Question: A control tab of an airplane elevator is hinged about an axis in the elevator, shown as point 0 in Fig., and activated by a control linkage behaving like a torsional spring of stiffness kT. The mass moment of inertia of the control tab is I, so that the natural frequency of the system is ωn = . Because kT. cannot be calculated exactly, it is necessary to
obtain the natural frequency con experimentally. To this end, the elevator is held fixed and the tab is excited harmonically by means of the spring k2 while restrained by the spring k1, as shown in Fig., and the excitation frequency ω is varied until the resonance frequency ωn is reached. Calculate the natural frequency can of the control tab in terms of ωr and the parameters of the experimental setup.