Application of Aeroelastic Tailoring for Load Alleviation on a Flying Demonstrator Wing

This article presents the application of aeroelastic tailoring in the design of wings for a flying demonstrator, as well as the validation of the design methodology with flight test results. The investigations were performed in the FLEXOP project (Flutter Free Flight Envelope Expansion for Economical Performance Improvement), funded under the Horizon 2020 framework. This project aimed at the validation of methods and tools for active flutter control, as well as at the demonstration of the potential of passive load alleviation through composite tailoring. The technologies were to be demonstrated by the design, manufacturing and flight testing of an unmanned aerial vehicle of approximately 7 m wingspan. This article addresses the work towards the load alleviation goals. The design of the primary load carrying wing box in this task is performed using a joint DLR-TU Delft optimization strategy. Two sets of wings are designed in order to demonstrate the potential benefits of aeroelastic tailoring - first, a reference wing in which the laminates of the wing-box members are restricted to balanced and symmetric laminates; second, a tailored wing in which the laminates are allowed to be unbalanced, hence allowing for the shear-extension and bending-torsion couplings essential for aeroelastic tailoring. Both designs are numerically optimized, then manufactured and extensively tested to validate and improve the simulation models corresponding to the wing designs. Flight tests are performed, the results of which form the basis for the validation of the applied aeroelastic tailoring approach presented in the article

A review of modelling and analysis of morphing wings

Morphing wings have a large potential to improve the overall aircraft performances, in a way like natural flyers do. By adapting or optimising dynamically the shape to various flight conditions, there are yet many unexplored opportunities beyond current proof-of-concept demonstrations. This review discusses the most prominent examples of morphing concepts with applications to two and three-dimensional wing models. Methods and tools commonly deployed for the design and analysis of these concepts are discussed, ranging from structural to aerodynamic analyses, and from control to optimisation aspects. Throughout the review process, it became apparent that the adoption of morphing concepts for routine use on aerial vehicles is still scarce, and some reasons holding back their integration for industrial use are given. Finally, promising concepts for future use are identified

On the Importance of Morphing Deformation Scheduling for Actuation Force and Energy

Morphing aircraft offer superior properties as compared to non-morphing aircraft. They can achieve this by adapting their shape depending on the requirements of various conflicting flight conditions. These shape changes are often associated with large deformations and strains, and hence dedicated morphing concepts are developed to carry out the required changes in shape. Such intricate mechanisms are often heavy, which reduces, or even completely cancels, the performance increase of the morphing aircraft. Part of this weight penalty is determined by the required actuators and associated batteries, which are mainly driven by the required actuation force and energy. Two underexposed influences on the actuation force and energy are the flight condition at which morphing should take place and the order of the morphing manoeuvres, also called morphing scheduling. This paper aims at highlighting the importance of both influences by using a small Unmanned Aerial Vehicle (UAV) with different morphing mechanisms as an example. The results in this paper are generated using a morphing aircraft analysis and design code that was developed at the Delft University of Technology. The importance of the flight condition and a proper morphing schedule is demonstrated by investigating the required actuation forces for various flight conditions and morphing sequences. More importantly, the results show that there is not necessarily one optimal flight condition or morphing schedule and a tradeoff needs to be made

Passive loads alleviation through aeroelastic tailoring

The presentation covered work performed by TU Delft and DLR on a hybrid aeroelastic tailoring process, in the framework of the European 7FP Smart Fixed Wing Aircraft (SFWA) project. Aim of the work package 'Adaptive Wing' in SFWA was to create design processes and solutions for aircraft wings giving optimal response with respect to loads, comfort and performance by the introduction of passive and active concepts. Central activity of the work was the design and optimization of adaptive wing structures, for complete wings as well as for special components. The design is performed with respect to loads, comfort and performance. This process, often called "aeroelastic tailoring" for passive solutions and "aeroservoelastic tailoring" for solutions including control devices and an active control loop, formed the backbone of the work package

Implementation of Active and Passive Load Alleviation Methods on a Generic mid-Range Aircraft Configuration

The influence of passive and active load alleviation methods on the structure weight has been investigated on the wing of a Generic Mid-Range aircraft configuration. The models have been created with ModGen, an in-house program at DLR-AE (Institute of Aeroelasticity, DLR German Aerospace Center). 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 analyses and subsequent structure sizing has been conducted. The loads analyses consist 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

Adaptive Wing: Investigations of Passive Wing Technologies for Loads Reduction in the CleanSky Smart Fixed Wing Aircraft (SFWA) Project

In the work package “Adaptive Wing” in the Clean-Sky “Smart Fixed Wing Aircraft” (SFWA) project, design processes and solutions for aircraft wings have been created, giving optimal response with respect to loads, comfort and performance by the introduction of passive and active concepts. Central activity of the work was the design and optimization of adaptive wing structures, for complete wings as well as for special components. This process, often called "aeroelastic tailoring", formed the backbone of the work package. Other important contributions have encompassed the development and improve-ment of methods for loads analysis, by extending the classical linear tool set by fast non-linear approach-es. Partners from industry and research involved in the work package contribute with special expertise to the process. The paper gives an outline of the objectives and the work done in the work package, as well as an over-view of the integration of the “Adaptive Wing” activi-ties in the framework of the SFWA project

Dynamic response of aeroelastically tailored composite wing: Analysis and experiment

The paper contributes to the state of the art in the field of experimental aeroelasticity applied to composite wings. A dynamic aeroelastic wind tunnel experiment of aeroelastically tailored wings under a harmonic pitching excitation is conducted. A set of validation data for the aeroelastic analysis of flexible composite wings subjected to harmonic pitching excitation is provided. The experimental data contains aerodynamic lift and root bending moment coefficient, bending and torsion deformation at the wing tip. Finally, the experimental data is compared to numerical results obtained using the dynamic aeroelastic analysis framework developed at the Delft University of Technology showing good agreement