The significance of the influence of operating propellers on the aircraft aerodynamic characteristics is well-known. Wind tunnel testing of an airplane model with operating propellers is a complex task regarding the required similarity of the full-scale and the model case. Matching sufficient similarity in axial and rotational velocities in the propeller slipstream is the primordial c... https://www.roneverhart.com/OTTO-CAP-5-Panel-Mid-Profile-Mesh-Back-Trucker-Hat-OTTO-32-285/