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SpaceX’s Starship Raptor Vacuum engine plans laid out by CEO Elon Musk
Elon Musk says that SpaceX Starship engine upgrades are on track to begin static fire tests of a Raptor Vacuum variant as few as a “couple months” from now.
Designed to enable more efficient performance in thin atmosphere or vacuum, Musk admitted that the first version(s) of Raptor Vacuum (RVac) will likely be a compromise between efficiency and speed of development. Nevertheless, the faster SpaceX can prepare Raptor Vacuum for flight, the easier it will be for Starship to begin serious (sub)orbital flight tests.
As it turns out, SpaceX’s first and only official render of Raptor – published in September 2016 – showed the engine’s vacuum-optimized variant. In the years since, CEO Elon Musk has vacillated between keeping the vacuum engines as a central Starship feature and simply replacing them with regular sea level Raptors to expedite the spacecraft’s debut. The 2016 and 2017 vehicles featured a mixture of vacuum and sea-level engines, whereas Musk revealed a vehicle with sea-level engines only in 2018.
Perhaps less than a month after Musk’s September 2018 presentation, the SpaceX CEO made the decision to radically redesign the vehicle – newly christened Starship and Super Heavy – by moving from a carbon composite aerostructure to stainless steel. At first, the seven SL Raptors remained a part of the design, but Musk took to Twitter in 2019 to indicate that SpaceX had changed gears again and had reprioritized Raptor Vacuum development.
This came as a bit of surprise and it should go without saying that there’s a significant chance that Musk/SpaceX will oscillate in the opposite direction once again before Raptor Vacuum is actually ready for flight. This time, though, Musk has sketched out a development schedule and strategy that suggests SpaceX is much more serious this time.
Most notably, Musk claims that the first Raptor Vacuum prototype could be ready for static fire testing just a “couple months” from now, an immensely ambitious schedule for any large liquid rocket engine development program. Nevertheless, Musk did indicate that the “V1.0” Raptor Vacuum design would be significantly compromised and “suboptimal”, an intentional decision to prioritize the engine’s “speed of development”.
Even then, Musk believes that the first variant – featuring a shortened bell nozzle – could still be up to 12% more efficient than sea level Raptors and thus already 70-80% of the way to the physical limit of methane-oxygen rocket efficiency.
On a positive note, shrinking V1.0 Raptor Vacuum’s nozzle a bit from its nominal length will likely mean that SpaceX can static fire fully-integrated engines at its McGregor, TX test facilities, critical for speedy development. If not, the company has experience with alternatives through Merlin Vacuum, which can only be tested on the ground with its lengthy nozzle detached. This method just makes it dramatically harder to optimize a vacuum nozzle design, as full-scale, flight-like testing is nearly impossible if a given vacuum engine can’t be tested on the ground with said nozzle installed.
Vacuum engines need such large and unwieldy nozzles in order to make them as efficient as possible. In a very simplistic sense, a rocket engine nozzle directs the flow of superheated, ultrafast gases in order to squeeze as much momentum transfer as possible out of available propellant. The lower the pressure of the surrounding atmosphere is, the more those gases will expand immediately after leaving the nozzle – giant vacuum nozzles simply try to harness the additional momentum available from that extra expansion. This is why rocket exhausts appear to spread and thin out as launch vehicles reach higher and higher altitudes.
In this sense, the perfect theoretical vacuum nozzle is quite literally infinitely long. The job of vacuum rocket engineers is to find the perfect balance between that impractical theoretical perfection and the limits of real-world materials and dynamics. In theory, SpaceX’s sea-level Raptor engines have already been designed to operate in vacuum conditions, while the engine’s closed-cycle design and regeneratively (i.e. propellant) cooled nozzle should apply well to a vacuum design.
If SpaceX is lucky, there will be few roadblocks in the way of simply lengthening a SL Raptor-style nozzle and calling it a day, in which case it would be impressive but not all that surprising if SpaceX is actually able to begin RVac testing before the end of 2019. Once a rough V1.0 engine is in place, the process of optimizing efficiency can be done slowly and methodically, all while exploiting an unprecedented wealth of data from flight and orbit-tested Raptor Vacuum engines.
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Tesla analyst Gary Black of The Future Fund claims that the company is making a big mistake getting rid of the Model S and Model X. Instead, he believes another vehicle within the company’s lineup should be discontinued: the Cybertruck.
Black divested The Future Fund from all Tesla holdings last year, but he still covers the stock as an analyst as it falls in the technology and autonomy sectors, which he covers.
In a new comment on Thursday, Black said the Cybertruck should be the vehicle Tesla gets rid of due to the negatives it has drawn to the company.
The Cybertruck is also selling in an underwhelming fashion considering the production capacity Tesla has set aside for it. It’s worth noting it is still the best-selling electric pickup on the market, and it has outlasted other EV truck projects as other manufacturers are receding their efforts.
Black said:
“IMHO it’s a mistake to keep Tesla Cybertruck which has negative brand equity and sold 10,000 units last year, and discontinue S/X which have strong repeat brand loyalty and together sold 30K units and are highly profitable. Why not discontinue CT and covert S/X to be fully autonomous?”
IMHO it’s a mistake to keep $TSLA Cybertruck which has negative brand equity and sold 10,000 units last year, and discontinue S/X which have strong repeat brand loyalty and together sold 30K units and are highly profitable. Why not discontinue CT and covert S/X to be fully…
— Gary Black (@garyblack00) January 29, 2026
On Wednesday, CEO Elon Musk confirmed that Tesla planned to transition Model S and Model X production lines at the Fremont Factory to handle manufacturing efforts of the Optimus Gen 3 robot.
Musk said that it was time to wind down the S and X programs “with an honorable discharge,” also noting that the two cars are not major contributors to Tesla’s mission any longer, as its automotive division is more focused on autonomy, which will be handled by Model 3, Model Y, and Cybercab.
Tesla begins Cybertruck deliveries in a new region for the first time
The news has drawn conflicting perspectives, with many Tesla fans upset about the decision, especially as it ends the production of the largest car in the company’s lineup. Tesla’s focus is on smaller ride-sharing vehicles, especially as the vast majority of rides consist of two or fewer passengers.
The S and X do not fit in these plans.
Nevertheless, the Cybertruck fits in Tesla’s future plans. Musk said the pickup will be needed for the transportation of local goods. Musk also said Cybertruck would be transitioned to an autonomous line.
In a groundbreaking new report from Reuters, SpaceX is reportedly discussing merger possibilities with xAI ahead of the space exploration company’s plans to IPO later this year, in what would be a blockbuster move.
The outlet said it would combine rockets and Starlink satellites, as well as the X social media platform and AI project Grok under one roof. The report cites “a person briefed on the matter and two recent company filings seen by Reuters.”
Musk, nor SpaceX or xAI, have commented on the report, so, as of now, it is unconfirmed.
With that being said, the proposed merger would bring shares of xAI in exchange for shares of SpaceX. Both companies were registered in Nevada to expedite the transaction, according to the report.
On January 21, both entities were registered in Nevada. The report continues:
“One of them, a limited liability company, lists SpaceX and Bret Johnsen, the company’s chief financial officer, as managing members, while the other lists Johnsen as the company’s only officer, the filings show.”
The source also stated that some xAI executives could be given the option to receive cash in lieu of SpaceX stock. No agreement has been reached, nothing has been signed, and the timing and structure, as well as other important details, have not been finalized.
SpaceX is valued at $800 billion and is the most valuable privately held company, while xAI is valued at $230 billion as of November. SpaceX could be going public later this year, as Musk has said as recently as December that the company would offer its stock publicly.
The plans could help move along plans for large-scale data centers in space, something Musk has discussed on several occasions over the past few months.
At the World Economic Forum last week, Musk said:
“It’s a no-brainer for building solar-powered AI data centers in space, because as I mentioned, it’s also very cold in space. The net effect is that the lowest cost place to put AI will be space and that will be true within two to three years, three at the latest.”
He also said on X that “the most important thing in the next 3-4 years is data centers in space.”
If the report is true and the two companies end up coming together, it would not be the first time Musk’s companies have ended up coming together. He used Tesla stock to purchase SolarCity back in 2016. Last year, X became part of xAI in a share swap.
Tesla has announced it has hit a major milestone with Full Self-Driving subscriptions, shortly after it said it would exclusively offer the suite without the option to purchase it outright.
Tesla announced on Wednesday during its Q4 Earnings Call for 2025 that it had officially eclipsed the one million subscription mark for its Full Self-Driving suite. This represented a 38 percent increase year-over-year.
This is up from the roughly 800,000 active subscriptions it reported last year. The company has seen significant increases in FSD adoption over the past few years, as in 2021, it reported just 400,000. In 2022, it was up to 500,000 and, one year later, it had eclipsed 600,000.
NEWS: For the first time, Tesla has revealed how many people are subscribed or have purchased FSD (Supervised).
Active FSD Subscriptions:
• 2025: 1.1 million
• 2024: 800K
• 2023: 600K
• 2022: 500K
• 2021: 400K pic.twitter.com/KVtnyANWcs— Sawyer Merritt (@SawyerMerritt) January 28, 2026
In mid-January, CEO Elon Musk announced that the company would transition away from giving the option to purchase the Full Self-Driving suite outright, opting for the subscription program exclusively.
Musk said on X:
“Tesla will stop selling FSD after Feb 14. FSD will only be available as a monthly subscription thereafter.”
The move intends to streamline the Full Self-Driving purchase option, and gives Tesla more control over its revenue, and closes off the ability to buy it outright for a bargain when Musk has said its value could be close to $100,000 when it reaches full autonomy.
It also caters to Musk’s newest compensation package. One tranche requires Tesla to achieve 10 million active FSD subscriptions, and now that it has reached one million, it is already seeing some growth.
The strategy that Tesla will use to achieve this lofty goal is still under wraps. The most ideal solution would be to offer a less expensive version of the suite, which is not likely considering the company is increasing its capabilities, and it is becoming more robust.
Tesla is shifting FSD to a subscription-only model, confirms Elon Musk
Currently, Tesla’s FSD subscription price is $99 per month, but Musk said this price will increase, which seems counterintuitive to its goal of increasing the take rate. With that being said, it will be interesting to see what Tesla does to navigate growth while offering a robust FSD suite.
Tesla analyst claims another vehicle, not Model S and X, should be discontinued
SpaceX reportedly discussing merger with xAI ahead of blockbuster IPO
