Photo: Joby Aviation
Joby Aviation has modified its pre-production S4 aircraft to develop a hydrogen-powered full-scale demonstrator. Supported by the U.S. Air Force’s Agility Prime program, this demonstrator completed a 523-mile (842-kilometer) test flight in California in 2024, significantly extending its range compared to the 155 miles (245 km) achieved by the battery-electric S4 in 2021. The successful flight lasted four hours and 47 minutes and landed with 10% of its hydrogen fuel remaining.
The demonstrator employs a hybrid propulsion system combining liquid hydrogen and a fuel cell with the S4’s existing battery system, allowing longer flights and greater efficiency. It features a 40-kilogram liquid hydrogen tank and a 175-kilowatt fuel cell developed by Joby’s H2Fly subsidiary.
Leveraging its vertically integrated approach, Joby is optimizing the hydrogen-electric system and integrating this technology with its ongoing battery-electric certification efforts. The company views the hydrogen-electric aircraft as complementary to battery-electric models, aiming to serve both short urban trips and longer regional routes. Joby founder and CEO JoeBen Bevirt invites readers to envision flying between major cities, such as San Francisco and San Diego, without needing to travel to airports and with only water emissions.
Although Joby has not provided a specific timeline for the hydrogen-electric air taxi’s commercial launch, it anticipates that the development process will be similar to that of its battery-electric aircraft, with Federal Aviation Administration (FAA) certification expected in 2025. The company has secured over $2 billion in funding from investors, including Toyota, Delta Air Lines, and Uber, and has a $131 million contract with the U.S. Air Force. Joby aims to redefine regional travel with both electric and hydrogen-powered aircraft.
