Lilium says it has achieved the critical transition from vertical hover to wing-borne cruise flight with its Phoenix 2 eVTOL technology demonstrator. The company reported the landmark on May 31, a few weeks after resuming flight testing in Spain, and claims that it’s the first such transition by what it calls a full-sized electric jet aircraft with ducted fan engines and a fixed-wing. Several lift-and-cruise eVTOL aircraft with open rotors have reportedly achieved the transition, including the Joby Aviation prototype.
The Phoenix 2 is essentially a subscale version of the seven-seat Lilium Jet with which the German start-up now expects to complete type certification in 2025. In March, it reported a program delay that will see it build the first production-conforming aircraft in 2023, at which point it will start a 15- to 18-month certification flight test campaign.
“From a flight physics perspective, completing transition means the airflow goes over the flaps, attaches, and becomes smooth, allowing the lift to be generated by the wing (as in a conventional fixed-wing aircraft), rather than by the engines (which is the case during the hovering phase),” Lilium explained in its press statement. The company said that the required airflow had now been achieved across the entire main wing surface, while at the same time keeping the aircraft stable and within the performance envelope predicted by its proprietary Flight Dynamics Model.
Lilium said that it now intends to extend the flight test envelope with the Phoenix 2 aircraft throughout the summer months. One of its next objectives is to achieve a full airflow transition with the forward canards and also start high-speed flights.
Earlier this week, Lilium announced that Spanish aerostructures and components group Aernnova is to make the flaps for the Lilium Jet. These are critical to redirecting the airflow generated by the aircraft’s 30 electric fan engines.
The piloted Lilium Jet will have a range of 155 miles and fly at speeds up to 175 mph. Lilium believes that the design could be scaled up for a version that would accommodate between 10 and 15 seats.
