Analysis of dynamic characteristics between prototype aircraft and scaled-model of virtual flight test in wind tunnel

This paper presents a virtual flight testing system in low speed wind tunnel, which has a 3-degree-of-freedom (3-DOF) gimbal mechanism to connect a dynamically-scaled wind tunnel model supported by a vertical strut. The model can freely rotate around the center of gravity due to the aerodynamic moments. Obviously the constrained motion is different from the real 6-DOF free flight in the air. So the influencing factors which contribute to the dynamic characteristics' differences between the prototype aircraft and scaled-model are individually compared and investigated through flight dynamics simulation. The results demonstrate that the constrained translational movement has a significant impact on the dynamic characteristics while the dynamic response of the scaled-model and full-scale aircraft meets the similarity law; both the 3-DOF bearing friction and the non-coincidence between center of gravity and center of gimbal has small influence; the constant moment disturbance has some impact on the initial response. The comparison and analysis can provide a guide for the virtual flight test in wind tunnel, and are also helpful for the improvement and application of the wind tunnel testing technique.