Spirit Level

# The simple math Elon Musk used to come up with Tesla, SpaceX and the Boring Company — Quartz

His solution? “I do my favorite thing which is apply physics first principles,” he said. “It’s like the best tool possible.”

This time the factory was reduced to a different equation: output = volume x density x velocity. Need to bring down the cost of batteries? Fill as much of the factory’s volume possible with equipment. Instead of using 3% of the volumetric space, Tesla plans to use at least 30% to get more production per unit of space. Need to produce 500,000 cars per year rather than the 50,000 Tesla has managed so far? Speed up the assembly line by a factor of seven from its typical 0.2 meters per second to 1.5 meters per second. Then build factories as a series of mini facilities, each one iterating on the design of the last so incremental improvements can be rolled out to Tesla’s battery, solar panel, and car plants.

Building a better battery.(Reuters/James Glover II)

SpaceX seems to have sprung from the same thinking. The moment of SpaceX’s conception is not documented, but Ashlee Vance’s book Elon Musk: Tesla, SpaceX, and the Quest for a Fantastic Future comes close. On a flight back from Moscow after the Russians dismissed Musk’s offer to buy retooled intercontinental ballistic missiles, Musk was furiously crunching numbers on his laptop. As the plane ascended, Vance recounted the moment when Musk’s companions on the flight, two aerospace engineers, first saw the spreadsheet laying out how he planned to build a cheaper, faster rocket:

Musk wheeled around and flashed a spreadsheet he’d created. “Hey, guys,” he said, “I think we can build this rocket ourselves.”

“We’re thinking, Yeah, you and whose ***## army,” [SpaceX founding team member Jim] Cantrell said “But, Elon says, ‘No, I’m serious. I have this spreadsheet.’” Musk passed his laptop over to [future NASA administrator] Mike Griffin and Cantrell, and they were dumbfounded. The document detailed the costs of the materials needed to build, assemble, and launch a rocket. According to Musk’s calculations, he could undercut existing launch companies by building a modest-sized rocket that would cater to a part of the market that specialized in carrying smaller satellites and research payloads to space. The spreadsheet also laid out the hypothetical performance characteristics of the rocket in fairly impressive detail. “I said, ‘Elon, where did you get this?’” Cantrell said.

Musk had spent months studying the aerospace industry and the physics behind it. From Cantrell and others, he’d borrowed Rocket Propulsion Elements, Fundamentals of Astrodynamics, and Aerothermodynamics of Gas Turbine and Rocket Propulsion, along with several more seminal texts. Musk had reverted to his childhood state as a devourer of information and had emerged from this meditative process with the realization that rockets could and should be made much cheaper than what the Russians were offering.