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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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Elon Musk
The Boring Company’s latest Tesla tunnel truck mod “fits like a glove”
The Boring Company has modified a Tesla powered tunnel truck to carry freight containers underground.
The Boring Company has found a second job for the Tesla hardware it already runs underground. In a post on X, Elon Musk’s tunneling company showed its latest Prufrock Liner Truck modified to carry a standard 20 foot shipping container. “Using TBC tunnels to transport freight,” the company wrote. “The latest Prufrock Liner Truck (using Tesla Model 3 batteries and drive units) has been modified to carry a standard 20′ shipping container. Fits like a glove!”
The photo shows a red container sitting on a long, low white chassis parked outside, with drive hardware visible at one end. The Boring Company did not say where or when freight hauling would start, which customers it has in mind, or how many trucks it is converting.
Using TBC tunnels to transport freight.
The latest Prufrock Liner Truck (using Tesla Model 3 batteries and drive units) has been modified to carry a standard 20’ shipping container.
Fits like a glove! https://t.co/VV0phWK4fc
— The Boring Company (@boringcompany) October 19, 2026
Until now, the liner trucks have hauled concrete. Teslarati reported in August on Liner Truck 3, which uses Model 3 battery packs and drive units to move more than 22,000 pounds of precast tunnel segments to the boring machine. It has 28 miles of range, tops out at 12 mph, and is piloted remotely from the company’s operations center in Texas. The freight version appears to be the same platform with a different bed, and The Boring Company has not said whether it will also be remotely piloted.
Freight has been on the company’s menu for years. When TBC updated its product lineup in 2021, its freight tunnel was described as sized to fit a standard shipping container, “barely.” The company later used the idea at Tesla’s own factory, where Prufrock 3 dug a tunnel to Giga Texas that now moves finished Cybertrucks away from the production line.
The Boring Company closed a $3 billion Series D in September at a $23 billion valuation, and Teslarati has covered how that money is tied to a UAE tunneling push and a faster Nashville build. In Nashville, Prufrock MB1 and MB2 are mining at the same time, and a third machine is expected to launch in late October. Each machine needs a steady supply of liner trucks, so any design that works for segments and containers alike gives the company more use out of the same Tesla parts.
The Vegas Loop remains the only Boring Company system open to the public, and it moves passengers in Tesla vehicles. A freight service would be a separate product, and the post gave no indication that one is close to launch. For now, it is a truck, a container and a short caption saying they fit together.
Elon Musk said he is planning to give “every one of his SpaceX shares to every kid in America” in 2027, stating that “this will be the first of many.”
SpaceX went public earlier this year, and its stock price has been relatively stable since leveling off shortly after its IPO. Based on its current price, it’s a gift of just over $10 billion to children across the United States.
It appears to be closely related to President Donald Trump’s bank accounts for children, which were set up earlier this year as Trump Accounts.
Just hours earlier, Anthropic had announced the establishment of its Anthropic Public Benefit Fund, “a new wholly-owned entity dedicated entirely to public benefit.” Musk responded by stating he recommended “giving the shares directly to the public,” and that he would be doing it that way.
Just a little bit later, Musk said children across the U.S. would be getting a share from him:
Next year, I will give one of my SpaceX shares to every kid in America.
This will be the first of many.
— Elon Musk (@elonmusk) October 19, 2026
There are roughly 70 million children, meaning someone under the age of 18, in the United States, according to the Federal Interagency Forum on Child and Family Statistics. Musk’s ownership of SpaceX stock shows he has around 849 million Class A shares of SpaceX stock, according to filings with the SEC.
Elon Musk revealed in a post on X that “Permits were impossible to get,” explaining the fate of The Boring Company’s most ambitious East Coast proposal.
The comment responded to a query about what became of his July 20, 2017 announcement that he had “just received verbal govt approval” for an underground Hyperloop connecting New York City, Philadelphia, Baltimore, and Washington, D.C., capable of carrying passengers from the Big Apple to the Nation’s Capital in just 29 minutes.
The Boring Company receives verbal ‘approval’ to build NY to DC Hyperloop tunnel
The 2017 post, which envisioned city-center stations and multiple elevators in each city, sparked immediate scrutiny. Local and state officials in New York, Philadelphia, Baltimore, and D.C. said they had no knowledge of any approval. A White House spokesperson confirmed only “promising conversations” about the transformative infrastructure.
Musk clarified shortly after that there was “still a lot of work” to do for formal approvals.
@cybrtrkguy Permits were impossible to get
— Elon Musk (@elonmusk) October 19, 2026
Limited progress followed, as Maryland Governor Larry Hogan’s administration issued a conditional utility permit and supported work near Fort Meade. In 2018, Washington, D.C., granted a preliminary permit for site preparation and excavation on a vacant lot at 53 New York Ave. NE in the NoMa neighborhood, which The Boring Company said could become a station.
A draft environmental assessment for a D.C.-Baltimore segment was released in 2019. Yet, by April 2021, the company had removed the project from its website, and the Federal Highway Administration reported receiving no indication of further interest. Communication with Maryland officials had ceased.
The full corridor would have required coordination among the District of Columbia, Maryland, Pennsylvania, New York, the Federal Highway Administration, the Army Corps of Engineers, the National Park Service, and other agencies.
Environmental reviews under the National Environmental Policy Act, utility clearances, and approvals for novel infrastructure added to the overall complexity of the project and its approval.
Speculation on the permitting barriers centers around a few factors, but a multi-state, multi-level route involving unproven high-speed vacuum-tube technology inherently triggers exhaustive safety, environmental, and engineering reviews that can stretch for years, even for conventional projects.
There are also other elements, of course, like officials who may face political exposure if a privately funded, untested system encountered anything such as cost overruns, delays, or safety issues. On the outset of this project, there were limited things such as engineering plans or demonstrated technology maturity, which also added to the potential skepticism.
The East Coast vision for Boring Co., once framed as a privately funded revolution that could reshape Northeast travel, quietly ended without construction of the promised network. Musk’s recent statement frames the outcome as a regulatory impasse, unfortunate but not unexpected.
The Boring Company’s latest Tesla tunnel truck mod “fits like a glove”
Elon Musk will give ‘every kid in America’ a SpaceX share in 2027
Elon Musk reveals why Boring Co’s biggest East Coast project never happened
SpaceX reveals how its 1 Million AI satellite network will work and prevent space collisions
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