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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.

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.

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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.

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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Investor's Corner

Tesla needs to confront these concerns as its ‘wartime CEO’ returns: Wedbush

Tesla will report earnings for Q2 tomorrow. Here’s what Wedbush expects.

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Credit: Tesla

Tesla (NASDAQ: TSLA) is set to report its earnings for the second quarter of 2025 tomorrow, and although Wall Street firm Wedbush is bullish as the company appears to have its “wartime CEO” back, it is looking for answers to a few concerns investors could have moving forward.

The firm’s lead analyst on Tesla, Dan Ives, has kept a bullish sentiment regarding the stock, even as Musk’s focus seemed to be more on politics and less on the company.

However, Musk has recently returned to his past attitude, which is being completely devoted and dedicated to his companies. He even said he would be sleeping in his office and working seven days a week:


Nevertheless, Ives has continued to push suggestions forward about what Tesla should do, what its potential valuation could be in the coming years with autonomy, and how it will deal with the loss of the EV tax credit.

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Tesla preps to expand Robotaxi geofence once again, answering Waymo

These questions are at the forefront of what Ives suggests Tesla should confront on tomorrow’s call, he wrote in a note to investors that was released on Tuesday morning:

“Clearly, losing the EV tax credits with the recent Beltway Bill will be a headwind to Tesla and competitors in the EV landscape looking ahead, and this cash cow will become less of the story (and FCF) in 2026. We would expect some directional guidance on this topic during the conference call. Importantly, we anticipate deliveries globally to rebound in 2H led by some improvement on the key China front with the Model Y refresh a catalyst.”

Ives and Wedbush believe the autonomy could be worth $1 trillion for Tesla, especially as it continues to expand throughout Austin and eventually to other territories.

In the near term, Ives expects Tesla to continue its path of returning to growth:

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“While the company has seen significant weakness in China in previous quarters given the rising competitive landscape across EVs, Tesla saw a rebound in June with sales increasing for the first time in eight months reflecting higher demand for its updated Model Y as deliveries in the region are starting to slowly turn a corner with China representing the heart and lungs of the TSLA growth story. Despite seeing more low-cost models enter the market from Chinese OEMs like BYD, Nio, Xpeng, and others, the company’s recent updates to the Model Y spurred increased demand while the accelerated production ramp-up in Shanghai for this refresh cycle reflected TSLA’s ability to meet rising demand in the marquee region. If Musk continues to lead and remain in the driver’s seat at this pace, we believe Tesla is on a path to an accelerated growth path over the coming years with deliveries expected to ramp in the back-half of 2025 following the Model Y refresh cycle.”

Tesla will report earnings tomorrow at market close. Wedbush maintained its ‘Outperform’ rating and held its $500 price target.

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Investor's Corner

Tesla (TSLA) Q2 2025 earnings call: What investors want to know

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Credit: Tesla Asia/X

Tesla (NASDAQ:TSLA) is set to report its second-quarter 2025 financial results on Wednesday, July 23, after markets close. With this in mind, Tesla investors have aggregated their top questions for the company at its upcoming Q&A session.

The upcoming earnings report follows a mixed delivery quarter. Tesla produced over 410,000 vehicles and delivered more than 384,000 units globally. In the energy segment, Tesla deployed 9.6 GWh of storage products, continuing momentum for its Megapack business. Tesla’s vehicle sales are currently down year-over-year, though a good part of this was due to the Model Y changeover in the first quarter.

Following are Tesla investors’ top questions for management, as aggregated in Say.

  1. Can you give us some insight (into) how robotaxis have been performing so far and what rate you expect to expand in terms of vehicles, geofence, cities, and supervisors?
  2. What are the key technical and regulatory hurdles still remaining for unsupervised FSD to be available for personal use? Timeline?
  3. What specific factory tasks is Optimus currently performing, and what is the expected timeline for scaling production to enable external sales? How does Tesla envision Optimus contributing to revenue in the next 2–3 years?
  4. Can you provide an update on the development and production timeline for Tesla’s more affordable models? How will these models balance cost reduction with profitability, and what impact do you expect on demand in the current economic climate?
  5. When do you anticipate customer vehicles to receive unsupervised FSD?
  6. Are there any news for HW3 users getting retrofits or upgrades? Will they get HW4 or some future version of HW5?
  7. Have any meaningful Optimus milestones changed for this year or next, and will thousands of Optimus be performing tasks in Tesla factories by year-end?
  8. Will there be a new AI day to explain the advancements the Autopilot, Optimus, and Dojo/chip teams have made over the past several years? We still do not know much about HW4.
  9. Cybertruck ramp is now a year in, but sales have lagged other models. How are you thinking through boosting sales of such an incredible product?
  10. When will there be a new CEO compensation package presented and considered for the next stage of the company’s growth?

Tesla will release its Q2 update letter on its Investor Relations website after markets close on Wednesday. A live Q&A webcast with management will then follow at 4:30 p.m. CT (5:30 p.m. ET) to discuss the company’s performance and outlook.

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Tesla Model Y becomes dual champ in China’s vehicle sales rankings

The Model Y’s recent accomplishments suggest that Tesla really has created something special with the all-electric crossover.

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Credit: Tesla Asia/X

The Tesla Model Y was recently deemed a double champion in China, with the all-electric crossover topping two notable sales charts in the country’s automotive sector. 

The Model Y’s recent accomplishments suggest that Tesla really has created something special with the all-electric crossover, as it has continued to outsell even vehicles that are newer and more affordable. 

Tesla China’s announcement

In a post on Weibo, Tesla China VP Grace Tao highlighted that the Model Y topped China’s sales of SUVs, as well as vehicles that are priced in the 200,000-400,000 yuan range. This is quite remarkable, as the Model Y is one of the more costly entries in both lists. She also invited everyone to try out the vehicle for themselves. “You will know the champion strength after a try,” the Tesla VP wrote.

For the first half of the year, the Tesla Model Y sold 171,491 units domestically in China. This number was enough to make it the country’s best-selling SUV and vehicle priced in the 200,000-400,000 yuan range, but it could still easily be higher in the second half of 2025.

This was because Tesla initiated a changeover in Gigafactory Shanghai to shift the facility’s Model Y line to the vehicle’s new iteration. Had Tesla sold the Model Y in full force during the first half of 2025 in China, the vehicle’s domestic sales figures would have been even more impressive.

Model Y L coming

Tesla China’s Model Y sales could see a notable boost in the second half of the year due to the addition of the Model Y L, an extended wheelbase version of the all-electric crossover. Tesla is yet to announce the details for the Model Y L, though the vehicle was listed in the MIIT regulatory catalog as a six-seater. This is game-changing, as the Model Y’s previous seven-seat configurations have caught criticism for being far too cramped and unusable for adults.

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With the six-seat Model Y in the company’s lineup, Tesla would be able to compete with popular vehicles from rivals like BYD, which have made it a point to release spacious three-row vehicles that are designed to carry the whole family. Provided that the Model Y L is priced correctly, it could very well raise Tesla’s vehicle sales this year.

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