RECENT ADVANCES IN LIFTING SURFACE METHODS

Recent advances in two lifting surface methods are reported. The prese nt subsonic constant pressure method improves upon the program robustn ess of the doublet lattice method. The present unified supersonic-hype rsonic method extends the range of applicability of lifting surf-ace t heory to the Newtonian limit. Based on a uniformly-valid series formul ation, the method accurately approximates the non-linear thickness eff ect, whereas this effect is neglected by the linear theory and overest imated by piston theory. In fact, the present results generally agree well with the trends of several Euler solutions. Among other findings, cases computed by the unified method confirm that the effect of thick ness is to reduce the supersonic flutter speed.