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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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Tesla’s launch of the “Emergency Drive Away” function a few months back offered owners a safe option to evacuate an area if they were in reasonable danger. The function finally got its first use in the real world, but it appears it was by mistake.
A video shared by u/Joshalander in the r/TeslaLounge subreddit recorded the instance from his vehicle and said the incident took place in Austin this past weekend during the city’s F1 Race.
“Was charging around 6 AM this past Sunday in Austin before heading to the F1 race and heard a pop. Looked over and saw the new emergency drive-away feature in action. Genuinely felt bad for the dude when he got out and realized what happened, since he looked exhausted and only seemed to half-read the prompts.”
🚨 Here’s the first look at Tesla’s Emergency Drive Away function in action:
Apparently this driver accidentally enabled it and drove forward; you can see the Supercharger pull with the car.
Tesla said previously this would cost up to $25k if not used properly. https://t.co/B4qQRrsO6B
— TESLARATI (@Teslarati) October 28, 2026
Emergency Drive Away unlatches the Supercharger connector from the vehicle, but still causes damage to both the car and the Supercharger. Tesla has said that it will cost up to $25,000 in repairs to have everything fixed back to normal.
Additionally, the company said that if it were not used in an emergency situation, the driver of the vehicle who activated the Emergency Drive Away feature would be responsible for all repair costs.
Tesla constitutes the following situations as reasonable justifications for activating the feature:
- You face an immediate threat to your life or personal safety.
- You must leave the area immediately.
- Exiting the vehicle is unsafe.
- Unplugging the charge connector would unreasonably delay your departure or expose you to a risk to your personal safety.
After using the feature, Tesla requires the driver to schedule Service so the car can be inspected.
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Tesla’s Cybercab battery design could make robotaxis even cheaper
Tesla built the Cybercab’s battery pack with spare room for a future switch to LFP.
Tesla built the Cybercab’s battery pack with empty space inside it on purpose, and the reason points to a cheaper robotaxi down the road.
Robert Sumpf, Tesla’s director of mechanical design engineering for battery modules and packs, said the extra room beside and beneath the Cybercab’s modules was left there so the company can move to lithium iron phosphate cells later. “So, we protected this pack to go to an even lower energy dense chemistry as we scale and need to bring LFP into the platform,” Sumpf said in a Cybercab deep dive with Munro Live.
The Cybercab runs on Tesla’s own 4680 cells with a nickel chemistry today. LFP cells store less energy for their size, so a straight swap would cut range. The reserved space lets Tesla add more LFP cells to make up the difference. In return, Tesla would get cells that cost less, run cooler and survive more charge cycles. LFP became the most used EV battery chemistry in the world last year.
Not all of that room was planned for a chemistry change. Lars Moravy, Tesla’s Vice President of Vehicle Engineering, said part of it exists because “we didn’t need as many batteries as we thought we did.” Tesla told Sandy Munro in early 2025 that it was targeting a Cybercab pack under 50 kWh with close to 300 miles of range.
The pack also breaks from the structural design Tesla used in some Model Y and Cybertruck builds. Instead of potting hundreds of cells into one block, the Cybercab uses four separate, individually sealed modules, so a bad module can be replaced without scrapping the whole pack. Sumpf was blunt about the older approach, giving the Model Y structural battery “a grade D” because it was hard to build and nearly impossible to repair. He estimated a fully structural pack gains about 10% more cell volume, but said “the issue is the service cost.”
That cost matters more for a car that rarely sits parked. Cybercab chief engineer Eric Earley said replacing an entire pack “before half a million miles is a killer on cost,” which is why remanufacturing and serviceability were built into the design from the start.
The same Munro Live tour produced Moravy’s admission that the Cybercab line at Giga Texas is now outpacing Robotaxi deployments, along with a look at the robotaxi’s unorthodox paint process. Tesla is aiming to deliver the first Cybercabs to outside customers by the end of 2026, though Elon Musk has said the vast majority will stay owned by Tesla and run as a transport service.
Sumpf did not give a date for an LFP version, name a cell supplier or say how a chemistry change would affect range. For now, the 4680 cars keep piling up: Texas DMV records from Tuesday list 544 Cybercabs authorized for Tesla’s Robotaxi fleet, more than the 507 Model Ys on the same roster for the first time.
United Airlines CEO Scott Kirby said that SpaceX’s Starlink satellite internet is its leading competitive advantage in the U.S. airline industry. However, in recent comments, while he described the service as “the biggest competitive advantage” the carrier currently holds, he also acknowledged that the edge is temporary.
“…everybody eventually is going to have high-speed low earth orbit internet connectivity. It’s going to be a must-have. We are going to have a few years of being the only airline that has it at scale, and that’s our mission,” Kirby said. Until everyone has it, United aims to capitalize on its head start by converting trial users into long-term loyal customers.
🚨 United CEO Scott Kirby calls Starlink “the biggest competitive advantage,” but says it’s temporary.
“I think it’s the biggest competitive advantage. And it’s temporary. Like it’s not, everybody eventually is going to have high speed low earth orbit internet connectivity. It’s going to be a must-have. But we are going to have a few years of being the only airline that has it at scale, and that’s our mission.”
“I think we’re going to convince customers that United is the best airline and we’re going to get customers to switch their loyalty, to get our credit card, switch their loyalty to United. Not because of Starlink. They’re going to try us for Starlink and they’re going to stay with all the other technology, and everything else is better, and the technology in particular is so much better than technology other, and it’s accelerating because we’ve got the right tech stack, and because we’re like, our gap is getting wider and wider with our technology every day.”
Next: LAX becomes United’s first 100% Starlink hub in the first half of next year, and the United app will show your Starlink odds for each flight. https://t.co/hToyFWaWj7
— TESLARATI (@Teslarati) October 27, 2026
United has moved faster than its rivals on Starlink installations. As of mid-to-late October 2026, the system was on roughly 43 percent of its fleet, with plans to reach 61 percent by year-end, 87 percent by June 2027, and full fleet coverage by the end of next year.
The airline already operates more Starlink-equipped flights than the rest of the U.S. industry combined. Los Angeles International Airport is scheduled to become United’s first 100 percent Starlink hub in the first half of 2027, and the carrier’s app will display the likelihood that any given flight has the service.
Kirby has pointed to early evidence that the offering influences booking decisions. Some passengers loyal to other airlines are already switching flights for Starlink connectivity, something the airline, along with American Airlines, has tried to leverage against competing airlines. Both companies used status-match programs, and some of those customers are pursuing company-specific credit cards, which signals an intent to stay.
Once onboard, these customers encounter the airline’s broader investments in aircraft, larger seat-back screens, oversized bins, connection tools, and a mobile app that Kirby says outperforms competitors. Wi-Fi satisfaction scores on Starlink-equipped planes have been reported to be nearly double those on aircraft with other systems.
Competitors are moving slowly to do the same. Southwest Airlines began installations in 2025 and expects to complete them soon. Delta is pursuing Amazon’s Leo system, while American expects to start Starlink work in early 2027 and has not yet detailed regional-fleet plans. This timeline gap gives United a multi-year window in which it remains the only major U.S. carrier offering Starlink at scale.
Kirby has framed the strategy as pressing that advantage while simultaneously widening gaps in other technology areas so that customers who try United for the Wi-Fi remain for the overall experience.
The approach reflects a calculated bet that superior in-flight connectivity can accelerate share gains and support longer-term financial targets, including a 10 percent pre-tax margin goal.
High-speed internet is particularly valued by premium and business travelers who can work or stream reliably. As low-Earth-orbit service becomes ubiquitous, the temporary nature of the pure connectivity edge means United’s retention will depend on whether its other product and operational improvements keep pace.
Tesla’s ‘Emergency Drive Away’ function gets its first use in the real world
Tesla’s Cybercab battery design could make robotaxis even cheaper
