Determination of static and dynamic stability characteristics of a sailplane based on CFD analysis. Part 2 dynamic stability

The aim of this research is to evaluate static and dynamic stability characteristics of an aircraft with high aspect ratio wing. In the current paper - part 2, the dynamic stability is studied. Conventional ways of determining flight stability characteristics are based on semi-analytical models comprised of equations and formulas, which are not easily applicable in cases such as that of the design of a sailplane, due to the relatively high aspect ratio, lack of thrust force, weight requirements and complex geometry. Instead a new method that is based on CFD analysis is developed. A sequence of numerical studies is executed in Ansys - Fluent. Transient case analyses are performed using sliding mesh and dynamic mesh methods. All surveys are conducted for the case a prototype trainer sailplane. Moments and forces acting on the aircraft, along with their derivatives, required for the dynamic analysis, are obtained. Laws of pure pitching, rolling and yawing motions are obtained. Coupled lateral-directional motion is analysed. Evaluation of Dutch roll and spiral mode is made. All results of the study are used in the design process a prototype sailplane. All results from the proposed method are confirmed by analysing existing aircraft of the same type and mission.