Aeroelasticity of Box Wings and PrandtlPlane (a subgroup of Joined Wings) is here addressed. Previous literature work on the topic is reported and critically discussed. Original contribution of each paper is underlined, and results are analyzed selectively and also on a more general perspective providing a critical comparison with the other findings. This gives the opportunity to clearly outline the state of art regarding aeroelasticity of Box Wings. Particularly relevant for the aeroelastic design is the inclusion of rigid-body modes. In some cases interaction between elastic and rigid-body (pitching) modes are observed to induce the so called body freedom flutter. In other cases, flutter occurs following frequency coalescence of two elastic modes (cantilever flutter), one of them featuring an in-phase bending of the wings, the other showing an out-of-phase bending consequence of a tilting of the lateral joint in the longitudinal plane. This effort analyzes aeroelastic properties of a PrandtlPlane in the lateral-directional plane (antisymmetric case). Dynamic aeroelastic behavior is investigated first excluding and then considering rigid-body motion (calculated considering the contribution of the rigid fuselage's inertial effects). The resulting flutter speeds differ to a large extent between the two cases. In order to gain insight, fuselage moments of inertia are then varied, showing the transition between the two cases. Considering the existing design of mobile surfaces on a reference PrandtlPlane studied in previous efforts by partner universities, freeplay is taken into account and its effects on the aeroelastic stability properties of the system are investigated.
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