billion in value.

That return would represent one of the most significant venture capital outcomes in modern Silicon Valley history, with a growth of 131,150% to 262,400%.

Alphabet Inc., Google’s parent company, invested $900 million into SpaceX in 2015 and is estimated to hold between 6% and 7% of the private space firm. At the projected IPO valuation, that stake could be worth between $105 billion and $122.5 billion. That’s a growth of 11,566% to 14,455%.

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Other major backers highlighted in the post include Fidelity Investments, Baillie Gifford, Valor Equity Partners, Bank of America, and Andreessen Horowitz, each potentially sitting on multibillion-dollar gains.

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