Aeronautics is the science or art involved with the study, design, and manufacturing of air flight capable machines, and the techniques of operating aircraft and rockets within the atmosphere. The British Royal Aeronautical Society identifies the aspects of "aeronautical Art, Science and Engineering" and "the profession of Aeronautics (which expression includes Astronautics)." 
While the term originally referred solely to operating the aircraft, it has since been expanded to include technology, business, and other aspects related to aircraft. The term "aviation" is sometimes used interchangeably with aeronautics, although "aeronautics" includes lighter-than-air craft such as airships, and includes ballistic vehicles while "aviation" technically does not.
Attempts to fly without any real aeronautical understanding have been made from the earliest times, typically by constructing wings and jumping from a tower with crippling or lethal results.
Wiser investigators sought to gain some rational understanding through the study of bird flight. An early example appears in ancient Egyptian texts. Later medieval Islamic scientists also made such studies. The founders of modern aeronautics, Leonardo da Vinci in the Renaissance and Cayley in 1799, both began their investigations with studies of bird flight.
Man-carrying kites are believed to have been used extensively in ancient China. In 1282 the European explorer Marco Polo described the Chinese techniques then current. The Chinese also constructed small hot air balloons, or lanterns, and rotary-wing toys.
An early European to provide any scientific discussion of flight was Roger Bacon, who described principles of operation for the lighter-than-air balloon and the flapping-wing ornithopter, which he envisaged would be constructed in the future. The lifting medium for his balloon would be an "aether" whose composition he did not know.
In the late fifteenth century, Leonardo da Vinci followed up his study of birds with designs for some of the earliest flying machines, including the flapping-wing ornithopter and the rotating-wing helicopter. Although his designs were rational, they were not based on particularly good science. Many of his designs, such as a four-person screw-type helicopter, have severe flaws. He did at least understand that "An object offers as much resistance to the air as the air does to the object." (Newton would not publish the Third law of motion until 1687.) His analysis led to the realisation that manpower alone was not sufficient for sustained flight, and his later designs included a mechanical power source such as a spring. Da Vinci's work was lost after his death and did not reappear until it had been overtaken by the work of George Cayley.
The modern era of lighter-than-air flight began early in the 17th century with Galileo's experiments in which he showed that air has weight. Around 1650 Cyrano de Bergerac wrote some fantasy novels in which he described the principle of ascent using a substance (dew) he supposed to be lighter than air, and descending by releasing a controlled amount of the substance. Francesco Lana de Terzi measured the pressure of air at sea level and in 1670 proposed the first scientifically credible lifting medium in the form of hollow metal spheres from which all the air had been pumped out. These would be lighter than the displaced air and able to lift an airship. His proposed methods of controlling height are still in use today; by carrying ballast which may be dropped overboard to gain height, and by venting the lifting containers to lose height. In practice de Terzi's spheres would have collapsed under air pressure, and further developments had to wait for more practicable lifting gases.
From the mid-18th century the Montgolfier brothers in France began experimenting with balloons. Their balloons were made of paper, and early experiments using steam as the lifting gas were short-lived due to its effect on the paper as it condensed. Mistaking smoke for a kind of steam, they began filling their balloons with hot smoky air which they called "electric smoke" and, despite not fully understanding the principles at work, made some successful launches and in 1783 were invited to give a demonstration to the French Académie des Sciences.
Meanwhile, the discovery of hydrogen led Joseph Black in c. 1780 to propose its use as a lifting gas, though practical demonstration awaited a gas tight balloon material. On hearing of the Montgolfier Brothers' invitation, the French Academy member Jacques Charles offered a similar demonstration of a hydrogen balloon. Charles and two craftsmen, the Robert brothers, developed a gas tight material of rubberised silk for the envelope. The hydrogen gas was to be generated by chemical reaction during the filling process.
The Montgolfier designs had several shortcomings, not least the need for dry weather and a tendency for sparks from the fire to set light to the paper balloon. The manned design had a gallery around the base of the balloon rather than the hanging basket of the first, unmanned design, which brought the paper closer to the fire. On their free flight, De Rozier and d'Arlandes took buckets of water and sponges to douse these fires as they arose. On the other hand, the manned design of Charles was essentially modern. As a result of these exploits, the hot-air balloon became known as the Montgolfière type and the hydrogen balloon the Charlière.
Charles and the Robert brothers' next balloon, La Caroline, was a Charlière that followed Jean Baptiste Meusnier's proposals for an elongated dirigible balloon, and was notable for having an outer envelope with the gas contained in a second, inner ballonet. On 19 September 1784, it completed the first flight of over 100 km, between Paris and Beuvry, despite the man-powered propulsive devices proving useless.
In an attempt the next year to provide both endurance and controllability, de Rozier developed a balloon having both hot air and hydrogen gas bags, a design which was soon named after him as the Rozière. The principle was to use the hydrogen section for constant lift and to navigate vertically by heating and allowing to cool the hot air section, in order to catch the most favourable wind at whatever altitude it was blowing. The balloon envelope was made of goldbeater's skin. The first flight ended in disaster and the approach has seldom been used since.
Sir George Cayley (1773-1857) is widely acknowledged as the founder of modern aeronautics. He was first called the "father of the aeroplane" in 1846 and Henson called him the "father of aerial navigation." He was the first true scientific aerial investigator to publish his work, which included for the first time the underlying principles and forces of flight.
In 1809 he began the publication of a landmark three-part treatise titled "On Aerial Navigation" (1809–1810). In it he wrote the first scientific statement of the problem, "The whole problem is confined within these limits, viz. to make a surface support a given weight by the application of power to the resistance of air." He identified the four vector forces that influence an aircraft: thrust, lift, drag and weight and distinguished stability and control in his designs.
He developed the modern conventional form of the fixed-wing aeroplane having a stabilising tail with both horizontal and vertical surfaces, flying gliders both unmanned and manned.
He introduced the use of the whirling arm test rig to investigate the aerodynamics of flight, using it to discover the benefits of the curved or cambered aerofoil over the flat wing he had used for his first glider. He also identified and described the importance of dihedral, diagonal bracing and drag reduction, and contributed to the understanding and design of ornithopters and parachutes.
Another significant invention was the tension-spoked wheel, which he devised in order to create a light, strong wheel for aircraft undercarriage.
Pedro Paulet, scientist born in the city of Arequipa, Peru in the year of 1874, was one of the first to experiment with propulsion rockets being considered the «Father of Modern Rocket» and by others as the «Father of Aeronautics Modern ». He developed plans for a "torpedo plane", which is why he is considered ahead of his time. When the internal explosion engines were invented, small enough to be able to propel a flying device with them, a race started between two flight possibilities: the lighter than the air (dirigibles) and the heavier than the air (aeroplanes) .
Aviation is the art or practice of aeronautics. Historically aviation meant only heavier-than-air flight, but nowadays it includes flying in balloons and airships.
Aeronautical science covers the practical theory of aeronautics and aviation, including operations, navigation, air safety and human factors.
A candidate pilot is likely to study for a qualification in aeronautical science.
Aeronautical engineering covers the design and construction of aircraft, including how they are powered, how they are used and how they are controlled for safe operation.
A major part of aeronautical engineering is aerodynamics, the science of passing through the air.
With the increasing activity in space flight, nowadays aeronautics and astronautics are often combined as aerospace engineering.
The science of aerodynamics deals with the motion of air and the way that it interacts with objects in motion, such as an aircraft.
The study of aerodynamics falls broadly into three areas:
Incompressible flow occurs where the air simply moves to avoid objects, typically at subsonic speeds below that of sound (Mach 1).
Compressible flow occurs where shock waves appear at points where the air becomes compressed, typically at speeds above Mach 1.
Transonic flow occurs in the intermediate speed range around Mach 1, where the airflow over an object may be locally subsonic at one point and locally supersonic at another.
A rocket or rocket vehicle is a missile, spacecraft, aircraft or other vehicle which obtains thrust from a rocket engine. In all rockets, the exhaust is formed entirely from propellants carried within the rocket before use. Rocket engines work by action and reaction. Rocket engines push rockets forwards simply by throwing their exhaust backwards extremely fast.
Rockets for military and recreational uses date back to at least 13th-century China. Significant scientific, interplanetary and industrial use did not occur until the 20th century, when rocketry was the enabling technology of the Space Age, including setting foot on the moon.
Rockets are used for fireworks, weaponry, ejection seats, launch vehicles for artificial satellites, human spaceflight and exploration of other planets. While comparatively inefficient for low speed use, they are very lightweight and powerful, capable of generating large accelerations and of attaining extremely high speeds with reasonable efficiency.
Chemical rockets are the most common type of rocket and they typically create their exhaust by the combustion of rocket propellant. Chemical rockets store a large amount of energy in an easily released form, and can be very dangerous. However, careful design, testing, construction and use minimizes risks.
Sir George Cayley is one of the most important people in the history of aeronautics. Many consider him the first true scientific aerial investigator and the first person to understand the underlying principles and forces of flight.
Media related to Aeronautics at Wikimedia Commons
A companion to the physical exhibition
Aerospace engineering is the primary field of engineering concerned with the development of aircraft and spacecraft. It has two major and overlapping branches: aeronautical engineering and astronautical engineering. Avionics engineering is similar, but deals with the electronics side of aerospace engineering.
Aeronautical engineering was the original term for the field. As flight technology advanced to include craft operating in outer space (astronautics), the broader term "aerospace engineering" has come into common use. Aerospace engineering, particularly the astronautics branch is often colloquially referred to as "rocket science".Aircraft pilot
An aircraft pilot or aviator is a person who controls the flight of an aircraft by operating its directional flight controls. Some other aircrew members, such as navigators or flight engineers, are also considered aviators, because they are involved in operating the aircraft's navigation and engine systems. Other aircrew members, such as flight attendants, mechanics and ground crew, are not classified as aviators.
In recognition of the pilots' qualifications and responsibilities, most militaries and many airlines worldwide award aviator badges to their pilots.American Institute of Aeronautics and Astronautics
The American Institute of Aeronautics and Astronautics (AIAA) is a professional society for the field of aerospace engineering. The AIAA is the U.S. representative on the International Astronautical Federation and the International Council of the Aeronautical Sciences. In 2015, it had more than 30,000 members among aerospace professionals worldwide (a majority are American and/or live in the United States).Ceiling (aeronautics)
With respect to aircraft performance, a ceiling is the maximum density altitude an aircraft can reach under a set of conditions, as determined by its flight envelope.Chord (aeronautics)
In aeronautics, a chord is the imaginary straight line joining the leading and trailing edges of an aerofoil. The chord length is the distance between the trailing edge and the point on the leading edge where the chord intersects the leading edge.The point on the leading edge that is used to define the chord can be defined as either the surface point of minimum radius, or the surface point that will yield maximum chord length.
The wing, horizontal stabilizer, vertical stabilizer and propeller of an aircraft are all based on aerofoil sections, and the term chord or chord length is also used to describe their width. The chord of a wing, stabilizer and propeller is determined by measuring the distance between leading and trailing edges in the direction of the airflow. (If a wing has a rectangular planform, rather than tapered or swept, then the chord is simply the width of the wing measured in the direction of airflow.) The term chord is also applied to the width of wing flaps, ailerons and rudder on an aircraft.
The term is also applied to aerofoils in gas turbine engines such as turbojet, turboprop, or turbofan engines for aircraft propulsion.
Most wings are not rectangular so they have a different chord at different positions along their span. To give a characteristic figure that can be compared among various wing shapes, the mean aerodynamic chord, or MAC, is used. The MAC is somewhat more complex to calculate, because most wings vary in chord over the span, growing narrower towards the outer tips. This means that more lift is generated on the wider inner portions, and the MAC moves the point to measure the chord to take this into account.Civil Aeronautics Board
The Civil Aeronautics Board (CAB) was an agency of the federal government of the United States, formed in 1938 and abolished in 1985, that regulated aviation services including scheduled passenger airline service and provided air accident investigation. The agency headquarters were in Washington, D.C.Cranfield University
Cranfield University is a British postgraduate and research-based public university specialising in science, engineering, technology and management. Cranfield was founded as the College of Aeronautics in 1946. Through the 1950s and 1960s, the development of many aspects of aircraft research and design led to considerable growth and diversification into other areas such as manufacturing and management. In 1967, the Cranfield School of Management was founded. In 1969, the College of Aeronautics became The Cranfield Institute of Technology incorporated by Royal Charter and gained degree awarding powers and became a university in its own right. In 1993, it adopted its current name.Cranfield University has two campuses: the main campus is at Cranfield, Bedfordshire, and the second is at the Defence Academy of the United Kingdom at Shrivenham, southwest Oxfordshire. The main campus is unique in the United Kingdom and Europe for having a semi-operational airport (Cranfield Airport) on campus. Cranfield University owns and operates the airport. The airport facilities are used by Cranfield University's own aircraft in the course of aerospace teaching and research.
Cranfield University's motto, 'post nubes lux', means 'after clouds light'. It is depicted on the Cranfield University coat of arms which was introduced when the University was awarded its Royal Charter.Division of Military Aeronautics
For the current active service branch, see United States Air ForceThe Division of Military Aeronautics was the name of the aviation organization of the United States Army for a four-day period during World War I. It was created by a reorganization by the War Department of the Aviation Section, U.S. Signal Corps on April 24, 1918, still as part of the Signal Corps. It was removed from the Aviation Section by executive order on May 20, 1918, and existed as the sole Army aviation agency until a War Department general order issued May 24, 1918, established it and the Bureau of Aircraft Production, created by the same reorganization on April 24, as coordinate components of the "Air Service". As such, it is recognized by the United States Air Force as the third of its antecedents.
As a subordinate component of the Air Service, the DMA continued until March 19, 1919, when the Board of Aircraft Production was consolidated with it into the Air Service, United States Army.Elevator (aeronautics)
Elevators are flight control surfaces, usually at the rear of an aircraft, which control the aircraft's pitch, and therefore the angle of attack and the lift of the wing. The elevators are usually hinged to the tailplane or horizontal stabilizer. They may be the only pitch control surface present, and are sometimes located at the front of the aircraft (early airplanes) or integrated into a rear "all-moving tailplane", also called a slab elevator or stabilator.Hindustan Aeronautics Limited
Hindustan Aeronautics Limited (HAL) is an Indian state-owned aerospace and defence company headquartered in Bangalore, India. It is governed under the management of the Indian Ministry of Defence.
The government-owned corporation is primarily involved in the operations of the aerospace and is currently involved in the design, fabrication and assembly of aircraft, jet engines, helicopters and their spare parts. It has several facilities spread across India including Nasik, Korwa, Kanpur, Koraput, Lucknow, Bangalore, Hyderabad and Kasaragod. The HAL HF-24 Marut fighter-bomber was the first fighter aircraft made in India.List of Administrators and Deputy Administrators of NASA
The Administrator and Deputy Administrator of NASA are the highest-ranked officials of NASA, the space agency of the United States Federal Government. The Administrator serves as the senior space science advisor to the President of the United States. According to NASA, the role of the Administrator is to "lead the NASA team and manage its resources to advance the Vision for Space Exploration." The Deputy Administrator of NASA "serves as the agency’s second in command and is responsible to the administrator for providing overall leadership, planning, and policy direction for the agency. They represent NASA to the Executive Office of the President, Congress, heads of federal and other appropriate government agencies, international organizations, and external organizations and communities. They also oversee the day to day work of NASA’s functional offices, such as the Office of the Chief Financial Officer, Office of General Counsel and Strategic Communications", according to NASA (referring to Shana Dale).The first Administrator of NASA was Dr. T. Keith Glennan; during his term he brought together the disparate projects in space development research in the US. Daniel Goldin held the post for the longest term (nearly 10 years), and is best known for pioneering the "faster, better, cheaper" approach to space programs. The only person to hold the post twice is James C. Fletcher, who returned to NASA following the Challenger disaster.The longest-running (acting) Deputy Administrator was John R. Dailey, who held the post following his retirement from the United States Marine Corps. The longest-running full Deputy Administrator was Hugh Latimer Dryden, who was the first Deputy Administrator. William R. Graham has held the post of Deputy Administrator twice, and was the acting Administrator in between, as did Frederick D. Gregory. Dr. Daniel Mulville served as the acting Deputy Administrator twice, and was acting Administrator in between.The current Administrator is Jim Bridenstine, who was nominated by President Donald Trump on September 1, 2017. Bridenstine was confirmed on April 19, 2018, and was sworn in four days later on April 23, 2018.List of Space Shuttle missions
The Space Shuttle was a partially reusable low Earth orbital spacecraft system operated by the U.S. National Aeronautics and Space Administration (NASA). Its official program name was Space Transportation System (STS), taken from a 1969 plan for a system of reusable spacecraft of which it was the only item funded for development. Operational missions launched numerous satellites, conducted science experiments in orbit, and participated in construction and servicing of the International Space Station (ISS). The first of four orbital test flights occurred in 1981, leading to operational flights beginning in 1982.
From 1981 to 2011 a total of 135 missions were flown, all launched from Kennedy Space Center (KSC) in Florida. During that time period the fleet logged 1,322 days, 19 hours, 21 minutes and 23 seconds of flight time. The longest orbital flight of the shuttle was STS-80 at 17 days 15 hours, while the shortest flight was STS-51-L at one minute 13 seconds when the Space Shuttle Challenger broke apart during launch. The shuttles docked with Russian space station Mir nine times and visited the ISS thirty-seven times. The highest altitude (apogee) achieved by the shuttle was 350 miles (560km) when servicing the Hubble Space Telescope. The program flew a total of 355 people representing 16 countries. The Kennedy Space Center served as the landing site for 78 missions, while 54 missions landed at Edwards Air Force Base in California and 1 mission landed at White Sands, New Mexico.The first orbiter, Enterprise, was built solely for atmospheric flight tests and had no orbital capability. Four fully operational orbiters were initially built: Columbia, Challenger, Discovery, and Atlantis. Challenger and Columbia were destroyed in mission accidents in 1986 and 2003 respectively, killing a total of fourteen astronauts. A fifth operational orbiter, Endeavour, was built in 1991 to replace Challenger. The Space Shuttle was retired from service upon the conclusion of STS-135 by Atlantis on 21 July 2011.NASA
The National Aeronautics and Space Administration (NASA, ) is an independent agency of the United States Federal Government responsible for the civilian space program, as well as aeronautics and aerospace research.NASA was established in 1958, succeeding the National Advisory Committee for Aeronautics (NACA). The new agency was to have a distinctly civilian orientation, encouraging peaceful applications in space science. Since its establishment, most US space exploration efforts have been led by NASA, including the Apollo Moon landing missions, the Skylab space station, and later the Space Shuttle. NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle, the Space Launch System and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program which provides oversight of launch operations and countdown management for unmanned NASA launches.
NASA science is focused on better understanding Earth through the Earth Observing System; advancing heliophysics through the efforts of the Science Mission Directorate's Heliophysics Research Program; exploring bodies throughout the Solar System with advanced robotic spacecraft missions such as New Horizons; and researching astrophysics topics, such as the Big Bang, through the Great Observatories and associated programs.NASA insignia
The National Aeronautics and Space Administration (NASA) logo has three main official designs, although the one with stylized red curved text (the "worm") has been retired from official use since 1992. The three logos include the NASA insignia (also known as the "meatball"), the NASA logotype (also known as the "worm"), and the NASA seal.The NASA seal was approved by President Eisenhower in 1959, and slightly modified by President Kennedy in 1961.National Advisory Committee for Aeronautics
The National Advisory Committee for Aeronautics (NACA) was a U.S. federal agency founded on March 3, 1915, to undertake, promote, and institutionalize aeronautical research. On October 1, 1958, the agency was dissolved, and its assets and personnel transferred to the newly created National Aeronautics and Space Administration (NASA). NACA was an initialism, i.e. it was pronounced as discrete letters, rather than as a whole word (as was NASA during the early years after being established).Among other advancements, NACA research and development produced the NACA duct, a type of air intake used in modern automotive applications, the NACA cowling, and several series of NACA airfoils which are still used in aircraft manufacturing.
During World War II, NACA was described as "The Force Behind Our Air Supremacy" due to its key role in producing working superchargers for high altitude bombers, and for producing the laminar wing profiles for the North American P-51 Mustang. NACA was also key in developing the area rule that is used on all modern supersonic aircraft, and conducted the key compressibility research that enabled the Bell X-1 to break the sound barrier.National Aeronautics and Space Act
The National Aeronautics and Space Act of 1958 (Pub.L. 85–568) is the United States federal statute that created the National Aeronautics and Space Administration (NASA). The Act, which followed close on the heels of the Soviet Union's launch of Sputnik, was drafted by the United States House Select Committee on Astronautics and Space Exploration and on July 29, 1958 was signed by President Eisenhower. Prior to enactment, the responsibility for space exploration was deemed primarily a military venture, in line with the Soviet model that had launched the first orbital satellite. In large measure, the Act was prompted by the lack of response by a US military infrastructure that seemed incapable of keeping up the space race.
The original 1958 act charged the new Agency with conducting the aeronautical and space activities of the United States "so as to contribute materially to one or more of the following objectives:"
The expansion of human knowledge of phenomena in the atmosphere and space;
The improvement of the usefulness, performance, speed, safety, and efficiency of aeronautical and space vehicles;
The development and operation of vehicles capable of carrying instruments, equipment, supplies and living organisms through space;
The establishment of long-range studies of the potential benefits to be gained from, the opportunities for, and the problems involved in the utilization of aeronautical and space activities for peaceful and scientific purposes.
The preservation of the role of the United States as a leader in aeronautical and space science and technology and in the application thereof to the conduct of peaceful activities within and outside the atmosphere.
The making available to agencies directly concerned with national defenses of discoveries that have military value or significance, and the furnishing by such agencies, to the civilian agency established to direct and control nonmilitary aeronautical and space activities, of information as to discoveries which have value or significance to that agency;
Cooperation by the United States with other nations and groups of nations in work done pursuant to this Act and in the peaceful application of the results, thereof; and
The most effective utilization of the scientific and engineering resources of the United States, with close cooperation among all interested agencies of the United States in order to avoid unnecessary duplication of effort, facilities, and equipment.
In 2012, a ninth objective was added:
The preservation of the United States preeminent position in aeronautics and space through research and technology development related to associated manufacturing processes.
The Act abolished the National Advisory Committee for Aeronautics (NACA), transferring its activities and resources to NASA effective October 1, 1958. The Act also created a Civilian-Military Liaison Committee, for the purpose of coordinating civilian and military space applications, and keeping NASA and the Department of Defense "fully and currently informed" of each other's space activities. To this day, the United States has coordinated but separate military and civilian space programs, with much of the former involved in launching military and surveillance craft and, prior to the Partial Test Ban Treaty, planning counter-measures to the anticipated Soviet launch of nuclear warheads into space.
In addition, the new law made extensive modifications to the patent law and provided that both employee inventions as well as private contractor innovations brought about through space travel would be subject to government ownership. By making the government the exclusive provider of space transport, the act effectively discouraged the private development of space travel. This situation endured until the law was modified by the Commercial Space Launch Act of 1984, enacted to allow civilian use of NASA systems in launching space vehicles.The phrase "We came in peace for all mankind", inscribed on a plaque left on the Moon by the crew of Apollo 11, is derived from the Act's declaration of NASA's policy and purpose:
The Congress hereby declares that it is the policy of the United States that activities in space should be devoted to peaceful purposes for the benefit of all mankind.The Act was subsequently amended to remove gender bias, so that this policy statement now reads:
Devotion of Space Activities to Peaceful Purposes for Benefit of All Humankind.--Congress declares that it is the policy of the United States that activities in space should be devoted to peaceful purposes for the benefit of all humankind.Range (aeronautics)
The maximal total range is the maximum distance an aircraft can fly between takeoff and landing, as limited by fuel capacity in powered aircraft, or cross-country speed and environmental conditions in unpowered aircraft. The range can be seen as the cross-country ground speed multiplied by the maximum time in the air. The fuel time limit for powered aircraft is fixed by the fuel load and rate of consumption. When all fuel is consumed, the engines stop and the aircraft will lose its propulsion.
Ferry range means the maximum range the aircraft can fly. This usually means maximum fuel load, optionally with extra fuel tanks and minimum equipment. It refers to transport of aircraft without any passengers or cargo. Combat range is the maximum range the aircraft can fly when carrying ordnance. Combat radius is a related measure based on the maximum distance a warplane can travel from its base of operations, accomplish some objective, and return to its original airfield with minimal reserves.Spar (aeronautics)
In a fixed-wing aircraft, the spar is often the main structural member of the wing, running spanwise at right angles (or thereabouts depending on wing sweep) to the fuselage. The spar carries flight loads and 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 also sharing the loads where it is used. There may be more than one spar in a wing or 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 also 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.V speeds
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 (and not by, for example, the ground speed), so that pilots may use them directly, without having to apply correction factors, as aircraft instruments also show indicated airspeed.
In general aviation aircraft, the most commonly 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, and stalling speed with wing flaps fully 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, and then only with caution to avoid abrupt control movement, and 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.