This paper presents a semi-experimental method which can be used to predict the gust response of a wind tunnel model. The method incorporates transfer functions of the wind tunnel model – in this case a flexible forward swept wing – which are obtained using sweep excitations with a gust generator. The prediction results are then compared with those resulting from experimental measurements and numerical simulations. The observed quantities comprise accelerations and loads data. In the ideal case, the advantage of this semi-experimental prediction of the wing’s response to gusts lies mainly in the reduction of wind tunnel time. Instead of testing each gust profile at each frequency, a measurement of several sweep excitations would suffice.

Loads analysis and structural design are core steps of the aircraft design process. To reduce wing loads and with it the wing structural mass, methods of passive and active loads alleviation have been researched in recent years. However, those methods are currently implemented without the consideration of dynamic simulations or unsteady aerodynamics in the optimization process in aircraft predesign. The purpose of this research is to investigate the influence of passive and active loads alleviation methods on the structural mass in aircraft preliminary design. The methods have been applied on the wing of a Generic Mid-Range (GMR) aircraft configuration. The models have been created with ModGen, an in-house program at DLR Institute of Aeroelasticity. The models comprise FE-models for the structure and masses, as well as DLM (Doublet-Lattice-Method) model for the aerodynamics. For the investigation of the influence of the loads alleviation systems, a loop of loads analysis and subsequent structure optimization has been conducted. The loads analysis consists of gust and maneuver simulations. For the passive loads alleviation, an aeroelastic tailoring of the wing structure has been implemented, whereas for the active loads alleviation the ailerons are deflected to redistribute lift during maneuvers and to partially compensate lift increment during gust encounters. With the implemented methods, a first quantification of the influence of loads alleviation methods on the structural mass in aircraft predesign is possible.