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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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7 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.

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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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NVIDIA CEO Jensen Huang commends Tesla’s Elon Musk for early belief

“And when I announced DGX-1, nobody in the world wanted it. I had no purchase orders, not one. Nobody wanted to buy it. Nobody wanted to be part of it, except for Elon.”

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5 hours ago

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December 3, 2025

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Credit: NVIDIA

NVIDIA CEO Jensen Huang appeared on the Joe Rogan Experience podcast on Wednesday and commended Tesla CEO Elon Musk for his early belief in what is now the most valuable company in the world.

Huang and Musk are widely regarded as two of the greatest tech entrepreneurs of the modern era, with the two working in conjunction as NVIDIA’s chips are present in Tesla vehicles, particularly utilized for self-driving technology and data collection.

Nvidia CEO Jensen Huang regrets not investing more in Elon Musk’s xAI

Both CEOs defied all odds and created companies from virtually nothing. Musk joined Tesla in the early 2000s before the company had even established any plans to build a vehicle. Jensen created NVIDIA in the booth of a Denny’s restaurant, which has been memorialized with a plaque.

On the JRE episode, Rogan asked about Jensen’s relationship with Elon, to which the NVIDIA CEO said that Musk was there when nobody else was:

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“I was lucky because I had known Elon Musk, and I helped him build the first computer for Model 3, the Model S, and when he wanted to start working on an autonomous vehicle. I helped him build the computer that went into the Model S AV system, his full self-driving system. We were basically the FSD computer version 1, and so we were already working together.

And when I announced DGX-1, nobody in the world wanted it. I had no purchase orders, not one. Nobody wanted to buy it. Nobody wanted to be part of it, except for Elon.

He goes ‘You know what, I have a company that could really use this.’ I said, Wow, my first customer. And he goes, it’s an AI company, and it’s a nonprofit and and we could really use one of these supercomputers. I boxed one up, I drove it up to San Francisco, and I delivered it to the Elon in 2016.”

The first DGX-1 AI supercomputer was delivered personally to Musk when he was with OpenAI, which provided crucial early compute power for AI research, accelerating breakthroughs in machine learning that underpin modern tools like ChatGPT.

Tesla’s Nvidia purchases could reach $4 billion this year: Musk

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The long-term alliance between NVIDIA and Tesla has driven over $2 trillion in the company’s market value since 2016.

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GM CEO Mary Barra says she told Biden to give Tesla and Musk EV credit

“He was crediting me, and I said, ‘Actually, I think a lot of that credit goes to Elon and Tesla…You know me, Andrew. I don’t want to take credit for things.”

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16 hours ago

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December 3, 2025

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General Motors CEO Mary Barra said in a new interview on Wednesday that she told President Joe Biden to credit Tesla and its CEO, Elon Musk, for the widespread electric vehicle transition.

She said she told Biden this after the former President credited her and GM for leading EV efforts in the United States.

During an interview at the New York Times Dealbook Summit with Andrew Ross Sorkin, Barra said she told Biden that crediting her was essentially a mistake, and that Musk and Tesla should have been explicitly mentioned (via Business Insider):

“He was crediting me, and I said, ‘Actually, I think a lot of that credit goes to Elon and Tesla…You know me, Andrew. I don’t want to take credit for things.”

Back in 2021, President Biden visited GM’s “Factory Zero” plant in Detroit, which was the centerpiece of the company’s massive transition to EVs. The former President went on to discuss the EV industry, and claimed that GM and Barra were the true leaders who caused the change:

“In the auto industry, Detroit is leading the world in electric vehicles. You know how critical it is? Mary, I remember talking to you way back in January about the need for America to lead in electric vehicles. I can remember your dramatic announcement that by 2035, GM would be 100% electric. You changed the whole story, Mary. You did, Mary. You electrified the entire automotive industry. I’m serious. You led, and it matters.”

People were baffled by the President’s decision to highlight GM and Barra, and not Tesla and Musk, who truly started the transition to EVs. GM, Ford, and many other companies only followed in the footsteps of Tesla after it started to take market share from them.

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Elon Musk and Tesla try to save legacy automakers from Déjà vu

Musk would eventually go on to talk about Biden’s words later on:

“They have so much power over the White House that they can exclude Tesla from an EV Summit. And, in case the first thing, in case that wasn’t enough, then you have President Biden with Mary Barra at a subsequent event, congratulating Mary for having led the EV revolution.”

In Q4 2021, which was shortly after Biden’s comments, Tesla delivered 300,000 EVs. GM delivered just 26.

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Tesla Full Self-Driving shows confident navigation in heavy snow

So far, from what we’ve seen, snow has not been a huge issue for the most recent Full Self-Driving release. It seems to be acting confidently and handling even snow-covered roads with relative ease.

Published

19 hours ago

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December 3, 2025

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Credit: Grok

Tesla Full Self-Driving is getting its first taste of Winter weather for late 2025, as snow is starting to fall all across the United States.

The suite has been vastly improved after Tesla released v14 to many owners with capable hardware, and driving performance, along with overall behavior, has really been something to admire. This is by far the best version of FSD Tesla has ever released, and although there are a handful of regressions with each subsequent release, they are usually cleared up within a week or two.

Tesla is releasing a modified version of FSD v14 for Hardware 3 owners: here’s when

However, adverse weather conditions are something that Tesla will have to confront, as heavy rain, snow, and other interesting situations are bound to occur. In order for the vehicles to be fully autonomous, they will have to go through these scenarios safely and accurately.

One big issue I’ve had, especially in heavy rain, is that the camera vision might be obstructed, which will display messages that certain features’ performance might be degraded.

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So far, from what we’ve seen, snow has not been a huge issue for the most recent Full Self-Driving release. It seems to be acting confidently and handling even snow-covered roads with relative ease:

Moving into the winter months, it will be very interesting to see how FSD handles even more concerning conditions, especially with black ice, freezing rain and snow mix, and other things that happen during colder conditions.

We are excited to test it ourselves, but I am waiting for heavy snowfall to make it to Pennsylvania so I can truly push it to the limit.

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