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SpaceX to replace Falcon 9’s titanium grid fins with steel on Starship’s Super Heavy booster
Following a question on Twitter about how SpaceX intends to manufacture the truly massive grid fins shown in renders of Starship’s Super Heavy booster, CEO Elon Musk revealed that SpaceX will build them out of welded steel.
For the first several years of Falcon 9 and Falcon Heavy booster recovery operations, SpaceX built grid fins – used for maneuvering the rockets at high speeds – out of aluminum. With Falcon 9 Block 5, aluminum grid fins were phased out entirely in favor of larger titanium fins, necessitated by exceptionally high-speed reentries that nearly melted through the aluminum fins on several occasions. Now, SpaceX wants to move from titanium to steel fins for its next-generation Starship launch vehicle.
Welded steel— Elon Musk (@elonmusk) October 3, 2019
In response to the Twitter user’s question, Musk simply stated that Super Heavy’s grid fins would be manufactured out of “welded steel”, certainly keeping with the CEO’s now well-known love for the material. In October 2018, Musk finally managed to convince most of the senior engineers reporting to him that – despite years of work and full-scale testing – SpaceX needed to radically redesign Starship.
Prior to this radical change, SpaceX had spent at least 2-3 years on a Starship design (formerly Big F_____ Spaceship; BFS) made almost entirely out of carbon fiber composites, an extremely lightweight material that can be optimized for high strength. However, as Musk ultimately concluded in late 2018, although carbon composites are undeniably light and strong (optimal for spaceflight), they have extremely low heat tolerance and can react violently with supercooled liquid oxygen. Built almost entirely out of aluminum alloys with similarly low melting points, Falcon 9 has also struggled with the challenges posed by material choices, made far more difficult by the need to recover and reuse orbital-class rocket stages.
Musk ultimately decided that redesigning Starship with steel (alloys with particularly high melting points and good strength) was the right way to go. According to Musk, the high-quality carbon fiber composites SpaceX was originally pursuing cost something like $130,000 per metric ton, translating to a truly gobsmacking cost – accounting for unavoidable wastage – of $400M-$500M or more just to buy the materials needed to build a single Starship and Super Heavy booster. Steel, on the other hand, is quite literally 50 times cheaper, costing SpaceX around $2500 per ton, or as little as $10M in structural materials for each ship/booster pair.
Man of Stainless Steel
Speaking at a September 28th presentation on the 2019 status of Starship’s design, CEO Elon Musk couldn’t praise his decision to move to stainless steel enough, describing it as likely being the single best design decision he has ever made. It remains to be seen if the eccentric self-taught engineer’s decision was the correct one, but the progress SpaceX has made in just 10-11 months is undeniable. SpaceX has gone from a nearly blank slate to Starhopper’s 150m (500ft) test flight in ~6 months and gone from nothing to Starship Mk1 in another 6 or so months.
According to Musk, the properties of stainless steel – mainly a high melting point/working temperature and a tendency to strengthen at cryogenic temperatures – mean that the relatively heavy material is able to produce a launch vehicle that could eventually be far lighter and higher-performance than one made with carbon composites (BFR) or aluminum alloys (Falcon 9). Thanks to those properties, Starship/Super Heavy will become much stronger when filled with cold propellant and will also require little to no external heat shielding on its leeward half, whereas a reusable Al/composite rocket would require major thermal protection on nearly all exposed surfaces.
As part of the move to remove any ultra-expensive nonessential materials from the designs of Starship and Super Heavy, Musk has apparently also turned his gaze on the booster’s grid fins. As described at the top of this article, SpaceX replaced Falcon 9’s aluminum grid fins with titanium fins, requiring the company to create the largest single-piece titanium casting in the world. Musk has repeatedly indicated that each grid fin is extremely expensive.
In light of their expense, Musk (or SpaceX) has seemingly decided that future (larger?) SpaceX rockets will try to avoid large, titanium castings. Super Heavy nevertheless still needs massive grid fins: official renders published by SpaceX last month revealed a new diamond shape for the booster’s fins, and Musk later took to Twitter to reveal that they would be made out of welded steel instead of titanium.
Based on SpaceX’s official 2019 Super Heavy renders, the booster’s grid fins measure approximately 7m by 3m (23 ft by 10 ft), dwarfing Falcon 9’s titanium fins (perhaps 2m by 1.2m) with something like 8-10 times the surface area. Although 301-series stainless steel has a melting point and heat capacity roughly 15% lower than Grade 5 titanium, its strength characteristics are otherwise similar, while also remaining mechanically functional at almost three times the working temperature of titanium (840C vs. 330C).
Most importantly, not only is 301 steel roughly 15-20 times cheaper than titanium, but the process of fabricating large steel components – particularly with welding instead of casting – is dramatically faster, easier, and cheaper than working with and forming titanium. With their reasonably similar properties and the increased size of Super Heavy, it’s likely that steel grid fins would exhibit little to no ablation during even the hottest atmospheric reentries, and it would nevertheless be extremely easy and cheap to either repair or replace fins in the unlikely event of damage.
Given just how quickly and relatively easily SpaceX has built full-scale flight hardware out of steel and assuming there are no technical showstoppers caused by changing scales, it wouldn’t be surprising in the slightest to see SpaceX fabricate and test welded steel grid fins on Falcon 9 boosters in the near future.
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Tesla has taken another concrete step toward owning its battery supply chain, and it’s doing so with what is perhaps the most important vehicle in its short-but-storied history.
On September 23, Tesla announced that it has officially built the first Cybercab with cathode material produced in-house at the company’s first cathode plant in the U.S., and the first in the U.S. overall.
First Cybercab made using our in-house cathode material – from the first cathode plant in the Americas pic.twitter.com/X95aVXsT9H
— Robotaxi (@robotaxi) September 23, 2026
Active cathode material is the most expensive piece of a lithium-ion battery cell, and it often accounts for more than a third of cell cost. For years, the industry sourced a majority of it from Asia, but Tesla’s decision to make it in the United States bodes well for the Cybercab project. This is the latest chapter in Tesla’s vertical integration strategy, which began in public at Battery Day in 2020.
At the Battery Day Event, Elon Musk said the company would build a North American cathode plant and overhaul the process to cut costs and waste, while also making some of the most powerful and long-lasting cells in the industry.
The Austin facility took years to appear. Tesla filed permits for “Project Cathode” in 2022 on land near Giga Texas. By mid-2022, the building frame was up and Tesla later invested hundreds of millions of dollars as part of a larger expansion of the Giga Texas plant. The company stated it was operating the first large-scale cathode production facility in North America to supplement 4680 cell production.
One month later, that material reached a finished Cybercab.
Made with nickel cathode manufactured locally at Gigafactory Texas! https://t.co/DqMm5fZV3n
— Elon Musk (@elonmusk) September 24, 2026
The timing of this breakthrough is monumental for the Cybercab program. As Tesla officially launched the first Cybercab rides to the public earlier this month, production of the ride-hailing-geared vehicle is moving forward on the planned S-curve that CEO Elon Musk told everyone to expect.
Nevertheless, packs of Cybercab units have been spotted throughout the United States, in an effort to potentially activate the fleet as soon as the company gains regulatory approval in various geographic areas.
On top of that, Tesla owning the cathode step and pairing it with its own in-house lithium from the Gulf Coast refinery shortens the supply chain that once stretched thousands of miles and subjects every pack to fewer external price shocks and geopolitical risks.
Tesla is not yet independent of all of its foreign suppliers, as some precursor metals come from mines and chemical plants. But the first in-house cathode Cybercab shows the company is closing the most expensive and most concentrated gap in its battery production efforts. For a vehicle like Cybercab to operate at a high utilization within the Robotaxi network, that control over cost is so crucial.
It is arguably as important as the software that drives it.
Tesla is set to inaugurate its dedicated Semi factory in Sparks, Nevada, this evening, but drone footage has already started to show who is expected on the handover stage.
Zanegler, a drone operator who regularly documents Tesla Semi operations in Nevada, filmed a row of new-generation Semi units parked outside of the plant with customer branding applied. The liveries visible in the video include companies like PepsiCo, U.S. Foods, Einride, DHL, WattEV, and others that have committed to utilizing Tesla’s Class 8 electric truck in their fleets.
Tesla Semi Pre-Reveal Revealed!
Excited to share this segment of the drone flight one day prior to the Tesla Semi Reveal event.
They have added branding to several Tesla new generation semis.
Including:
Pepsico
US Foods
Einride
LTS
Nevoya
OK Produce
ABF Freight
DHL
WattEV… pic.twitter.com/KoFOg2FouR— Zanegler (@HinrichsZane) September 24, 2026
Several of those company names already sit within Tesla’s public ordering book, including PepsiCo, which has been the program’s primary anchor customer since the first Semi deliveries in December 2022. PepsiCo now runs dozens of Tesla Semi units in daily service, with drivers completing regional routes.
Einride placed a 500-unit order in August, which was, at the time, the largest single Semi commitment. First deployments of their Semi units are planned for this month and will eventually span across California, Texas, New Jersey, Illinois, and Georgia. Meanwhile, IMC Logistics announced a 50-truck California order this week.
Tesla Semi lands the biggest electric truck deal in U.S. history
Other names, like LTS, OK Produce, and HMD, have not been widely confirmed as firm buyers, but their presence on the lot is perhaps the clearest signal that Tesla intends to expand on that list this evening at the event.
Tesla first unveiled the Semi back in 2017 with a 2019 production target.
Limited pilot builds reached PepsiCo in late 2022, and high-volume production began at the new 1.7-million-square-foot plant that sits logically positioned next to Tesla’s Gigafactory Nevada. Tesla Semi program director Dan Priestley has said that Tesla expects to build “many thousands” of Semi units this year, but as with every Tesla release, there have been set expectations of an S-curve ramp.
Outside estimates still put 2026 deliveries in the 5,000-to-15,000 range, but it will ultimately depend on Tesla’s readiness to put those units out, as well as how smoothly production is moving internally.
Tesla’s Semi Rollout event is set to start tonight at the Sparks factory, and it will be livestreamed on X starting at 6 p.m. PDT / 9 p.m. ET.
The Tesla App is now giving owners a better indication of what to expect when visiting a Supercharger site, as it is now sharing Site Maps in the app itself, making the feature no longer exclusively available in the car.
Tesla owners can now preview a Supercharger’s layout and live stall status from their phone thanks to the App’s new software version, v4.61.0. Zooming into a supported Supercharger on the charging map now switches the familiar street view into a site-specific map that shows stall positions, occupied bays, out-of-service posts, and a live count of open Superchargers.
It will even show you which specific Tesla model is charging at each occupied stall.
You can now see Live Site Maps in the latest Tesla app (4.61.0.) pic.twitter.com/JIL8QzR8hu
— Zack (@BLKMDL3) September 18, 2026
This is the same view drivers first saw inside the car with the 2025 Holiday Update, which started as a pilot for Tesla in California and Texas. Those early maps showed layout, nearby amenities, and the status of each operational stall. The feature has spread to most Superchargers in the U.S., but now Tesla wants the feature available through the Smartphone App, which is now rolling out to owners.
The in-vehicle screen maps remain a richer 3D canvas and originally required AMD Ryzen infotainment hardware, which left many Intel-based Model 3 and Model Y owners without the view. The app version removes that hardware barrier, so any owner can now get a preview of their upcoming Supercharger stop on their phone.
Anyone with the updated version of the app can open a Site Map on their phone. The feature has provided some additional peace of mind to anxious travelers and those who might be looking for a place that is less congested for faster charging speeds. It is a meaningful addition to many owners, especially for trips to unfamiliar locations.
You can now pick a Supercharger location that might be more aligned with what you are looking for or need: you can pick a site based on what stalls are open, where ADA stalls sit, how you will pull in, and more, instead of circling a crowded lot after arriving. Owners of older cars now have access to the feature without having to purchase a new vehicle altogether.
Site Mpas will not reserve a stall, nor will it change how Fast Charging works. Tesla does something simpler and more useful by giving owners a dedicated preview of the Supercharger they’re about to charge, turning an unknown parking lot into a place that may seem more familiar thanks to the preview.
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Tesla Cybercab gets initial tie-in to localized, in-house cathode plant
Tesla leaks Semi customers ahead of handover event
