SpaceX

SpaceX goes all-in on steel Starship, scraps expensive carbon fiber BFR tooling

SpaceX's Port of LA-based BFR development tent is no more after the company presumably decided to scrap the entirety of it and its contents, March 14th. (Pauline Acalin)

In a wholly unforeseen turn of events, SpaceX has taken the extraordinary step of permanently scrapping both its Port of Los Angeles-based BFR development tent and what seem to be the majority of what it contained, irreparably destroying custom-built tooling meant to support the fabrication of carbon composite BFR spaceships and boosters.

Likely worth anywhere from several to tens of millions of dollars (USD), SpaceX’s advanced BFR production tools were procured from industry-expert Ascent Aerospace sometime in 2017 before being officially delivered to the rocket company’s newly-erected Port of LA tent around April 2018. Situated at the port specifically due to logistical concerns about the high cost of transporting 9m/30ft-diameter objects from SpaceX’s main Hawthorne facilities to a barge for transport east, the company has decided to unequivocally destroy its aerospace-grade composite tooling less than 12 months after accepting delivery. Put simply, this is the best evidence yet that SpaceX – willing or not – has gone all-in on build Starship and Super Heavy out of stainless steel less than six months after CEO Elon Musk began to hint at the program’s utterly radical pivot.

SpaceX’s Port of LA-based BFR development tent is no more after the company presumably decided to scrap the entirety of it and its contents, March 14th. (Pauline Acalin)

From the very beginning of SpaceX and Elon Musk’s serious pursuit of an entirely reusable launch vehicle capable of transporting dozens of astronauts and passengers to and from Earth and Mars, the plan had been to build the vast majority of the rocket’s booster and spacecraft structures out of advanced carbon fiber composite materials. Above all else, this fundamental architecture was motivated largely by the significant performance gains a rocket could achieve by replacing traditional aluminum tanks and structures with carbon fiber.

For a rocket (and especially an orbital spaceship) meant to somehow make Earth-Mars transport both routine and at least minutely affordable, focusing primarily on the optimization of the mass of cargo delivered relative to the empty weight of the spaceship and booster made (and still does make) a great deal of sense. Assuming that the reusability of a system is roughly constant, the only conceivable way to further lower the cost of price per unit of cargo or passenger ticket would be to increase the usable cargo/passenger capacity for each individual launch, making an extremely light and high-performance rocket the low-hanging fruit target.

Musk revealed the first iteration of BFR – known as the Interplanetary Transport System (ITS) – in 2016. Carbon fiber structures featured prominently. (SpaceX)
SpaceX even built a full-scale, 12m/40ft-diameter carbon composite liquid oxygen tank to begin the process of tech development. (Reddit)

The centrality of carbon fiber composites remained with SpaceX’s Sept. 2017 iteration of BFR, downsized by 25% to a diameter of 9m (~30 ft). Around six months later, that commitment to composites was further solidified by the delivery of the first 9m-diameter carbon fiber tooling in March or April 2018. The tooling used to mold and lay up aerospace-grade advanced carbon fiber structures is inherently expensive, demanding extremely low tolerances across massive surface areas and volumes in order to ensure the quality of the equally massive and low-tolerance composite structures they are used to build. Actual prices are often closely guarded and difficult to determine or extrapolate off of, but it’s safe to say that SpaceX likely spent months of effort and at least several million dollars to acquire its large BFR mandrel.

In the subsequent months of 2018, SpaceX’s BFR and composite R&D team spent tens of thousands of hours building out an ad-hoc advanced composites workshop inside a temporary tent in an industrial area, and ultimately managed to build a number of full-scale carbon fiber segments, including at least one large tank barrel section and the beginnings of a tank dome. In September 2018, that progress was partially revealed alongside the announcement that Japanese billionaire Yasuka Maezawa had purchased the first crewed lunar launch of BFR for several hundred million dollars, set to occur no earlier than 2023.

Two months after indicating that the first BFR “airframe/tank barrel section” would be built out of a “new carbon fiber material”, Musk provided the very first teaser for a “counterintuitive” development that would later be identified as the CEO’s decision to wholly replace BFR’s proposed used of composites with stainless steel and an advanced metallic heat shield. Still more than a little controversial and hard to follow almost half a year later, the feeling at the time was that SpaceX’s eccentric leader had decided to throw away more than 24 months of composite BFR design and development work for an almost entirely unproven alternative approach.

For better or for worse, it appears that SpaceX (or maybe just Musk) has quite literally trashed the most concrete demonstration of a prior commitment to advanced carbon fiber composites, scrapping the vast majority of its composite tooling and perhaps even the prototype BFR segments built in 2018.

RIP BFR mandrel and tent, we barely knew ye. (Pauline Acalin)

It remains to be seen whether the now-permanent decision to pursue a stainless steel design in place of carbon fiber was a very expensive mistake, a stroke of genius, or something in between, However, the undeniably brisk progress made with the BFR’s steel variant in last four or so months bodes well – at a minimum – for Musk’s optimism that this radical change will ultimately result in an operational vehicle far sooner (and presumably cheaper) than the composites route.

Generally speaking, it seems safe to – on the face of it – agree with Musk’s argument that steel should ultimately lend itself far more easily to reusability thanks to its high tolerance for extreme temperatures. Unlike Falcon 9’s aluminum structures (and even the most exotic, advanced carbon fiber composites), certain varieties of stainless steel can weather heating approaching that experienced during orbital reentry with minimal erosion or damage to its mechanical properties. As Musk puts it, the Super Heavy booster’s suborbital trajectory could require almost no heat shielding – and perhaps even paint – at all.

Only time will tell whether the inevitably harsher realities of real-life engineering are so kind. In the meantime, SpaceX is perhaps just hours away from the first attempted static-fire test of a Raptor installed on something approaching flight-hardware, in this case a full-scale Starship hop test prototype.

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SpaceX goes all-in on steel Starship, scraps expensive carbon fiber BFR tooling
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