Details of Research Outputs

Compressibility effects are inevitable when a Wing-in-Ground (WIG) craft flies at high speed. In this paper, the influence of air compressibility on the inherent stability of WIG crafts is investigated numerically. Firstly, a novel WIG craft model named AeroWIG was designed as a baseline WIG-craft model. The inviscid vortex lattice method with Prandtl-Glauert compressibility correction is employed to analyze the aerodynamic characteristics of AeroWIG in various ground clearance, angle of attack and Mach number. Secondly, the longitudinal stability matrix considering the compressibility effects was derived to analyze the eigenvalue and root locus at different flight conditions. It was found that the compressibility effects have a strong influence on the longitudinal inherent stability of both the short-period mode and phugoid mode in the ground effect when the Mach number is larger than 0.3. As the Mach number increases, the unstable eigenvalue corresponding to the phugoid mode moves towards the left half-plane hence becoming less unstable. The findings in this paper are very useful for designing inherent stable WIG crafts flying above Mach 0.3.