Fig. 14. Root locus plots showing the effect of introducing pitch rate damping by increasing the value of the pitch rate derivative M_q from zero. Symbols and axes are as in Fig. 11. (A) Locust `R'. (B) Locust `G'. (C) Locust `B'. Increasing M<sub>q</sub> has practically no effect upon the non-oscillatory modes, but causes the short period oscillatory mode to become more heavily damped. Eventually, critical damping is reached and the complex conjugate roots split into two negative real roots. The short period mode becomes non-oscillatory when the ratio M<sub>q</sub>:M is 0.035 in locust `R', 0.021 in locust `G', and 0.040 in locust `B'.

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