Fig 4. Propulsion efficiency as a function of reduced stiffness at three values of ${\overline{s}}_2$ (shown next to respective lines).

Conditions are those of cases 2 and 3 in Table 1. In (a), s_t is constant; in (b), s₂ is constant. The thick lines are the same as in Fig 2. Short lines adjacent to the left and right margins mark asymptotic values from Appendices E and F.