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SpaceX’s first Starship engine suffers “expected” damage during Raptor test fire

Sometimes you have to crack a few Raptor eggs to make a Starship omelette. (SpaceX)

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6 years ago

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SpaceX CEO Elon Musk says that the first full-scale Starship engine to be tested has already been pushed to the point of damage less than three weeks after the campaign began, setting the stage for the second full-scale Raptor to take over in the near future.

According to Musk, while most of the damaged pathfinder Raptor’s components should still be easily reusable, the assembly of the second finalized engine is “almost done” and that Raptor will take over near-term testing rather than waiting for repairs to the first engine. This is undoubtedly an extraordinarily aggressive test program, particularly for such a new and cutting-edge rocket propulsion system, but these latest developments are ultimately far more encouraging than they are concerning.

Although the Raptor engine family began integrated subscale static fires way back in September 2016, SpaceX’s propulsion team finalized Raptor’s baseline design and completed assembly, shipment, and an integrated static fire of the first full-scale engine on February 3rd, considerably less than three weeks before Musk took to Twitter. Aside from confirming that the new Raptor had been damaged during its most recent static fire several days prior, Musk indicated that the failure (unsurprisingly) was primarily attributed to the engine reaching the highest chamber pressures yet.

Raptor’s main combustion chamber (the bit directly above the nozzle) has been designed to nominally operate at and reliably withstand extraordinary pressures of 250+ bar (3600+ psi), performance that demands even higher pressures in the components that feed hot methane and oxygen gas into Raptor’s combustion chamber. One prime example hinted at by Musk in a 2018 tweet is its oxygen preburner, used to convert liquid propellant into a high-velocity gas that can then feed a dedicated oxygen turbopump. Aside from the absurdly corrosive environment created by extremely hot gaseous oxygen, the preburner must also survive pressures that could peak as high as 800+ bar, or 12,000 psi.

 

A lack of technical detail means that it’s hard to know what thrust or main chamber pressure Musk had in mind when referring to exotic alloys that would be needed to survive those pressures, but the performance statistics of a Raptor with a preburner operating at 800+ bar would probably outstrip anything Musk has thus far described. In other words, it’s safe to assume that Raptor has probably not been pushed to those performance levels just yet, although it’s still a distant possibility. More likely is that 800+ bar in the oxygen preburner is an extreme stretch-goal that will take concerted research, development, and optimization to achieve, with Raptor having suffered damage somewhere below those levels while still reaching eye-watering performance figures.

For an engine as complex as Raptor, there are countless dozens of potential failure modes the appearance of which would come as little surprise for an engine just days into full-scale testing. Above all else, the Raptor test schedule held by SpaceX’s world-class propulsion team – be it self-motivated or driven by reckless management-by-spreadsheet – has been fast-paced in the extreme, taking the first high-performance Raptor ever built from standstill to more than 90% thrust and chamber pressures of almost 270 bar (3900 psi) in – quite literally – less than one week. In the same period of time, more than half a dozen static fire tests (ranging from 1-10 seconds) were performed.

Within a few days of that February 10th milestone, in which Raptor reached chamber pressures comparable with the most advanced modern engines (namely RD-180/190/191), the engine was apparently pushed dramatically higher still, reaching a chamber pressure (and thus thrust) that wrought damage on some of the more sensitive parts of the engine’s plumbing. Despite the fact that the second production Raptor is apparently already “almost done”, Musk suggested that it would already feature changes (of unknown gravity) to mitigate the failure modes experienced by Raptor SN01.

In an industry where NASA and contractors like Aerojet-Rocketdyne will spend months between static fire tests of Space Shuttle engines that have each literally flown multiple (if not) dozens of missions to orbit and have a demonstrated performance and reliability record that is measured in the hundreds of thousands of seconds, the speed and agility of SpaceX’s Raptor development and test program is breathtaking. What remains to be seen is just how comparably reliable and successful the end results (i.e. operational Raptor) will be, but an attitude that actively accepts and even pursues testing to destruction can ultimately only serve to benefit the finished product at the cost of destroyed hardware and many on-ground lessons learned the hard ways.

Given the immense success of SpaceX’s Merlin family of engines and the aggressive strategy of development and continuous improvement that brought it from Merlin 1A to 1D and MVacD, SpaceX is clearly not fumbling around in the dark when it comes to Raptor R&D.

Check out Teslarati’s newsletters for prompt updates, on-the-ground perspectives, and unique glimpses of SpaceX’s rocket launch and recovery processes!

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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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SpaceX and Elon Musk explain potential reasons for Starship loss

Published

2 months ago

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January 17, 2025

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Credit: SpaceX

SpaceX and its CEO Elon Musk are starting to shed some light on the potential reasoning for the loss of Starship yesterday, which was lost after a successful launch and catch of the lower-stage booster.

Starship was lost during its ascension, and debris rained down over the Caribbean less than an hour after SpaceX lost all communication with the spacecraft.

A few hours after the launch was over, SpaceX started to shed some light after looking at preliminary data that the rocket left behind.

The company said that a fire developed in the aft section of Starship:

“Following stage separation, the Starship upper stage successfully lit all six Raptor engines and performed its ascent burn to space. Prior to the burn’s completion, telemetry was lost with the vehicle after approximately eight and a half minutes of flight. Initial data indicates a fire developed in the aft section of the ship, leading to a rapid unscheduled disassembly with debris falling into the Atlantic Ocean within the predefined hazard areas.”

Additionally, Musk said that there was some sort of oxygen or fuel leak in the cavity above the ship engine firewall.

The leak was evidently large enough to build more pressure than the vent was able to handle:

Some also seemed to recognize evidence of fires throughout the flight of Starship, which is obviously an anomaly:

There will be more information regarding the loss of Starship in the coming days and weeks, but Musk already believes that a bit of fire suppression and more volume in the cavity above the ship engine firewall could fix the issue.

“Nothing so far suggests pushing next launch past next month,” he said, so Flight 8 could happen sometime in February.

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SpaceX completes second catch of lower stage, but loses Starship

Published

2 months ago

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January 16, 2025

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Credit: SpaceX

SpaceX completed its seventh launch of Starship on Thursday, accomplishing a clean liftoff and catch of the first-stage booster. However, the upper stage was lost after its ascent.

The launch took place just a few minutes after 5 p.m. on the East Coast, as the first attempts at getting Starship in the air for the seventh time were delayed by weather both last week and this week.

Conditions were favorable on Thursday as SpaceX looked to follow up a successful campaign by Blue Origin, Jeff Bezos’s company, earlier today.

SpaceX went into the seventh Starship launch with plans for a catch attempt of the first-stage booster, something it attempted and completed during the fifth test launch last year. It decided to skip a catch attempt with the sixth test flight as conditions were not aligned.

For now, SpaceX is extremely selective as to when it attempts catches.

However, it was successful during this attempt, its second completed catch:

This flight differed from previous launches as SpaceX rolled out several improvements to the rocket and the processes as it featured plans to do a Starlink deployment simulation and had various adjustments to flap placement and avionics.

These plans were disrupted by the fact that SpaceX lost all communications with Starship about ten minutes into the flight, which the aerospace company confirmed was a result of losing the spacecraft sometime during its ascent.

Although the catch was successful, the loss of the actual rocket seemed to be a huge damper on the entire event. SpaceX confirmed several minutes after the loss of communications that the rocket was destroyed and was lost.

It was its first failure since the second Starship launch in November 2023. SpaceX had no answers for why the rocket was destroyed and lost.

We will keep you updated in the coming days.

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SpaceX confirms next Starship launch target – Here’s when it will take off

Published

2 months ago

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January 9, 2025

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spacex starship upper stage catch
Credit: Elon Musk | X

SpaceX has confirmed a new target date for the seventh Starship test launch after weather in Texas delayed the first scheduled date for “three or four days.”

The company is now targeting the launch for Monday, January 13, at 4 p.m. CST or 5 p.m. EST. The launch date is not set in stone as any variety of delays could impact this, but SpaceX hopes to finally take off after a delay that pushed it back from January 10.

What’s new with this Starship launch

With this being the seventh test launch of Starship, there are several things that the company will change and hope to accomplish. All of these launches are done in preparation for eventually taking flight to Mars, something that will happen next year, according to CEO Elon Musk.

First, SpaceX is rolling out a next-generation ship with “significant upgrades.” Forward flaps have been made smaller and are repositioned away from the heat shield, which will “reduce their exposure to reentry heating.”

SpaceX eyes 25 annual Starship launches starting next year

There is also a 25 percent increase in propellant volume, a new fuel feedline system for the Raptor vacuum engines, and a better-than-ever propulsion avionics module that will control the valves and reading sensors.

Avionics, as a whole, underwent a redesign and now have more capability and redundancy for missions as they become more complex.

Starlink test

SpaceX is also planning to deploy 10 Starlink simulators that are similar in size and weight to the next-generation Starlink satellites:

“While in space, Starship will deploy 10 Starlink simulators, similar in size and weight to next-generation Starlink satellites as the first exercise of a satellite deploy mission. The Starlink simulators will be on the same suborbital trajectory as Starship, with splashdown targeted in the Indian Ocean. A relight of a single Raptor engine while in space is also planned.”

Ship return and catch

There will be several experiments that have to do with returning Starship and various catch scenarios and sequences. One of which will see “a significant number of tiles be removed to stress-test vulnerable areas across the vehicle.”

The ship’s reentry profile was also intentionally designed to test the structural limits of the flaps while at the point of maximum dynamic pressure during reentry.

Currently, SpaceX did not detail whether it would attempt another catch during this test launch. These are usually game-time decisions.

Need accessories for your Tesla? Check out the Teslarati Marketplace:

Please email me with questions and comments at joey@teslarati.com. I’d love to chat! You can also reach me on Twitter @KlenderJoey, or if you have news tips, you can email us at tips@teslarati.com.

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