Flight dynamic characteristics of tiltrotor aircraft slung-load system

Taking the XV-15 tiltrotor aircraft as an example, the influence of an external slung load on the flight dynamic characteristics of tiltrotor aircraft is investigated in a study. A coupled mathematical model on the basis of blade-element theory and momentum theory is first introduced, taking the influence of the rotor wake on the wing, the horizontal stabilizer, and vertical stabilizers into account. A mass point model of a slung load is used to investigate the effects of a slung load on a tiltrotor aircraft slung-load system. The resulting nonlinear equations of motion for a tiltrotor aircraft slung-load system are established and trimmed for straightforward flight on a MATLAB platform with the Levenberg–Marquardt method. The representative trim values, stability characteristics, and SCAS-off step response are thoroughly compared to reveal the different flight dynamic characteristics of the tiltrotor aircraft with/without a slung load.