Batteries are doing such a great job replacing petroleum in car engines that it’s natural to think they might do the same in the skies. Efforts to make a working airplane prototype, however, perennially come up short.

Kitty Hawk, the startup backed by Google co-founder Larry Page that hoped to make an electric flying car, quietly abandoned the project after five years in 2020. Last year, two separate proposed battery planes being developed by ventures including Rolls-Royce Holdings Plc and Nasa were dropped within a month of each other.