Flight dynamics, handling and ride qualities of a flexible aircraft

Abstract

The effects of structural flexibility on aircraft flight dynamics and handling qualities are investigated. To do so, the equations of motion of an elastic vehicle are presented and then solved by means of trimming/simulation routines. The simulation results of a linear model are then compared with those of a nonlinear model of DLR’s Discus-2c sailplane. To further demonstrate the flexibility effects, two sets of modified aircraft models are developed. The first set alters the modal frequencies of DLR’s Discus-2c from their nominal values, whereas the second set alters the modal damping. The handling qualities, in terms of modal criteria and as compared to the MIL-STD-1797A, are examined for the first set of the modified aircraft models. With the second set of the modified aircraft models, the ride qualities in terms of acceleration at pilot location and biodynamic effects are examined.