The Airbus A380 represents the last superjumbo of a bygone, kerosene-guzzling era. Now the double-decker will serve as the unlikely testbed to help the industry fly into a fuel-efficient future. Airbus SE will use a model to test its first propulsion system using hydrogen, a fuel the planemaker wants to introduce on a new passenger aircraft by 2035. The modified jetliner, the first of its kind that Airbus ever built, will maintain its four conventional turbines, while a fifth engine adapted for hydrogen use will be mounted on the rear fuselage. The unusual design of the demonstration aircraft, developed in collaboration with engine-maker CFM International, will allow emissions to be monitored separately from those of the turbines powering the aircraft, including contrails, Airbus said in a statement. The wispy clouds planes leave behind in the sky are of growing concern […]