Search

ight performance and dynamic analysis can be performed. This framework prospectively enables development of morphing concepts, in addition to assessment activities from a conceptual design phase. An example small/ medium Unmanned Air Vehicle (UAV) (mass of 25 kg and nominal aspect ratio of 6.67) is used to demonstrate the tool, presenting results for both symmetric and asymmetric span retraction. The span retraction is performed using the outboard 50% of the main wing, with up to 50% allowable span retraction. Results presented are for a loiter mission. The loiter is at 55 (km/r) where the high speed cruise is from 75-110 km/hr. Span retraction is used to optimise the conguration performance for these ight phases. LTrim and dy- namic (both longitudinal and lateral) results are presented for both high speed cruise and loiter for straight and level conditions. Loiter results include lateral coordinated turn with varying strategies, which include using either rudder span retraction, to trim the UAV. Final results show the eect of modelling _ Ixx using a reduced model for roll dynamics. This investigation shows that the maximum error occurs where the roll and inertia dynamics are matched.

The concept of span morphing aircraft is attracting a lot of attention due to the demands to enhance flight performance and control authority. Corrugated laminates provide a good solution for the skin of a span morphing wing due to their extremely anisotropic behaviour. Although corrugated skins have been proposed for camber morphing, they have not been proposed for span morphing. Hence the main focus of this paper is to optimise the geometry of the corrugated skin to minimize the axial stiffness, with constraints of material strength limits and out-of-plane deformations due to the aerodynamics. Two aerodyanic solvers, Tornado Vortex Lattice Method (VLM) and XFOIL, are compared and a Genetic Algorithm (GA) is used as the optimizer. Parametric modeling and calculation by ANSYS APDL was used to generate the finite element model and perform the analysis automatically based on the global and local geometric parameters. The parameter sensitivity is also analyzed and discussed. The optimization results show that XFOIL is more accurate than VLM for this analysis. The maximum displacement constraint causes the optimizer to choose fewer corrugations rather than increase the sheet thickness. This implies that the thickness has a higher impact than the number of corrugations on the axial stiffness. The optimization results show that the corrugation height and angle are maximized as they seem to have less influence on the maximum out-of-plane displacement.

Morphing wing strategies can be applied to configure aircraft geometry to successfully complete a mission/s. This requires fulfillment of requirements set within a series of flight phases, which generally specify an objective to be completed and constraints to be satisfied whilst optimising some measure of performance or efficiency. The following paper presents results from a software framework to assess the potential benefits of span morphing in performance and efficiency. An investigation of the effect of morphing on flight stability and control is presented. As an example, span variation from a nominal aspect ratio of 6.67 for a Unmanned Air Vehicle (UAV) of 25kg is presented, with results given for a representative mission profile for typical operations. A structural concept that integrates span retraction is assumed.

The use of variable wing span to enhance flight performance and control authority of high endurance, medium altitude UAV is investigated. Asymmetric span extension is used to replace ailerons and maintain roll control over the entire flight envelope of the vehicle. The span extension required to generate a rolling moment equal to that produced by ailerons is estimated at four flight points. The study is performed using Tornado Vortex Lattice Method (VLM). 36% increase in wing semi-span is required to maintain roll authority. On the other hand, symmetric span morphing is used to reduce induced drag and enhance the endurance capability of the vehicle. 20% symmetric span morphing was found to be the optimum to reduce the overall drag of the wing by 10% at the start of cruise and 2.5% at the end of cruise. The morphing wing structure is to be designed using Zero Poisson’s ratio Accordion honeycomb with elastomeric skins. The geometry of the honeycomb will be optimised using the Genetic Algorithm (GA) optimiser to minimise the structural weight of the wing while meeting various design constraints.

This paper presents a suggested generic process for selecting and subsequently integrating arbitrary morphing devices specifically during aircraft conceptual and predesign stages. The absence of formally documented procedures by academia and industry alike necessitated the formulation of a standardized objective-driven, top-down approach where implementation of novel adaptive utilities could come into consideration. For the suggested hierarchical approach six top-down Morphing Resolution Levels (MRLs) are introduced where the contents are populated by an array of expert catalogues. Qualitative assessment follows the Georgia Institute of Technology Strategic Planning and Prioritization (SP2) process and encompasses five phases: (1) Problem Definition; (2) Effect Translation; (3) Outer Mold Line Morphing; (4) Structural Layout; and, (5) Technology Selection. This process results in a down-selection of the most pragmatically effective morphing schemes to be considered for further design investigation.

This paper presents the optimum design of a PID controller for the Adaptive Torsion Wing (ATW) using the genetic algorithm (GA) optimiser. The ATW is a thin-wall, twospar wingbox whose torsional stiffness can be adjusted by translating the spar webs in the chordwise direction inward and towards each. The reduction in torsional stiffness allows external aerodynamic loads to deform the wing and maintain its shape. The ATW is integrated within the wing of a representative UAV to replace conventional ailerons and provide roll control. The ATW is modelled as a two-dimensional equivalent aerofoil using bending and torsion shape functions to express the equations of motion in terms of the twist angle and plunge displacement at the wingtip. The full equations of motion for the ATW equivalent aerofoil were derived using Lagrangian mechanics. The aerodynamic lift and moment acting on the aerofoil were modelled using Theodorsen’s unsteady aerodynamic theory. The equations of motion are then linearized around an equilibrium position and the GA is employed to design a PID controller for the linearized system to minimise the actuation power require. Finally, the sizing and selection of a suitable actuator is performed.

This paper presents the conceptual analysis of a novel Active Aeroelastic Structure (AAS) device, which allows tailored twist deformations of wing structures to be achieved. The Adaptive Torsion Wing (ATW) concept is a thin-walled closed section two-spar wing-box whose torsional stiffness can be adjusted by changing the area enclosed between the front and rear spar webs. This is done by translating the spar webs in the chord-wise direction inward and towards each other using internal actuators. As the webs move closer to each other, the torsional stiffness of the structure reduces, while its bending stiffness in the span-wise direction is unaffected. The reduction in torsional stiffness allows external aerodynamic loads to induce twist on the structure and to maintain its deformed shape. These twist deformations can be controlled by changing the relative position of the webs as a function of the flight conditions to obtain an optimal or targeted level of performance. A Quasistatic Aeroelastic Suite has been developed in MATLAB TM to model the ATW concept and to study its behavior with respect to different web shifting strategies. Finally, the variation of structural figures of merit such as torsion constant, tip twist, shear centre position, and minimum actuation energy are evaluated and discussed.