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SpaceX fires up Starship rocket twice in 30 hours ahead of next big tests

Starship SN4 is looking downright shiny after successfully completing multiple wet dress rehearsals and two Raptor static fire tests. (NASASpaceflight - bocachicagal)

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6 years ago

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SpaceX has successfully fired up a full-scale Starship rocket for the second time in barely 30 hours and removed the ship’s Raptor engine to perform an additional suite of “cryo testing”.

Around 7pm CDT on May 6th, SpaceX technicians began loading the fourth full-scale Starship with liquid oxygen and methane, filling up a large portion of its massive propellant tanks. Just the latest in a line of several tests involving wet dress rehearsals (WDR) completed in the days prior, this test would soon become exceptional. About an hour and a half after work began, Starship SN4’s lone Raptor engine ignited and burned for ~3 seconds, marking the first time in history a next-generation SpaceX rocket truly came alive with one of the engines designed to take it all the way to orbit.

In line with tests performed with Starhopper – a low-fidelity, subscale tested that flew twice with Raptor – last year, it would have been business as usual if SpaceX had called it a day and moved on to something else with Starship SN4. Instead, Starship performed another WDR and fired up its Raptor engine for a second time in just 30 hours after SpaceX teams inspected the rocket and cleared it for another round. It’s unknown why two back-to-back static fires were performed but, to be clear, every step Starship SN4 takes forward is a step into uncharted territory. Already, the ship’s next steps could come as soon as Friday, May 8th.

According to CEO Elon Musk, SpaceX’s second Starship SN4 static fire test was completed successfully and actually marked the operational debut of a critical aspect of the next-generation launch vehicle and spacecraft. Known as header tanks, Starship needs two smaller secondary propellant tanks to complement its main tanks, a need driven mainly by the challenges of landing such a large and mobile spacecraft. Smaller header tanks will also make it dramatically easier for SpaceX to insulate cryogenic propellant and ensure it remains liquid over long-duration cruises in space, but safe and reliable landings are a more pressing concern for these early prototypes.

During landing operations, the main benefits smaller header tanks offer are relative ease of pressurization (needed to safely feed Raptor engines) and a much lower risk of issues from sloshing, which can introduce bubbles and voids that can obliterate rocket engines if ingested. Impressively, per Musk, Starship SN4 completed its second static fire test using its internal liquid methane header tank – a sort of bubble attached to the bottom of the main methane tank dome.

Starship SN5’s common methane and oxygen tank dome (and spherical methane header tank) is pictured here on May 1st. (NASASpaceflight – bocachicagal)
While header tanks will be invaluable for Starships attempting to landing on other planets or Moons after weeks- or months-long coasts in space, they’re also a great help for landing on Earth. (SpaceX)

Starship’s liquid oxygen header tank is situated at the tip of the conical nose section, a part that all full-scale ships have been tested without thus far. However, the use of the fuel header tank on May 7th means that Starship SN4 already has a functional, plumbed header tank installed, verifying the partial functionality of a critical part of the next-generation launch vehicle. A second static fire will have also provided SpaceX a wealth of extra data about Raptor’s performance while installed on Starship, invaluable at such an early stage of integrated testing.

Two Starship static fires now under its belt, SpaceX removed SN4’s Raptor engine around 12 hours after its second test and returned it to storage at the company’s nearby factory facilities. According to public notices provided by Cameron County, Texas officials, SpaceX’s next Starship SN4 activity is expected to occur on May 8th with backup windows on the 9th and 10th and will involve “cryo testing”.

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SpaceX removed Starship SN4’s Raptor engine after two successful back-to-back static fires. (NASASpaceflight – bocachicagal)

The most obvious conclusion is that SpaceX – having completed enough static fire testing to verify Starship SN4’s performance – now wants to really put the rocket through its paces with another cryogenic test. Completed on April 26th, the ship’s first cryogenic ‘proof’ test maxed out at around 4.9 bar (70 psi), enough for low-stress hop tests but well short of the sustained pressure needed for orbital spaceflight. While testing singular propellant tanks in the first few months of 2020, Musk revealed that SpaceX was targeting a minimum of 6 bar (~90 psi) for orbital Starship flights – ~8 bar (115 psi) with a 25% safety factor.

Pictured here on May 7th, Starship SN5 could be just days away from its final tank section stacking operation and just a week from rolling to the launch pad for proof testing. (NASASpaceflight – bocachicagal)

The company actually achieved 8.4 bar with one of its Starship test tanks, the same processes of which were used to build Starship SN4, but a full-scale ship has yet to demonstrate those pressures. Now, SpaceX already has a fifth full-scale prototype (Starship SN5) likely just a week or so away from pad readiness, meaning that Starship SN4’s potential destruction during pressure testing wouldn’t have a big impact on plans for a series of imminent flight tests. If SN4 survives pressure testing, it would likely have its Raptor engine reinstalled and move on to a 150m (500 ft) hop test.

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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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Elon Musk

Elon Musk and Trump are closer than ever, and Tesla could be the big winner

Elon Musk sat beside Trump as AI leaders signed a voluntary White House safety accord.

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2 hours ago

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September 29, 2026

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Elon Musk had the seat right next to President Donald Trump on Tuesday as the White House hosted the leaders of America’s biggest artificial intelligence companies for a lunch that ended with a voluntary industry accord on AI safety.

A seating chart Trump posted on Truth Social placed Musk at the president’s left in the East Room, with Nvidia CEO Jensen Huang on his right, according to an Associated Press reporter. Anthropic CEO Dario Amodei, OpenAI President Greg Brockman, Meta’s Mark Zuckerberg, Google’s Sundar Pichai, Microsoft’s Satya Nadella and Amazon founder Jeff Bezos also attended, along with Vice President JD Vance and House Speaker Mike Johnson.

After the lunch, Trump told reporters outside the West Wing that the executives had signed “The White House Accord on Superintelligence: A Joint Commitment on Frontier SI Responsibilities.” Johnson described it as a voluntary statement of principles built on “robust internal controls and layers of internal and external review,” while Zuckerberg said company boards would independently review reports from outside auditors. Trump called the document “morally binding,” said he would name a new AI czar within days, and signed an executive order formally renaming artificial intelligence “super intelligence,” CNBC reported.

Musk was not in the room for Tesla alone. Since SpaceX absorbed xAI, he runs the company behind Grok and one of the largest AI training operations anywhere. On September 25, he said another 220,000 Nvidia GB300 chips would come online at Colossus 2 within a week, with more expected in November and December.

SpaceX confirms third massive compute deal at Colossus data center

 

Musk also used the trip to restate his energy ambitions. “SpaceX is aiming together with Tesla to do 200 gigawatts of solar production per year,” he said at an event in Washington. It is the same combined target he laid out that feeds directly into Terafab, the Tesla and SpaceX chip venture that will need enormous amounts of power.

The showing between Musk and Trump has come a long way, since the two had the very public split in mid 2025 after Musk opposed the “Big Beautiful Bill” and left DOGE. They reconciled at Charlie Kirk’s memorial that September, and Trump later called their relationship “good”. Since then, Musk has joined Trump’s China delegation in May and attended last week’s White House state dinner for Chinese President Xi Jinping.

For Tesla, that access to government official could pay dividends. As Teslarati noted in January, federal autonomy rules, NHTSA oversight and a single national standard for driverless vehicles all run through an administration Musk can more easily reach directly as Tesla works to scale Robotaxi and Cybercab beyond Texas.

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Elon Musk

Tesla Roadster’s new patent preps white-knuckle speeds, keeping it grounded

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15 hours ago

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September 29, 2026

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Credit: @BLKMDL3/Twitter

Ahead of its highly anticipated unveiling, Tesla’s upcoming Roadster received a new patent that aims to keep it grounded while enabling white-knuckle speeds.

The patent, which was granted on September 29, is titled “Electric Car Fan,” bluntly stating its design but not its purpose, which is further detailed in the text of the application. Interestingly, it comes two weeks before the Roadster event, which was delayed due to unfavorable weather on Thursday, which could cause issues, as Tesla revealed the event must be held outdoors.

The purpose is to solve a problem that is relatively unique to high-performance electric cars. Instant motor torque is useless if the tires cannot plant that force, and conventional wings and underbody tunnels generate downforce only when air is already rushing past the car. At launch, in slow corners, and under hard braking from modest speed, passive aerodynamic additions contribute essentially very little to downforce.

Tesla’s filing says that its fans can produce the downforce needed, independent of vehicle velocity, then ease off so the same hardware does not pile on drag at highway speeds, an issue that can come from excessive body modifications.

The hardware outlined in the patent is a ducted-fan package that is placed into the rear of the vehicle. An underbody inlet between the rear wheels feeds a duct that rises to a wide outlet in the diffuser. In that outlet are four axial fans, which are divided by vertical strakes. They will pull air from under the floor and press the chassis onto the pavement.

The language in the patent claims it can cut drag rather than add to it while simultaneously increasing downforce.

Tesla Roadster event requires restricted airspace, and the FAA obliges

The fans run from the high-voltage battery and a vehicle control system, so output can be modulated rather than left on as a fixed penalty.

There are additional strengths that can come from this design, like extra tire load at low speed, which can contribute to even more face-melting acceleration rates, decrease stopping distance, and sharper turn-in before a wing has air to work with. Adjustable fan speed lets the car add grip only when needed, so it can be catered to the force of a turn or acceleration.

These designs were previously used, and banned, in some competitive settings. The Brabham BT46B was banned in F1 competition for using a similar fan design and being labeled as too effective.

Tesla still lists the Roadster as having a sub-two-second 0-60 MPH time and a 250-plus-MPH top speed, and there are expectations for a SpaceX cold-gas thruster package that could not only increase acceleration but potentially cause the vehicle to hover.

It is important to note that a patent is not a production part, and packaging four fans in a rear diffuser, managing noise, and potential debris are all things Tesla must consider. With that being said, the patent being granted shows Tesla is designing the Roadster to go fast, but it is also attempting to use unique strategies to combat any issues it might have at those speeds.

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Investor's Corner

Tesla showrooms picked clean ahead of Q3 end as demand looks strong

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17 hours ago

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September 29, 2026

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Credit: @thaichiminh1907/X

Tesla (NASDAQ: TSLA) showrooms have been picked clean ahead of the end of the third quarter of the year, as demand looks to be strong and delivery estimates for new vehicles are pushed into late 2026 and early 2027.

Tesla appears to have sold out of many of its Model 3 and Model Y trim levels in the United States, as only the Model Y RWD and Model Y All-Wheel-Drive are available for delivery before the end of the year.

Additionally, many showrooms are either completely empty or void of all but just one demo unit within the buildings themselves in an effort to bolster what could be one of Tesla’s best quarters in vehicle deliveries in recent memory.

Additionally, when I spoke to the guys at Tesla Mechanicsburg two weeks ago, when I returned the Model Y L, their third hauler of the week had just arrived, and every vehicle on it, along with every vehicle in their delivery lot, was accounted for and had a name attached to it for delivery.

Tesla saw a 25 percent increase in deliveries in Q2 compared to the same quarter the year before. The vast majority of the 480,126 units it delivered, 467,762 vehicles to be exact, were the Model 3 and Model Y.

In Q3 2025, Tesla delivered 497,099 vehicles, once again a figure that was dominated by the company’s two mass-market vehicles. Analysts have unusually wide predictions for this quarter, likely because so many firms missed the Q2 delivery figure by such a substantial margin; Wall Street predicted 408,000 cars, while Tesla delivered 480,000.

Goldman Sachs has Tesla slotted for 435,000 deliveries in Q3, while JPMorgan said it anticipates 482,000. The median guess is about 449,000 deliveries for Q3.

Interested in ordering a Tesla? Use my referral code for three free months of Full Self-Driving (Supervised) here.

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