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SpaceX’s Starship Raptor Vacuum engine plans laid out by CEO Elon Musk
Elon Musk says that SpaceX Starship engine upgrades are on track to begin static fire tests of a Raptor Vacuum variant as few as a “couple months” from now.
Designed to enable more efficient performance in thin atmosphere or vacuum, Musk admitted that the first version(s) of Raptor Vacuum (RVac) will likely be a compromise between efficiency and speed of development. Nevertheless, the faster SpaceX can prepare Raptor Vacuum for flight, the easier it will be for Starship to begin serious (sub)orbital flight tests.
As it turns out, SpaceX’s first and only official render of Raptor – published in September 2016 – showed the engine’s vacuum-optimized variant. In the years since, CEO Elon Musk has vacillated between keeping the vacuum engines as a central Starship feature and simply replacing them with regular sea level Raptors to expedite the spacecraft’s debut. The 2016 and 2017 vehicles featured a mixture of vacuum and sea-level engines, whereas Musk revealed a vehicle with sea-level engines only in 2018.
Perhaps less than a month after Musk’s September 2018 presentation, the SpaceX CEO made the decision to radically redesign the vehicle – newly christened Starship and Super Heavy – by moving from a carbon composite aerostructure to stainless steel. At first, the seven SL Raptors remained a part of the design, but Musk took to Twitter in 2019 to indicate that SpaceX had changed gears again and had reprioritized Raptor Vacuum development.
This came as a bit of surprise and it should go without saying that there’s a significant chance that Musk/SpaceX will oscillate in the opposite direction once again before Raptor Vacuum is actually ready for flight. This time, though, Musk has sketched out a development schedule and strategy that suggests SpaceX is much more serious this time.
Most notably, Musk claims that the first Raptor Vacuum prototype could be ready for static fire testing just a “couple months” from now, an immensely ambitious schedule for any large liquid rocket engine development program. Nevertheless, Musk did indicate that the “V1.0” Raptor Vacuum design would be significantly compromised and “suboptimal”, an intentional decision to prioritize the engine’s “speed of development”.
Even then, Musk believes that the first variant – featuring a shortened bell nozzle – could still be up to 12% more efficient than sea level Raptors and thus already 70-80% of the way to the physical limit of methane-oxygen rocket efficiency.
On a positive note, shrinking V1.0 Raptor Vacuum’s nozzle a bit from its nominal length will likely mean that SpaceX can static fire fully-integrated engines at its McGregor, TX test facilities, critical for speedy development. If not, the company has experience with alternatives through Merlin Vacuum, which can only be tested on the ground with its lengthy nozzle detached. This method just makes it dramatically harder to optimize a vacuum nozzle design, as full-scale, flight-like testing is nearly impossible if a given vacuum engine can’t be tested on the ground with said nozzle installed.
Vacuum engines need such large and unwieldy nozzles in order to make them as efficient as possible. In a very simplistic sense, a rocket engine nozzle directs the flow of superheated, ultrafast gases in order to squeeze as much momentum transfer as possible out of available propellant. The lower the pressure of the surrounding atmosphere is, the more those gases will expand immediately after leaving the nozzle – giant vacuum nozzles simply try to harness the additional momentum available from that extra expansion. This is why rocket exhausts appear to spread and thin out as launch vehicles reach higher and higher altitudes.
In this sense, the perfect theoretical vacuum nozzle is quite literally infinitely long. The job of vacuum rocket engineers is to find the perfect balance between that impractical theoretical perfection and the limits of real-world materials and dynamics. In theory, SpaceX’s sea-level Raptor engines have already been designed to operate in vacuum conditions, while the engine’s closed-cycle design and regeneratively (i.e. propellant) cooled nozzle should apply well to a vacuum design.
If SpaceX is lucky, there will be few roadblocks in the way of simply lengthening a SL Raptor-style nozzle and calling it a day, in which case it would be impressive but not all that surprising if SpaceX is actually able to begin RVac testing before the end of 2019. Once a rough V1.0 engine is in place, the process of optimizing efficiency can be done slowly and methodically, all while exploiting an unprecedented wealth of data from flight and orbit-tested Raptor Vacuum engines.
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The Tesla Semi was spotted mounted with ground truth validation equipment as the company nears its looming launch. The Semi is Tesla’s Class 8 all-electric truck, and has been utilized in its earlier stages by many companies like PepsiCo. and Frito-Lay, who have been using it in a pilot program.
The Semi was spotted in Sunnyvale, California, and sports a typical ground truth validation unit that Tesla routinely uses on its vehicles. Ground truth validation is essentially the process of training supervised algorithms to ensure they can perform reliably. Tesla typically performs this on vehicles that are being released soon:
Spotted the new semi adorned with ground truthing equipment. Haven’t seen anyone post this so figured I’d share.
The future is autonomous!!@SawyerMerritt @wholemars pic.twitter.com/qkPDHPUQZ6
— Danny (@dannywinner1) June 21, 2026
The Semi being spotted with this type of validation rig is important because it means the company is working on solidifying a Full Self-Driving model for its commercial vehicle offering. This would be a massive development for not only Tesla but also the logistics industry as a whole.
There are strict regulations on driving hours for commercial truck drivers, and autonomy is a way to potentially combat these issues. FSD is already a widely effective way that owners of typical passenger vehicles take stress out of travel. Even launching a semi-autonomous platform for truck drivers to use to increase safety, reduce fatigue, and increase productivity would be a huge development.
Tesla Semi gets strange-but-understandable comparison from Jay Leno
The Semi has already proven to be an ideal solution for companies that use commercial logistics. It has increased efficiency and reduced operating costs for many companies that have been able to use it in pilot programs.
There are expected to be some bumps along the way. Tesla saw some challenges with FSD on the Cybertruck, as it had never had a vehicle with cameras at that height, so some of the features with FSD were not immediately available. Just a week ago, Tesla launched Actually Smart Summon (ASS) for Cybertruck, nearly three years after the vehicle was first delivered to customers.
President Donald Trump unveiled an upgraded Boeing 747-8 at Joint Base Andrews on June 19, 2026, describing the Qatar-gifted aircraft as an interim Air Force One equipped with advanced communications systems, including Starlink, Elon Musk’s SpaceX satellite internet service.
The plane, valued at around $400 million and modified for presidential use, serves as a bridge until the delayed VC-25B replacements arrive. Trump highlighted its luxury features and new technology during remarks to service members.
Trump stated:
“We have communication equipment up there that nobody’s ever seen before. It’s the highest level and, uh, including Starlink. My friend Elon is going to be very happy, but, uh, Starlink and we have, uh, four or five different sets of double and triple communications like people haven’t seen.”
He added:
“And it represents what can happen with hard work, innovation, and aggressive timelines because we did this quickly and yet there’s never been communication like is on this plane.”
🚨 President Trump confirmed today that the new Air Force One is equipped with Starlink:
“We have communication equipment up there that nobody’s ever seen before, it’s the highest level and including Starlink…my friend Elon is going to be very happy.” pic.twitter.com/IhkDmtr5hL
— TESLARATI (@Teslarati) June 20, 2026
The aircraft features a redesigned red, white, and blue livery and has been outfitted with Starlink satellite connectivity alongside other secure systems.
Trump praised the plane’s uniqueness, calling it among the world’s most luxurious. The gift from Qatar and subsequent modifications have drawn attention, with the jet positioned as a solution for presidential travel. It is expected to support operations, including potential ceremonial roles such as Fourth of July flyovers.
The event marked the formal introduction of the converted jet, which will help maintain capabilities while the primary Air Force One fleet undergoes modernization. Defense observers note the inclusion of commercial satellite technology like Starlink as part of efforts to ensure resilient communications, crucial to keep the country running as the President is in the sky.
President Trump’s comments underscored appreciation for rapid upgrades and innovation in equipping the aircraft. The plane remains a U.S. government asset and is slated for eventual transfer related to presidential library purposes after its service.
Tesla just gave what is perhaps its biggest signal yet that the launch of the Cybercab, its autonomous ride-hailing-geared car, is imminent.
The Cybercab has been spotted outside of Gigafactory Texas in massive numbers over the past few days, with hundreds of units being stored on property just days after the vehicle received a Certificate of Conformity from the EPA.
Today, things were a bit different.
Cybercabs spotted on Giga Texas property today had an addition: a Cybercab decal on the side, reminiscent of the “Robotaxi” ones that were placed on Model Ys just as the company launched its ride-sharing platform about a year ago.
Giga Texas drone operator Joe Tegtmeyer noticed the change today:
Tesla Cybercabs are now getting “Cybercab” logos on the side of them!
Tesla did the same with Model Ys that were given “Robotaxi” logos: https://t.co/DanANtw1m7 pic.twitter.com/FqOhH0S9Ks
— TESLARATI (@Teslarati) June 19, 2026
Tesla could be signaling that the Cybercab is preparing to enter the Robotaxi fleet in the coming weeks or months with this move. It seems more symbolic than anything; Tesla is ready to throw Cybercabs in the ride-hailing platform just as it did with Model Ys last year.
The addition of the Certificate of Conformity awarded to the Cybercab is another major factor working to Tesla’s advantage. The company now has permission from the EPA to allow the vehicle to operate on public roads and enter the chain of commerce. It’s officially street legal.
Tesla Cybercab specs revealed: range, curb weight, range ratings, and more
The big question that remains is whether Tesla will be able to operate the car without a safety monitor, especially considering it plans to put the car out there without a steering wheel or pedals. With the Cybercab only having a seating capacity of two, it is hard to believe Tesla will even consider putting a Safety Monitor in the car.
It did recently self-certify as Level 4 and has the ability to operate driverless vehicles in the State of Texas under a law that took effect on May 28. You can read more about that here:
Tesla’s Robotaxi dreams just took a massive step toward reality
We’d imagine Cybercabs will be on the roads as soon as July, but August will likely be a better estimate of when the car will be entered into the Cybercab fleet. It all depends at where Tesla is, as they’ve truly prioritized safety with the rollout of the Robotaxi platform.
Tesla Semi spotted with ground truth validation equipment as launch looms
President Trump touts new Air Force One with Musk technology
