scholarly journals Experimental Validation and Evaluation of a Coupled Twist-Camber Morphing Wing Concept

2021 ◽  
Vol 11 (22) ◽  
pp. 10631
Author(s):  
José Lobo do Vale ◽  
John Raffaelli ◽  
Afzal Suleman
Keyword(s):  
Thickness Distribution ◽  
General Aviation ◽  
Morphing Wing ◽  
Flight Tests ◽  
Roll Control ◽  
Shape Adaptation ◽  
Line Theory ◽  
Drag Minimization ◽  
Drag Ratio ◽  
Lifting Line

A morphing wing concept allowing for coupled twist-camber shape adaptation is proposed. The design is based on an optimized thickness distribution both spanwise and chordwise to be able to morph the wing sections into targeted airfoil shapes. Simultaneously, the spanwise twist is affected by the actuation. The concept provides a higher degree of control on the lift distribution which can be used for roll control, drag minimization, and active load alleviation. Static deformation and flight tests have been performed to evaluate and quantify the performance of the proposed mechanism. The ground tests include mapped actuated wing shapes, and wing mass and actuation power requirements. Roll authority, load alleviation, and aerodynamic efficiency estimates for different configurations were calculated using a lifting line theory coupled with viscous 2D airfoil data. Roll authority was estimated to be low when compared to a general aviation aircraft while the load alleviation capability was found to be high. Differences between the lift to drag ratio between the reference and morphing wing configurations are considerable. Mass and actuation energy present challenges that can be mitigated. The flight tests were used to qualitatively assess the roll control capability of the prototype, which was found to be adequate.

Aileron size and location to minimise induced drag during rolling-moment production at zero rolling rate

2021 ◽  
Vol 125 (1287) ◽  
pp. 807-829
Author(s):  
J.R. Brincklow ◽  
D.F. Hunsaker
Keyword(s):  
Morphing Wing ◽  
Rolling Moment ◽  
Roll Control ◽  
Induced Drag ◽  
Wide Range ◽  
Line Theory ◽  
Potential Benefits ◽  
Rolling Rate ◽  
Lifting Line ◽  
Wing Tip

AbstractMost modern aircraft employ discrete ailerons for roll control. The induced drag, rolling moment, and yawing moment for an aircraft depend in part on the location and size of the ailerons. In the present study, lifting-line theory is used to formulate theoretical relationships between aileron design and the resulting forces and moments. The theory predicts that the optimum aileron geometry is independent of prescribed lift and rolling moment. A numerical potential flow algorithm is used to evaluate the optimum size and location of ailerons for a wide range of planforms with varying aspect ratio and taper ratio. Results show that the optimum aileron design to minimise induced drag always extends to the wing tip. Impacts to induced drag and yawing moment are also considered, and results can be used to inform initial design and placement of ailerons on future aircraft. Results of this optimisation study are also compared to theoretical optimum results that could be obtained from morphing-wing technology. Results of this comparison can be used to evaluate the potential benefits of using morphing-wing technology rather than traditional discrete ailerons.

Analysis of UAS-S4 Éhecatl aerodynamic performance improvement using several configurations of a morphing wing technology

2016 ◽  
Vol 120 (1231) ◽  
pp. 1337-1364 ◽  
Author(s):  
O. Şugar Gabor ◽  
A. Koreanschi ◽  
R.M. Botez
Keyword(s):  
Aerodynamic Characteristics ◽  
Morphing Wing ◽  
Flow Solver ◽  
Bee Colony ◽  
Gradient Based ◽  
Search Routine ◽  
Drag Ratio ◽  
Lifting Line ◽  
Lift To Drag Ratio ◽  
Lifting Line Method

ABSTRACTThe paper presents the results of the aerodynamic optimisation of an Unmanned Aerial System's wing using a morphing approach. The shape deformation of the wing is achieved by placing actuator lines at several positions along its span. For each flight condition, the optimal displacements are found by using a combination of the new Artificial Bee Colony algorithm and a classical gradient-based search routine. The wing aerodynamic characteristics are calculated with an efficient nonlinear lifting line method coupled with a two-dimensional viscous flow solver. The optimisations are performed at angles of attack below the maximum lift angle, with the aim of improving the Hydra Technologies UAS-S4 wing lift-to-drag ratio. Several configurations of the morphing wing are proposed, each with a different number of actuation lines, and the improvements obtained by these configurations are analysed and compared.

scholarly journals Analytic and computational analysis of wing twist to minimize induced drag during roll

2019 ◽  
Vol 234 (3) ◽  
pp. 788-803
Author(s):  
Douglas F Hunsaker ◽  
Zachary S Montgomery ◽  
James J Joo
Keyword(s):  
Lift Coefficient ◽  
Analytic Solutions ◽  
Rolling Moment ◽  
Morphing Aircraft ◽  
Roll Control ◽  
Induced Drag ◽  
Gradient Based ◽  
Line Theory ◽  
Rolling Rate ◽  
Lifting Line

Geometric and/or aerodynamic wing twist can be used to produce a lift distribution that results in a rolling moment. A decomposed Fourier-series solution to Prandtl’s lifting-line theory is used to develop analytic spanwise antisymmetric twist distributions for roll control that minimize induced drag on wings of arbitrary planform in pure rolling motion. Roll initiation, steady rolling rate, and the transition between the two are each considered. It is shown that if these antisymmetric twist distributions are used, the induced drag is proportional to the square of the rolling moment, and the induced drag during a steady rolling rate is equal to that on the wing at the same lift coefficient with no rolling rate or antisymmetric twist distribution. Results also show that if these antisymmetric twist distributions are used on straight, tapered wings without symmetric twist, any rolling maneuver for which the rolling rate and rolling moment have the same sign will always produce a yawing moment in the opposite direction. Computational results are also included, which were obtained using a gradient-based optimization algorithm in combination with a modern numerical lifting-line algorithm to find the optimum twist solutions. The resulting twist, induced drag, and yawing moment solutions compare favorably with the analytic solutions developed in the text. The solutions presented here can be used to inform the design of morphing aircraft.

Optimal wing twist distribution for roll control of MAVs

2011 ◽  
Vol 115 (1172) ◽  
pp. 641-649 ◽  
Author(s):  
M. R. Ahmed ◽  
M. M. Abdelrahman ◽  
G. M. ElBayoumi ◽  
M. M. ElNomrossy
Keyword(s):  
Roll Control ◽  
Induced Drag ◽  
Load Distributions ◽  
Air Vehicle ◽  
Gradient Based ◽  
Line Theory ◽  
Symmetric Load ◽  
Lifting Line ◽  
Lifting Line Theory

Abstract The aerodynamic design optimisation of a Micro Air Vehicle (MAV) wing is performed to obtain the optimal anti-symmetric wing twist distribution for the roll control of the MAV’s wing instead of using conventional ailerons. This twist distribution should produce minimum induced drag and achieve a better roll response. The implementation of several anti-symmetric load distributions such as the half lemniscates and the Horten distributions is studied leading to an initial solution for the optimal distribution that could achieve better roll requirements. Multhopp’s method based on Prandtl’s classical lifting line theory is used for the determination of the spanwise load distribution required during the optimisation process. The optimisation process is based on the modified feasible directions gradient based optimisation algorithm implemented in the optimisation system, VisualDOC, given by Dr. Garret Vanderplaats. The proposed optimisation process is applied to the ‘BARQ’developed MAV which has successful flight in July 2009.

scholarly journals Stall Recovery of a Morphing Wing via Extended Nonlinear Lifting-Line Theory

AIAA Journal ◽  
2017 ◽  
Vol 55 (9) ◽  
pp. 2956-2963 ◽  
Author(s):  
Lawren L. Gamble ◽  
Alexander M. Pankonien ◽  
Daniel J. Inman
Keyword(s):  
Morphing Wing ◽  
Line Theory ◽  
Lifting Line ◽  
Lifting Line Theory

Towards an optimum yacht sail

1978 ◽  
Vol 85 (3) ◽  
pp. 459-477 ◽  
Author(s):  
C. J. Wood ◽  
S. H. Tan
Keyword(s):  
Aspect Ratio ◽  
Water Surface ◽  
Control Problems ◽  
Unexpected Result ◽  
Rolling Moment ◽  
Line Theory ◽  
And Control ◽  
Drag Ratio ◽  
Lifting Line ◽  
Lifting Line Theory

This paper contains a simple and entirely conventional application of lifting-line theory to a close-hauled, high aspect ratio sail, set upright on a flat water surface. In seeking an optimum spanwise loading distribution however, an unconventional criterion is used, which leads to an unexpected result.By seeking to maximize the forward thrust for a given rolling moment, rather than maximizing the lift-drag ratio, an optimum loading distribution is obtained which departs dramatically from elliptic loading. It offers the prospect of a significant improvement in extreme yacht performance if the associated mechanical and control problems can ever be solved.

An improved nonlinear lifting-line theory.

AIAA Journal ◽  
1973 ◽  
Vol 11 (5) ◽  
pp. 739-742 ◽  
Author(s):  
CHUAN-TAU LAN
Keyword(s):  
Line Theory ◽  
Lifting Line ◽  
Lifting Line Theory

A comprehensive comparative investigation of the Lifting Line Theory and Blade Element Momentum Theory applied to small wind turbines

2021 ◽  
pp. 1-25
Author(s):  
K.A.R. Ismail ◽  
Willian Okita
Keyword(s):  
Wind Turbines ◽  
Power Coefficient ◽  
Computational Time ◽  
Local Flow ◽  
Small Wind Turbines ◽  
Wake Effects ◽  
Line Theory ◽  
Lifting Line ◽  
Lifting Line Theory ◽  
Blade Element

Abstract Small wind turbines are adequate for electricity generation in isolated areas to promote local expansion of commercial activities and social inclusion. Blade element momentum (BEM) method is usually used for performance prediction, but generally produces overestimated predictions since the wake effects are not precisely accounted for. Lifting line theory (LLT) can represent the blade and wake effects more precisely. In the present investigation the two methods are analyzed and their predictions of the aerodynamic performance of small wind turbines are compared. Conducted simulations showed a computational time of about 149.32 s for the Gottingen GO 398 based rotor simulated by the BEM and 1007.7 s for simulation by the LLT. The analysis of the power coefficient showed a maximum difference between the predictions of the two methods of about 4.4% in the case of Gottingen GO 398 airfoil based rotor and 6.3% for simulations of the Joukowski J 0021 airfoil. In the case of the annual energy production a difference of 2.35% is found between the predictions of the two methods. The effects of the blade geometrical variants such as twist angle and chord distributions increase the numerical deviations between the two methods due to the big number of iterations in the case of LLT. The cases analyzed showed deviations between 3.4% and 4.1%. As a whole, the results showed good performance of both methods; however the lifting line theory provides more precise results and more information on the local flow over the rotor blades.

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