Similarity theory

A conventional virtual flight test generally refers to a 3-DOF dynamic flight test in a wind tunnel. In the wind tunnel test, the model aircraft is connected to the strut through a 3-DOF rotation mechanism and installed in the wind tunnel test section so that the model displacement is constrained but has 3 degrees of angular motion freedom. Open-loop and closed-loop control of the aircraft model is achieved by directly driving the rudder surface or by using commands from the flight control system.