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.

scholarly journals Aerodynamic effects of a folding wingtip to increase take-off, landing and cruise performance.

2022 ◽  
pp. 35-44
Author(s):  
S Rajat Singh ◽  
Amala Raja Rajeswar Gajula ◽  
Praneetha Maccha
Keyword(s):  
High Pressure ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Fuel Efficiency ◽  
Bottom Surface ◽  
Induced Drag ◽  
The World ◽  
Gust Loads ◽  
Folding Wing ◽  
Wing Tip

The main purpose of a folding wing tip is to allow aerodynamically efficient high aspect ratio wing. To allow a wing tip to move in flight is to alleviate the loads and achieve lower wing weight or enable wing span to maximize. Thus reduces the induced drag and improve fuel efficiency. The folding wing tip may include spring devices in order to provide an additional gust loads alleviation ability in flight. A wing without a winglet produces wingtip vortices which increases drag as the air from the bottom surface of the wing (high pressure) tries to move to the upper surface (low pressure). To avoid this and have less vortices a winglet is used, around which the flow is same on both surfaces. A folding wingtip can be set at an angle of 0° to have maximum cruise performance and aspect ratio. If the wingtip is set in the range of 15°-50° it can increase lift during take-off. This folding wingtip can access any airport in the world because if it is folded at an angle of 90°, it can meet the gate requirements and restrictions of any airport. To study the performance of this mechanism, the wing tip was designed by using CATIA V5 software. The analysis of the wingtip at different angle of attacks was done using ANSYS and XFLR 5 softwares.

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.

Correction: Testing of Folding Wing-Tip for Gust Load Alleviation in High Aspect Ratio Wing

2019 ◽  
Author(s):  
Ronald C. Cheung ◽  
Djamel Rezgui ◽  
Jonathan E. Cooper ◽  
Thomas Wilson
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Folding Wing ◽  
Gust Load Alleviation ◽  
Wing Tip

Experimental studies of viscous regions near streamlined wing tips

1987 ◽  
Vol 91 (910) ◽  
pp. 470
Author(s):  
H. P. Horton ◽  
X. M. Xenophontos
Keyword(s):  
Practical Importance ◽  
Experimental Studies ◽  
Vortex Sheet ◽  
Tip Vortex ◽  
Tip Vortices ◽  
Induced Drag ◽  
Wing Tips ◽  
Wing Tip ◽  
Complex Manner ◽  
Made In

Wing-tip vortices are of considerable practical importance, primarily because of the associated induced drag. A number of investigations have been made in the past into the development of vortices trailing behind wings, but little attention has been given to the mechanism of generation of such vortices. In the region of a wing-tip the boundary layers, which are usually turbulent at full-scale, separate from the wing surface in a rather complex manner to form a vortex sheet which rolls up into the tip vortex. Although the gross effects of the tip vortex can be predicted by inviscid theory, a detailed understanding of the behaviour of the viscous layers around wing-tips could lead to better optimisation of their design.

An experimental parametric study on planar sheared wings tip devices for low-to-moderate aspect ratio wings

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Lourelay Moreira dos Santos ◽  
Guilherme Ferreira Gomes ◽  
Rogerio F. Coimbra
Keyword(s):  
Wind Tunnel ◽  
Aspect Ratio ◽  
Parametric Study ◽  
Leading Edge ◽  
Aerodynamic Characteristics ◽  
Sweep Angle ◽  
Wind Tunnel Tests ◽  
Content Type ◽  
Wing Tips ◽  
Wing Tip

Purpose The purpose of this study is to investigate the aerodynamic characteristics of a low-to-moderate-aspect-ratio, tapered, untwisted, unswept wing, equipped of sheared wing tips. Design/methodology/approach In this work, wind tunnel tests were made to study the influence in aerodynamic characteristics over a typical low-to-moderate-aspect-ratio wing of a general aviation aircraft, equipped with sheared – swept and tapered planar – wing tips. An experimental parametric study of different wing tips was tested. Variations in its leading and trailing edge sweep angle as well as variations in wing tip taper ratio were considered. Sheared wing tips modify the flow pattern in the outboard region of the wing producing a vortex flow at the wing tip leading edge, enhancing lift at high angles of attack. Findings The induced drag is responsible for nearly 50% of aircraft total drag and can be reduced through modifications to the wing tip. Some wing tip models present complex geometries and many of them present benefits in particular flight conditions. Results have demonstrated that sweeping the wing tip leading edge between 60 and 65 degrees offers an increment in wing aerodynamic efficiency, especially at high lift conditions. However, results have demonstrated that moderate wing tip taper ratio (0.50) has better aerodynamic benefits than highly tapered wing tips (from 0.25 to 0.15), even with little less wing tip leading edge sweep angle (from 57 to 62 degrees). The moderate wing tip taper ratio (0.50) offers more wing area and wing span than the wings with highly tapered wing tips, for the same aspect ratio wing. Originality/value Although many studies have been reported on the aerodynamics of wing tips, most of them presented complex non-planar geometries and were developed for cruise flight in high subsonic regime (low lift coefficient). In this work, an exploration and parametric study through wind tunnel tests were made, to evaluate the influence in aerodynamic characteristics of a low-to-moderate-aspect-ratio, tapered, untwisted, unswept wing, equipped of sheared wing tips (wing tips highly swept and tapered).

Sizing of High Aspect Ratio Wings with Folding Wing Tips

2022 ◽  
Author(s):  
Huaiyuan Gu ◽  
Fintan Healy ◽  
Djamel Rezgui ◽  
Jonathan E. Cooper
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Folding Wing ◽  
Wing Tips

scholarly journals Testing of Folding Wing-Tip for Gust Load Alleviation in High Aspect Ratio Wing

2019 ◽  
Author(s):  
Ronald C. Cheung ◽  
Djamel Rezgui ◽  
Jonathan E. Cooper ◽  
Thomas Wilson
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Folding Wing ◽  
Gust Load Alleviation ◽  
Wing Tip

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 GLIDING BIRDS: REDUCTION OF INDUCED DRAG BY WING TIP SLOTS BETWEEN THE PRIMARY FEATHERS

1993 ◽  
Vol 180 (1) ◽  
pp. 285-310 ◽  
Author(s):  
V. A. Tucker
Keyword(s):  
Angle Of Attack ◽  
Aerodynamic Forces ◽  
Vortex Sheets ◽  
Balsa Wood ◽  
Induced Drag ◽  
Wing Tips ◽  
D Values ◽  
Lift And Drag ◽  
The Individual ◽  
Wing Tip

1. The feathers at the wing tips of most birds that soar over land separate both horizontally and vertically in flight to form slotted tips. The individual feathers in the slotted tips resemble the winglets used on the wing tips of some aircraft to reduce induced drag. 2. A wing that produces lift leaves a pair of vortex sheets in its wake. Wing theory shows that winglets can reduce the kinetic energy left in the vortex sheets, and hence the induced drag, by spreading vorticity both horizontally and vertically. 3. This paper describes the aerodynamic forces on a wing made of a base wing and different wing tips. The feathered wing tip was slotted and was made of four primary feathers from a Harris' hawk (Parabuteo unicinctus). The Clark Y tip was unslotted and was made of balsa wood shaped to a Clark Y aerofoil. The balsa feather tip was slotted and was made of three balsa wood wings shaped like feathers. 4. The base wing in a wind tunnel at an air speed of 12.6 m s-1 generated upwash angles as high as 15° at the end of the wing when the angle of attack of the wing was 10.5°. The feathered tip responded to upwash by increasing its lift to drag ratio (L/D) by 107 %, from 4.9 to 10.1, as the angle of attack of the base wing increased from 4° to 14°. The L/D values of the balsa feather tip and the Clark Y tip increased by 49 % and 5 %, respectively, for the same change in angle of attack. 5. With the angle of attack of the base wing fixed at 13°, changing the angle of attack of the wing tip changed the drag of the base wing. The drag of the base wing increased by 25 % as the angle of attack of the Clark Y tip increased from 0° to 15°. The base wing drag decreased by 6 % for the same change in the angle of attack of the feathered tip. 6. The total drag of the wing with the feathered tip was 12 % less than that of a hypothetical wing with the same lift and span, but with tip feathers that did not respond to upwash at the end of the base wing. This value is consistent with wing theory predictions on drag reduction from winglets. 7. Wings with the tip and the base wing locked together had lift and drag that increased with increasing base wing angle of attack, as expected for conventional wings. Span factors were calculated from these data - a large span factor indicates that a wing has low induced drag for a given lift and wing span. The wing with the Clark Y tip had a span factor that decreased from 1 to 0.75 as the angle of attack of the base wing increased. Over the same range of angle of attack, the span factor of the wing with the feathered tip remained constant at 0.87. As the angle of attack of this wing increased, aerodynamic forces spread the feathers vertically to form slots. With fully formed slots, the wing had a higher span factor than the wing with the unslotted Clark Y tip. 8. Flow visualization with helium-filled bubbles showed that the addition of two winglets to the tip of a model wing spread vorticity both horizontally and vertically in the wake of the tip. 9. These observations taken together provide strong evidence that the tip slots of soaring birds reduce induced drag in the sense that the separated tip feathers act as winglets and increase the span factor of the wings.

scholarly journals Induced Drag Savings From Ground Effect and Formation Flight in Brown Pelicans

1988 ◽  
Vol 135 (1) ◽  
pp. 431-444 ◽  
Author(s):  
F. REED HAINSWORTH
Keyword(s):  
Ground Effect ◽  
Formation Flight ◽  
Tip Vortex ◽  
Wing Beat ◽  
Vertical Variation ◽  
Induced Drag ◽  
Brown Pelicans ◽  
Vertical Displacements ◽  
Wing Tips ◽  
Wing Tip

Ciné films of brown pelicans flying in formation were used to measure altitudes and wing tip spacing (WTS, distance perpendicular to the flight path between wing tips of adjacent birds at maximum span) for birds flying in ground effect, and vertical displacements and WTS for birds flying out of ground effect. Views were near coplanar with the plane of flight paths, and maximum wing span was used for scale. Induced drag savings in ground effect averaged 49% for gliding. Average WTS varied considerably with no evidence for systematic positioning near an optimum. There were also no differences in average WTS between flapping and gliding in or out of ground effect. Vertical displacements out of ground effect varied less than WTS but more than vertical displacements in ground effect. Few birds had wing beat frequencies similar to the bird ahead as would be needed to track vertical variation in trailing wing tip vortex positions. Imprecision in WTS may be due to unpredictable flow fields in ground effect, and difficulty in maintaining position under windy conditions out of ground effect.

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