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.

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.

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.

Comparison of Inviscid Flow Methods for Lift and Drag Calculations Over Thin-Sail Geometries

2012 ◽  
Author(s):  
Robert E. Spall ◽  
Warren F. Phillips ◽  
Brian B. Pincock
Keyword(s):  
Vortex Lattice ◽  
Lift Coefficient ◽  
Computational Cost ◽  
Inviscid Flow ◽  
Induced Drag ◽  
Line Theory ◽  
Lift And Drag ◽  
Lifting Line ◽  
Lifting Line Theory ◽  
Better Than

Solutions obtained from lifting-line, vortex-lattice, and the Euler equations are presented for a series of rigid, thin wing and sail geometries. Initial calculations were performed for an untwisted, rectangular wing. For this case, lifting line theory, vortex lattice, and Euler solutions were all in reasonable agreement. However, the lifting-line theory was the only method to predict a constant ratio of induced drag coefficient to lift coefficient squared. Similar results were found for a forward-swept, tapered wing. Additional results are presented in terms of lift and drag coefficients for an isolated mainsail, and mainsail/jib combinations with sails representative of both a standard and tall rig Catalina 27. Although experimental data is lacking, overall conclusions are that the accuracy realized from lifting-line solutions is as good as or better than that obtained from vortex-lattice solutions and inviscid CFD solutions, but at a fraction of the computational cost. The linear lifting-line results compared quite well with the nonlinear lifting-line results, with the exception of the downstream mainsail when considering jib/mainsail combinations.

Unsteady aerodynamics investigation of deploying tandem-wing with different methods

2018 ◽  
Vol 233 (10) ◽  
pp. 3714-3733 ◽  
Author(s):  
Hao Cheng ◽  
Hua Wang ◽  
Qingli Shi ◽  
Mengying Zhang
Keyword(s):  
Fore Wing ◽  
Vortex Lattice ◽  
Lift Coefficient ◽  
Unsteady Aerodynamics ◽  
Lattice Method ◽  
Vortex Lattice Method ◽  
Induced Drag ◽  
Lifting Line ◽  
Lifting Line Method ◽  
Unsteady Lift

In the rapidly deploying process of the unmanned aerial vehicle with folding wings, the aerodynamic characteristics could be largely different owing to the effects of deformation rate and the aerodynamic interference. The investigation on the unsteady aerodynamics is of great significance for the stability analysis and control design. The lifting-line method and the vortex-lattice method are improved to calculate the unsteady aerodynamics in the morphing stage. It is validated that the vortex-lattice method predicts the unsteady lift coefficient more appropriately than the lifting-line method. Different tandem wing configurations with deployable wings are simulated with different deformation rates during the morphing stage by the vortex-lattice method. As results indicated, the unsteady lift coefficient and the induced drag of the fore wing rise with the deformation rate increasing, but it is reversed for the hind wing. Additionally, the unsteady lift coefficient of the tandem wing configuration performs well with a larger stagger, a larger magnitude of the gap and a larger wingspan of the fore wing; however, the total induced drag has a larger value for the configuration that the two lifting surfaces with the same wingspans are closer to each other.

Induced-drag reduction of wing–wings and wings–ground configurations

2004 ◽  
Vol 108 (1088) ◽  
pp. 523-530
Author(s):  
L. Marino
Keyword(s):  
Drag Reduction ◽  
Ground Effect ◽  
Formation Flight ◽  
Optimum Configuration ◽  
Induced Drag ◽  
Aerodynamic Model ◽  
Line Theory ◽  
Aerodynamic Parameters ◽  
Lifting Line ◽  
Lifting Line Theory

Abstract The problem of induced drag reduction during formation flight is revisited by means of a simple aerodynamic model based on lifting line theory. The optimum configuration for minimum induced drag is analysed both in and out of the ground effect and the influence of the main geometrical and aerodynamic parameters is considered. The results are discussed and compared with existing numerical and experimental data.

scholarly journals AN ALTERNATIVE APPROACH TO INDUCED DRAG REDUCTION

Aviation ◽  
2021 ◽  
Vol 25 (3) ◽  
pp. 202-210
Author(s):  
Nikolaos Kehayas
Keyword(s):  
Aspect Ratio ◽  
Drag Reduction ◽  
Structural Constraints ◽  
Induced Drag ◽  
Alternative Approach ◽  
Body Design ◽  
Line Theory ◽  
Drag And Lift ◽  
Lifting Line ◽  
Wing Tip

Induced drag constitutes approximately 40% of the total drag of subsonic civil transport aircraft at cruise conditions. Various types of winglets and several non-planar concepts, such as the C-wing, the joined wings, and the box plane, have been proposed for its reduction. Here, a new approach to induced drag reduction in the form of a combination of an elliptical and an astroid hypocycloid lift distribution is put forward. Lift is mainly generated from high circulation in the center part of the wing and fades away along the semi-span towards the wing tip. Using lifting line theory, the analysis shows that for fixed lift and wingspan the combined lift distribution results in an induced drag reduction of 50% with respect to the elliptical distribution. Due to its wing planform the combined lift distribution leads to a 51.5% higher aspect ratio. If structural constraints are placed, then the higher aspect ratio may affect wing weight. Although any substantial increase of wing weight is not envisaged, further study of the matter is required. Zero-lift drag and lift-dependent drag due to skin friction and viscosity-related pressure remain unaffected. The proposed lift distribution is particularly useful in a blended wing-body design.

scholarly journals A Study on Aerodynamics and Stability Characteristics of a Bell-Shaped Span-Load Wing

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Nadhiratul Akmal Ab Razak ◽  
◽  
Mohd Fadhli Zulkafli ◽  
Keyword(s):  
Angle Of Attack ◽  
Aerodynamic Characteristics ◽  
Stability Characteristic ◽  
Design Team ◽  
Optimum Angle ◽  
Induced Drag ◽  
Line Theory ◽  
The Difference ◽  
Lifting Line ◽  
Lifting Line Theory

The existence of the new bell-shaped span-load wing is said to has the best lift distribution especially comparing to the elliptical wing. Bell-shaped span-load wing is designed by configuring the twist of the wing. However, the information on the aerodynamic and stability characteristics of the bell-shaped span-load wing is limited. Thus, the main purpose of the research is to evaluate the aerodynamic and stability characteristic to strengthen the claim of the capability of bell-shaped span-load wing in producing minimum induced drag. As the research is expected to be beneficial to the aviation design team, detailed information regarding the lift distribution as well as the induced drag produced is analysed at the optimum angle of attack and the results is further explained in this research. The numerical method for the analysis is done by using Lifting Line Theory (LLT) in the XFLR5 software which can analyse the wings of aircraft in terms of its aerodynamic and stability characteristic. Then, the comparison of the aerodynamic characteristics for bell-shaped span-load, elliptical span-load and tapered wing done in this research is to strengthen the appeal made stating that the bell-shaped span-load wing is the best type of wing ever existed and may replace the elliptical wing as the best wing shape with aerodynamically most efficient. The research has proven that along the wingspan, the bell-shaped span-load wing produced the lowest and minimum induced drag when being compared. At the optimum angle of attack of bell-shaped span-load wing, though the lift produced is slightly lower than the elliptical and tapered wing, the difference in the induced drag is obvious as bell-shaped span-load wing produces induced drag that is lower than 0. In other words, starting from the semi span of the wing to the wingtip, the bell-shaped span-load wing managed to be the most aerodynamically efficient wing.

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.

Predicting Maximum Lift Coefficient for Compound Wings Using Lifting Line Theory

2021 ◽  
pp. 1-16
Author(s):  
Oliverio E. Velazquez Salazar ◽  
François Morency ◽  
Julien Weiss
Keyword(s):  
Lift Coefficient ◽  
Line Theory ◽  
Lifting Line ◽  
Lifting Line Theory
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