SpaceX CEO Elon Musk has taken to Twitter to publish yet more photos of the company’s Starship Mk1 rocket prototype, this time posting what are – by far – the best official photos of Raptor engines yet taken.
This marks the first time that a SpaceX prototype of any kind has had more than one Raptor engine installed, a fairly symbolic but still significant milestone that follows in the footsteps of Starhopper’s successful single-engine flight test campaign. With Starhopper now heading into retirement, Starship Mk1 is preparing to support the program’s next major steps: full-scale, high-altitude flight tests powered by three Raptor engines.
The sight of three Raptor engines installed on the first true Starship prototype is undeniably hard to downplay. In barely seven months, SpaceX has gone from the very first static fire of a full-scale Raptor engine – serial number 01 – to flight-testing Raptor SN06 and producing enough engines to bestow Starship Mk1 with its own set of three engines. According to the latest comments from Elon Musk, Starship is meant to be powered by three ‘sea level’ Raptors and three vacuum-optimized Raptors – RVacs. RVac may or may not be ready to support the flight tests of early prototypes like Mk1 and Mk2, meaning that their three SL engines will likely be the sole propulsion for the time being.
Together, three SL Raptors operating at full thrust should be capable of producing up to 600 tons (1.3M lbf) of thrust. Per Musk’s note that Starship Mk1 likely weighs around 200 tons (~450,000 lb) empty, this means that a triple-engined Starship will be able to lift off with up to 400 tons (900,000 lb) of propellant, likely translating into roughly 200-300 seconds of untethered triple-engine operation.
“NOT FOR FLIGHT”
However, the engine installation milestone and subsequent photos are undeniably spectacular, but signs suggest that some level of pragmatism is in order. Visible in two of the three photos published by Musk, all three Raptors still have their transport rings installed just below each engine’s throat. Hardware at the base of one photo indicates that they were likely taken yesterday, on the evening of September 25th. Musk revealed that the three Raptors were installed late on September 22nd, up to three days prior.
Combined, the presence of the transport rings – “NOT FOR FLIGHT”, as their labels note – is a strong indicator that their installation is only temporary, likely in support of Elon Musk’s imminent September 28th Starship presentation. Without more information, it’s impossible to read much further into the temporary installation of Raptors. What it does confirm is that – for any number of reasons – flight-ready Raptors are not quite ready to support the Starship Mk1/Mk2. SpaceX has proven that Raptor is capable of supporting Starhopper for almost a full minute of powered flight, but behaviors observed near the end of that flight suggest that even that may have been pushing the engine’s limits.
All things considered, SpaceX is making progress at an almost unfathomable pace. Just seven months into full-scale Raptor test fires, it’s easy to believe that a lot of development work and refinement remains before the new engine family will be ready to reliably support multi-minute flight tests, let alone orbital launch attempts. Most orbital-class engine development programs aim for tens or even hundreds of thousands of seconds of test fires before attempting their first flights, but SpaceX is not most companies and is sticking closely to its preferred “test as you fly” methods and agile development strategies.
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