Low-order aeromechanics of tilt-rotor helicopters

Abstract

The conversion corridor represents the safe region of flight for tilt-rotor aircraft during the transition between helicopter and aeroplane mode. A low-order rotary-wing model has been established and validated throughout the conversion corridor, showing good agreement with experimental data. Furthermore, the equations of motion for longitudinal flight have been derived and solved to determine the conversion corridor boundaries with the results correlating well with published data. The largest discrepancy was observed at the lower boundary which indicated a downwash model of the rotor wake over the wing was required. Additionally, from a trimmed flight perspective, it was found the tilt-rotor aircraft had transitioned from helicopter to aeroplane mode by the approximate shaft angle ? = 600