G Warwick, Hydrogen rising, Aviation Week & Space Technology, 15-28 July 2024, p 24

 In US, Joby Aviation has initiated the VTOL S4 prototype modified with a liquid hydrogen tank and fuel cell to increase the previous 155mi range to 523mi. The liquid hydrogen tank is installed in the fuselage, together with an oil- cooling heat exchanger in the nose. The low-temperature proton exchange membrane fuel cell was developed by Germany’s H2Fly.