Figure 6. Proportional change in moment-of-inertia for pitch (I_Φ) and roll (I_Ψ) as a function of θ.

The moment of inertia of the body for a given flexion angle (0<θ<55°) is divided by the moment of inertia of the beetle at the pre-jump posture (θ = 0°). Two alternative calculations are shown. Data points and the thick lines represent calculated estimates using the instantaneous center of mass. The thin lines are the same estimates calculated assuming the center of rotation stays at the initial position of the center of mass as the beetle left the ground (i.e. θ = 55°).