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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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Tesla called ‘biggest meme stock we’ve ever seen’ by Yale associate dean

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Credit: Tesla

Tesla (NASDAQ: TSLA) is being called “the biggest meme stock we’ve ever seen” by Yale School of Management Senior Associate Dean Jeff Sonnenfeld, who made the comments in a recent interview with CNBC.

Sonnenfeld’s comments echo those of many of the company’s skeptics, who argue that its price-to-earnings ratio is far too high when compared to other companies also in the tech industry. Tesla is often compared to companies like Apple, Nvidia, and Microsoft when these types of discussions come up.

Fundamentally, yes, Tesla does trade at a P/E level that is significantly above that of any comparable company.

However, it is worth mentioning that Tesla is not traded like a typical company, either.

Here’s what Sonnenfeld said regarding Tesla:

“This is the biggest meme stock we’ve ever seen. Even at its peak, Amazon was nowhere near this level. The PE on this, well above 200, is just crazy. When you’ve got stocks like Nvidia, the price-earnings ratio is around 25 or 30, and Apple is maybe 35 or 36, Microsoft around the same. I mean, this is way out of line to be at a 220 PE. It’s crazy, and they’ve, I think, put a little too much emphasis on the magic wand of Musk.”

Many analysts have admitted in the past that they believe Tesla is an untraditional stock in the sense that many analysts trade it based on narrative and not fundamentals. Ryan Brinkman of J.P. Morgan once said:

“Tesla shares continue to strike us as having become completely divorced from the fundamentals.”

Dan Nathan, another notorious skeptic of Tesla shares, recently turned bullish on the stock because of “technicals and sentiment.” He said just last week:

“I think from a trading perspective, it looks very interesting.”

Nathan said Tesla shares show signs of strength moving forward, including holding its 200-day moving average and holding against current resistance levels.

Sonnenfeld’s synopsis of Tesla shares points out that there might be “a little too much emphasis on the magic wand of Musk.”

Elon Musk just bought $1 billion in Tesla stock, his biggest purchase ever

This could refer to different things: perhaps his recent $1 billion stock buy, which sent the stock skyrocketing, or the fact that many Tesla investors are fans and owners who do not buy and sell on numbers, but rather on news that Musk might report himself.

Tesla is trading around $423.76 at the time of publication, as of 3:25 p.m. on the East Coast.

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Tesla makes big change to Full Self-Driving doghouse that drivers will like

Now, it is changing the timeframe of which strikes will be removed, cutting it in half. The strikes will be removed every 3.5 days, as long as no strikes are received during the time period.

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Tesla's Cabin-facing camera is used to monitor driver attentiveness. (Credit: Andy Slye/YouTube)

Tesla is making a big change to its Full Self-Driving doghouse that drivers will like.

The doghouse is a hypothetical term used to describe the penalty period that Tesla applies to drivers who receive too many infractions related to distracted driving.

Previously, Tesla implemented a seven-day ban on the use of Full Self-Driving for those who received five strikes in a vehicle equipped with a cabin camera and three strikes for those without a cabin camera.

It also forgave one strike per week of Full Self-Driving use, provided the driver did not receive any additional strikes during the seven-day period.

Now, it is changing the timeframe of which strikes will be removed, cutting it in half. The strikes will be removed every 3.5 days, as long as no strikes are received during the time period.

The change was found by Not a Tesla App, which noticed the adjustment in the Owner’s Manual for the 2025.32 Software Update.

The system undoubtedly helps improve safety as it helps keep drivers honest. However, there are definitely workarounds, which people are using and promoting for monetary gain, and you can find them on basically any online marketplace, including TikTok shop and Amazon:

People are marketing the product as an FSD cheat device, which the cabin-facing camera will not be able to detect, allowing you to watch something on a phone or look through the windshield at the road.

The safeguards implemented by Tesla are designed to protect drivers from distractions and also protect the company itself from liability. People are still using Full Self-Driving as if it were a fully autonomous product, and it is not.

Tesla even says that the driver must pay attention and be ready to take over in any scenario:

“Yes. Autopilot is a driver assistance system that is intended to be used only with a fully attentive driver. It does not turn a Tesla into a fully autonomous vehicle.

Before enabling Autopilot, you must agree to “keep your hands on the steering wheel at all times” and to always “maintain control and responsibility for your vehicle.” Once engaged, Autopilot will also deliver an escalating series of visual and audio warnings, reminding you to place your hands on the wheel if insufficient torque is applied or your vehicle otherwise detects you may not be attentive enough to the road ahead. If you repeatedly ignore these warnings, you will be locked out from using Autopilot during that trip.

You can override any of Autopilot’s features at any time by steering or applying the accelerator at any time.”

It is good that Tesla is rewarding those who learn from their mistakes with this shorter timeframe to lose the strikes. It won’t be needed forever, though, as eventually, the company will solve autonomy. The question is: when?

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Elon Musk teases the capabilities of the Tesla Roadster once again

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Elon Musk has once again teased the capabilities of the Tesla Roadster, fueling the anticipation that many have for the vehicle, despite it still having no public production or delivery date.

The Roadster is among the most anticipated vehicles in the automotive sector currently, and as Tesla has teased its capabilities, from a lightning-fast 1.1-second 0-60 MPH acceleration to potential hovering with cold-gas thrusters, people are eager to see it.

Although the design seemed to be finalized, there was still more work to be done. Earlier this year, as Tesla was showcasing some of the Roadster’s capabilities to Musk, he stated that it was capable of even more.

This pushed back its production date even further, much to the chagrin of those who have been waiting years for it.

Musk continues to tease us all, and as we sit here waiting hopelessly for it to be revealed, he said today that it is “something special beyond a car.”

Musk’s words were in response to a video posted by Tesla China, showing the Roadster in a new promotional video created by a fan.

The Roadster was planned to be released in 2020, but here we are in 2025, and there is still no sign of the vehicle entering production. However, Tesla did say earlier this year that it would host a demo event for the Roadster, where the company would showcase its capabilities.

Lars Moravy said earlier this year:

“Roadster is definitely in development. We did talk about it last Sunday night. We are gearing up for a super cool demo. It’s going to be mind-blowing; We showed Elon some cool demos last week of the tech we’ve been working on, and he got a little excited.”

Tesla exec gives big update on Roadster, confirming recent rumor

The delays have been attributed to “radically increased design goals” for the vehicle, which have, without a doubt, improved its capabilities, but at the same time, we just want to know if it’s ever going to come.

Tesla can always make it “better,” but at what point do you say, “Okay, it’s time to show this thing off.” They could always build another, even more capable supercar in the next ten years.

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