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SpaceX sends “radically redesigned” Starship engine to Texas for hot-fire tests
SpaceX has shipped one of the first of a group of Starship engines known as Raptor, described last month by CEO Elon Musk as “radically redesigned”. A culmination of more than 24 months of prototype testing, the first flight-worthy Raptor could be ignited for the first time as early as February.
According to Musk, three of these redesigned Raptors will power the first full-scale BFR prototype, a Starship (upper stage) test article meant to conduct relatively low-altitude, low-velocity hop tests over the southern tip of Texas. Those tests could also begin next month, although a debut sometime in March or April is increasingly likely.
Engines currently on Starship hopper are a blend of Raptor development & operational parts. First hopper engine to be fired is almost finished assembly in California. Probably fires next month.
— Elon Musk (@elonmusk) January 5, 2019
Effectively designed on a blank slate, Raptor began full-scale component-level tests in 2014 at NASA’s Mississippi-based Stennis Space Center, evolving from main injector development to oxygen preburner hot-fires in 2015. Soon after Raptor’s prototype preburner design was validated at Stennis, SpaceX moved testing to its privately-owned and operated facilities in McGregor, Texas, where Raptor static fire testing has remained since.
Mach diamonds pic.twitter.com/TCX7ZGFnN0
— Elon Musk (@elonmusk) September 26, 2016
Just days before CEO Elon Musk was scheduled to reveal SpaceX’s next-generation rocket (BFR, formerly known as the Interplanetary Transport System or ITS) in September 2016, he announced in a tweet that propulsion engineers and technicians had successful hot-fired an integrated Raptor prototype – albeit subscale – for the first time ever. Just 12 months later, Musk once again took to the stage to announce an update to BFR’s design, while also revealing that prototype Raptor engines had already completed more than 1200 seconds (20 minutes) of cumulative hot-fire tests, an extremely aggressive and encouraging rate of progress for such a new engine.
SpaceX has completed over 1,200 seconds of firing across 42 main Raptor engine tests. pic.twitter.com/EhxbPjd8Cj
— SpaceX (@SpaceX) September 29, 2017
Although Raptor undoubtedly borrows heavily from much of the same expertise that designed Merlin 1 and operated and improved it for years, that is roughly where the similarities between Raptor and M1D end. M1D, powered by refined kerosene (RP-1) and liquid oxygen, uses a combustion cycle (gas-generator) that is relatively simple and reliable at the cost of engine efficiency, although SpaceX propulsion expertise still managed to give M1D the highest thrust-to-weight ratio of any liquid rocket engine ever flown. Still, measured by ISP (instantaneous specific impulse), M1D’s inefficient kerolox gas-generator cycle ultimately means that the engine simply can’t compete with the performance of engines with more efficient propellants and combustion cycles.
While SpaceX’s Falcon 9 and Heavy rockets – powered by Merlin 1D and Merlin Vacuum – are more than adequate in and around Earth orbit, a far more efficient engine was needed for the company to enable the sort of interplanetary colonization Musk had in mind when he created SpaceX. Raptor was the answer. Ultimately settling on liquid methane and oxygen (methalox) as the propellant and a full-flow staged-combustion (FFSC) cycle, Raptor was designed to be extraordinarily reliable and efficient in order to safely power a spacecraft (BFS/Starship) meant to ferry dozens or hundreds of people to and from Mars.
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- The only official render of Raptor, published by SpaceX in September 2016. The Raptor departing Hawthorne in Jan ’19 looked reasonably similar. (SpaceX)
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- SpaceX technicians wrench on Merlin 1D and Merlin Vacuum engines. Raptor was apparently dramatically larger in person. (SpaceX)
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- Starhopper’s Raptors feature a very distinct seam and second curve, indicative of a dual-bell nozzle. (NASASpaceflight /u/bocachicagal)
Raptor enters a new era
For all the extensive and invaluable testing SpaceX has done with a series of prototype Raptor engines, the engines tested were subscale versions with around 30% the thrust of the c. 2016 Raptor and around 40-50% of the updated c. 2017 iteration, producing almost the same amount of thrust as Merlin 1D (914 kN to Raptor’s ~1000 kN). In September 2018, Musk described Raptor as an “approximately…200-ton (~2000 kN) thrust engine” that would eventually operate with a chamber pressure as high as 300 bar (an extraordinary ~4400 psi), requiring at least one of the FFSC engine’s two preburners (used to power separate turbopumps) to operate at a truly terrifying ~810 bar (nearly 12,000 psi).
Conveniently stood beside a Merlin 1D engine also ready for hot-fire acceptance testing, the Raptor engine spotted departing SpaceX’s Hawthorne, CA factory last week was reportedly immense in person, towering over an M1D engine. Raptor also featured a mass of spaghetti-like plumbing (complexity necessary for its advanced combustion cycle), with a significant fraction of the metallic pipes and tubes displaying mirror-like finishes. Most notable was an obvious secondary preburner/turbopump stack and the lack of any exhaust port, whereas M1D relies on a single turbopump and exhausts the gases used to power it. Raptor’s full-flow staged-combustion cycle uses separate oxygen and methane preburners to power separate turbopumps, significantly improving mass flow rate and smoothing out combustion mixing.
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- SpaceX’s current Texas facilities feature a test stand for Raptor, the engine intended to power BFR and BFS to Mars. (SpaceX)
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- SpaceX’s subscale Raptor engine has completed more than 1200 seconds of testing in less than two years. (SpaceX)
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- A gif of Raptor throttling over the course of a 90+ second static-fire test in McGregor, Texas. (SpaceX)
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- A September 2018 render of Starship (then BFS) shows one of the vehicle’s two hinged wings/fins/legs. (SpaceX)
Unlike all previous hot-fired Raptors, those shipping now to McGregor, Texas are expected to be the first completed engines with a finalized design, arrived at only after a period of extensive testing and iterative improvement. They also appear to be full-scale, meaning that the test bays dedicated to Raptor will likely need to be upgraded (if they haven’t been already) to support a two- or threefold increase in maximum thrust.
Yes. Radically redesigned Raptor ready to fire next month.
— Elon Musk (@elonmusk) December 22, 2018
SpaceX’s Starship hopper will need three finalized engines, meaning that the Raptor now in McGregor, Texas may not have been the first to arrive. Nevertheless, the shipment of full-scale hardware is always an extremely encouraging milestone for any advanced technology development program, while also foreshadowing the first imminent static-fires of the “radcally redesigned” rocket engine. With hardware now at the test site before January is out, a February test debut – one month behind a January debut teased by Elon Musk last December – is not out of the question.
News
SpaceX set to launch astronauts and a classified Falcon Heavy mission on the same day
SpaceX plans three launches Thursday, including Crew-13 astronauts and Falcon Heavy’s first classified NRO mission.
SpaceX is lining up one of the busiest single days in its history, and the company offered a preview on Wednesday morning with a simple post on X: “Sunrise at pad 40.” The video and photos show Falcon 9 standing at Space Launch Complex 40 at Cape Canaveral, roughly a day before it is scheduled to carry four astronauts to the International Space Station.
That launch is only the first of three SpaceX missions planned for Thursday, October 1, across both coasts.
Sunrise at pad 40 pic.twitter.com/J7Qme4VvIX
— SpaceX (@SpaceX) September 30, 2026
Crew-13 is targeting liftoff at 11:10 a.m. ET, with a backup opportunity Friday at 10:47 a.m. ET. NASA astronaut Jessica Watkins will command the mission, with NASA’s Luke Delaney as pilot and Canadian Space Agency astronaut Joshua Kutryk and Roscosmos cosmonaut Sergey Teteryatnikov serving as mission specialists. According to NASA, Dragon is set to dock with the forward port of the station’s Harmony module around 8 p.m. ET, less than nine hours after launch. Watkins is the only member of the crew who has flown before, and Kutryk will become the first Canadian to reach orbit through NASA’s Commercial Crew Program.
The Falcon 9 booster is flying for the third time after supporting Crew-12 and a Starlink mission, and it will attempt a landing at Landing Zone 40 beside the pad. That site made its debut in February when the Crew-12 booster touched down there, as Teslarati reported at the time. Crew-13 will relieve the Crew-12 astronauts, who have been aboard the station since the middle of February.
On the West Coast, another Falcon 9 is scheduled to lift off from Vandenberg Space Force Base in a window running from 2:18 to 3:16 p.m. ET, a flight NASASpaceflight lists as a Transporter rideshare mission.
The day is set to close at 11:53 p.m. ET, when Falcon Heavy launches from Launch Complex 39A with NROL-97, the first National Reconnaissance Office payload ever to fly on the rocket. SpaceX rolled the vehicle out to the pad Tuesday night. Its two side boosters, which previously flew GOES-U, ViaSat-3 F3 and NASA’s Roman Space Telescope, will return to Landing Zones 1 and 2, while a new center core will be expended in the Atlantic. The Roman launch took place on August 30, so NROL-97 will come barely a month later as Falcon Heavy’s third flight of 2026 and 14th overall.
NASA taps SpaceX to launch the telescope that could unlock new worlds
If all three Florida boosters land as planned, it would be the first time the Space Coast has seen landings at LZ-40, LZ-1 and LZ-2 on the same day, according to the Orlando Sentinel, which has warned residents in Brevard, Orange and Volusia counties that more than one sonic boom is possible.
The schedule arrives just three days after Starship reached orbit for the first time on Flight 14 from Starbase, Texas, deploying 26 Starlink V3 satellites. If Thursday’s missions stay on time, SpaceX will have flown Starship, Falcon 9 and Falcon Heavy from four different pads in about four days.
Crew-13 is also the start of a longer run for Dragon. NASA recently added Crew-15, Crew-16 and Crew-17 to SpaceX’s contract in a $946 million modification, keeping Dragon as the agency’s only operational ride to the station while Boeing’s Starliner remains grounded.
Although the two vehicles are built for completely different use cases, Tesla utilized engineering expertise while developing both the Cybercab and Semi to build a thermal architecture that would fit both vehicles. Of course, with some slight revisions.
The development was noted by Lars Moravy and Dan Priestley last week at Tesla’s Semi Handover event in Sparks, Nevada, where the company showed off its dedicated production facility for the Class 8 truck.
🚨 Tesla designed the integrated thermal systems for Cybercab and Semi at the same time as the vehicles were both in development
Tesla wanted to build one thermal system that worked with both vehicles, apart from small modifications.
Semi and Cybercab share parts 🤯 pic.twitter.com/KmzSsUbrcg
— TESLARATI (@Teslarati) September 25, 2026
Tesla’s decision to develop one thermal architecture for both the Cybercab and Semi is one of the more revealing engineering choices in the company’s 2026 lineup:
“We designed it at the same time we designed the Cybercab and we said okay we’re going to take our most efficient vehicle and our biggest vehicle and we’re going to take one thermal system and make it work for both.”
Core parts, meaning the compressor, pumps, and heat exchangers, are shared, with only modest changes to cooling-loop sizing and a larger radiator on the truck. The result, they said, is a compressor and thermal stack already proven across millions of miles, delivering “reliability from day one.”
Priestley also highlighted a practical payoff of the indirect design:
“There’s no AC lines, there’s no refrigerant lines…It comes from the factory fully charged, sealed with refrigerant, and it just exchanges coolant. It doesn’t actually run refrigerant up to the front of the vehicle.”
This eliminates potentially leak-prone plumbing that would otherwise require hands-on service, reducing overall uptime and potentially cutting into business margins. The megamanifold runs cabin HVAC and every powertrain heating and cooling loop at once, recapturing waste heat from motors and the battery instead of dumping it the way a diesel engine does.
The approach is just the latest chapter in a continuing story of stretching thermal solutions across wildly different vehicles. Model Y’s Octovalve evolved into the Super Manifold used on Cybertruck, and later Model S/X refreshes. Cybercab then introduced Supermanifold V3, which Tesla says is 80 percent automated to build and 38 percent more efficient than typical automotive thermal systems.
This thermal system is also shared with Cybercab – one thermal system for both our most efficient vehicle & our biggest vehicle
— Tesla Semi (@tesla_semi) September 25, 2026
Tesla has done the same with the 4680 cells, both being utilized in the Cybertruck and Semi, and with heat-pump compressors that Priestley noted were already common across the passenger-car fleet.
Concurrent development of crucial vehicle elements buys scale and reliability that a truck-only thermal system could not match. High-volume passenger car parts are cheaper and more accessible, which can give fleets a sealed, low-maintenance loop of operation from their first day of operation.
For owners and operators, that translates into less energy spent on cabin heat in the colder months, fewer refrigerant-related repairs, and a thermal architecture already stress-tested at passenger-car volumes before the first high-volume Semi left the lines in Nevada.
Tesla CEO Elon Musk certainly tipped off some details of the Tesla Roadster event with a broadening of information regarding the company’s decision to delay the unveiling for two weeks.
For years, people have speculated about what the Roadster will be capable of. While there have been plenty of things said about what it *could* do, we have not seen or been told by Tesla what it will actually be capable of.
However, over the past few days, Tesla’s weather updates have truly pushed the speculation into Plaid Mode, basically all but confirming the car will have some sort of aerial capability — whether that would be hovering or fully flying remains to be seen — but it definitely seems that it will be able to leave the ground intentionally.
“Because this event can only be held outdoors…”
Tesla posted on Monday that it would delay the Roadster event until October 15, and it indicated that it had to do this because the event “can only be held outdoors.”
With the potential SpaceX collaboration to develop cold-gas thrusters that will help the vehicle go airborne, doing this indoors is probably not a safe, or even plausible, possibility.
Roadster event update
We’ve been tracking the weather closely with local meteorologists, but given the severe conditions predicted & because this event can only be held outdoors, we’ve made the difficult decision to reschedule.
New date is October 15. Additional details to…
— Tesla (@Tesla) September 28, 2026
FAA Airspace Restriction
The FAA gave Tesla a Temporary Flight Restriction (TFR) for 10,000 feet above ground level, much higher than the typical 2,000-foot restrictions that are usually placed at SpaceX’s McGregor, Texas site.
Tesla Roadster event requires restricted airspace, and the FAA obliges
Some have said that this massive increase is due to Tesla’s need to restrict unauthorized drone use for spying on the event.
Elon Admits High Winds
“Due to high winds, the new Roadster demo is postponed by 2 weeks,” Musk said in a post on X yesterday.
Due to high winds, the new Roadster demo is postponed by 2 weeks https://t.co/dV3ojDh1iT
— Elon Musk (@elonmusk) September 30, 2026
A reply reading, “What’s strong wind got to do with a car demo with four grounded wheels?” was directly below Musk’s post, satirically and sarcastically probing for more details.
All signs are pointing toward an aerial demonstration for the Roadster.
SpaceX set to launch astronauts and a classified Falcon Heavy mission on the same day
Tesla Cybercab and Semi have more in common than you might think
