Fig. 12. Schematic, not to scale, for evaluating the drag force and torque acting on a ventral or dorsal mechanoreceptor sensillum contained in a plane passing through the flagellum axis and oriented at an angle with respect to the local tangent to the flagellum surface. The velocity components, U_x(x) and U_z(x), inducing the drag and torque are respectively normal and parallel to the local tangent to the flagellum surface and, at any location along the sensillum, U_ns()=U_x(x)cos+U_z(x)sin where x=sin.