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Wing

A wing is a type of fin that produces both lift and drag while moving through air. Like a sail on a boat or a blade on a windmill, wings generate aerodynamic forces to enable flight or propulsion. They are essential components in aviation for fixed-wing aircraft, rotorcraft, and gliding vehicles, as well as in nature for birds, bats, insects, and other flying animals. Wings vary in design based on geometric configurations such as straight, swept, or delta shapes, optimized for factors like speed, efficiency, and maneuverability. In biology, wings have evolved independently multiple times for flight, gliding, or display. Engineered wings incorporate materials like aluminum, composites, and advanced alloys, with control surfaces for stability. For other uses, including the Alphabet Inc. drone delivery subsidiary, see Wing (disambiguation).

Etymology and Definitions

Etymology

The word "wing" originates from Old Norse vængr, meaning the wing of a bird or an extension of a building, entering Middle English around the late 12th century as winge or wenge. It initially referred to the forelimbs of birds used for flight and later extended to human arms, building sections, and by the 16th century, to aircraft structures. The term is akin to Danish and Swedish vinge.^[1]^[2]

Definitions and Contexts

In aviation and aerospace engineering, a wing is a fixed or movable airfoil-shaped structure that generates lift through aerodynamic forces while minimizing drag, typically spanning from the fuselage to produce controlled flight. Wings are characterized by their planform (top-view shape) and airfoil cross-section.^[3] In biology, a wing refers to one of a pair of appendages in certain animals, such as birds, insects, or bats, evolved for propulsion, gliding, or powered flight through flapping, often covered in feathers, membranes, or chitin.^[4] In non-aviation engineering contexts, "wing" can denote lateral extensions of structures, such as building wings or vehicle fenders, providing stability or enclosure rather than lift.^[5]

Aerodynamic Principles

Lift and Drag Generation

Lift is the aerodynamic force that opposes the weight of an aircraft, primarily generated by the wings through their interaction with the airflow. This force acts perpendicular to the direction of motion and arises from two key principles: Bernoulli's principle, which attributes lift to the pressure differential created by faster airflow over the curved upper surface of the wing compared to the lower surface, and Newton's third law, which explains lift as the reaction to the wing's deflection of air downward. Both the upper and lower surfaces of the wing contribute to turning the airflow, with the net result being an upward force.^[6] Drag is the aerodynamic force parallel and opposed to the direction of motion, resisting the forward progress of the wing through the air. It comprises two main categories: parasite drag and induced drag. Parasite drag includes form drag, caused by pressure differences around the wing's shape that create high-pressure regions ahead and low-pressure wakes behind, and skin friction drag, resulting from the viscous shearing in the boundary layer along the wing surface. Induced drag, unique to lifting surfaces, stems from the generation of lift and is produced by wingtip vortices formed due to the pressure disparity between the upper and lower wing surfaces; these vortices dissipate energy and increase total drag, with lower values achieved using high-aspect-ratio wings.^[7]

Airfoil Profiles

An airfoil profile represents the two-dimensional cross-section of a wing, perpendicular to the span, which fundamentally determines its aerodynamic behavior by shaping the flow of air over the surface.^[8] Cambered airfoils, characterized by an asymmetric shape with a curved mean line, generate lift at zero angle of attack and are suited for low-speed flight where enhanced lift is required.^[9] In contrast, symmetric airfoils feature identical upper and lower surfaces relative to the chord line, providing no lift at zero angle of attack but offering stability and predictability in high-speed regimes.^[8] The National Advisory Committee for Aeronautics (NACA) developed standardized airfoil series to classify these profiles systematically, with the four-digit series being one of the most widely used.^[8] For instance, the NACA 2412 designation indicates a maximum camber of 2% of the chord length located at 40% of the chord from the leading edge, followed by a 12% maximum thickness-to-chord ratio.^[8] Key characteristics of airfoil profiles include the thickness ratio, defined as the maximum distance between the upper and lower surfaces divided by the chord length, which influences structural strength and drag; the camber line, representing the curve midway between the surfaces, which affects lift distribution; and the shapes of the leading and trailing edges, where a rounded leading edge promotes smooth flow attachment and a sharp trailing edge minimizes wake turbulence.^[10] These features impact stall behavior by altering boundary layer development: thicker profiles with higher camber often delay stall through better flow reattachment but can lead to abrupt separation if the boundary layer thickens excessively, while thinner sections may exhibit gradual stall with earlier separation points.^[10] For transonic flight, supercritical airfoils were developed to mitigate wave drag by featuring a flattened upper surface that allows extensive supersonic flow without strong shock waves, followed by isentropic recompression to reduce boundary layer disruption.^[11] These profiles, pioneered by NASA in the 1960s and 1970s, maintain pressure recovery aft of the shock, enabling higher cruise efficiencies compared to conventional airfoils.^[11] Such airfoil profiles contribute to overall lift generation by directing airflow to create a pressure differential across the wing surface.^[9]

Wing Loading and Efficiency

Wing loading, defined as the aircraft's total weight divided by its wing reference area (W/S), is a critical metric that determines the structural and aerodynamic demands on the wing during various flight phases.^[12] Higher wing loading increases the required lift coefficient for a given speed, thereby elevating stall speeds and necessitating longer runways for takeoff and landing, while lower wing loading enables short takeoff and landing (STOL) capabilities by allowing operations at reduced speeds.^[13] For instance, STOL aircraft designs often target wing loadings below 50 kg/m² to achieve field lengths under 300 meters, prioritizing maneuverability in confined spaces over cruise efficiency.^[14] Efficiency in wing performance is primarily assessed through the lift-to-drag ratio (L/D), with its maximum value (L/D_max) serving as a key indicator of overall aerodynamic effectiveness, particularly in cruise and unpowered flight.^[15] The glide ratio, which quantifies the horizontal distance traveled per unit of altitude lost in a steady glide, directly corresponds to L/D at the speed for minimum sink rate and is essential for evaluating energy-efficient descent profiles. For example, modern gliders achieve glide ratios exceeding 40:1, reflecting optimized wing designs that minimize energy loss.^[16] These metrics are visualized and analyzed using the polar curve, a plot of the lift coefficient (C_L) against the drag coefficient (C_D), which reveals the trade-offs between lift generation and drag penalties across operating conditions.^[17] The aspect ratio (AR), calculated as the square of the wing span (b) divided by the wing area (S), or AR = b²/S, profoundly influences induced drag, which arises from wingtip vortices and constitutes a major component of total drag at low speeds.^[12] Higher aspect ratios reduce induced drag proportionally to 1/AR, enhancing efficiency for applications like gliding where sustained lift with minimal power is paramount; gliders typically feature AR values above 20 to achieve this low-drag profile.^[18] Analysis of the polar diagram further elucidates optimal conditions: the tangent from the origin to the C_L-C_D curve identifies the maximum L/D point for best glide, while the minimum C_D location supports efficient climb rates by balancing power input against drag.^[17]

Design and Construction

Structural Elements

Aircraft wings are primarily semi-monocoque structures designed to withstand aerodynamic loads, including bending, shear, and torsion. The main structural components include spars, ribs, stringers, and skin.^[19] Spars are the primary load-carrying members, typically consisting of a web and caps (flanges). They run spanwise and carry the majority of bending moments and shear forces, with the highest loads at the wing root. Modern designs often feature two spars to form a torsion-resistant box structure.^[20] Ribs are chordwise elements that define the wing's airfoil shape, support the skin against buckling, and serve as attachment points for control surfaces, fuel tanks, and landing gear. They also help distribute loads from the skin to the spars.^[19] Stringers, or stiffeners, are longitudinal members attached to the skin between ribs. They prevent buckling under compressive loads from bending and torsion, and contribute to carrying axial loads.^[20] The skin forms the outer aerodynamic surface and, in conjunction with the spars, creates a torsion box. It transmits shear loads and provides resistance to bending in the caps.^[19]

Materials and Manufacturing

Traditional aircraft wings are constructed from aluminum alloys due to their high strength-to-weight ratio, corrosion resistance, and ease of fabrication. Common alloys include 2024 and 7075 for high-stress areas like spars and skins. Steel alloys are used sparingly for high-strength components, while titanium offers superior strength and corrosion resistance in critical parts, though at higher cost.^[21] In modern designs, composite materials such as carbon fiber reinforced polymers (CFRP) are increasingly prevalent, providing even greater weight savings and fatigue resistance. Composites are used for skins, ribs, and control surfaces, as seen in aircraft like the Boeing 787 and Airbus A350.^[22] Manufacturing involves assembling the internal framework of spars and ribs, often at specialized facilities. Systems like fuel tanks and control mechanisms are integrated, followed by skin attachment via riveting or bonding. For composites, automated layup and curing processes are employed. Wings are tested for structural integrity before transportation to final assembly sites. As of 2023, innovations like Airbus's Wing of Tomorrow program aim to reduce assembly time by over 50% using advanced automation.^[22]

Control and High-Lift Devices

Control surfaces on the wing enable maneuvering and stability, while high-lift devices enhance performance during takeoff and landing. Primary control surfaces include ailerons, located on the outboard trailing edge, which control roll by differentially increasing or decreasing lift on each wing.^[23] Spoilers, deployed from the upper wing surface, reduce lift and increase drag for descent control or to assist in roll when used asymmetrically, minimizing adverse yaw.^[23] High-lift devices include trailing-edge flaps and leading-edge slats. Flaps, such as plain, slotted, or Fowler types, increase camber and sometimes wing area to boost lift at low speeds, though they also increase drag. Slats extend forward from the leading edge, creating a slot for energized airflow to delay stall. Krueger flaps are another leading-edge device used on some commercial aircraft. These are deployed during low-speed phases to allow smaller wings for efficient cruise.^[24]^[23]

Configurations and Types

Geometric Configurations

Straight and rectangular wings feature a constant chord length along the span, providing simple geometry suited for low-speed flight regimes where stability is prioritized. These configurations offer predictable handling and efficient lift generation at subsonic speeds, as seen in general aviation aircraft like the Cessna 172, which employs a rectangular planform for enhanced low-speed stability during takeoff and landing.^[3] Swept-back wings, where the leading and trailing edges are angled rearward, and swept-forward wings, angled forward, are designed to delay the onset of compressibility effects in transonic and supersonic flight by reducing wave drag. The sweep angle effectively shortens the chordwise component of airflow, allowing higher cruise speeds without excessive drag rise; for instance, the Boeing 747 incorporates a 37.5-degree swept-back wing to optimize performance at transonic Mach numbers around 0.85.^[3]^[25]^[26] Delta wings adopt a triangular planform with high sweep angles, typically exceeding 50 degrees, enabling efficient high-speed flight through low wave drag and strong vortex lift at high angles of attack. The ogival variant, a curved delta shape, further refines low-speed performance while maintaining supersonic capabilities, as exemplified by the Concorde's ogival delta wing, which supported sustained Mach 2 cruise with improved stability across speed regimes. Variable-sweep wings, or swing wings, allow in-flight adjustment of the sweep angle to adapt to varying flight conditions, combining low-speed lift of unswept positions with high-speed efficiency of swept ones; the F-14 Tomcat features wings adjustable from 20 to 68 degrees, facilitating transitions from carrier operations to supersonic dashes.^[3]^[27]^[28] The taper ratio, defined as the ratio of tip chord to root chord, influences lift distribution and structural efficiency in planform design, with lower ratios promoting more uniform loading and reduced induced drag on swept or tapered wings. Dihedral, an upward angle of the wing tips relative to the root, enhances roll stability by creating a restoring moment during sideslip, commonly applied in transport aircraft for safer lateral handling. Conversely, anhedral, a downward angle, reduces roll stability to improve agility and roll rates, often used in fighters to enhance maneuverability without compromising overall control. These geometric elements collectively impact aerodynamic efficiency by optimizing lift-to-drag ratios for specific mission profiles, such as extended range in subsonic transports or rapid acceleration in combat aircraft.^[29]^[30]^[3]

Specialized Types

Elliptical wings feature a planform where the chord length varies elliptically along the span, minimizing induced drag for optimal aerodynamic efficiency in subsonic flight. This design, famously used in the Supermarine Spitfire, provides nearly ideal lift distribution but is complex to manufacture.^[3] Wingtip devices, such as winglets, are upturned extensions at the wing ends that reduce vortex-induced drag by diffusing wingtip vortices, improving fuel efficiency and range. Introduced on the Boeing 747-400 in the 1980s, modern variants like blended winglets are common on commercial airliners.^[31] Flying wings represent a configuration where the aircraft's fuselage is integrated into the wing structure, eliminating a traditional tail for reduced drag and weight. Examples include the Northrop Grumman B-2 Spirit bomber, which employs a flying wing design for stealth and efficiency.^[32]

Applications and Uses

Aviation and Aerospace

Wings are fundamental to fixed-wing aircraft, generating lift through aerodynamic principles to enable sustained flight, takeoff, and landing. In commercial aviation, high-aspect-ratio wings on airliners like the Boeing 787 optimize fuel efficiency for long-haul routes. Military applications include swept or delta wings on fighter jets such as the F-22 Raptor for supersonic performance and maneuverability. In aerospace, winged designs appear in space vehicles like the Space Shuttle for atmospheric re-entry glide, balancing lift and stability.^[33]

Non-Aviation Engineering

In non-aviation engineering, wing-like structures, often designed as airfoils, are applied to harness fluid dynamics for energy generation, propulsion, and drag management in terrestrial and aquatic systems. These adaptations leverage principles such as lift generation and pressure differentials, similar to those in aeronautics, but optimized for stationary or low-speed environments.^[34] Wind turbine blades in horizontal-axis wind turbines (HAWTs) function as specialized airfoils to convert kinetic wind energy into rotational mechanical power. These blades typically employ a distribution of airfoil profiles, with thicker sections like the DU 40 near the root for structural integrity and thinner ones like NACA 63₆-618 toward the tip to maximize lift-to-drag ratios, often exceeding 140 in mid-span regions. To achieve uniform aerodynamic loading across the blade span and optimize power output, blades incorporate geometric twist, varying from approximately 25° at the root to 4° at the tip, which adjusts the angle of attack as rotational speed increases with radius. This design enables HAWTs to attain power coefficients up to 0.48 at tip speed ratios around 9, enhancing overall efficiency in power generation.^[35] Hydrofoils serve as wing analogs in marine engineering, generating lift to elevate a boat's hull above the water surface and thereby minimize hydrodynamic drag. In high-speed planing boats, strategically placed hydrofoils, such as NACA-series profiles mounted at the stern or struts, produce upward forces that reduce the wetted surface area, leading to significant resistance reductions—up to 30.74% at speeds around 8 m/s in computational fluid dynamics analyses. This lift mechanism disrupts wave-making and frictional drag, allowing vessels to achieve higher velocities with lower power requirements, as validated through model-scale experiments and numerical simulations.^[36] In automotive engineering, particularly for high-performance vehicles, spoilers and diffusers emulate inverted airfoils to produce downforce, enhancing traction and stability at high speeds. Rear spoilers and front wings in Formula 1 cars, for instance, operate as upside-down airfoils, accelerating airflow over the upper surface to create low-pressure zones beneath, generating downward forces that can exceed 2.5 times the vehicle's weight at top speeds. Diffusers at the rear further amplify this by accelerating exhaust airflow under the car, forming venturi-like effects that contribute to overall downforce without excessive drag penalties, as seen in designs integrating sidepod-mounted inverted wings. These features, refined through wind tunnel testing, improve cornering grip and braking performance in racing applications.^[37]^[38] Industrial fans and propellers incorporate wing-like blades to facilitate air movement through aerodynamic lift, pressurizing fluids in HVAC, ventilation, and process systems. Axial fans, such as vaneaxial types, use airfoil-shaped blades to generate lift parallel to the rotation axis, achieving efficiencies up to 85% by minimizing stall through guide vanes that recover swirl energy. Centrifugal fans with backward-inclined airfoil blades convert rotational kinetic energy into static pressure more effectively than radial designs, operating efficiently in clean airstreams for applications like dust collection or cooling towers. These blade profiles reduce energy losses and noise, supporting annual industrial air movement demands exceeding 79 billion kWh.^[34]

Emerging Technologies

Morphing wings represent a key emerging technology for enhancing aerodynamic efficiency by enabling real-time shape adaptation without traditional mechanical hinges, utilizing smart materials such as shape-memory alloys (SMAs) and piezoelectric actuators. The DARPA Smart Wing program, conducted in the early 2000s by Northrop Grumman and partners, demonstrated this through seamless trailing-edge control surfaces that deflected up to 10 degrees, achieving a 20% increase in lift-to-drag ratio in wind-tunnel tests at transonic speeds. These actuators allow wings to morph in response to flight conditions, reducing drag and fuel consumption while improving maneuverability, with ongoing research extending applications to unmanned aerial vehicles (UAVs) for adaptive performance.^[39] Bio-inspired designs draw from avian and insect flight mechanics to develop ornithopter-style flapping wings for drones, offering superior agility and efficiency in confined or gusty environments compared to fixed-wing or rotary systems. The DelFly series, developed at Delft University of Technology since the mid-2000s, exemplifies this with lightweight, tailless micro-air vehicles (MAVs) weighing under 20 grams that achieve sustained flight durations of up to 9 minutes through biomimetic flapping at 12-15 Hz, incorporating clap-and-fling mechanisms for enhanced thrust. Recent iterations, like the DelFly Micro, integrate onboard cameras for autonomous navigation, paving the way for applications in surveillance and environmental monitoring where hovering and omnidirectional maneuverability are essential.^[40]^[41] Sustainable materials are advancing wing construction to minimize environmental impact, with post-2020 research emphasizing bio-composites from mycelium and recycled carbon fibers to replace virgin petroleum-based resins. Mycelium-based composites, grown from fungal networks on agricultural waste, offer biodegradable alternatives for non-structural aviation components, reducing lifecycle environmental impact compared to traditional composites. Similarly, recycled carbon fiber reinforcements in wing spars have demonstrated mechanical properties retaining 85-90% of virgin material strength, enabling scalable production for aircraft structures while diverting end-of-life composites from landfills, as validated in scaled wing spar prototypes tested under flexural loads exceeding 5 kN.^[42]^[43] Hypersonic wings, particularly waverider configurations, are critical for Mach 5+ travel, where the wing integrates with the vehicle's shockwave to generate lift with minimal drag in extreme thermal environments. The X-51A Waverider, a U.S. Air Force scramjet demonstrator tested between 2010 and 2013, achieved sustained flight at Mach 5.1 for over 210 seconds, validating the design's ability to maintain structural integrity at temperatures above 1,200°C using carbon-carbon composites for leading edges. This technology supports future hypersonic cruise vehicles by enabling efficient airbreathing propulsion, with implications for rapid global strike and space access missions.^[44]

Wings in Biology

Avian and Insect Wings

Bird wings represent modified forelimbs adapted for flight, consisting of a skeletal framework that includes the humerus in the upper arm, the radius and ulna in the forearm, and a fused carpometacarpus forming the wrist and hand for structural support.^[45]^[46] These bones articulate to enable a wide range of motion, with the ulna featuring quill knobs that anchor flight feathers, enhancing rigidity during flapping.^[47] The wing surface is covered by feathers, which are lightweight, asymmetrical structures that create an airfoil shape; primary feathers at the wingtip provide propulsion during the downstroke by generating thrust, while secondary feathers along the forearm contribute to lift by supporting the wing's camber.^[48]^[49] In contrast, insect wings emerge as extensions of the chitinous exoskeleton from the thorax, the middle body segment, and consist of thin, veined membranes that provide a flexible yet durable surface for aerial locomotion.^[50]^[51] Most insects possess two pairs of wings attached to the meso- and metathorax, with the forewings and hindwings often coupled through mechanical linkages or synchronous motion to enhance stability, particularly during maneuvers like hovering.^[52] For example, dragonflies utilize four independently movable wings in an out-of-phase counter-stroking pattern during hover, which suppresses vibrations and maintains aerodynamic balance by adjusting stroke amplitude and phase between fore- and hindwings.^[53]^[54] Bird flight mechanics vary between active flapping and passive gliding, with flapping involving muscle-powered oscillation of the wings driven by the pectoralis and supracoracoideus muscles to produce rhythmic up-and-down strokes.^[55] In small species like hummingbirds, this oscillation reaches frequencies up to 80 Hz, allowing sustained hovering through rapid, figure-eight wing paths that generate both lift and thrust continuously.^[56] Larger birds, such as the albatross, favor passive soaring and gliding, extending their long, high-aspect-ratio wings to exploit wind gradients and thermal updrafts without significant muscle activity, thereby conserving energy over vast distances.^[57]^[58] Insects achieve micro-scale flight through exceptionally low wing loading, defined as the ratio of body mass to total wing area, which enables high maneuverability and efficiency in small-bodied species.^[59] This low wing loading—often on the order of 0.1–6 N/m² in tiny insects—facilitates the generation of sufficient lift via rapid flapping and unsteady aerodynamics, such as leading-edge vortices, despite their minute size and limited power output.^[60] Such ratios underscore the evolutionary refinement of insect wings for agile, short-range flights in cluttered environments. These biological structures share aerodynamic principles with engineered wings, including airfoil shaping for lift, though adapted to vastly different scales and mechanisms.^[55]

Evolutionary Adaptations

The evolution of insect wings dates to the Devonian period around 400 million years ago, based on molecular clock estimates.^[61] The precise origin remains debated, with hypotheses including gill-like precursors derived from evaginated tracheae or abdominal limb bases in aquatic ancestors, or expansions of tergal plates from leg segments.^[61]^[62] These structures, resembling flap-like gills in modern mayfly nymphs, provided initial advantages for aquatic locomotion and gas exchange before transitioning to terrestrial environments. Fossil evidence from the Carboniferous period documents the emergence of fully veined wings in pterygotes, enabling powered flight and contributing to insects' ecological dominance through enhanced dispersal and predation avoidance.^[63] In birds, wings originated from feathered proto-wings in theropod dinosaurs during the Late Jurassic, approximately 150 million years ago, with Archaeopteryx representing a transitional form featuring asymmetric flight feathers suited for gliding from tree-dwelling ancestors.^[64] These proto-wings, initially adapted for display, balance during leaps, or short glides, gradually evolved into structures capable of powered flight through modifications in feather structure and skeletal support, as evidenced by maniraptoran fossils showing increasing forelimb elongation.^[65] This progression from gliding to sustained flapping flight marked a pivotal adaptation, allowing birds to exploit aerial niches post-Cretaceous extinction. Adaptive variations in wing morphology reflect diverse flight demands across species. In seabirds like the albatross, high-aspect-ratio wings with long, narrow spans minimize induced drag for efficient dynamic soaring over oceans, enabling long-distance migration with minimal energy expenditure.^[66] Conversely, raptors such as eagles employ slotted primary feathers at the wingtips, which create high-lift slots to delay stall and enhance maneuverability during hunting dives and turns.^[67] Bats, evolving powered flight around 52 million years ago, developed membrane wings (patagia) stretched across greatly elongated digits of the forelimb, providing flexibility for echolocation-guided navigation and hovering in cluttered environments.^[68] Wings exemplify convergent evolution, arising independently in insects from gill-derived appendages or tergal expansions, in birds from feathered dinosaur forelimbs, in bats from mammalian digit elongation, and in pterosaurs from a single hyper-elongated fourth finger supporting a membranous flight surface around 228 million years ago.^[69] This repeated innovation across arthropods and vertebrates underscores flight's selective pressures for mobility, despite distinct anatomical origins and developmental pathways.^[70]

Historical Development

Early Innovations

The development of wings in aviation began in the late 19th century with glider experiments. Otto Lilienthal's 1890s gliders featured cambered wings inspired by bird anatomy, achieving controlled flights and establishing basic aerodynamic principles like lift generation through curved surfaces.^[71] The Wright brothers advanced wing design with their 1903 Flyer, introducing wing warping for roll control and a high aspect ratio wing (6.5:1) with a modified Lilienthal airfoil, enabling the first powered flight. By World War I, biplane configurations dominated, offering structural simplicity and maneuverability, as seen in the Sopwith Camel with its staggered wings for improved stability.^[72] In the interwar period (1920s-1930s), the transition to monoplanes revolutionized efficiency. The Junkers J 1 (1915) pioneered all-metal cantilever wings without external bracing, while the 1930s saw retractable landing gear and slotted flaps for better low-speed performance. NACA's early airfoil series (e.g., 4-digit, 1920s) optimized camber and thickness, reducing drag and influencing designs like the Boeing 247 (1933).^[73]

Modern Advancements

During World War II, advancements in wing design addressed the challenges of high-speed flight, particularly with the advent of jet propulsion. The Messerschmitt Me 262, the world's first operational jet fighter introduced in 1944, featured swept wings with an 18.5-degree sweep angle to delay the onset of compressibility effects and reduce drag at transonic speeds.^[74] This design was informed by earlier theoretical work on swept wings to mitigate shock wave formation, marking a pivotal shift toward aerodynamic configurations optimized for jet aircraft.^[75] Concurrently, laminar flow airfoils emerged as a key innovation, with the National Advisory Committee for Aeronautics (NACA) developing low-drag profiles that maintained smooth airflow over a larger portion of the wing surface to enhance efficiency. Aircraft like the North American P-51 Mustang incorporated these NACA 6-series airfoils, achieving up to 50% drag reduction in clean configurations compared to earlier designs, though practical benefits were limited by manufacturing tolerances and operational debris.^[76] In the jet age of the 1960s and 1970s, supercritical airfoils represented a major leap in transonic performance, pioneered by NASA researcher Richard T. Whitcomb. These airfoils featured a flatter upper surface and a rear-loaded camber to suppress shock waves and drag divergence, allowing commercial and military jets to cruise closer to the speed of sound with improved fuel efficiency.^[11] Tested on modified aircraft like the F-8 Crusader starting in 1971, the design influenced wide-body airliners and reduced transonic drag by up to 25% relative to conventional airfoils.^[77] By the 21st century, composite materials revolutionized wing construction for weight savings and structural integrity. The Boeing 787 Dreamliner, entering service in 2011, utilized carbon fiber-reinforced polymer composites for 50% of its airframe by weight, including the wings, which enabled a 20% improvement in fuel efficiency over predecessors through reduced weight and corrosion resistance.^[78] Supersonic aircraft designs in the mid-20th century introduced variable-geometry wings to balance low-speed lift and high-speed aerodynamics. The General Dynamics F-111 Aardvark, with its first flight in 1964, employed swing wings that varied sweep from 16 to 72.5 degrees, optimizing performance across subsonic and supersonic regimes and enabling Mach 2.5 dashes while maintaining short takeoff and landing capabilities.^[79] Later, stealth requirements drove blended wing-body configurations, as seen in the Northrop Grumman B-2 Spirit bomber, which achieved its maiden flight in 1989. This flying wing design integrated the fuselage seamlessly with highly swept wings to minimize radar cross-section, achieving low-observability while supporting intercontinental range and payload delivery.^[80] Recent decades have focused on drag mitigation and adaptive technologies to further enhance efficiency. Winglets, developed by NASA in the 1970s and first applied commercially by Boeing on the 747-400 in 1988, curve upward at wingtips to reduce induced drag from wingtip vortices, yielding 4-6% fuel savings on long-haul flights—equivalent to billions of gallons annually across the global fleet.^[81] In the 2010s, active flow control research advanced plasma actuators for boundary layer manipulation without moving parts. Dielectric barrier discharge (DBD) plasma actuators, tested on wing models, generate ionized airflow to delay separation and improve lift-to-drag ratios by up to 15% at high angles of attack, with NASA and AIAA studies demonstrating viability for future high-lift systems on subsonic transports.^[82] As of 2025, ongoing innovations include morphing wing technologies for adaptive aerodynamics. NASA's 2023-2025 tests on flexible trailing edges demonstrated up to 10% drag reduction during cruise by optimizing camber in real-time, paving the way for more efficient urban air mobility vehicles. Additionally, sustainable composites with recycled carbon fibers, as implemented in Airbus A350 updates by 2024, aim to reduce lifecycle emissions while maintaining structural performance.^[83]^[84]

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[PDF] Chapter 5: Aerodynamics of Flight - Federal Aviation Administration
If the wings have the same proportion and airfoil sections, a wing with a planform area of 200 square feet lifts twice as much at the same AOA as a wing with an ...Missing: delta aa.
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[PDF] a review of the planform effects on the low-speed aerodynamic ...
They p o s t u l a t e t h a t the triangular wing can be approximated by a series of rectangular planform wings of varying aspect ratio, the most forward wing ...
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[PDF] Improving Fan System Performance - A Sourcebook for Industry
The air is pressurized by the aerodynamic lift generated by the fan blades, much like a propeller and an airplane wing. Although they can sometimes be used ...
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[PDF] Horizontal-Axis Wind Turbine Wake Sensitivity to Different Blade ...
Two different wind turbine blade designs are proposed and modeled using a free-wake, vortex lattice method, the Code for Axial and Crossflow TUrbine ...
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https://ntrs.nasa.gov/api/citations/19810016532/downloads/19810016532.pdf
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Design of hydrofoil for the resistance improvement of planing boat ...
Jul 1, 2022 · At 8 m/s, the hydrofoil designed in this paper can reduce boat resistance by up to 30.74%.To analyze the principle of hydrofoil, the flow field ...
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[PDF] Aerodynamic study of the evolution of a Formula 1 front wing with ...
The car had inverted wings inside the sidepods, creating two venturi tunnels and generating downforce over the entire underside of the car. This design was ...
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[PDF] Aerodynamic analysis of the undertray of Formula 1 | UPCommons
Nov 11, 2016 · Ground effects turned the entire car into a large, inverted wing, using side skirts and underbody design to literally glue the car to the ...
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Overview of the DARPA Smart Wing Project - J. N. Kudva, 2004
Designing and testing shape memory alloy actuators for smart aircraft wings ... Progress in Bionic Deformable Wing of Aircraft Driven by Shape Memory Alloy.
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DelFly
DelFly is a tailless, agile robot controlled by flapping wings, capable of hovering, flying in any direction, and has a long flight time and range.DelFly Micro · The DelFly Project · DelFly Explorer · History of the DelFly projectMissing: ornithopter | Show results with:ornithopter
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(PDF) Design, Aerodynamics, and Vision-Based Control of the DelFly
Aug 7, 2025 · In this article, we discuss the DelFly project, in which we follow a top-down approach to ever smaller and more autonomous ornithopters.
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[PDF] The Integration of Bioplastics into the Aviation Industry
Mycelium has been identified as a remarkably sustainable material, due to its ability to feed from carbon-based waste stocks. Page 3. Declaration. I Kyle Davies ...
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Evaluating the Performance of Recycled Carbon Fibre Composites ...
Following this line, this work aims to apply the recycled carbon fibres obtained by the pyrolysis process to test the feasibility of building a wing spar for a ...
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X-51A Waverider > Air Force > Fact Sheet Display - AF.mil
The X-51A Waverider is an experimental, unmanned, hypersonic flight test demonstrator designed to ride its own shockwave and reach Mach 6. It is a technology ...
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[PDF] Reinforcing Structures in Avian Wing Bones - Dr. Marc A. Meyers
The bird wing consists of several main bones such as humerus ('upper arm'), radius and ulna ('forearm'), carpometacarpus to form the 'wrist' and 'hand' of the ...
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Bird Dissection | University of Puget Sound
The orientation of the upper arm (humerus) and forearm (radius and ulna) is much like that in reptiles, but the wrist and hand are fused, elongated, and ...
[40]
Skeleton - Fernbank Science Center
The radius and ulna form the support for the mid-wing. The outer wing or "hand" bones are highly fused for strength and feather support.
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Biology 2e, Biological Diversity, Vertebrates, Birds | OpenEd CUNY
Two types of flight feathers are found on the wings, primary feathers and secondary feathers (Figure). Primary feathers are located at the tip of the wing ...
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[PDF] Group Based Rigging of Realistically Feathered Wings - OAKTrust
bone and feather structure which can be seen in most flighted birds [Sibley 2000]. Bones: Bird wings are a modified forelimb, similar to the human arm: Scapula,.
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Insect Anatomy - Extension Entomology - Purdue University
An insect exoskeleton is composed of a hardened material called chitin ... The thorax is the middle body part to which the legs and wings are attached.
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[PDF] Insect Anatomy and Growth - Colorado Master Gardener
Wings – Insects may have one or two pairs of wings or no wings. The wings are attached to the latter two thorax segments. The wing venation (arrangement of the.
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Superphylum Ecdysozoa: Arthropods - OpenEd CUNY
Arthropods have an exoskeleton made principally of chitin—a waterproof, tough polysaccharide composed of N-acetylglucosamine. Phylum Arthropoda is the most ...Phylum Arthropoda · Morphology · Subphylum Crustacea
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[PDF] Design and Experiments of a Dragonfly-Inspired Robot
During hovering, dragonflies employ out-of-phase counter-stroking of the forewing and hindwing, mostly due to stability and vibration suppression purposes.
[47]
[PDF] Four Wing Flapping Micro Air Vehicles - Dragonflies or X-Wings?
The aerodynamic feats of dragonflies are well documented. However, human beings have created flying vehicles that do not mimic nature, e.g. helicopters and ...
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Avian Flight
However, unlike the pterosaur wing, the bird wing (shown above) is primarily supported by an elongated radius, ulna, and modified wrist bones (the ...
[49]
[PDF] Three-Dimensional Kinematics of Hummingbird Flight
The inverse of the duration of the wingbeat gave wingbeat frequency (f, Hz). ... to vary throughout the wingbeat cycle of hummingbirds, and this variation ...
[50]
[PDF] Anatomy and Histochemistry of Spread-Wing Posture in Birds. 3 ...
First, we wanted to quantify the presence of slow muscle fi- bers within muscles that we believe are associated with gliding and soaring behavior in albatrosses.
[51]
Flight speed and performance of the wandering albatross with ...
Mar 7, 2018 · Albatrosses and other large seabirds use dynamic soaring to gain sufficient energy from the wind to travel large distances rapidly and with ...
[52]
[PDF] A nondestructive method of calculating the wing area of insects
Mar 17, 2022 · Most insects engage in winged flight. Wing loading, that is, the ratio of body mass to total wing area, has been demonstrated to reflect flight ...
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[PDF] Design and Performance of Insect-Scale Flapping-Wing Vehicles
In this process, vehicle performance requirements are plotted against potential choices for thrust-to-weight ratio (T/W) and wing loading (W/S). The minimum ...
[54]
[PDF] Flapping Wing Micro Air Vehicles: An Analysis of the Importance of ...
It follows from the wing area-wing weight relationship that the weight of the wings will comprise a steadily increasing percentage of total body weight as ...
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Insect Flight: State of the Field and Future Directions - PMC
The evolution of flight in an early winged insect ancestral lineage is recognized as a key adaptation explaining the unparalleled success and ...
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[PDF] Diverse Adaptations of an Ancestral Gill: A Common Evolutionary ...
Oct 1, 2002 · that insects' wings most likely originated from one of expression in insect wings and crustacean gills (Figure the gills of ancestral ...
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[PDF] Origin and evolution of insect wings and their relation to ...
There is an indication in the fossil evidence that all these characters might have evolved already in the pre-flight wings (see following section on origin of ...
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The origin of birds - Understanding Evolution
Birds evolved from small carnivorous theropod dinosaurs, with Archaeopteryx being the first known bird. The ancestor of all living birds lived in the Late ...Missing: 150 | Show results with:150
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Evolution of Flight Muscle Contractility and Energetic Efficiency - PMC
Oct 9, 2020 · Fossil evidence indicates that birds evolved from small carnivorous dinosaurs during the late Jurassic era ∼150 Mya (Brusatte et al., 2015).
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[PDF] Birds and their Wing Shapes - Cornell Lab of Ornithology
However, these birds are much more dependent on wind currents than passive soaring birds. Examples of birds with this wing type are albatrosses, gulls, and.
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The Biomechanics of Flight - GEOL431 - Vertebrate Paleobiology
Thermal soaring: In order to avoid the shearing loads that would go with a high aspect ratio wing, they typically opt for shorter wings with slotted tips. (E.G ...Missing: eagle | Show results with:eagle
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Understanding of bat wing evolution takes flight - PubMed Central
Several morphological changes were required to derive the bat wing from its ancestral form, including increasing the membrane surface area between the digits ...
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The Three Solutions to Flight
THE THREE SOLUTIONS TO FLIGHT. Pterosaur, bat, and bird. Possibly the most amazing example of convergent evolution among vertebrates is the evolution of flight ...
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[PDF] Convergent Evolution
Two classic examples of convergence in vertebrates are: (1) the independent evolution of wings in birds, bats and pterosaurs, and (2) the overall similarity ...
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The World's First Combat Jet - Smithsonian Magazine
Sep 19, 2013 · Germany's Messerschmitt Me 262 was by far the fastest fighter of World War II. It was powered by jet engines, a new technology that was not always reliable.
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[PDF] the wind tunnel that Busemann's 1935 supersonic swept wing theory ...
The Me 262 had first flown i n 1942, and advanced versions incorporating wings w i t k sweep angles as high as 50' were studied (ref. 3). A 40' sweep version,.Missing: history | Show results with:history
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[PDF] A History of suction-Type Laminar-Flow control - NASA
development of laminar-flow airfoils in the late 1930s and early 1940s, the British flight tests of natural laminar-flow airfoils on the King Cobra and ...
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Where Are They Now: F-8 Supercritical Wing - NASA
Jul 10, 2015 · In the early 1960s, Richard T. Whitcomb, chief of the Transonic Aerodynamics Branch, Langley Research Center, Hampton, VA, conducted exploratory ...
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[PDF] 787 Dreamliner Difference - Boeing
Sep 17, 2024 · With an airframe comprised of 50% carbon fiber reinforced plastic and other composites, the 787 entered history as the. Boeing commercial ...
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General Dynamics F-111A Aardvark - Air Force Museum
An interesting feature of the aircraft was its variable-geometry wings. While in the air, the wings could be swept forward for takeoffs, landings or slow ...
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B-2 Spirit > Air Force > Fact Sheet Display - AF.mil
Its low-observable, or "stealth," characteristics give it the unique ability to penetrate an enemy's most sophisticated defenses and threaten its most valued, ...
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Winglets Save Billions of Dollars in Fuel Costs | NASA Spinoff
The technology typically produces a 4- to 6-percent fuel savings, which can translate to thousands of gallons of fuel saved per plane, per year.
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[PDF] DBD Plasma Actuators for Flow Control in Air Vehicles and Jet ...
Jan 7, 2011 · The majority of the research in the DBD actuators area has been focused on applications in external flows, particularly for wings and airframes, ...