Wingtip devices are intended to improve the efficiency of fixed-wing aircraft by reducing drag. Although there are several types of wing tip device, which function in different manners, their intended effect is always to reduce an aircraft's drag by partial recovery of the tip vortex energy. Wingtip devices can improve aircraft handling characteristics and enhance safety for following aircraft; such devices increase the effective aspect ratio of a wing without increasing the wingspan. Extending the span would lower lift-induced drag, but would increase parasitic drag and would require boosting the strength and weight of the wing. At some point, there is no net benefit from further increased span. There may be operational considerations that limit the allowable wingspan. Wingtip devices increase the lift generated at the wingtip and reduce the lift-induced drag caused by wingtip vortices, improving lift-to-drag ratio; this increases fuel efficiency in powered aircraft and increases cross-country speed in gliders, in both cases increasing range.
U. S. Air Force studies indicate that a given improvement in fuel efficiency correlates directly with the causal increase in the aircraft's lift-to-drag ratio; the initial concept dates back to 1897, when English engineer Frederick W. Lanchester patented wing end-plates as a method for controlling wingtip vortices. In the United States, Scottish-born engineer William E. Somerville patented the first functional winglets in 1910. Somerville installed the devices on his early monoplane designs. Vincent Burnelli received US Patent no: 1,774,474 for his "Airfoil Control Means" on August 26, 1930; the earliest-known implementation of a Hoerner-style downward-angled "wingtip device" on a jet aircraft was the so-called Lippisch-Ohren attributed to the Messerschmitt Me 163's designer Alexander Lippisch, first added to the M3 and M4 third and fourth prototypes of the Heinkel He 162A Spatz jet light fighter for evaluation. This was done in order to counteract the dutch roll characteristic the marked three degrees of dihedral angle for each wing panel that the original He 162 design's wings possessed.
As production of the Third Reich's chosen turbojet-powered emergency fighter was of prime importance at the start of 1945, disruption of the production line to make other types of changes to correct such a problem were not to have been available, the added wingtip devices became a standard feature of the 320 completed He 162A jet fighters built, with hundreds more He 162A airframes going unfinished by V-E Day. Following the end of World War II, Dr. Sighard F. Hoerner was a pioneer researcher in the field, having written a technical paper published in 1952 that called for drooped wingtips whose pointed rear tips focused the resulting wingtip vortex away from the upper wing surface. Drooped wingtips are called "Hoerner tips" in his honor. Gliders and light aircraft have made use of Hoerner tips for many years; the term "winglet" was used to describe an additional lifting surface on an aircraft, like a short section between wheels on fixed undercarriage. Richard Whitcomb's research in the 1970s at NASA first used winglet with its modern meaning referring to near-vertical extension of the wing tips.
The upward angle of the winglet, its inward or outward angle, as well as its size and shape are critical for correct performance and are unique in each application. The wingtip vortex, which rotates around from below the wing, strikes the cambered surface of the winglet, generating a force that angles inward and forward, analogous to a sailboat sailing close hauled; the winglet converts some of the otherwise-wasted energy in the wingtip vortex to an apparent thrust. This small contribution can be worthwhile over the aircraft's lifetime, provided the benefit offsets the cost of installing and maintaining the winglets. Another potential benefit of winglets is; those pose a hazard to other aircraft. Minimum spacing requirements between aircraft operations at airports are dictated by these factors. Aircraft are classified by weight because the vortex strength grows with the aircraft lift coefficient, thus, the associated turbulence is greatest at low speed and high weight, which produced a high angle of attack.
Winglets and wingtip fences increase efficiency by reducing vortex interference with laminar airflow near the tips of the wing, by'moving' the confluence of low-pressure and high-pressure air away from the surface of the wing. Wingtip vortices create turbulence, originating at the leading edge of the wingtip and propagating backwards and inboard; this turbulence'delaminates' the airflow over a small triangular section of the outboard wing, which destroys lift in that area. The fence/winglet drives the area where the vortex forms upward away from the wing surface, since the center of the resulting vortex is now at the tip of the winglet. Aircraft such as the Airbus A340 and the Boeing 747-400 use winglets while other designs such as versions of the Boeing 777 and the Boeing 747-8 have raked wingtips; the fuel economy improvement from winglets increases with the mission length. Blended winglets allow a steeper angle of attack reducing takeoff distance. Richard T. Whitcomb, an engineer at NASA's Langley Research Center, further developed Hoerner's concept in response to the sharp increase in the cost of fuel after the 1973 oil crisis.
With careful aeronautical design, he showed that angled and shaped winglets could maintain the same or lower bending moment with a smaller wingspan and
In a fixed-wing aircraft, the spar is the main structural member of the wing, running spanwise at right angles to the fuselage. The spar carries the weight of the wings while on the ground. Other structural and forming members such as ribs may be attached to the spar or spars, with stressed skin construction sharing the loads where it is used. There may be more than one spar in a none at all. However, where a single spar carries the majority of the forces on it, it is known as the main spar. Spars are used in other aircraft aerofoil surfaces such as the tailplane and fin and serve a similar function, although the loads transmitted may be different from those of a wing spar; the wing spar provides the majority of the weight support and dynamic load integrity of cantilever monoplanes coupled with the strength of the wing'D' box itself. Together, these two structural components collectively provide the wing rigidity needed to enable the aircraft to fly safely. Biplanes employing flying wires have much of the flight loads transmitted through the wires and interplane struts enabling smaller section and thus lighter spars to be used at the cost of increasing drag.
Some of the forces acting on a wing spar are: Upward bending loads resulting from the wing lift force that supports the fuselage in flight. These forces are offset by carrying fuel in the wings or employing wing-tip-mounted fuel tanks. Downward bending loads while stationary on the ground due to the weight of the structure, fuel carried in the wings, wing-mounted engines if used. Drag loads dependent on airspeed and inertia. Rolling inertia loads. Chordwise twisting loads due to aerodynamic effects at high airspeeds associated with washout, the use of ailerons resulting in control reversal. Further twisting loads are induced by changes of thrust settings to underwing-mounted engines; the "D" box construction is beneficial to reduce wing twisting. Many of these loads are reversed abruptly in flight with an aircraft such as the Extra 300 when performing extreme aerobatic manoeuvers. Early aircraft used spars carved from solid spruce or ash. Several different wooden spar types have been used and experimented with such as spars that are box-section in form.
Wooden spars are still being used in light aircraft such as its relatives. A disadvantage of the wooden spar is the deteriorating effect that atmospheric conditions, both dry and wet, biological threats such as wood-boring insect infestation and fungal attack can have on the component. Wood wing spars of multipiece construction consist of upper and lower members, called spar caps, vertical sheet wood members, known as shear webs or more webs, that span the distance between the spar caps. In modern times, "homebuilt replica aircraft" such as the replica Spitfires use laminated wooden spars; these spars are laminated from spruce or douglas fir. A number of enthusiasts build "replica" Spitfires that will fly using a variety of engines relative to the size of the aircraft. A typical metal spar in a general aviation aircraft consists of a sheet aluminium spar web, with "L" or "T" -shaped spar caps being welded or riveted to the top and bottom of the sheet to prevent buckling under applied loads. Larger aircraft using this method of spar construction may have the spar caps sealed to provide integral fuel tanks.
Fatigue of metal wing spars has been an identified causal factor in aviation accidents in older aircraft as was the case with Chalk's Ocean Airways Flight 101. The German Junkers J. I armoured fuselage ground-attack sesquiplane of 1917 used a Hugo Junkers-designed multi-tube network of several tubular wing spars, placed just under the corrugated duralumin wing covering and with each tubular spar connected to the adjacent one with a space frame of triangulated duralumin strips — in the manner of a Warren truss layout — riveted onto the spars, resulting in a substantial increase in structural strength at a time when most other aircraft designs were built completely with wood-structure wings; the Junkers all-metal corrugated-covered wing / multiple tubular wing spar design format was emulated after World War I by American aviation designer William Stout for his 1920s-era Ford Trimotor airliner series, by Russian aerospace designer Andrei Tupolev for such aircraft as his Tupolev ANT-2 of 1922, upwards in size to the then-gigantic Maksim Gorki of 1934.
A design aspect of the Supermarine Spitfire wing that contributed to its success was an innovative spar boom design, made up of five square concentric tubes that fitted into each other. Two of these booms were linked together by an alloy web, creating a lightweight and strong main spar. A version of this spar construction method is used in the BD-5, designed and constructed by Jim Bede in the early 1970s; the spar used in the BD-5 and subsequent BD projects was aluminium tube of 2 inches in diameter, joined at the wing root with a much larger internal diameter aluminium tube to provide the wing structural integrity. In aircraft such as the Vickers Wellington, a geodesic wing spar structure was employed, which had the advantages of being lightweight and able to withstand heavy battle damage with only partial loss of strength. Many modern aircraft use carbon fibre and Kevlar in their construction, ranging in size from large airliners to small h
A glider or sailplane is a type of glider aircraft used in the leisure activity and sport of gliding. This unpowered aircraft uses occurring currents of rising air in the atmosphere to remain airborne. Gliders are aerodynamically streamlined and are capable of gaining altitude and remaining airborne, maintaining forward motion. Gliders benefit from producing the least drag for any given amount of lift, this is best achieved with long, thin wings, a faired narrow cockpit and a slender fuselage. Aircraft with these features are able to soar - climb efficiently in rising air produced by thermals or hills. In still air, gliders can glide long distances at high speed with a minimum loss of height in between. Gliders have either skids or undercarriage. In contrast hang gliders and paragliders use the pilot's feet for the start of the launch and for the landing; these latter types are described in separate articles, though their differences from gliders are covered below. Gliders are launched by winch or aerotow, though other methods: auto tow and bungee, are used.
Some gliders do not soar and are engineless aircraft towed by another aircraft to a desired destination and cast off for landing. Military gliders are single-use only, are abandoned after landing, having served their purpose. Motor gliders are gliders with engines which can be used for extending a flight and in some cases, for take-off; some high-performance motor gliders may have an engine-driven retractable propeller which can be used to sustain flight. Other motor gliders have enough thrust to launch themselves before the engine is retracted and are known as "self-launching" gliders. Another type is the self-launching "touring motor glider", where the pilot can switch the engine on and off in flight without retracting their propellers. Sir George Cayley's gliders achieved brief wing-borne hops from around 1849. In the 1890s, Otto Lilienthal built gliders using weight shift for control. In the early 1900s, the Wright Brothers built gliders using movable surfaces for control. In 1903, they added an engine.
After World War I gliders were first built for sporting purposes in Germany. Germany's strong links to gliding were to a large degree due to post-WWI regulations forbidding the construction and flight of motorised planes in Germany, so the country's aircraft enthusiasts turned to gliders and were encouraged by the German government at flying sites suited to gliding flight like the Wasserkuppe; the sporting use of gliders evolved in the 1930s and is now their main application. As their performance improved, gliders began to be used for cross-country flying and now fly hundreds or thousands of kilometres in a day if the weather is suitable. Early gliders had the pilot sat on a small seat located just ahead of the wing; these were known as "primary gliders" and they were launched from the tops of hills, though they are capable of short hops across the ground while being towed behind a vehicle. To enable gliders to soar more than primary gliders, the designs minimized drag. Gliders now have smooth, narrow fuselages and long, narrow wings with a high aspect ratio and winglets.
The early gliders were made of wood with metal fastenings and control cables. Fuselages made of fabric-covered steel tube were married to wood and fabric wings for lightness and strength. New materials such as carbon-fiber, fiber glass and Kevlar have since been used with computer-aided design to increase performance; the first glider to use glass-fiber extensively was the Akaflieg Stuttgart FS-24 Phönix which first flew in 1957. This material is still used because of its high strength to weight ratio and its ability to give a smooth exterior finish to reduce drag. Drag has been minimized by more aerodynamic shapes and retractable undercarriages. Flaps are fitted to the trailing edges of the wings on some gliders to minimize the drag from the tailplane at all speeds. With each generation of materials and with the improvements in aerodynamics, the performance of gliders has increased. One measure of performance is the glide ratio. A ratio of 30:1 means that in smooth air a glider can travel forward 30 meters while losing only 1 meter of altitude.
Comparing some typical gliders that might be found in the fleet of a gliding club – the Grunau Baby from the 1930s had a glide ratio of just 17:1, the glass-fiber Libelle of the 1960s increased that to 39:1, modern flapped 18 meter gliders such as the ASG29 have a glide ratio of over 50:1. The largest open-class glider, the eta, has a span of 30.9 meters and has a glide ratio over 70:1. Compare this to the Gimli Glider, a Boeing 767 which ran out of fuel mid-flight and was found to have a glide ratio of 12:1, or to the Space Shuttle with a glide ratio of 4.5:1. Due to the critical role that aerodynamic efficiency plays in the performance of a glider, gliders have aerodynamic features found in other aircraft; the wings of a modern racing glider have a specially designed low-drag laminar flow airfoil. After the wings' surfaces have been shaped by a mold to great accuracy, they are highly polished. Vertical winglets at the ends of the wings are computer-designed to decrease drag and improve handling performance.
Special aerodynamic seals are used at the ailerons and elevator to prevent the flow of air through control surface gaps. Turbulator devices in the form of a zig-zag tape or multiple blow holes positioned in a span-wise line along the wing are used to trip laminar flow air into turbulent flow at a desired location on the wing; this flow control prevents the formation of laminar flow bubbles and ensures t
Schleicher ASW 19
The ASW 19 is a single-seat glider built by Alexander Schleicher GmbH & Co. It was designed as a Standard Class glider, but now competes in the Club Class; the ASW 19 is known for its pleasant handling and some clubs use it as a training glider. It was succeeded by the all-new Schleicher ASW 24. Schempp-Hirth metal air brakes are fitted on the upper surface of the wing, models received modified brakes with an additional panel due to the somewhat disappointing effectiveness; the wings are held in place with two main pins. Up to 80 kg of water ballast can be carried; the tail unit is of glassfibre/foam sandwich, the horizontal tailplane has a fixed stabilizer. The fibreglass fuselage is built without the honeycombs that were used on the ASW 15B and ASW 17, it has a winch hook, covered by the main wheel doors, an aerotow hook situated one foot from the nose. With the ASW 19b version, the maximum allowed amount of water ballast increased and the take-off weight can be raised to 454 kg. ASW 19B were delivered with an instrument panel that lifts with the canopy.
This feature can be retrofitted to older models. The ASW 19 Club is a version with a fixed unsprung monowheel and no water ballast carried. Only five were built for the Royal Air Force, where they were known as the Valiant TX.1. A single ASW 19 was fitted with a new wing profile featuring turbulator blow holes at the Technical University of Delft; this ASW 19X showed improved gliding capabilities with a best glide ratio of about 1:41. United KingdomRoyal Air Force France3 French Air Force Data from Jane's all the World's Aircraft 1980–81General characteristics Crew: 1 Capacity: 80 kg water ballast Length: 6.82 m Wingspan: 15 m Height: 1.45 m Wing area: 11 m2 Aspect ratio: 20.4 Airfoil: root: Wortmann FX-61-163.
The Office National d'Etudes et de Recherches Aérospatiales is the French national aerospace research centre. It is a public establishment with industrial and commercial operations, carries out application-oriented research to support enhanced innovation and competitiveness in the aerospace and defense sectors. ONERA was created in 1946 as "Office National d’Études et de Recherches Aéronautiques". Since 1963, its official name has been "Office National d’Études et de Recherches Aérospatiales". However, in January 2007, ONERA has been dubbed "The French Aerospace Lab" to improve its international visibility. ONERA’s historic roots are in the Paris suburb of Meudon, south of Paris; as early as 1877, this site hosted an aeronautical research center for military aerostats: Etablissement central de l’aérostation militaire. ONERA was created in May 1946 to relaunch aeronautics research, an activity that had gone into hibernation during the Second World War and the German occupation, its creation reflected the government’s decision to recover the large wind tunnel in Ötztal, Austria, in the French administrative zone, move it to France.
Today, ONERA’s extensive array of wind tunnels is one of its main assets. ONERA operates a world-class fleet of the largest in Europe; the S1MA wind tunnel at Modane-Avrieux, developing 88 MW of total power, is the world’s largest sonic wind tunnel. The Chairman and CEO of ONERA is appointed by the French Council of Ministers, acting on a proposal by the Minister of Defense. Since June 2014, the Chairman and CEO is Bruno Sainjon. ONERA is organized in eight geographic areas, it has about 2,000 employees, with scientists, as well as support staff. Three centers in the greater Paris area: Palaiseau, current headquarters Châtillon MeudonTwo centers in the Midi-Pyrenees region of southwest France: Toulouse, near the leading aeronautical engineering schools ISAE-Sup’Aéro and ENAC Fauga-Mauzac, south of Toulouse. Three other centers: Lille, northern France Salon-de-Provence, southern France, on the site of the Ecole de l’air flying school Modane-Avrieux, in the Savoy region of southeast France. ONERA is organized in four scientific branches: Fluid Energetics.
Wind tunnel testing is managed in the GMT department. Aerospace prospective depends on a specific department. Unlike NASA in the United States, ONERA is not an agency for space exploration. However, it carries out a wide range of research for space agencies, both CNES in France and the European Space Agency, as well as for the French defense agency, DGA. ONERA independently conducts its own long-term research to anticipate future technology needs, it focuses on scientific research, for example in aerodynamics for concrete applications on aircraft, the design of launchers and new defense technologies, such as drones or unmanned aerial systems. ONERA uses its research and innovation capabilities to support both French and European industry. ONERA has contributed to a number of landmark aerospace and defense programs in recent decades, including Airbus, Rafale, Falcon and Concorde. ONERA’s customer-partners include Airbus, Dassault Aviation and other major industry players. Innovative small businesses are encouraged to call on the expertise of ONERA’s scientists and engineers, to take advantage of technology transfer opportunities.
The company Tefal was created by two ONERA engineers, the inventors of the “non-stick pan”. These products were produced and sold by Tefal S. A., subsequently acquired by SEB ONERA Meudon – Châtillon – Palaiseau ONERA Lille ONERA Salon de Provence ONERA Fauga–Mauzac ONERA Toulouse ONERA Modane French space program CNES Aerospace Valley Official website
In aviation, V-speeds are standard terms used to define airspeeds important or useful to the operation of all aircraft. These speeds are derived from data obtained by aircraft designers and manufacturers during flight testing for aircraft type-certification testing. Using them is considered a best practice to maximize aviation safety, aircraft performance or both; the actual speeds represented by these designators are specific to a particular model of aircraft. They are expressed by the aircraft's indicated airspeed, so that pilots may use them directly, without having to apply correction factors, as aircraft instruments show indicated airspeed. In general aviation aircraft, the most used and most safety-critical airspeeds are displayed as color-coded arcs and lines located on the face of an aircraft's airspeed indicator; the lower ends of the green arc and the white arc are the stalling speed with wing flaps retracted, stalling speed with wing flaps extended, respectively. These are the stalling speeds for the aircraft at its maximum weight.
The yellow range is the range in which the aircraft may be operated in smooth air, only with caution to avoid abrupt control movement, the red line is the VNE, the never exceed speed. Proper display of V-speeds is an airworthiness requirement for type-certificated aircraft in most countries; the most common V-speeds are defined by a particular government's aviation regulations. In the United States, these are defined in title 14 of the United States Code of Federal Regulations, known as the Federal Aviation Regulations. In Canada, the regulatory body, Transport Canada, defines 26 used V-speeds in their Aeronautical Information Manual. V-speed definitions in FAR 23, 25 and equivalent are for designing and certification of airplanes, not for their operational use; the descriptions below are for use by pilots. These V-speeds are defined by regulations, they are defined with constraints such as weight, configuration, or phases of flight. Some of these constraints have been omitted to simplify the description.
Some of these V-speeds are specific to particular types of aircraft and are not defined by regulations. Whenever a limiting speed is expressed by a Mach number, it is expressed relative to the speed of sound, e.g. VMO: Maximum operating speed, MMO: Maximum operating Mach number. V1 is takeoff decision speed, it is the speed above which the takeoff will continue if an engine fails or another problem occurs, such as a blown tire. The speed will vary among aircraft types and varies according to factors such as aircraft weight, runway length, wing flap setting, engine thrust used and runway surface contamination, thus it must be determined by the pilot before takeoff. Aborting a takeoff after V1 is discouraged because the aircraft will by definition not be able to stop before the end of the runway, thus suffering a "runway overrun". V1 is defined differently in different jurisdictions: The US Federal Aviation Administration defines it as: "the maximum speed in the takeoff at which the pilot must take the first action to stop the airplane within the accelerate-stop distance.
V1 means the minimum speed in the takeoff, following a failure of the critical engine at VEF, at which the pilot can continue the takeoff and achieve the required height above the takeoff surface within the takeoff distance." Transport Canada defines it as: "Critical engine failure recognition speed" and adds: "This definition is not restrictive. An operator may adopt any other definition outlined in the aircraft flight manual of TC type-approved aircraft as long as such definition does not compromise operational safety of the aircraft." Getting to grips with aircraft performance. Flight Operations Support & Line Assistance. Airbus Customer Services. January 2002
An airfoil or aerofoil is the cross-sectional shape of a wing, blade, or sail. An airfoil-shaped body moved through a fluid process, produces an aerodynamic force; the component of this force perpendicular to the direction of motion is called lift. The component parallel to the direction of motion is called drag. Subsonic flight airfoils have a characteristic shape with a rounded leading edge, followed by a sharp trailing edge with a symmetric curvature of upper and lower surfaces. Foils of similar function designed with water as the working fluid are called hydrofoils; the lift on an airfoil is the result of its angle of attack and shape. When oriented at a suitable angle, the airfoil deflects the oncoming air, resulting in a force on the airfoil in the direction opposite to the deflection; this force can be resolved into two components: lift and drag. Most foil shapes require a positive angle of attack to generate lift, but cambered airfoils can generate lift at zero angle of attack; this "turning" of the air in the vicinity of the airfoil creates curved streamlines, resulting in lower pressure on one side and higher pressure on the other.
This pressure difference is accompanied by a velocity difference, via Bernoulli's principle, so the resulting flowfield about the airfoil has a higher average velocity on the upper surface than on the lower surface. The lift force can be related directly to the average top/bottom velocity difference without computing the pressure by using the concept of circulation and the Kutta-Joukowski theorem. A fixed-wing aircraft's wings and vertical stabilizers are built with airfoil-shaped cross sections, as are helicopter rotor blades. Airfoils are found in propellers, fans and turbines. Sails are airfoils, the underwater surfaces of sailboats, such as the centerboard and keel, are similar in cross-section and operate on the same principles as airfoils. Swimming and flying creatures and many plants and sessile organisms employ airfoils/hydrofoils: common examples being bird wings, the bodies of fish, the shape of sand dollars. An airfoil-shaped wing can create downforce on an automobile or other motor vehicle, improving traction.
Any object, such as a flat plate, a building, or the deck of a bridge, with an angle of attack in a moving fluid will generate an aerodynamic force perpendicular to the flow. Airfoils are more efficient lifting shapes, able to generate more lift than sized flat plates, to generate lift with less drag. A lift and drag curve obtained in wind tunnel testing is shown on the right; the curve represents an airfoil with a positive camber so some lift is produced at zero angle of attack. With increased angle of attack, lift increases in a linear relation, called the slope of the lift curve. At about 18 degrees this airfoil stalls, lift falls off beyond that; the drop in lift can be explained by the action of the upper-surface boundary layer, which separates and thickens over the upper surface at and past the stall angle. The thickened boundary layer's displacement thickness changes the airfoil's effective shape, in particular it reduces its effective camber, which modifies the overall flow field so as to reduce the circulation and the lift.
The thicker boundary layer causes a large increase in pressure drag, so that the overall drag increases near and past the stall point. Airfoil design is a major facet of aerodynamics. Various airfoils serve different flight regimes. Asymmetric airfoils can generate lift at zero angle of attack, while a symmetric airfoil may better suit frequent inverted flight as in an aerobatic airplane. In the region of the ailerons and near a wingtip a symmetric airfoil can be used to increase the range of angles of attack to avoid spin–stall, thus a large range of angles can be used without boundary layer separation. Subsonic airfoils have a round leading edge, insensitive to the angle of attack; the cross section is not circular, however: the radius of curvature is increased before the wing achieves maximum thickness to minimize the chance of boundary layer separation. This moves the point of maximum thickness back from the leading edge. Supersonic airfoils are much more angular in shape and can have a sharp leading edge, sensitive to angle of attack.
A supercritical airfoil has its maximum thickness close to the leading edge to have a lot of length to shock the supersonic flow back to subsonic speeds. Such transonic airfoils and the supersonic airfoils have a low camber to reduce drag divergence. Modern aircraft wings may have different airfoil sections along the wing span, each one optimized for the conditions in each section of the wing. Movable high-lift devices and sometimes slats, are fitted to airfoils on every aircraft. A trailing edge flap acts to an aileron. A laminar flow wing has a maximum thickness in the middle camber line. Analyzing the Navier–Stokes equations in the linear regime shows that a negative pressure gradient along the flow has the same effect as reducing the speed. So with the maximum camber in the middle, maintaining a laminar flow over a larger percentage of the wing at a higher cruising speed is possible. However, some surface contamination will disrupt the laminar flow. For example, with rain on the wing, the flow will be turbulent.
Under certain conditions, insect debris on the wing will cause the loss of small regions of laminar f