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SpaceX’s Starship hopper spotted with trio of dual-bell Raptor engines

Starship revealed a trio of what appear to be new Raptor engines when SpaceX technicians moved the assembly from stand to ground. (NSF - bocachicagal)

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Following a brief ‘hop’ (via crane) off of a concrete build stand, the aft section of SpaceX’s first full-scale Starship hopper (Starhopper?) revealed that SpaceX technicians have already installed what appear to be three real Raptor engines, presumably the first time the propulsion system has ever been mounted to something that might eventually fly.

For a number of reasons, there is a strong chance that these Raptors are actually just boilerplate placeholders standing in as structural guides for the real deal some months down the line. On the other hand, there are also a number of reasons to assume that these apparent engines are indeed real Raptors.

Despite an already shocking series of rapid-fire developments in the South Texas Starhopper saga, the abrupt appearance of what appears to be three Raptor engines – mirroring CEO Elon Musk’s recent statement that the test vehicle would sport three Raptors – is by far the most unexpected moment yet for the prototype Starship. Purportedly a full-scale prototype of BFR’s upper stage/spaceship (now known as Starship), Musk indicated over the last two weeks that the hopper has been designed to perform a number of hop tests in which the craft’s three Raptors would power it to a range of (relatively low) altitudes above Boca Chica, Texas.

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According to a recent FCC filing related to this test program, SpaceX is currently seeking a license for Starship hop tests that will not exceed 5 km (3.1 mi) in altitude and/or 6 minutes in duration. There is admittedly nothing mentioned about the maximum allowed velocity during those tests, but – much like Blue Origin performs supersonic tests of New Shepard in Cape Horn, Texas – SpaceX will likely seek and be granted permission to break the sound barrier during those hypothetical tests. Nevertheless, a 5km ceiling is a fairly significant cap on the range of performance Starhopper will be able to test – accelerating vertically at 2Gs, Starhopper could travel from sea level to 5km in less than 30 seconds while reaching speeds no higher than Mach 1-1.5.

 

Combined with the apparent fact that this Starhopper’s fins seem unlikely to ever actuate (i.e. no aerodynamic control surfaces), it’s probable that this ad hoc prototype is only meant to perform a very limited range of hop tests, perhaps as basic as ironing out the kinks of operating a trio of gimballed Raptors and ensuring that they can safely and reliably launch, hover, and land a very large Starship-shaped mass simulator. Falcon 9’s Grasshopper and F9R reusability testbeds performed a very similar task some five years ago, offering SpaceX engineers the opportunity to optimize software and hardware needed to reliably recover real orbital-class rockets after launch. Although Falcon 9 has nine gimballed Merlin 1D engines, SpaceX has long sided with the sole center Merlin as the dedicated landing engine and has only briefly experimented with triple-Merlin landing burns.

Dual-expansion whaaaaat?

According to Musk, Raptor –  an advanced liquid methane and oxygen engine with a uniquely efficient propulsion cycle – was expected to produce an impressive ~2000 kN (200 ton, 450K lbf) of thrust in its finished form as of September 2018. However, Musk also mentioned in a late-2017 Reddit AMA that SpaceX engineers were modifying the ship’s design to ensure engine-out reliability during all regimes of flight, landing in particular. To accomplish this feat with an engine as powerful as Raptor, two or three Raptors – capable of producing as much as 600 tons of thrust total – would need to reliably throttle as low as 25%, assuming a landing mass of around 150t. To allow a nearly empty ship (~100t) to still reliably land with three Raptors ignited, the engines would need to be able to throttle to 20% or less.

A trio of Raptors (or Raptor stand-ins) were spotted on Starhopper on Dec 31 by NASASpaceflight user bocachicagal.

Known as deep throttling in rocketry, ensuring stable combustion and thrust at 20% (let alone 40%) throttle is an extraordinarily challenging feat, often subjecting engines to forces that can literally tear non-optimized hardware apart. To achieve such a deep throttle capability without excessively disrupting the engine’s design, SpaceX appears to have potentially sided with less efficient but extremely simple alternative, known as a dual-bell (or dual-expansion) rocket nozzle. A 1999 Rocketdyne paper concisely explained the primary draws of such a nozzle:

“The [altitude-compensating] dual-bell nozzle offers a unique combination of performance, simplicity, low weight, and ease of cooling” – Horn & Fisher, 1999

Given that SpaceX has decided to delay the introduction and certification of a vacuum-optimized Raptor engine, choosing to instead use the same Raptor on both BFR stages, something like a dual-bell nozzle would be one of the best possible ways for the company to retain some of the efficiency benefits of a vacuum engine while also drastically improving design simplicity, ease of manufacturing, and cutting development time. Aside from offering efficiency gains by way of altitude compensation, a dual-bell nozzle also happens to enable a given engine to operate a much wider throttle range by mitigating problems with flow separation and instability.

 

For Starhopper and Starship, both aspects are an undeniable net-gain and it’s entirely possible that these dual-bell nozzles – if successfully demonstrated – could find their way onto Falcon 9 and Falcon Heavy to further boost their booster performance and efficiency.


For prompt updates, on-the-ground perspectives, and unique glimpses of SpaceX’s rocket recovery fleet check out our brand new LaunchPad and LandingZone newsletters!

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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

SpaceX posts Starship booster feat that’s so nutty, it doesn’t even look real

The Super Heavy booster’s feat was so impressive that the whole maneuver almost looked like it was AI-generated.

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Credit: SpaceX/X

SpaceX has shared a video of a remarkable feat achieved by Starship’s Super Heavy booster during its 11th flight test.

The Super Heavy booster’s feat was so impressive that the whole maneuver, which was captured on video, almost looked like it was AI-generated.

Super Heavy’s picture perfect hover

As could be seen in the video shared by SpaceX, Starship’s Super Heavy booster, which is nearly 400 feet tall, smoothly returned to Earth and hovered above the Gulf of America for a few seconds before it went for its soft water landing. The booster’s picture-perfect maneuver before splashing down all but capped a near-flawless mission for Starship, which is about to enter its V3 era with Flight 12.

The booster’s balance and stability were so perfect that some users on X joked that the whole thing looked AI-generated. Considering the size of Super Heavy, as well as the fact that the booster was returning from space, the hovering display all but showed that SpaceX is dead serious about keeping its dominant lead in the spaceflight sector.

Starship V2’s curtain call

As noted in a Space.com report, Flight Test 11 achieved every major goal SpaceX had set for the mission, including deploying Starlink mass simulators, relighting Raptor engines in space, and executing a stable reentry for both the Starship Upper Stage and the Super Heavy booster. The feat also marked the second time a Super Heavy booster has been reflown, a milestone in SpaceX’s quest to make the entire Starship system fully reusable.

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Starship’s V2 vehicle will now give way to the upgraded Starship V3, which is designed for faster turnaround and higher payload capacity. The Starship program is expected to pursue even more aggressive targets in the coming months as well, with Elon Musk stating on social media platform X that SpaceX will attempt a tower catch for Starship Upper Stage as early as spring 2026.

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Elon Musk

Starship’s next chapter: SpaceX eyes tower catch after flawless Flight 11

Elon Musk has revealed the tentative timeframe for Starship’s next milestone that would push the spacecraft’s reusability to a whole new level. 

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Credit: SpaceX

Elon Musk has revealed the tentative timeframe for Starship’s next milestone that would push the spacecraft’s reusability to a whole new level. 

Following Flight 11’s flawless mission, Musk noted on X that SpaceX will be aiming to catch the Starship Upper Stage with its launch tower as early as spring 2026. This should pave the way for SpaceX to start optimizing Starship for maximum reusability.

Flight 11 closes the Starship V2 chapter on a high note

Starship’s eleventh flight, which launched from Starbase, Texas, achieved every major mission objective. The Super Heavy booster completed a successful ascent, hover, and soft splashdown in the Gulf of America, while the upper stage executed an orbit burn, deployed Starlink simulators, and returned with a controlled reentry over the Indian Ocean.

This mission officially closed the chapter on the second-generation Starship and first-generation Super Heavy booster, and it set the stage for a redesigned vehicle built for orbital payload missions, propellant transfer, and beyond. It should be noted that Elon Musk has mentioned on X that Starship V3, at least if things go well, might be capable of reaching Mars.

Elon Musk confirms tower catch attempt set for spring

After Flight 11’s success, Musk confirmed that SpaceX will attempt to catch the Starship Upper Stage with its launch tower arms, fondly dubbed by the spaceflight community as “chopsticks,” in the coming months. Musk’s announcement came as a response to an X user who asked when the tower could start catching the Starship Upper Stage. In his reply, Musk simply wrote “Springtime.” 

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Starship’s reusability is a key feature of the spacecraft, with SpaceX aiming to achieve a launch cadence that is almost comparable to conventional aircraft. For such a scenario to be feasible, launch tower catches of both Starship’s Upper Stage and its Super Heavy booster have to be routine.

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Elon Musk

SpaceX is preparing to launch Starship V2 one final time

The mission will test reentry dynamics, new landing burn configurations, and heat-shield upgrades.

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Credit: SpaceX/X

SpaceX is preparing to launch its final Starship V2 rocket on October 13, 2025. The launch closes the curtain on Starship V2 and marks the start of the ambitious spacecraft’s V3 era. 

Liftoff for Flight 11 is scheduled for 7:15 p.m. ET from Starbase in South Texas, with a 75-minute launch window. The mission will test reentry dynamics, new landing burn configurations, and heat-shield upgrades ahead of the transition to the next-generation Starship V3.

Starship V3 and beyond

Elon Musk confirmed on X that Starship V3 is already in production and could be “built & tested” and perhaps even flown before the end of 2025. The new version is expected to feature major performance and scale improvements, with Musk stating that Starship V3, provided that things go well, might be capable of reaching Mars, though V4 is more likely to perform a full-scale mission to the red planet. 

“Only one more V2 left to launch,” Musk wrote back in August following Starship’s successful Flight 10 mission. In another post, Musk stated that “Starship V3 is a massive upgrade from the current V2 and should be through production and testing by end of year, with heavy flight activity next year.”

Starship V2’s final mission

Flight 11 is designed to push the limits of Starship V2. SpaceX engineers have intentionally removed heat-shield tiles in vulnerable areas to analyze how the vehicle handles atmospheric reentry under stress, as noted in a Space.com report. The test will also refine subsonic guidance algorithms and new landing burn sequences for the Super Heavy booster that would be used for Starship V3.

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“Super Heavy will ignite 13 engines at the start of the landing burn and then transition to a new configuration with five engines running for the divert phase. Previously done with three engines, the planned baseline for V3 Super Heavy will use five engines during the section of the burn responsible for fine-tuning the booster’s path, adding additional redundancy for spontaneous engine shutdowns. 

“The booster will then transition to its three center engines for the end of the landing burn, entering a full hover while still above the ocean surface, followed by shutdown and dropping into the Gulf of America,” SpaceX wrote in a post on its official website.

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