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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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8 years ago

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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.

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.

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.

 

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.

Check out Teslarati’s newsletters for prompt updates, on-the-ground perspectives, and unique glimpses of SpaceX’s rocket launch and recovery processes!

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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 hints its already prepping for Cybercab fleet orders

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3 hours ago

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September 3, 2026

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Tesla Cybercab fleet spotted at Gigafactory Texas [Credit: Joe Tegtmeyer)

Tesla has quietly opened a public interest form for companies that want to buy fleets of its purpose-built Cybercab robotaxis, marking the first official channel for commercial purchases of the two-seat autonomous vehicle. The form went live on September 3, the same day Tesla hosted an invite-only Cybercab launch event in Austin, Texas.

Tesla titled the page “Help Us Build Our Robotaxi Network.” Applicants provide name, email, phone number, company name, and deployment region. They then select one or more categories: Cybercab fleet vehicle purchasing, mobility hubs and infrastructure, event collaboration, or other. Tesla says a representative will follow up with those who express commercial interest.

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Until now, the company had no public ordering path for the vehicle, which was first shown as a concept at the October 2024 “We, Robot” event.

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The Cybercab is designed from the ground up for unsupervised operation. It has no steering wheel and no pedals.

Regulatory filings list a 48-kilowatt-hour battery, a single 219-horsepower front motor, a curb weight of 3,113 pounds, and an EPA-adjusted range near 290 to 300 miles. Tesla has already registered dozens of the vehicles with Texas authorities and has been testing them on public streets around Austin.

Tesla Cybercab sightings broaden well outside of Austin with autonomy in focus

The company’s existing Robotaxi service, which currently uses modified Model Y vehicles in parts of Texas and Florida, is expected to add Cybercabs as production ramps up at Gigafactory Texas.

The form signals that Tesla is preparing to treat the Cybercab as more than an in-house fleet asset. Investors and operators have discussed buying groups of the vehicles and placing them on Tesla’s ride-hailing network, with Tesla taking a platform fee. High-profile figures have publicly stated plans to acquire fleets if Tesla allows third-party ownership.

The new page gives those parties a direct way to register interest rather than waiting for a conventional configurator.

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Whether the form leads quickly to firm purchase agreements remains unclear. Regulatory approval for widespread unsupervised operation still varies by state, and Tesla has not published pricing or delivery timelines for fleet customers. The company has previously discussed a target price near $25,000 to $30,000 per vehicle.

For now, the form is an early signal that Tesla wants partners to help scale the network rather than operate every Cybercab itself.

Pairing the launch of the Cybercab fleet form with the Austin event is no coincidence. Tesla is inviting businesses to participate in the next phase of its Robotaxi plan at the moment the production vehicle first appears in public.

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Tesla Robotaxi riders will face the best dilemma when booking a ride

Published

7 hours ago

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September 3, 2026

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Credit: Joe Tegtmeyer | X

Tesla has updated its Robotaxi app so riders can pick which vehicle they want before they book. The latest in-app screens now show two options side by side: the two-seat Cybercab and the four-seat Model Y.

A screenshot circulating Thursday shows the change in practice. In Austin, a rider could choose a gold Cybercab for two people or a Model Y for four. Tesla’s updated description calls Cybercab “our first purpose-built autonomous vehicle,” designed for safety, accessibility, and comfort, and says the lineup is available only through the Robotaxi app.

The distinction is more than cosmetic, and it’s important to note that Robotaxi refers to the platform, while Cybercab refers to a vehicle.

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Model Y Robotaxis have carried the service since it opened in Austin in mid-2025 and later expanded to Dallas, Houston, and parts of Florida. Those vehicles are converted production SUVs that still have steering wheels and pedals.

Cybercab is different. It has no driver controls, butterfly doors, a low seat height meant to work with wheelchairs, extra trunk space for assistive devices, and braille on the handles. Tesla has registered dozens of the two-seaters with Texas regulators in the days leading up to its September 3 Austin event.

Giving riders a choice lets Tesla match the vehicle to the trip. Most rides involve one or two people, which is where Cybercab is meant to be cheaper and more efficient to operate. Groups of three or four, or anyone who needs more space, can still request a Model Y.

The same app handles booking, payment, cabin settings, and, on Cybercab, features such as phone-based door opening and in-cabin voice controls.

Tesla Cybercab event gains steam ahead of massive launch

The update does not mean every city suddenly has both cars available. Cybercab support is listed for Austin first, and the purpose-built fleet is still small compared with the existing Model Y roster. Even so, the app change marks a shift from a single-vehicle pilot to a mixed fleet.

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Riders can now choose between the compact, purpose-built robotaxi and the familiar SUV that launched the service.

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Tesla Cybercab sightings broaden well outside of Austin with autonomy in focus

Published

10 hours ago

on

September 3, 2026

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Credit: Tesla Robotaxi | X

Tesla Cybercab sightings are broadening far and wide, well outside of downtown Austin, Texas, with autonomy in focus as the company plans to launch the all-electric, two-seater this evening in the Lone Star State.

Tesla is set to launch Cybercab to a small group of people this evening in a dedicated event in Austin, Texas. Public details on the event are relatively slim.

However, Tesla’s focus on Cybercab falls well outside of the downtown Austin area and is expanding well across the United States as things continue to move quickly with the company’s autonomous efforts in 2026. Today, various images of Cybercab fleets in interesting locations have started to circulate.

The most notable is a fleet of at least 20 Cybercabs at Miami International Airport in Florida. Spotted last night, the fleet is expansive and is indicative of a looming release of Cybercabs once regulatory boxes are checked off.

Tesla has already been operating the Robotaxi platform in Miami for several months, but this Cybercab fleet at the airport could be joining the ride-hailing platform as approvals arrive:

Another fleet of Cybercabs was spotted at the Devon, PA showroom just outside of Philadelphia. We have seen several Cybercab units testing around the Philadelphia Metro Area, which is interesting considering Tesla does not have any active Robotaxi geofence in Pennsylvania.

Philadelphia would be an ideal location to test ride-hailing due to its dense tourist population, large, sprawling city layout, and to compete with other ride-hailing companies that operate in the city.

Expansive fleets of Cybercabs will be popping up in and around major cities throughout the rest of the year, if we were betting on it. Tesla has made it obvious that the Cybercab rollout will be aggressive and fast-paced, but within reason. Tesla is still prioritizing safety, so these testing phases will likely go on for some period of time before more members of the public are able to snag a Cybercab for a personal chariot.

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