Fig. 22. Summary diagram of the relationship between steering muscle activity and control of the aerodynamic force vector. (A) Firing phase preference of the basalare muscles (left). Basalare muscle activity is correlated with strong modulation of the downstroke force and weak modulation of the upstroke force magnitude. Firing phase preference of pterale III muscles (right). Upstroke force magnitudes are relatively large during Mode 2. (B) Firing phase preference of muscle I1. Upstroke force magnitudes are much smaller during Mode 1 than during Mode 2. (C) Presumed firing phase of unknown muscle and modulation of the upstroke force inclination correlated with dorsal amplitude.