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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 dispels reports of ‘sales suspension’ in California
“This was a “consumer protection” order about the use of the term “Autopilot” in a case where not one single customer came forward to say there’s a problem.
Sales in California will continue uninterrupted.”
Tesla has dispelled reports that it is facing a thirty-day sales suspension in California after the state’s Department of Motor Vehicles (DMV) issued a penalty to the company after a judge ruled it “misled consumers about its driver-assistance technology.”
On Tuesday, Bloomberg reported that the California DMV was planning to adopt the penalty but decided to put it on ice for ninety days, giving Tesla an opportunity to “come into compliance.”
Tesla enters interesting situation with Full Self-Driving in California
Tesla responded to the report on Tuesday evening, after it came out, stating that this was a “consumer protection” order that was brought up over its use of the term “Autopilot.”
The company said “not one single customer came forward to say there’s a problem,” yet a judge and the DMV determined it was, so they want to apply the penalty if Tesla doesn’t oblige.
However, Tesla said that its sales operations in California “will continue uninterrupted.”
It confirmed this in an X post on Tuesday night:
This was a “consumer protection” order about the use of the term “Autopilot” in a case where not one single customer came forward to say there’s a problem.
Sales in California will continue uninterrupted.
— Tesla North America (@tesla_na) December 17, 2025
The report and the decision by the DMV and Judge involved sparked outrage from the Tesla community, who stated that it should do its best to get out of California.
One X post said California “didn’t deserve” what Tesla had done for it in terms of employment, engineering, and innovation.
Tesla has used Autopilot and Full Self-Driving for years, but it did add the term “(Supervised)” to the end of the FSD suite earlier this year, potentially aiming to protect itself from instances like this one.
This is the first primary dispute over the terminology of Full Self-Driving, but it has undergone some scrutiny at the federal level, as some government officials have claimed the suite has “deceptive” naming. Previous Transportation Secretary Pete Buttigieg was vocally critical of the use of the name “Full Self-Driving,” as well as “Autopilot.”
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New EV tax credit rule could impact many EV buyers
We confirmed with a Tesla Sales Advisor that any current orders that have the $7,500 tax credit applied to them must be completed by December 31, meaning delivery must take place by that date. However, it is unclear at this point whether someone could still claim the credit when filing their tax returns for 2025 as long as the order reflects an order date before September 30.
Tesla owners could be impacted by a new EV tax credit rule, which seems to be a new hoop to jump through for those who benefited from the “extension,” which allowed orderers to take delivery after the loss of the $7,500 discount.
After the Trump Administration initiated the phase-out of the $7,500 EV tax credit, many were happy to see the rules had been changed slightly, as deliveries could occur after the September 30 cutoff as long as orders were placed before the end of that month.
However, there appears to be a new threshold that EV buyers will have to go through, and it will impact their ability to get the credit, at least at the Point of Sale, for now.
Delivery must be completed by the end of the year, and buyers must take possession of the car by December 31, 2025, or they will lose the tax credit. The U.S. government will be closing the tax credit portal, which allows people to claim the credit at the Point of Sale.
🚨UPDATE: $7,500 Tax Credit Portal “Closes By End of Year”.
This is bad news for pending Tesla buyers (MYP) looking to lock in the $7,500 Tax Credit.
“it looks like the portal closes by end of the year so there be no way for us to guarantee the funds however, we will try our… pic.twitter.com/LnWiaXL30k
— DennisCW | wen my L (@DennisCW_) December 15, 2025
We confirmed with a Tesla Sales Advisor that any current orders that have the $7,500 tax credit applied to them must be completed by December 31, meaning delivery must take place by that date.
However, it is unclear at this point whether someone could still claim the credit when filing their tax returns for 2025 as long as the order reflects an order date before September 30.
If not, the order can still go through, but the buyer will not be able to claim the tax credit, meaning they will pay full price for the vehicle.
This puts some buyers in a strange limbo, especially if they placed an order for the Model Y Performance. Some deliveries have already taken place, and some are scheduled before the end of the month, but many others are not expecting deliveries until January.
Elon Musk
Elon Musk takes latest barb at Bill Gates over Tesla short position
Bill Gates placed a massive short bet against Tesla of ~1% of our total shares, which might have cost him over $10B by now
Elon Musk took his latest barb at former Microsoft CEO Bill Gates over his short position against the company, which the two have had some tensions over for a number of years.
Gates admitted to Musk several years ago through a text message that he still held a short position against his sustainable car and energy company. Ironically, Gates had contacted Musk to explore philanthropic opportunities.
Elon Musk explains Bill Gates beef: He ‘placed a massive bet on Tesla dying’
Musk said he could not take the request seriously, especially as Gates was hoping to make money on the downfall of the one company taking EVs seriously.
The Tesla frontman has continued to take shots at Gates over the years from time to time, but the latest comment came as Musk’s net worth swelled to over $600 billion. He became the first person ever to reach that threshold earlier this week, when Tesla shares increased due to Robotaxi testing without any occupants.
Musk refreshed everyone’s memory with the recent post, stating that if Gates still has his short position against Tesla, he would have lost over $10 billion by now:
Bill Gates placed a massive short bet against Tesla of ~1% of our total shares, which might have cost him over $10B by now
— Elon Musk (@elonmusk) December 17, 2025
Just a month ago, in mid-November, Musk issued his final warning to Gates over the short position, speculating whether the former Microsoft frontman had still held the bet against Tesla.
“If Gates hasn’t fully closed out the crazy short position he has held against Tesla for ~8 years, he had better do so soon,” Musk said. This came in response to The Gates Foundation dumping 65 percent of its Microsoft position.
Tesla CEO Elon Musk sends final warning to Bill Gates over short position
Musk’s involvement in the U.S. government also drew criticism from Gates, as he said that the reductions proposed by DOGE against U.S.A.I.D. were “stunning” and could cause “millions of additional deaths of kids.”
“Gates is a huge liar,” Musk responded.
It is not known whether Gates still holds his Tesla short position.
Tesla dispels reports of ‘sales suspension’ in California
New EV tax credit rule could impact many EV buyers
