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SpaceX CEO Elon Musk posts uncut Raptor, drone videos of Starhopper’s flight test debut
Some two hours after Starhopper’s inaugural untethered flight, SpaceX CEO Elon Musk took to Twitter to post an uncut video showing the ungainly rocket’s launch and landing from the perspective of both a drone and Starhopper’s lone Raptor engine.
As noted by commenters, Starhopper’s first flight also marks perhaps an even more fascinating milestone: it’s technically the first launch ever of a full-flow staged-combustion (FFSC) rocket engine. Whether or not the development hell Raptor required is or was worth it to SpaceX, the company has become the first and only entity on Earth to develop and fly a FFSC engine, beating out the national space agencies of both the United States and Soviet Union, both of which built – but never flew – prototypes.
Instead of inexplicably shelving a mature prototype development and test program, SpaceX iterated through several subscale Raptor prototypes, test-fired the engines for more than 1200 seconds total, used that data to design and build full-scale Raptors, and finally sped into a hardware-rich test campaign with six (soon to be seven) new engines. After SpaceX settled on a full-flow staged-combustion cycle and methane/oxygen (methalox) propellant, Raptor conducted its first full-scale tests all the way back in 2014, performing preburner flow and ignition tests at NASA’s Stennis Space Center.
Two years and many additional subcomponent tests later, SpaceX successfully performed the inaugural static fire test of its first completed subscale Raptor, a huge milestone for any rocket engine. In the 12 months following its first static fire (September 2016), SpaceX performed dozens of static fire tests with several subscale engines, putting the new propulsion system through >1200 seconds of combined testing.
A year after that, SpaceX was still testing subscale engines but the first full-scale Raptor engine was just a few months away from completing assembly in Hawthorne and heading to McGregor to kick off full-scale static fire testing. Indeed, four months after CEO Elon Musk’s September 2018 update, Raptor serial number 01 (SN01) shipped to Texas in late January and successfully ignited for the first time on February 3rd. SpaceX’s finalized full-scale Raptor engine is designed to produce more than 2000 kN (450,000 lbf, 200 tons) of thrust at full-throttle.
Since that inaugural ignition, SpaceX’s propulsion team – perhaps to their detriment, under orders from Musk – pushed SN01 and several of its successors to their limits as quickly as possible, resulting in severe, irreparable damage in several cases. On the other hand, the no-holds-barred, ‘hardware-rich’ (i.e. destructive) test program has allowed SpaceX to relatively quickly solve several major bugs that prevented the engine from passing longer test fires.
Raptor SN05 was originally expected to support Starhopper’s first flight(s) but had to be passed up after suffering damage in one of its final June 2019 acceptance tests. Raptor SN06 became the first engine – likely thanks to tweaks afforded by data gathered from its failed brethren – to pass all of those acceptance tests, leading to its eventual installation on Starhopper in early July.
Raptor’s impressive development culminated on July 25th with the engine’s first untethered flight while attached to Starhopper, a 9m-diameter (30 ft) low-fidelity prototype that is more or less a mobile test stand for the next-generation SpaceX engine. Raptor is now the only FFSC engine in history that has powered a flight-capable vehicle’s launch and landing, even if said flight featured an apogee of just 20-30 meters (65-100 ft).
“In full-flow staged combustion (FFSC), even more complexity is added as all propellant that touches the engine must necessarily end up traveling through the main combustion chamber to eke every last ounce of thrust out of the finite propellant a rocket lifts off with. As such, FFSC engines can be about as efficient as the laws of physics allow any given chemical rocket engine to be, at the cost of exceptional complexity and brutally difficult development.“
SpaceX delays Starhopper’s first flight a few days despite Raptor preburner test success
For more on what exactly makes full-flow staged-combustion engines uniquely capable and challenging to develop, the subject has been covered at length in past Teslarati articles.
According to Musk, the next major challenge facing Starhopper and (presumably) Raptor SN06 is far more ambitious 200-meter (650 ft) hop and flight test that could happen as soon as the first half of August.
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Tesla starts Robotaxi testing without any vehicle occupants
This development, in terms of the Robotaxi program, is massive. Tesla has been working incredibly hard to expand its fleet of Robotaxi vehicles to accommodate the considerable demand it has experienced for the platform.
Tesla has started Robotaxi testing in Austin, Texas, without any vehicle occupants, the company’s CEO Elon Musk confirmed on Sunday. Two Tesla Model Y Robotaxi units were spotted in Austin traveling on public roads with nobody in the car.
The testing phase begins just a week after Musk confirmed that Tesla would be removing Safety Monitors from its vehicles “within the next three weeks.” Tesla has been working to initiate driverless rides by the end of the year since the Robotaxi fleet was launched back in June.
Two units were spotted, with the first being seen from the side and clearly showing no human beings inside the cabin of the Model Y Robotaxi:
A Tesla without a driver was spotted traveling on public roads! pic.twitter.com/ZLbduf4cKa
— TESLARATI (@Teslarati) December 14, 2025
Another unit, which is the same color but was confirmed as a different vehicle, was spotted just a few moments later:
NEWS: A second Tesla Model Y Robotaxi running FSD Unsupervised has just been spotted driving itself on public roads in Austin, Texas, with no one in the front seats.
This is a different car from the one spotted earlier. They have different license plates.
h/t @Mandablorian https://t.co/5URYsUGyD0 pic.twitter.com/CIUi4mXi33
— Sawyer Merritt (@SawyerMerritt) December 14, 2025
The two units are traveling in the general vicinity of the South Congress and Dawson neighborhoods of downtown Austin. These are located on the southside of the city.
This development, in terms of the Robotaxi program, is massive. Tesla has been working incredibly hard to expand its fleet of Robotaxi vehicles to accommodate the considerable demand it has experienced for the platform.
However, the main focus of the Robotaxi program since its launch in the Summer was to remove Safety Monitors and initiate completely driverless rides. This effort is close to becoming a reality, and the efforts of the company are coming to fruition.
Testing is underway with no occupants in the car
— Elon Musk (@elonmusk) December 14, 2025
It is a drastic step in the company’s trek for self-driving technology, as it plans to expand it to passenger vehicles in the coming years. Tesla owners have plenty of experience with the Full Self-Driving suite, which is not fully autonomous, but is consistently ranked among the best-performing platforms in the world.
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Tesla refines Full Self-Driving, latest update impresses where it last came up short
We were able to go out and test it pretty extensively on Saturday, and the changes Tesla made from the previous version were incredibly impressive, especially considering it seemed to excel where it last came up short.
Tesla released Full Self-Driving v14.2.1.25 on Friday night to Early Access Program (EAP) members. It came as a surprise, as it was paired with the release of the Holiday Update.
We were able to go out and test it pretty extensively on Saturday, and the changes Tesla made from the previous version were incredibly impressive, especially considering it seemed to excel where it last came up short.
Tesla supplements Holiday Update by sneaking in new Full Self-Driving version
With Tesla Full Self-Driving v14.2.1, there were some serious regressions. Speed Profiles were overtinkered with, causing some modes to behave in a strange manner. Hurry Mode was the most evident, as it refused to go more than 10 MPH over the speed limit on freeways.
It would routinely hold up traffic at this speed, and flipping it into Mad Max mode was sort of over the top. Hurry is what I use most frequently, and it had become somewhat unusable with v14.2.1.
It seemed as if Speed Profiles should be more associated with both passing and lane-changing frequency. Capping speeds does not help as it can impede the flow of traffic. When FSD travels at the speed of other traffic, it is much more effective and less disruptive.
With v14.2.1.25, there were three noticeable changes that improved its performance significantly: Speed Profile refinements, lane change confidence, and Speed Limit recognition.
🚨 Many of you asked us to test highway driving with Tesla Full Self-Driving v14.2.1.25. Here’s what we noticed:
✅ Speed Profiles are significantly improved. Hurry Mode is no longer capped at 10 MPH over the speed limit, and now travels with the flow of traffic. This is much… pic.twitter.com/48ZCGbW0JO
— TESLARATI (@Teslarati) December 13, 2025
Speed Profile Refinement
Speed Profiles have been significantly improved. Hurry Mode is no longer capped at 10 MPH over the speed limit and now travels with the flow of traffic. This is much more comfortable during highway operation, and I was not required to intervene at any point.
With v14.2.1, I was sometimes assisting it with lane changes, and felt it was in the wrong place at the wrong time more frequently than ever before.
However, this was one of the best-performing FSD versions in recent memory, and I really did not have any complaints on the highway. Speed, maneuvering, lane switching, routing, and aggressiveness were all perfect.
Lane Changes
v14.2.1 had a tendency to be a little more timid when changing lanes, which was sort of frustrating at times. When the car decides to change lanes and turn on its signal, it needs to pull the trigger and change lanes.
It also changed lanes at extremely unnecessary times, which was a real frustration.
There were no issues today on v14.2.1.25; lane changes were super confident, executed at the correct time, and in the correct fashion. It made good decisions on when to get into the right lane when proceeding toward its exit.
It was one of the first times in a while that I did not feel as if I needed to nudge it to change lanes. I was very impressed.
Speed Limit Recognition
So, this is a complex issue. With v14.2.1, there were many times when it would see a Speed Limit sign that was not meant for the car (one catered for tractor trailers, for example) or even a route sign, and it would incorrectly adjust the speed. It did this on the highway several times, mistaking a Route 30 sign for a 30 MPH sign, then beginning to decelerate from 55 MPH to 30 MPH on the highway.
This required an intervention. I also had an issue leaving a drive-thru Christmas lights display, where the owners of the private property had a 15 MPH sign posted nearly every 200 yards for about a mile and a half.
The car identified it as a 55 MPH sign and sped up significantly. This caused an intervention, and I had to drive manually.
It seems like FSD v14.2.1.25 is now less reliant on the signage (maybe because it was incorrectly labeling it) and more reliant on map data or the behavior of nearby traffic.
A good example was on the highway today: despite the car reading that Route 30 sign and the Speed Limit sign on the center screen reading 30 MPH, the car did not decelerate. It continued at the same speed, but I’m not sure if that’s because of traffic or map data:
🚨 We listened to and read a lot of you who had a complaint of Tesla Full Self-Driving v14.2.1 incorrectly reading Speed Limit signs
This appears to be resolved in v14.2.1.25.
Here’s a breakdown: pic.twitter.com/TEP03xrMbt
— TESLARATI (@Teslarati) December 13, 2025
A Lone Complaint
Tesla has said future updates will include parking improvements, and I’m really anxious for them, because parking is not great. I’ve had some real issues with it over the past couple of months.
Today was no different:
🚨 My lone complaint with my drive on Tesla FSD v14.2.1.25 was this strange parking instance.
FSD swung out wide to the left to pull into this spot and this is where it seemed to be stumped. I gave it about 10 seconds after the car just stopped moving for it to make some… https://t.co/ZEkhTHOihG pic.twitter.com/TRemXu5DLf
— TESLARATI (@Teslarati) December 13, 2025
Full Self-Driving v14.2.1.25 is really a massive improvement over past versions, and it seems apparent that Tesla took its time with fixing the bugs, especially with highway operation on v14.2.1.
News
Tesla hints at Starlink integration with recent patent
“By employing polymer blends, some examples enable RF transmission from all the modules to satellites and other communication devices both inside and outside the vehicle.”
Tesla hinted at a potential Starlink internet terminal integration within its vehicles in a recent patent, which describes a vehicle roof assembly with integrated radio frequency (RF) transparency.
The patent, which is Pub. No U.S. 2025/0368267 describes a new vehicle roof that is made of RF-transparent polymer materials, allowing and “facilitating clear communication with external devices and satellites.”
Tesla believes that a new vehicle roof design, comprised of different materials than the standard metallic or glass elements used in cars today, would allow the company to integrate modern vehicular technologies, “particularly those requiring radio frequency transmission and reception.
Tesla has recently filed a US patent application on integrating RF transparent materials into the roof structure.
“facilitating clear communication with external devices and satellites”
Tesla fleet is getting @Starlink connectivity integration soon. LFG @Tesla @elonmusk… pic.twitter.com/bLa8YtPLd1
— Chansoo Byeon (@Chansoo) December 9, 2025
Instead of glass or metallic materials, Tesla says vehicles may benefit from high-strength polymer blends, such as Polycarbonate, Acrylonitrile Butadiene Styrene, or Acrylonitrile Styrene Acrylate.
These materials still provide ideal strength metrics for crashworthiness, stiffness for noise, vibration, and harshness control, and are compliant with head impact regulations.
They would also enable better performance with modern technologies, like internet terminals, which need an uninterrupted signal to satellites for maximum reception. Tesla writes in the patent:
“By employing polymer blends, some examples enable RF transmission from all the modules to satellites and other communication devices both inside and outside the vehicle.”

One of the challenges Tesla seems to be aware of with this type of roof design is the fact that it will still have to enable safety and keep that at the forefront of the design. As you can see in the illustration above, Tesla plans to use four layers to increase safety and rigidity, while also combating noise and vibration.
It notes in the patent that disclosed examples still meet the safety requirements outlined in the Federal Motor Vehicle Safety Standards (FMVSS).
Starlink integrated directly into Tesla vehicles would be a considerable advantage for owners. It would come with a handful of distinct advantages.
Initially, the inclusion of Starlink would completely eliminate cellular dead zones, something that is an issue, especially in rural areas. Starlink would provide connectivity in these remote regions and would ensure uninterrupted service during road trips and off-grid adventures.
It could also be a critical addition for Robotaxi, as it is crucial to have solid and reliable connectivity for remote monitoring and fleet management.
Starlink’s growing constellation, thanks to SpaceX’s routine and frequent launch schedule, will provide secure, stable, and reliable internet connectivity for Tesla vehicles.
Although many owners have already mounted Starlink Mini dishes under their glass roofs for a similar experience, it may be integrated directly into Teslas in the coming years, either as an upgrade or a standard feature.