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SpaceX’s Starship Raptor Vacuum engine plans laid out by CEO Elon Musk

A 2016 render of Raptor Vacuum. Much has changed about the engine's design in the three years since, but SpaceX is still pursuing a vacuum variant. (SpaceX)

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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.

Known as the Interplanetary Transport System in 2016, the ship featured six vacuum Raptors and 3 SL engines. (SpaceX)
In 2017, Big Falcon Spaceship shrunk and changed to 4 x RVac and 3x x Raptor SL engines. (SpaceX)
In 2018, Musk decided to sidestep vacuum engines entirely, moving to 7 SL Raptors. (SpaceX)

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.

A sea-level Raptor engine is static-fired at SpaceX’s McGregor, TX test facilities. (SpaceX)

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.

A Falcon 9 upper stage’s vacuum nozzle glows white hot during an orbital MVac burn. (SpaceX)

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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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 is now a remote DOGE worker: White House Chief of Staff

The Tesla and SpaceX CEO Elon Musk is no longer working from the West Wing.

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Credit: Elon Musk/X

In a conversation with the New York Post, White House Chief of Staff Susie Wiles stated that Tesla and SpaceX CEO Elon Musk is no longer working from the West Wing.

As per the Chief of Staff, Musk is still working for DOGE—as a remote worker, at least.

Remote Musk

In her conversation with the publication, Wiles stated that she still talks with Musk. And while the CEO is now working remotely, his contributions still have the same net effect. 

“Instead of meeting with him in person, I’m talking to him on the phone, but it’s the same net effect,” Wiles stated, adding that “it really doesn’t matter much” that the CEO “hasn’t been here physically.” She also noted that Musk’s team will not be leaving.

“He’s not out of it altogether. He’s just not physically present as much as he was. The people that are doing this work are here doing good things and paying attention to the details. He’ll be stepping back a little, but he’s certainly not abandoning it. And his people are definitely not,” Wiles stated.

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Musk has been a frequent presence in the White House during the Trump administration’s first 100 days in office. But during the Q1 2025 Tesla earnings call, Musk stated that he would be spending substantially less time with DOGE and substantially more time with Tesla. Musk did emphasize, however, that DOGE’s work is extremely valuable and critical.

“I think I’ll continue to spend a day or two per week on government matters for as long as the President would like me to do so and as long as it is useful. But starting next month, I’ll be allocating probably more of my time to Tesla and now that the major work of establishing the Department of Government Efficiency is done,” Musk stated.

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Tariff reprieve might be ‘Tesla-friendly,’ but it’s also an encouragement to others

Tesla stands to benefit from the tariff reprieve, but it has some work cut out for it as well.

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tesla employee
(Photo: Tesla)

After Secretary of Commerce Howard Lutnick made adjustments to the automotive tariff program that was initially announced, many quickly pointed to the reprieve as “Tesla-friendly.”

While that may be the case right now, it was also a nudge of encouragement to other companies, Tesla included, to source parts from the U.S. in an effort to strengthen domestic manufacturing. Many companies are close, and it will only take a handful of improvements to save themselves from tariffs on their cars as well.

Yesterday, Sec. Lutnick confirmed that cars manufactured with at least 85 percent of domestic content will face zero tariffs. Additionally, U.S. automakers would receive credit up to 15 percent of the value of vehicles to offset the cost of imported parts.

Big Tesla win? Sec Lutnick says cars with 85% domestic content will face zero tariffs

“This is ‘finish your cars in America and you win’,” Lutnick said.

Many were quick to point out that only three vehicles currently qualify for this zero-tariff threshold: all three are Teslas.

However, according to Kelley Blue Book’s most recent study that revealed who makes the most American cars, there are a lot of vehicles that are extremely close to also qualifying for these tariff reductions.

Tesla has three vehicles that are within five percent, while Ford, Honda, Jeep, Chevrolet, GMC, and Volkswagen have many within just ten percent of the threshold.

Tesla completely dominates Kogod School’s 2024 Made in America Auto Index

It is within reach for many.

Right now, it is easy to see why some people might think this is a benefit for Tesla and Tesla only.

But it’s not, because Tesla has its Cybertruck, Model S, and Model X just a few percentage points outside of that 85 percent cutoff. They, too, will feel the effects of the broader strategy that the Trump administration is using to prioritize domestic manufacturing and employment. More building in America means more jobs for Americans.

Credit: Tesla

However, other companies that are very close to the 85 percent cutoff are only a few components away from also saving themselves the hassle of the tariffs.

Ford has the following vehicles within just five percent of the 85 percent threshold:

  • Ford Mustang GT automatic (80%)
  • Ford Mustang GT 5.0 (80%)
  • Ford Mustang GT Coupe Premium (80%)

Honda has several within ten percent:

  • Honda Passport All-Wheel-Drive (76.5%)
  • Honda Passport Trailsport (76.5)

Jeep has two cars:

  • Jeep Wrangler Rubicon (76%)
  • Jeep Wrangler Sahara (76%)

Volkswagen has one with the ID.4 AWD 82-kWh (75.5%). GMC has two at 75.5% with the Canyon AT4 Crew Cab 4WD and the Canyon Denali Crew Cab 4WD.

Chevrolet has several:

  • Chevrolet Colorado 2.7-liter (75.5%)
  • Chevrolet Colorado LT Crew Cab 2WD 2.7-liter (75.5%)
  • Chevrolet Colorado Z71 Crew Cab 4WD 2.7-liter (75.5%)

These companies are close to reaching the 85% threshold, but adjustments need to be made to work toward that number.

Anything from seats to fabric to glass can be swapped out for American-made products, making these cars more domestically sourced and thus qualifying them for the zero-tariff boundary.

Frank DuBois of American University said that manufacturers like to see stability in their relationships with suppliers and major trade partners. He said that Trump’s tariff plan could cause “a period of real instability,” but it will only be temporary.

Now is the time to push American manufacturing forward, solidifying a future with more U.S.-made vehicles and creating more domestic jobs. Tesla will also need to scramble to make adjustments to its vehicles that are below 85%.

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Tesla Cybertruck RWD production in full swing at Giga Texas

Videos of several freshly produced Cybertruck LR RWD units were shared on social media platform X.

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Credit: Joe Tegtmeyer/X

It appears that Tesla is indeed ramping the production of the Cybertruck Long Range Rear Wheel Drive (LR RWD), the most affordable variant of the brutalist all-electric pickup truck.

Videos of several freshly produced Cybertruck LR RWD units were shared on social media platform X.

Giga Texas Footage

As per longtime Tesla watcher Joe Tegtmeyer, Giga, Texas, was a hotbed of activity when he conducted his recent drone flyover. Apart from what seemed to be Cybercab castings being gathered in the complex, a good number of Cybertruck LR RWD units could also be seen in the facility’s staging area. The Cybertruck LR RWD units are quite easy to spot since they are not equipped with the motorized tonneau cover that is standard on the Cybertruck AWD and Cyberbeast.

The presence of the Cybertruck LR RWD units in Giga Texas’ staging area suggests that Tesla is ramping the production of the base all-electric pickup truck. This bodes well for the vehicle, which is still premium priced despite missing a good number of features that are standard in the Cybertruck AWD and Cyberbeast.

Cybertruck Long Range RWD Specs

The Cybertruck LR RWD is priced at $69,990 before incentives, making it $10,000 more affordable than the Cybertruck AWD. For its price, the Cybertruck Long Range RWD offers a range of 350 miles per charge if equipped with its 18” standard Wheels. It can also add up to 147 miles of range in 15 minutes using a Tesla Supercharger.

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Much of the cost-cutting measures taken by Tesla are evident in the cabin of the Cybertruck LR RWD. This could be seen in its textile seats, standard console, seven-speaker audio system with no active noise cancellation, and lack of a 9.4” second-row display. It is also missing the motorized tonneau cover, the 2x 120V and 1x 240V power outlets on the bed, and the 2x 120V power outlets in the cabin. It is also equipped with an adaptive coil spring suspension instead of the adaptive air suspension in the Cybertruck AWD and Cyberbeast.

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