2021/01/11 by Rocco Bombardieri, Rauno Cavallaro, Bombardieri, Rocco +5
Engineering · #Aeroelasticity and Vibration Control #Vibration Control and Rheological Fluids #Vehicle Dynamics and Control Systems
paper · pdf · doi:10.48550/arxiv.2101.04087
The PrandtlPlane aircraft has been recently considered as a possible\ncandidate to foster the ambition of a greener aviation. Despite the relevant\namount of research carried out in the last years, several aspects of this novel\nconfiguration still need further insight to pave the way to future\napplications. Among them, the coupled flight-dynamic and aeroelastic response\nis addressed in this work by means of a dedicated in-house framework. For the\nevaluation of the aerodynamic forces, an enhanced Doublet Lattice Method, able\nto take into account terms typically neglected by classic formulations, is\nemployed. First, flight-dynamic aspects are considered, showing how effects of\ninteraction between Short Period or Dutch Roll with elastic modes remarkably\ndeteriorate the flying qualities. Then, focus is on the aeroelastic stability\nof the aircraft. As observed also in previous literature efforts on this\nconfiguration, flutter onset is considerably different when considering the\naircraft being free in the air or fixed in space. Thanks to the adopted\nformulation it is shown how, for this PrandtlPlane, the aerodynamic coupling of\nelastic and rigid modes has a beneficial effect on flutter onset. However, the\ndifferent modal properties, consequence of the diverse boundary conditions,\nwhen switching from fixed-in-space to free-flying aircraft, also play a\nrelevant role in determining the occurrence of flutter. Whereas for the\nlongitudinal case both effects contribute increasing flutter speed, for the\nlateral-directional case the variation in modal properties has a detrimental\nand dominating effect, leading to a flutter speedwell within the flight\nenvelope.Finally,the work discusses the contributions of the additional terms\nmodeled by the enhanced Doublet Lattice Method, showing how they induce a\nconsiderable effect when modeling the flight dynamics of the flexible aircraft.\n