Journal of Aviation 2 (2): 77-86 (2018) https://javsci.com - http://dergipark.gov.tr/jav e-ISSN: 2587-1676 Research Article DOI : 10.30518/jav.482507 Received : 14.11.2018 & Accepted : 10.12.2018 & Published (online) : 23.12.2018 Effectiveness of Twist Morphing Wing on Aerodynamic Performance and Control of an Aircraft Erdoğan KAYGAN¹*, Ceren ULUSOY1 1 School of Aviation, Girne American University, Kyrenia, PO Box 5, 99428, Cyprus Abstract In this paper, effectiveness of twist varied wing configurations for aircraft control and performance is described. The primary variables investigated involved changing the wing twist angle of a comparable Airbus A320 wing structure by identifying the ideal angle of twist. The aerodynamic performance and control of the morphing wing is characterised in AVL (Athena Vortex Lattice Method). In order to better understand the aerodynamic performance and control of twist morphing wing for diverse flight regimes, predetermined values of twist (-8°< ϕ <8°, in steps of ±2°) were examined. The results from this work indicate that if morphing wings were employed on aircraft, performance benefits could be achieved. Keywords: Aerodynamics, Aircraft, Control, Morphing, Twist 1. Introduction and rudder for yaw control). Alas, fixed positioned, Current interest in morphing vehicle is conventional wings with these traditional control accelerating with the development of advanced surfaces do not provide the optimum solution for materials, sensors, and actuators. Although this area aircraft performance in all flight regimes as the lift is fairly new, the applications were developed many requirements for aircraft can vary within a typical years ago. Wing warping techniques were flight due to fuel burn. In consequence of these practically applied by the Wright Brothers to control reasons, many designers lean towards the search for the first powered, heavier than air, aircraft through variable morphing concepts. wing twist via subtended cables [1]. However in today’s aviation world, this technique is no longer The idea of variable wings, ’morphing’, comes from available and replaced by compliant based the observation of flying birds where they tend to techniques which are widely accepted techniques of change wings geometry during the flight to adapt strategically placed, small deflection, discrete various flight conditions such as take-off, landing, control surfaces (aileron for roll, elevator for pitch gliding, soaring, and so on. In this regard, a detailed * Corresponding Author: Dr Erdogan Kaygan, Girne American Citation: Kaygan E., Ulusoy C. (2018). Effectiveness of Twist University, School of Aviation [email protected] Morphing Wing on Aerodynamic Performance and Control of an Aircraft. Journal of Aviation, 2 (2), 77-87. DOI: 10.30518/jav.482507 77 JAV e-ISSN:2587-1676 Journal of Aviation 2 (2): 77-86 (2018) description of past and current morphing aircraft good aerodynamic efficiency. The fishbone active concepts are well summarized by Barbarino et camber wing concepts were introduced by Woods et al.[2], and Weissahaar et al. [3]. According to their al. [24]. The core of the Fish Bone Active Camber survey, numerous morphing designs were discussed (FishBAC) concept is a compliant skeletal structure and the benefits, as well as the difficulties, were inspired by the anatomy of fish. Wind tunnel testing clearly expressed. Similarly, Ajaj et al. [4] showed that using the FishBAC morphing structure succinctly mapped out the morphing applications by remarkable increase in the lift-to-drag ratio of 20%– highlighting the latest research as well as presenting 25% was achieved compared to the flapped airfoil the historical connections of adaptive aerial over the range of angles of attack. Recently, active vehicles. Moreover, several adaptive wing concepts wing twist concepts investigated by Kaygan et al. of varying complexity were investigated and [25,26]. Novel design concepts with multiple categorized by Jha et al. [5]. According to the morphing elements were utilised and the results investigation, the most significant challenges tend show the concept is superior to more traditional to be in the structural design of the concepts, methods under selected test conditions such as ϕ=- morphing the skin, and the mechanisms employed. 6° with both sufficient compliance in twist, adequate resistance to aerodynamic bending, and A study of early designs and approximation minimal surface distortion all demonstrated techniques made the assumption that changing the successfully in flight. In addition to all, the twist in the outboard sections of the wings can aerodynamic and structural performance of a improve the desired control forces needed for morphing wing concept, based on fully compliant maneuvering flight. Prandtl’s Lifting Line Theory structures and actuated by closed-loop controlled was the initial numerical technique to assess the solid state piezoelectric actuators, is investigated performance of a wing’s lift capabilities for an aerial numerically and experimentally by Molinari et al. vehicle [6]; being thereafter modified by Philips [27]. The concept was tested in the wind tunnel and [7,8] to estimate the effects of wing twist on lift also deployed to model aircraft to demonstrate the distribution. Following this seminal work, more roll capability of an aircraft. The results showed the studies have taken cognizance of morphing wing concept would be one of the promising morphing twist structure both theoretically and wing designs by achieving significant efficiency experimentally, to examine influences on the improvements as well as illustrating similar aerodynamic performance of an aircraft. Recent controllability with traditional aileron systems. work have detailed of wing twist systems using piezoelectric and pneumatic actuators [9-11], torque Although the variety of morphing mechanisms rods [12-14], adaptive stiffness structures[15], for both fixed and rotating wing applications threaded rods [16], and shape memory alloys[17- concepts were explored and huge possible 19]. Similar to wing twist concepts, winglet and/or advantages have been discussed over the last several wingtip twist can also provide performance decades, the majority of concepts have been limited increases. Proof of this can be found in the due to problems such as excess weight, cost, significant number of studies available in the structural integrity, skin configuration, and smooth current literature. Bourdin et al.[20,21] and Alvin et surface design [28,29]. An efficient widely accepted al. [22] investigated the adjustable cant angled mechanism with a corresponding to realistic skin winglets to increase aerodynamic performance and still eludes development and widespread control of a flying wing aerial vehicles. The concept application. Smart materials aim to meet these consists of a pair of winglets with an adjustable cant needs; nonetheless, the skin problem remains angle, independently actuated and mounted at the unsolved. The morphing skin remains one of the tips of a baseline flying wing. Studies using novel significant challenges in this area. design concepts of twisted and cant angled C The purpose of the current study is to investigate wingtip configurations were also investigated by the aerodynamic characteristics of a variable twist Smith et al. [23] and results indicating that the high morphing wing to enhance aerodynamic twist angles tended to increase the lift coefficient performance and control of an aerial vehicle. The with winglet twist angles of up to ϕ=-3° providing 78 JAV e-ISSN:2587-1676 Journal of Aviation 2 (2): 77-86 (2018) primary variables investigated involved changing section(as shown in Figure 2 (d), which is an the wing twist angle of a comparable Airbus A320 asymmetrical airfoil that allows the plane to wing structure by identifying the ideal angle of generate more lift and less drag force [31]), Ʌ=25° twist. To that end, the remaining sections of this leading edge sweep angle, 34m wingspan, 6.5m root paper will describe the computational chord, 1.5m tip chord, with aspect and tip ratios of methodologies and aerodynamic analysis of 8.5 and 0.23 respectively. In order to better selected twist cases. understand the aerodynamic performance and control of twist morphing wing for diverse flight Airbus A320-200 Stability regimes, predetermined values of twist (-8°< θ <8°, and Control Surfaces. in steps of ±2°) were examined. An initial expiratory investigation was conducted on a baseline configuration (without having a twist angle) and then for each twist cases, new geometry structure was generated. 2.2 Aerodynamic Model and Computational Method Aerodynamic modeling and numerical analysis Non-uniform were carried out using Athena Vortex Lattice trailing edge (AVL) software, which was originally coded by sweep angle. Harold Younger and further developed by Mark Drela [32]. Athena Vortex Lattice is a numerical Simulated AVL simulation package that determines the solutions to Wing Configuration; a linear aerodynamic flow model. For all without control simulations, modeling was performed from a set of surfaces. wing panels along the wing span and chord axes (computational model of wing structure is shown in Figure 2(a) and Figure 3). The variation in lift can be modeled as a step change Uniform trailing from one panel to other. The control points are edge sweep placed at 3/4 chord for each panel at the midpoint angle. position in the spanwise direction to achieve the required vortex strength by applying the flow