Elastomeric Structural Attachment Concepts for Aircraft Flap Noise Reduction

Airframe noise is a significant part of the overall noise of typical transport aircraft during the approach and landing phases of flight. Airframe noise reduction is currently emphasized under the Environmentally Responsible Aviation (ERA) and Fixed Wing (FW) goals of NASA. A promising concept for trailing-edge-flap noise reduction is a flexible structural element or link that bridges the gap between the wing and the deployable flap side edges. The proposed solution is distinguished by minimization of the span-wise extent of the structural link, thereby minimizing the aerodynamic load on the link structure at the expense of increased deformation requirement. Development of such a flexible structural link necessitated application of hyperelastic materials, atypical structural configurations, and novel interface hardware. The resulting highly deformable structural concept was termed the FLEXible Side Edge Link (FLEXSEL) concept. Prediction of atypical elastomeric deformation responses from detailed structural analysis was essential for evaluating concepts that met legacy design constraints.