C.I.P.A.S
Crossflow Induced Propeller Autorotation Solver
CIPAS is a specialized aerodynamics application developed to model the transient dynamics of unpowered electric propellers subjected to crossflow-induced autorotation. This analysis is particularly relevant to the design of modern eVTOL aircraft, which frequently incorporate additional aft-mounted propellers to satisfy the high thrust requirements of vertical flight. In many configurations, these propellers are non-vectorable and fixed in a vertical orientation. When left unpowered (and free to rotate) during forward flight, they experience crossflow (air moving parallel to the plane of rotation), inducing autorotation. This phenomenon generates a temporal aerodynamic profile that can significantly impact aircraft performance. CIPAS uses a custom blade element theory adapted for crossflow conditions to compute transient kinematic and aerodynamic states of the propeller, guiding critical design decisions.