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.

An Alternative Approach to the High Aspect Ratio Wing With Jet Flap by Matched Asymptotic Expansions

1978 ◽  
Vol 29 (4) ◽  
pp. 227-250 ◽  
Author(s):  
T. Kida ◽  
Y. Miyai
Keyword(s):  
Aspect Ratio ◽  
Asymptotic Expansions ◽  
High Aspect Ratio ◽  
Three Dimensional ◽  
Matched Asymptotic Expansions ◽  
Alternative Approach ◽  
Line Theory ◽  
Physical Insight ◽  
Lifting Line ◽  
Lifting Line Theory

SummaryAn alternative method is described for solving the problem of a three-dimensional jet-flapped wing with a high aspect-ratio. This method is similar to the lifting-line theory of Kerney6 or Tokuda7, but differs in that the method of matched asymptotic expansions is applied to an integral equation, derived from the lifting surface theory, rather than a partial differential equation. The advantage of the present method over those used previously is that the necessary outer solutions are obtained directly; it is not necessary to rely upon physical insight or considerable ingenuity. The final results are different from those obtained by the previous authors; it is shown that the present result is correct, by noting some errors in the earlier theories.

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.

Minimum Induced Drag of Non-Planar Ground Effect Wings with Small Tip Clearance

1974 ◽  
Vol 25 (1) ◽  
pp. 19-36 ◽  
Author(s):  
T Kida ◽  
Y Miyai
Keyword(s):  
Present Method ◽  
Ground Effect ◽  
Tip Clearance ◽  
Approximate Theory ◽  
Circular Arc ◽  
Induced Drag ◽  
Line Theory ◽  
Lifting Line ◽  
Wing Tip ◽  
Lifting Line Theory

SummaryThis paper treats theoretically the problem of the minimum induced drag of non-planar ground effect wings with both tips very close to the ground, within the limitations of the linearised lifting-line theory. The gap clearance between the wing tip and the ground is assumed to be very small and, using this small parameter, an approximate theory, which yields the minimum induced drag of a non-planar ground effect wing, is formulated by the method of matched asymptotic expansions. As a check on the accuracy of the method, this theory is compared with the exact theory for a semicircular wing. This shows that the present method is accurate within the small gap clearance. Moreover, the present method is applied to other wing configurations, such as semi-elliptic wings and wings with endplates, circular arc wings in a tube and circular arc wings. These computations show the theory to be very effective and it can be easily extended to various spanwise cambers.

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.

scholarly journals Preliminary investigation of use of flexible folding wing tips for static and dynamic load alleviation

2016 ◽  
Vol 121 (1235) ◽  
pp. 73-94 ◽  
Author(s):  
A. Castrichini ◽  
V. Hodigere Siddaramaiah ◽  
D.E. Calderon ◽  
J.E. Cooper ◽  
T. Wilson ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Preliminary Investigation ◽  
Aircraft Design ◽  
Dynamic Loads ◽  
Induced Drag ◽  
Aeroelastic Model ◽  
Static And Dynamic Loads ◽  
Folding Wing ◽  
Wing Tips ◽  
Wing Tip

ABSTRACTA recent consideration in aircraft design is the use of folding wing-tips with the aim of enabling higher aspect ratio aircraft with less induced drag while also meeting airport gate limitations. This study investigates the effect of exploiting folding wing-tips in flight as a device to reduce both static and dynamic loads. A representative civil jet aircraft aeroelastic model was used to explore the effect of introducing a wing-tip device, connected to the wings with an elastic hinge, on the load behaviour. For the dynamic cases, vertical discrete gusts and continuous turbulence were considered. The effects of hinge orientation, stiffness, damping and wing-tip weight on the static and dynamic response were investigated. It was found that significant reductions in both the static and dynamic loads were possible. For the case considered, a 25% increase in span using folding wing-tips resulted in almost no increase in loads.

Numerical Study in Wing Tip Vortex for a Modified Commercial Boeing Aircraft

2008 ◽  
Author(s):  
Ricardo Hernandez-Rivera ◽  
Abel Hernandez-Guerrero ◽  
Cuauhtemoc Rubio-Arana ◽  
Raul Lesso-Arroyo
Keyword(s):  
Numerical Study ◽  
Tip Vortex ◽  
Total Drag ◽  
The Core ◽  
Induced Drag ◽  
Wing Tip Vortex ◽  
Drag And Lift ◽  
Wing Tips ◽  
Wing Tip ◽  
Constant Mach Number

Recent studies have shown that the use of winglets in aircrafts wing tips have been able to reduce fuel consumption by reducing the lift-induced drag caused by wing tip vortex. This paper presents a 3-D numerical study to analyze the drag and lift forces, and the behavior of the vortexes generated in the wing tips from a modified commercial Boeing aircraft 767-300/ER. This type of aircraft does not contain winglets to control the wing tip vortex, therefore, the aerodynamic effects were analyzed adding two models of winglets to the wing tip. The first one is the vortex diffuser winglet and the second one is the tip fence winglet. The analyses were made for steady state and compressible flow, for a constant Mach number. The results show that the vortex diffuser winglet gives the best results, reducing the core velocity of the wing tip vortex up to 19%, the total drag force of the aircraft up to 3.6% and it leads to a lift increase of up to 2.4% with respect to the original aircraft without winglets.

scholarly journals Lifting-Line Predictions for Induced Drag and Lift in Ground Effect

2013 ◽  
Vol 50 (4) ◽  
pp. 1226-1233 ◽  
Author(s):  
W. F. Phillips ◽  
D. F. Hunsaker
Keyword(s):  
Ground Effect ◽  
Induced Drag ◽  
Drag And Lift ◽  
Lifting Line

Aircraft Configuration Improvement Study from Aerodynamic and Structure Standpoints

2015 ◽  
Vol 798 ◽  
pp. 565-570
Author(s):  
Luciano Magno Fragola Barbosa ◽  
Ricardo Luiz Utsch de Freitas Pinto ◽  
Bernardo Oliveira Hargreaves
Keyword(s):  
Finite Element ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Load Distribution ◽  
Structural Deformation ◽  
Load Factor ◽  
Aircraft Wing ◽  
Induced Drag ◽  
Vertical Displacements ◽  
Lifting Line

In this work improvements on the geometry of a high aspect ratio aircraft wing are studied, in order to reduce the wing in-flight deformation, without changing the drag of the aircraft and without increasing the structural weight. For this, from a reference rectangular wing, one new wing with elliptical planform has been defined; and comparative analyses of loads and structural deformation have been made for the wings considered: the original rectangular wing and the new corresponding elliptical wing. The aerodynamic analysis is based on the lifting line approach. A computer routine is made by the authors based on this approach, to obtain both induced drag values and the load distribution of the two wings, the original one and the corresponding elliptical. Based on the loads, spars for the two wings have been defined, and in order to evaluate the vertical displacements in flight, a finite element routine have been used. The main result of this study is the comparison of the deformation of wings considered, subjected to the same load factor, and for the same aircraft mass. The results obtained are encouraging for further developments using the present methodology.

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.

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