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SpaceX tests Starhopper’s maneuvering thrusters ahead of inaugural flight test

On July 22nd, SpaceX technicians and engineers spent the evening testing Starhopper's nitrogen gas maneuvering thrusters, taken straight off of Falcon 9. (NASASpaceflight - bocachicagal)

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7 years ago

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Late at night on July 22nd, SpaceX’s South Texas team of technicians and engineers were busy testing a small but critical component of Starhopper, a testbed and low-fidelity Starship prototype meant to attempt its first untethered flight test as early as July 24th.

Monday evening’s testing centered around Starhopper’s cold gas nitrogen thrusters, multi-nozzle assemblies that appear to have quite literally been taken off of flight-proven Falcon 9 boosters. For Starhopper, they will act in a similar – albeit significantly reduced – fashion, serving to control the giant steel prototype’s attitude and augment its lone Raptor engine’s own thrust vectoring (i.e. steering) capability.

Although SpaceX has never released official numbers for the thrust of the cold gas thrusters used on Falcon 9 boosters and upper stages, it’s safe to say from their performance that the low-efficiency nitrogen thrusters produce roughly 5 kN (~1100 lbf) of thrust, perhaps up to 10+ kN. For an almost empty Falcon 9 booster, this translates to extremely rapid (sub-10s) flip maneuvers during return-to-launch-site (RTLS) landings.

At the same time, Falcon boosters have two sizes of cold-gas thrusters, with much larger high-performance (>10 kN) pods – located on the larger of the booster’s two raceways – focused on settling the rocket’s propellant after recovery-related coast periods. A duo of smaller 3-axis pods situated on the outside of the interstage serve as true attitude control system (ACS) thrusters, precisely pointing, flipping, and orienting boosters during vacuum operations and partially augmenting grid fin control authority during the late stages of landings. Despite their much smaller size, they still pack an impressive punch and are famous for almost saving tipping Falcon boosters during early (failed) landing attempts.

Starhopper, meanwhile, is dramatically larger than the Falcon 9 and Heavy boosters its tacked-on ACS thruster pods were designed for. It’s hard to know for sure but safe estimates peg the testbed’s dry mass somewhere around 50-75 metric tons (110,000-165,000 lb) thanks to the thick steel it was constructed out of. In other words, Starhopper likely weighs at least twice as much as an empty Falcon 9 booster (~25 metric tons).

To alleviate this mismatch, SpaceX arrived at a hilariously simple and cheap solution: install double the number of grave-robbed Falcon 9 thruster pods on Starhopper and voila! It was that duo of thruster pod pairs that were tested on July 22nd, visibly producing four distinct jets of pressurized nitrogen gas. Whenever Starhopper gets to hopping, those ACS thrusters should help the rocket precisely control its rotation, attitude, and – to a lesser extent – translation, hopefully helping to ensure a successful inaugural hover and divert test.

Scheduled to occur no earlier than Wednesday, July 24th, SpaceX plans to deconflict Cargo Dragon’s CRS-18 launch and Starhopper’s hover test, meaning that they will not happen simultaneously. In the ~70%-likely event that bad Florida weather delays CRS-18 to Thursday, July 25th, the road before Starhopper will be clear for an attempted hover on the 24th. Additionally, also reported first by NASASpaceflight.com, the test is expected to involve a divert, meaning that Starhopper will lift off, hover roughly 20m (65 ft) off the ground, and then carefully travel a few hundred feet East to a recently-constructed concrete pad for a soft landing.

This divert was tacitly confirmed by the arrival of a robotic transport mechanism, already used once before to move Starhopper from its build site to the launch pad. If the divert goes as planned, the transport equipment will be used to return Starhopper to its spartan launch mount and ground support equipment (GSE) umbilicals.

If Starhopper survives and Raptor SN06 performs nominally, it’s all but certain that the testbed rocket will be put through a series of increasingly ambitious test flights over the coming months – at least before SpaceX’s first higher-fidelity “Mk 1” Starship prototypes begin their own flight tests. According to CEO Elon Musk, those Starship test hops and flights could begin as few as 2-3 months from now – September or October 2019.

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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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3 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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16 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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18 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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