Transition Performance Of Tilt Propeller Aircraft

A simple model of the transition aerodynamics of Joby Aviation's electric tilt-propeller VTOL aircraft was developed by combining a surrogate model of CFD propeller solutions with semi-empirical models of airframe aerodynamics and interactional aerodynamics. The model was calibrated to match CFD results of the entire aircraft, as well as flight test results of the actual aircraft. Using this model, loads and power requirements across the range of shaft tilt angle and airspeed combinations for trimmed flight - -the "conversion corridor" often described in tiltrotor performance reports - -are analyzed, and resulting performance limitations are discussed. Additionally, a novel approach to transition flight is introduced in which the angle of attack and shaft angle are automatically determined by the flight controller, rather than manually controlled. Using the simple transition aerodynamics model, transition loads and power requirements with this control approach are discussed, and transition flight using this control approach is shown to allow for high performance given reasonable limitations.