Piper J-3 Cub
The Piper J-3 Cub is an American light aircraft, built between 1937 and 1947 by Piper Aircraft. The aircraft has a simple, lightweight design which gives it good low-speed handling properties and short-field performance; the Cub is Piper Aircraft's most-produced model, with nearly 20,000 built in the United States. Its simplicity and popularity invokes comparisons to the Ford Model T automobile; the aircraft is a strut-braced monoplane with a large-area rectangular wing. It is most powered by an air-cooled, flat-4 piston engine driving a fixed-pitch propeller, its fuselage is a welded steel frame covered in seating two people in tandem. The Cub was intended as a trainer and had great popularity in this role and as a general aviation aircraft. Due to its performance, it was well suited for a variety of military uses such as reconnaissance and ground control, it was produced in large numbers during World War II as the L-4 Grasshopper. Many Cubs are still flying today. Notably, Cubs are prized as bush aircraft.
The aircraft's standard chrome yellow paint has come to be known as "Cub Yellow" or "Lock Haven Yellow". The Taylor E-2 Cub first appeared in 1930, built by Taylor Aircraft in Pennsylvania. Sponsored by William T. Piper, a Bradford industrialist and investor, the affordable E-2 was meant to encourage greater interest in aviation. In 1930, the company went bankrupt, with Piper buying the assets, but keeping founder C. Gilbert Taylor on as president. In 1936, an earlier Cub was altered by employee Walter Jamouneau to become the J-2 while Taylor was on sick leave.. When he saw the redesign, Taylor was so incensed. Piper, had encouraged Jamouneau's changes and hired him back. Piper bought Taylor's share in the company, paying him $250 per month for three years. Although sales were slow, about 1,200 J-2s were produced before a fire in the Piper factory, a former silk mill in Bradford, ended its production in 1938. After Piper moved his company from Bradford to Lock Haven, PA; the changes amounted to integrating the vertical fin of the tail into the rear fuselage structure and covering it with each of the fuselage's sides, changing the rearmost side window's shape to a smoothly curved half-oval outline and placing a true steerable tailwheel at the rear end of the J-2's leaf spring-style tailskid, linked for its steering function to the lower end of the rudder with springs and lightweight chains to either end of a double-ended rudder control horn.
Powered by a 40 hp engine, in 1938, it sold for just over $1,000. A number of different air-cooled engines, most of flat-four configuration, were used to power J-3 Cubs, resulting in differing model designations for each type: the J3C models used the Continental A series, the J3F used the Franklin 4AC, the J3L used the Lycoming O-145. A few examples, designated J3P, were equipped with Lenape Papoose 3-cylinder radial engines; the outbreak of hostilities in Europe in 1939, along with the growing realization that the United States might soon be drawn into World War II, resulted in the formation of the Civilian Pilot Training Program. The Piper J-3 Cub became the primary trainer aircraft of the CPTP and played an integral role in its success, achieving legendary status. About 75% of all new pilots in the CPTP were trained in Cubs. By war's end, 80% of all United States military pilots had received their initial flight training in Piper Cubs; the need for new pilots created an insatiable appetite for the Cub.
In 1940, the year before the United States' entry into the war, 3,016 Cubs had been built. Prior to the United States entering World War II, J-3s were part of a fund-raising program to support the United Kingdom. Billed as a Flitfire, a Piper Cub J3 bearing Royal Air Force insignia was donated by W. T. Piper and Franklin Motors to the RAF Benevolent Fund to be raffled off. Piper distributors nationwide were encouraged to do the same. On April 29, 1941, all 48 Flitfire aircraft, one for each of the 48 states that made up the country at that time, flew into La Guardia Field for a dedication and fundraising event which included Royal Navy officers from the battleship HMS Malaya, in New York for repairs, as honored guests. At least three of the original Flitfires have been restored to their original silver-doped finish; the Piper Cub became a familiar sight. First Lady Eleanor Roosevelt took a flight in a J-3 Cub, posing for a series of publicity photos to help promote the CPTP. Newsreels and newspapers of the era featured images of wartime leaders, such as Generals Dwight Eisenhower, George Patton and George Marshall, flying around European battlefields in Piper Cubs.
Civilian-owned Cubs joined the war effort as part of the newly formed Civil Air Patrol, patrolling the Eastern Seaboard and Gulf Coast in a constant search for German U-boats and survivors of U-boat attacks. Piper developed a military variant, variously designated as the O-59, L-4 and NE; the L-4 Grasshopper was mechanically identical to the J-3 civilian Cub, but was distinguishable by the use of a Plexiglas greenhouse skylight and rear windows for improved visibility, much like the Taylo
The Lycoming O-540 is a family of air-cooled six-cylinder, horizontally opposed fixed-wing aircraft and helicopter engines of 541.5 cubic inch displacement, made by Lycoming Engines. The engine is a six-cylinder version of the four-cylinder Lycoming O-360; these engines produce 230 to 350 horsepower. They are installed on a large number of different aircraft types, their main competitive engine is the Continental IO-550 series. The AEIO version was developed for high-performance competition aerobatics aircraft. Starting at 260 hp, the power was improved to 300 hp; the AEIO-540 family has achieved tremendous results in competition aircraft such as the Extra 300, CAP 232, Zivko Edge 540. All engines have an additional prefix preceding the 540 to indicate the specific configuration of the engine; the numerous engine suffixes denote different accessories such as different manufacturers' carburetors, or different magnetos. O-540 Standard, direct-drive aspirated Opposed engine, equipped with a carburetorIO-540 Normally aspirated engine with fuel InjectionAEIO-540 Normally aspirated engine with fuel injection and inverted lubrication for Aerobatic useTIO-540 Turbocharged and fuel-injected TEO-540 Turbocharged with independent Electronic sensors and fuel injection controls for each cylinder, which manage detonation and exhaust gas temperature, make the engine compatible with a range of fuel compositions, producing up to 350 horsepower.
LTIO-540 Left-hand rotation, fuel-injected. Retrieved: 1 September 2008. Type: Six-cylinder air-cooled horizontally opposed engine Bore: 5.125 in Stroke: 4.375 in Displacement: 541.5 in³ Dry weight: 438 lb Valvetrain: Two overhead valves per cylinder Fuel system: Fuel injection Fuel type: 100 octane rating gasoline Cooling system: Air-cooled Power output: 300 hp at 2,700 rpm at sea level Specific power: 0.55 hp/in³ Compression ratio: 8.7:1 Power-to-weight ratio: 0.68 hp/lb Related development Lycoming IO-580 Comparable engines Continental O-520 Continental IO-550Related lists List of aircraft engines 540 Series homepage at Lycoming.com
The Piper PA-11 Cub Special is a later-production variant of the J-3 Cub manufactured by Piper Aircraft. The airframe is the same as a J-3, but the engine mount is angled lower, with the windshield sloped at a shallower angle. Both seats were moved back, solo flying was from the front seat. Early PA-11s had a Continental A65-8 engine, while the ones had the option of a Continental C90-8. On the early PA-11s, the fuselage was painted with a metallic blue on the lower half the rest being Lock Haven Yellow; the PA-11s were all yellow with a simple brown stripe. With a gross weight of 1,220 lb and average empty weight of 750 lb, the PA-11 is a light enough to perform well, yet heavy enough to maneuver in more wind than the lighter J-3 Cub; the PA-11 is capable of short takeoffs and landings, yet has a respectable cruising speed for its configuration. Given that the PA-11 falls into the modern day category of light sport aircraft, it is a popular airplane to acquire and commands a premium price; the PA-11 was one of the first aircraft to be used in experiments with the nose wheel configuration.
Although its original design is intended to be a tail-dragger, a modification was created to mount a nose wheel. The nose wheel is attached to the two rear engine mounts by y-shaped steel tubes attached to a steel tube with a shaft that slides with the wheel. Cables run underneath the belly directly from fixtures on the rudder pedals to the nose wheel shaft; this gave the ability to steer by pivoting the nose wheel shaft with the rudder pedals. The shock system consisted of six circular bungee cords, sometimes four for softer landings, located on either side of the nose wheel shaft to ears on the top tube and the bottom shaft connected to the wheel. For the aircraft to balance properly with the nose wheel, the main gear was flipped around so that the center of balance would move forward; the pilot would sit in the front seat for added stability. Most PA-11s in service today retain the original tail wheel undercarriage layout. Numbers of Cub Specials have been converted for flight operation using floats.
The PA-11 formed the basis for the next evolution in the Cub series, the PA-18 Super Cub, which shares many features. Piper PA-11 Cub Special Two-seat light aircraft, powered by a 65 hp Continental A65-8 piston engine L-18B Military version of the PA-11 Cub Special, powered by a 95 hp Continental C90-8F piston engine, 105 built and delivered to Turkey, under the Military Assistance Program IsraelIsraeli Air Force Turkey Data from Piper Aircraft and Their Forerunners General characteristics Crew: 1 Capacity: 1 passenger Payload: 470 lbs Length: 22 ft 4 in Wingspan: 35 ft 2 in Height: 6 ft 8 in Empty weight: 750 lb Useful load: 470 lb Loaded weight: 1,220 lb Powerplant: × 1 Continental C90-8, 90 hp eachPerformance Maximum speed: 112 mph Cruise speed: 100 mph Stall speed: 40 mph Range: 350 miles Service ceiling: 16,000 ft Notes Bibliography Media related to Piper PA-11 Cub Special at Wikimedia Commons
Piper Aircraft, Inc. is a manufacturer of general aviation aircraft, located at the Vero Beach Municipal Airport in Vero Beach, United States and owned since 2009 by the Government of Brunei. In the late 20th century it was considered to be one of the "Big Three" in the field of general aviation manufacturing, along with Beechcraft and Cessna. Between its founding in 1927 and the end of 2009, the company produced 144,000 aircraft in 160 certified models, of which 90,000 are still flying; the company was founded as the Taylor Brothers Aircraft Manufacturing Company in September 1927 by Clarence Gilbert Taylor and Gordon A. Taylor in Rochester, New York; the company was renamed Taylor Brothers Aircraft Corporation in April 1928, shortly before Gordon Taylor died in an aircraft accident on April 24, 1928. The company was enticed to move to Bradford, with the promise of larger facility and investment capital from local businessmen, including an initial investment of $400 from local oil industry engineer William T. Piper.
The move was completed in September 1929. In late 1930, the company filed for bankruptcy and William T. Piper purchased the assets of the company for $761. Reorganized as the Taylor Aircraft Company, Piper took control of the firm when he assumed the position of corporate secretary-treasurer, although he retained C. G. Taylor in the role of president. Piper called the "Henry Ford of Aviation" believed a simple-to-operate, low-cost, private airplane would flourish in the darkest depths of the Great Depression; this aircraft was the E-2 Cub. In December 1935, after a series of clashes, William Piper bought out C. G. Taylor, who left the company and went on to form the Taylorcraft Aircraft Company. On March 16, 1937 a fire destroyed the Bradford factory and the company relocated to an abandoned silk mill in Lock Haven, Pennsylvania. In 1937, it was renamed Piper Aircraft Corporation. Piper continued operations in Lock Haven throughout World War II, building military versions of its J-3 Cub as the L-4 Grasshopper.
A total of 5,941 powered aircraft were built by the company for the US armed forces during the war, as well as training gliders, aircraft components for other manufacturers, but its main contribution to the war effort was in the fabrication of steel masts for mounting radar antennas. In 1946, the company opened a new factory in Ponca City and transferred production of the Cub from Lock Haven; that year, Piper led the American industry in light aircraft production. 7,800 of the 35,000 civil aircraft built in the United States that year were Pipers, but a strike led to a shortage of steel tubing, interrupting production, 1,900 workers had to be suspended as a result. The following year, the postwar general aviation boom ended. Piper's output reached 3,500 aircraft, less than half its 1946 total, the company suffered an operating loss of more than $560,000; the board of directors replaced William Piper with a former Chrysler executive. Under Shriver, the product line was expanded with the introduction of the PA-14 Family Cruiser and PA-15 Vagabond.
Piper introduced the "Taxicub" light charter concept at 52 distributors. In 1948, with two thirds of its workforce laid off, Piper only lost $75,000, but it found itself no longer the leader in a shrinking market, falling behind Cessna, which itself only delivered 1,600 aircraft. At the end of 1948, Piper bought the Stinson Aircraft Company for $3 million and Shriver left the company; the outbreak of the Korean War in 1950 helped to stimulate production at Piper, which again won large orders for military versions of the Cub. William Piper regained control of the company the same year, the decision was made to develop a twin-engine aircraft; the company investigated producing the Baumann Brigadier, but decided to develop a Stinson design, which became the PA-23 Apache. In its business planning following the war, it became clear the Lock Haven facility would not support larger manufacturing efforts, in 1955 it acquired rights to property at the Vero Beach Municipal Airport. Vero Beach was used as a center for design work under Fred Weick, with the first aircraft developed there being Piper's first agricultural aircraft, the PA-25 Pawnee, announced in 1958 and entering production the following year at Lock Haven.
In 1960, the line of Piper aircraft consisted of an agricultural- and two-passenger variants of the Super Cub, the Caribbean and Tri-Pacer, two versions of the PA-24 Comanche, the Pawnee, the Apache and its new larger derivative the Aztec. The following year, the PA-28 Cherokee was the first type to enter production at the new Vero Beach factory; the Cherokee replaced the Tri-Pacer and Colt, which ended their production runs in 1961 and 1964 respectively. By the part of the decade, Vero Beach was building 7,000 Cherokees per year. In September 1964, Piper flew the prototype of its new PA-31 Navajo cabin-class twin for the first time, after two-and-a-half years of development. In 1969, the Piper family agreed to sell Piper Aircraft to Bangor Punta Corporation, which started an eight-year court battle with the losing bidder, Chris-Craft Industries, culminating in a Supreme Court decision in 1977. Piper discussed a merger with Swearingen but the deal was not completed; the Lock Haven facility was nearly destroyed in 1972 when torrential rains from Hurricane Agnes caused the Susquehanna River to flood in June.
The manufacturing plant was flooded to a depth of 16 feet destroying about 100 aircraft and causing an estimated $23 million in damage. Much of the tooling necessary for production of several designs, including the Aztec and Comanche, was destroyed, the Piper PA-31T Cheyenne program receive
The Taylor Cub was designed by C. Gilbert Taylor as a small and simple utility aircraft, evolved from the Arrowing Chummy, it is the forefather of the popular Piper J-3 Cub, total production of the Cub series was 23,512 aircraft. In 1930 with C. G. Taylor as Chief Engineer the Taylor Aircraft Company embarked on the production of a two-seat tandem low-powered aircraft, designated the Taylor Cub; the Cub featured a design with wings mounted high on the fuselage, an open cockpit, fabric-covered tubular steel fuselage and wooden wings which used the USA-35B airfoil. It was powered by a 20 horsepower Brownback "Tiger Kitten" engine. Since the young offspring of the tiger is called a cub, Taylor's accountant, Gilbert Hadrel, was inspired to name the little airplane "The Cub"; the "Tiger Kitten" engine was not strong enough to power the Cub. On September 12, 1930, a test flight of the Taylor Cub ended abruptly when the aircraft ran out of runway. In October, a Salmson AD-9 radial engine produced in France was fitted to the Cub giving good performance, but it was expensive to maintain.
In February 1931, Taylor introduced an improved Cub airframe, powered by the newly developed Continental Motors 37 horsepower A-40 engine. The new Taylor E-2 Cub was awarded Category 2 or "Memo" certificate 2-358 on June 15, 1931 and licensed by the U. S. Department of Commerce for manufacture. Twenty-two E-2 Cubs were sold during 1931, retailing for $1,325. Taylor E-2 Prototype first flown in September 1930 with a 20 hp Brownbach Tiger Kitten engine, engine changed to a 40 hp Salmson D-9 radial in October 1930. Although the D-9 had enough power for the E-2 it was expensive and was built to metric sizes which would have caused maintenance problems. Taylor E-2 Cub Production variant of the E-2 with the Continental A-40-2 or in production the improved A-40-3 engine, produced from 1931 to 1936. Taylor F-2 Persistent troubles with the early A-40 engines on the E-2 led to a search for other suitable powerplants. First choice was the Aeromarine AR-3-40, a three-cylinder air-cooled radial engine which produced 40 horsepower at 2050 RPM.
The Aeromarine-powered Cub was designated the F-2. One float-equipped aircraft was designated F-2S. Approved Type Certificate A-525 was awarded on February 16, 1934, the F-2 had an initial price of $1495. 33 were made. Taylor G-2 In another search for a replacement for the A-40, Taylor went to the extreme of designing and building his own 35-40 horsepower engine; this was fitted to serial number 149, registration X14756. The Taylor-powered Cub was designated the G-2. No information was published about the one-off engine, no details are known today. With a new engine, this aircraft would become the Taylor H-2. Taylor H-2 The G-2 Cub was re-engined with a 35 horsepower Szekely SR-3-35, another three-cylinder air-cooled radial engine which produced 35 hp at 1750 RPM; the Szekely-powered Cub was designated the H-2. Approved Type Certificate A-572 was awarded on May 28, 1935. Three F-2's were converted for a total of four H-2's. In 1937, Beverly Dodge and a passenger set the women's altitude record in a Szekely powered Taylor H-2.
Taylor J-2 The Taylor J-2 was the final iteration of the Cub series under the Taylor name, before the company renamed itself to Piper Aircraft in November 1937, production had moved from Bradford to Lock Haven, Pennsylvania earlier in 1937 following the destruction of the Bradford factory by fire. Taylorcraft A When C. G. Taylor broke with Taylor Aircraft and founded the new company Taylor-Young, its first aircraft known as the Taylor-Young Model A, was little more than a refined Cub with side-by-side seating. Taylor-Young soon changed its name to Taylorcraft and the Model A became the Taylorcraft A, first in the Taylorcraft series. NicaraguaNicaraguan Air Force - One aircraft Data from General characteristics Crew: 1 Capacity: 1 passenger Length: 22 ft 6 in Wingspan: 35 ft 2 in Height: 6 ft 6 in Wing area: 184 ft² Empty weight: 510 lb Max. Takeoff weight: 970 lb Powerplant: 1 × Continental A-40-2, 35 hp Performance Maximum speed: 61 kt Cruise speed: 54 kt Range: 156 nm Service ceiling: 12,000 ft Rate of climb: 400 ft/min Wing loading: 6 lb/ft² Power/mass: 25 lb/hp Related development Taylor J-2 Cub Piper J-3 Cub Taylor Taylor BirdAircraft of comparable role and era Aeronca C-2 Notes SourcesBowers, Peter M..
Piper Cubs. McGraw Hill. ISBN 0-8306-2170-9. "The Piper Cub" by Roger Guillemette, US Centennial of Flight Commission, retrieved December 6, 2005 "Szekely SR-3 L" Old Rhinebeck Aerodrome, retrieved December 6, 2005 Taylor E-2 Cub - Holcomb's Aerodrome Taylor Cub - A version of the original E-2 Cub manufactured by the Taylorcraft Company ATC 455, the FAA type certificate data sheet for the Taylor E-2
Piper PA-18 Super Cub
The Piper PA-18 Super Cub is a two-seat, single-engine monoplane. Introduced in 1949 by Piper Aircraft, it was developed from the Piper PA-11, traces its lineage back through the J-3 to the Taylor E-2 Cub of the 1930s. In close to 40 years of production, over 9,000 were built. Super Cubs are found in roles such as bush flying, banner towing and glider towing. While based on the design of the earlier Cubs, the addition of an electrical system, a more powerful engine, made it a different flying experience. Although the "standard" Super Cub was fitted with a 150-horsepower Lycoming engine, it is not uncommon to see them equipped with a 160-horsepower O-320-B2B, or 180 horsepower Lycoming O-360 powerplant; the high-lift wing and powerful engine made the Super Cub a prime candidate for conversion to either floatplane or skiplane. In addition, the PA-18A was produced for applying either dry chemical or liquid spray; the Super Cub retained the basic "tube" structure of the earlier J-3 Cub. The first true "Super" Cubs had flaps, dual fuel tanks, an O-235 Lycoming engine producing about 108 hp.
However, a 90 hp Continental variant without flaps and an optional second wing tank was available. Their empty weight was, on the average, 800–1000 pounds with a gross weight of 1,500 lb; these Cubs would land in about 300 feet. The Super Cub is renowned for its ability to take off and land in short distances; the first Super Cubs were going to be offered with a unique four-wheel tandem main landing gear designed for landing and takeoff from rough terrain, but this was replaced with conventional landing gear. The O-290 Lycoming powered Cubs would take off in about 200 feet; the landing distance remained the same at 300 feet using flaps. With the use of the Lycoming O-320 at 150–160 hp, the Cub's allowable gross weight increased to 1,750 lb while retaining the capability of a mere 200 feet required for takeoff; the PA-18 has developed a dedicated following in the bush-flying community, many modifications have been developed for it, to the point where it is quite rare to find an original stock Super Cub.
Modifications include extended baggage compartments, external luggage pods, fuel pods, lumber racks for carrying construction materials into unimproved bush runways. The removal of header tanks, larger 24 or 30 gallon wing fuel tanks, extended main landing gear for better ground clearance of the propeller, strengthened tailwheel springs, the addition of a small third passenger seat in the luggage area and lightweight generators and starters. Various different mount areas for the battery, various different tailfin shapes to increase surface area, lengthened flaps, various wingtip designs, vortex generators on the leading edge of the wings, movement of the electrical panel from the right wing root to the dashboard to reduce fire hazard during a crash, the addition of a constant-speed propeller. Above all, the most common modification is the addition of "bush wheels", soft, low pressure balloon-tires designed to absorb impacts from rocks and boulders, to not sink into sand or other soft surfaces, ideal for off-runway landings.
PA-18 Super Cub Prototype and production variant powered by a 95 hp Continental C-90-8F piston engine, sometimes known as the PA-18-95. PA-18-105 Super Cub Production variant fitted with a 105 hp Lycoming O-235-C1 piston engine and larger tailplane. PA-18-105 Special Special variant built in 1952 and 1953 for the Civil Air Patrol as a trainer with horn-balanced elevators and provision for seat parachutes. PA-18-125 Super Cub Variant to replace the PA-18-95 with flaps and horn-balanced elevators and a 125 hp Lycoming O-290-D piston engine and either wood or metal controllable-pitch propeller. PA-18-135 Super Cub Variant with a 135 hp Lycoming O-290-D piston engine and fitted with two wing tanks as standard. PA-18-150 Super Cub 1954 variant with a 150 hp Lycoming O-320. PA-18-180 Super Cub Experimental variant with a 180 hp Lycoming O-360 engine, one built in 1980 by Piper. Other aircraft have been re-engined under a Supplemental Type Certificate. PA-18A Designation for production agricultural aircraft, including cropdusters and sprayer variants and incorporating a different rear fuselage profile to allow fitting of a hopper-tank in the rear seat position.
PA-18S Designation for production aircraft fitted with floats. PA-18AS Designation of a small number of agricultural aircraft fitted with floats. PA-19 Super Cub Original designation of the military variant of the PA-18, only three built and all subsequent military production were designated as PA-18s. Aeromod Loadstar Model 100 Biplane conversion of Super Cub, powered by 135 hp O-290-D engine, designed for improved capability from high-altitude airfields. SAFAT 01 A Sudanese development / copy built by the SAFAT Aviation Complex at Khartoum. L-18C Super Cub Military designation of the PA-18 Super Cub for the United States Army, powered by a 95 hp Continental C90-8F piston engine, 838 delivered, at least 156 of which were delivered to other nations under MDAP. YL-21 Super Cub Two Super Cub 135s for evaluation by the United States Army. L-21A Super Cub Military designation of the Super Cub 125, powered by a 125 hp Avco Lycoming 0-290-II piston engine, 150 delivered. L-21B Super Cub Military designation of the S
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