“Hardware is hard,” venture capitalist Marc Andreessen famously declared at a tech investors’ event in 2013. Explaining the longstanding preference for software startups among VCs, Andreessen said, “There are so many more things that can go wrong in a hardware company. There are so many more ways a hardware company can blow up in a nonrecoverable way.”

Even as Andreessen was speaking, however, the seeds were being sown for one of the biggest and most sustained infusions of cash into a hardware-based movement in the last decade. Since then, the design and construction of electric vertical-takeoff-and-landing (eVTOL) aircraft has been propelled by waves of funding from some of the biggest names in tech. And, surprisingly for such a large movement, the funding is mostly coming from sources outside of the traditional venture-capital community—rich investors and multinational corporations. The list includes Google cofounder Larry Page, autonomy pioneer Sebastian Thrun, entrepreneur Martine Rothblatt, LinkedIn cofounder Reid Hoffman, Zynga founder Mark Pincus, investor Adam Grosser, entrepreneur Marc Lore, and companies including Uber, Mercedes-Benz, Airbus, Boeing, Toyota, Hyundai, Honda, JetBlue, American Airlines, Virgin Atlantic, and many more.

Today, some 250 companies are working toward what they hope will be a revolution in urban transportation. Some, such as Wisk and Kittyhawk and Joby, are flying a small fleet of prototype aircraft; others have nothing more than a design concept. If the vision becomes reality, hundreds of eVTOLs will swarm over the skies of a big city during a typical rush hour, whisking small numbers of passengers at per-kilometer costs no greater than those of driving a car. This vision, which goes by the name urban air mobility or advanced air mobility, will require backers to overcome entire categories of obstacles, including certification, technology development, and the operational considerations of safely flying large numbers of aircraft in a small airspace.

Even tech development, considered the most straightforward of the challenges, has a way to go. Joby, one of the most advanced of the startups, provided a stark reminder of this fact when it was disclosed on 16 February that one of its unpiloted prototypes crashed during a test flight in a remote part of California. Few details were available, but reporting by FutureFlight suggested the aircraft was flying test routes at altitudes up to 1,200 feet and at speeds as high as 240 knots.

No one expects the urban air mobility market, if it does get off the ground, to ever be large enough to accommodate 250 manufacturers of eVTOLs, so a cottage industry has sprung up around handicapping the field. SMG Consulting (founded by Sergio Cecutta, a former executive at Honeywell and Danaher) has been ranking eVTOL startups in its Advanced Air Mobility Reality Index since December 2020. Its latest index—from which our chart below has been adapted, with SMG’s kind permission—suggests that the top 10 startups have pulled in more than US $6 billion in funding; the next couple of hundred startups have combined funding in the several hundred million at most.

Cecutta is quick to point out that funding, though important, is not everything when it comes to ranking the eVTOL companies. How they will navigate the largely uncharted territory of certifying and manufacturing the novel fliers will also be critical. “These companies are all forecasting production in the hundreds, if not thousands” of units per year, he says.

“The aerospace industry is not used to producing in those kinds of numbers….The challenge is to be able to build at that rate, to have a supply chain that can supply you with the components you need to build at that rate. Aerospace is a team sport. There is no company that does 100 percent in-house.” Hardware really is hard.