Basic concepts and definitions 43 AC,(x/c) 0.16 - 0.02. 0 0.2 0.4 0.6 0.8 1.0 C, = C, cos a - C, sin a = +042 C, = C, sin a + C, cos a = +0.0182 Fig. 1.20 (Continued) Fig. 1.21 The simplified horseshoe vortex system