Details of Research Outputs

The lift augmentation and drag reduction are considered as the two main ground effect phenomena, namely the ram ground effect and span dominated ground effect, respectively. In this paper, the focus is to reveal the inherent stability differences for a given WIG-craft in various ground effects. The aerodynamic characteristics of a WIG craft are investigated numerically in both ram ground effect and span dominated ground effect. Firstly, a novel WIG craft model named AeroWIG with a high-aspect-ratio wing was designed as the baseline model. The inviscid vortex lattice method was employed to analyze the aerodynamic characteristics of AeroWIG in various ground clearance and angle of attack. Secondly, the longitudinal stability matrix was derived to analyze the eigenvalues and root locus in both ram ground effect and span dominated ground effect region. It was found that in span dominated ground effect, the short period and phugoid mode changed insignificantly while the speed substance mode becomes more stable, at the same time, the lift-to-drag ratio increases noticeably due to the reduction of the induced drag. As the ground clearance is further reduced to the ram ground effect region, the stability changes significantly and the phugoid mode trends to become unstable. These findings in this paper are very useful for designing inherent stable WIG craft flying in different ground effect phenomenon regions.