# angle of attack

Angle of attack (AOA, , Greek letter alpha) is a term used in aerodynamics to describe the angle between the airfoil's chord line and the relative airflow, wind, effectively the direction in which the aircraft is currently moving. It can be described as the angle between where the wing is pointing and where it is going.

The amount of lift generated by a wing is directly related to the angle of attack, with greater angles generating more lift (and more drag). This remains true up to the stall point, where lift starts to decrease again because of flow separation.

Planes flying at high angles of attack can suddenly enter a stall if, for example, a strong wind gust changes the direction of the relative wind. Also, to maintain a given amount of lift, the angle of attack must be increased as speed through the air decreases. This is why stalling is an effect that occurs more frequently at low speeds.

Nonetheless, a wing (or any other airfoil) can stall at any speed. Planes that already have a high angle of attack, for example because they are pulling g or a heavy payload, will stall at speed well above the normal stall speed, since only a small increase in the angle of attack will take the wing above the critical angle.

The critical angle is typically around 15° for most airfoils. Using a variety of additional aerodynamic surfaces — known as high-lift devices — like leading edge extensions (leading edge wing root extensions), fighter aircraft have increased the potential flyable alpha from about 20° to over 45°, and in some designs, 90° or more. That is, the plane remains flyable when the wing's chord is perpendicular to the direction of motion.

Some aircraft are equipped with a built-in flight computer that automatically prevents the plane from lifting its nose any further when the maximum angle of attack is reached, irrespective of pilot input. This is called the angle of attack limiter or alpha limiter. Modern airliners which limit the angle of attack by means of computers include the Airbus 320, 330, 340 and 380 series.

The pilot may disengage the alpha limiter at any time, thus allowing the plane to perform tighter turns (but with considerably higher risk of going into a stall). A famous military example of this is Pugachev's Cobra. Currently, the highest angle of attack recorded for a duration of more than 10 seconds is 89.8 degrees, performed in the Russian Su-35 (Flanker-E)/Su-37 (Flanker-F) family.

## Sailing

In sailing, the angle of attack is the angle between a mid-sail and the direction of the wind. The physical principles involved are the same as for aircraft. See points of sail.

Greek alphabet
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ISO 15924 Grek

Alpha (Greek ἄλφα), (uppercase Α, lowercase α) is the first letter of the Greek alphabet. In the system of Greek numerals it has a value of 1. It was derived from the Phoenician letter Aleph .

Aerodynamics (shaping of objects that affect the flow of air or gas) is a branch of fluid dynamics concerned with the study of forces generated on a body in a flow.
angle (in full, plane angle) is the figure formed by two rays sharing a common endpoint, called the vertex of the angle. The magnitude of the angle is the "amount of rotation" that separates the two rays, and can be measured by considering the length of circular arc swept
airfoil (in American English, or aerofoil in British English) is the shape of a wing or blade (of a propeller, rotor or turbine) or sail as seen in cross-section.

An airfoil shaped body moved through a fluid produces a force perpendicular to the motion called lift.
chord refers to the distance between the leading edge and trailing edge of a wing, measured in the direction of the normal airflow. These front and back points are referred to as the leading edge and trailing edge.
WIND (SOLARWIND) was a NASA spacecraft launched on November 1, 1994. It was deployed to study radio and plasma that occur in solar wind, in the Earth's magnetosphere. The spacecraft's original mission was to orbit the Sun at the L1
aircraft is a vehicle which is able to fly through the air (or through any other atmosphere). All the human activity which surrounds aircraft is called aviation. (Most rocket vehicles are not aircraft because they are not supported by the surrounding air).
The lift force, lifting force or simply lift is a mechanical force generated by solid objects as they move through a fluid.[1]

While many types of objects can generate lift, the most common and familiar object in this category is the airfoil, a
drag (sometimes called resistance) is the force that resists the movement of a solid object through a fluid (a liquid or gas). Drag is made up of friction forces, which act in a direction parallel to the object's surface (primarily along its sides, as friction forces at the
For other uses, see stall.

In aerodynamics, a stall is a sudden reduction in the lift forces generated by an airfoil. This most usually occurs when the critical angle of attack for the airfoil is exceeded.
All solid objects travelling through a fluid (or alternatively a stationary object exposed to a moving fluid) acquire a boundary layer of fluid around them where friction between the fluid molecules and the object's rough surface occurs.
g-force (also g-load) is a measurement of an object's acceleration expressed in g's. It may also informally refer to the reaction force resulting from an acceleration, with the causing acceleration expressed in g's.
Leading edge extensions or LEX (also referred to as leading edge root extensions or LERX or strakes) are fillets added to the front of a modern fighter aircraft's wings in order to provide usable airflow at high angles of attack.
Leading edge extensions or LEX (also referred to as leading edge root extensions or LERX or strakes) are fillets added to the front of a modern fighter aircraft's wings in order to provide usable airflow at high angles of attack.
fighter aircraft is a military aircraft designed primarily for attacking other aircraft, as opposed to a bomber, which is designed to attack ground targets, primarily by dropping bombs. Fighters are comparatively small, fast, and maneuverable.
Airbus, see Bellanca Aircruiser.

Airbus S.A.S.

Subsidiary
Founded 1970 (Airbus Industrie)
2001 (Airbus S.A.S.)

Key people Thomas Enders, CEO
Hans Peter Ring, CFO
John Leahy, Sales Director
For other uses, see stall.

In aerodynamics, a stall is a sudden reduction in the lift forces generated by an airfoil. This most usually occurs when the critical angle of attack for the airfoil is exceeded.
Pugachev's Cobra (or Pugachev Cobra) is an aircraft manoeuvre. It is a demonstration of the pitch control authority, high angle of attack (AOA) stability and engine/inlet compatibility at high angles of attack of the aircraft (i.e. supermanoeuvrability[1]).
Type Multirole fighter
Manufacturer Sukhoi
Designed by Mikhail Simonov
Maiden flight May 1988
Status Production
Primary user 12 in service with the Russian Air Force
Unit cost US \$35 million

Type Multirole Fighter
Manufacturer Sukhoi
Maiden flight 2 April 1996
Status Prototype
Produced Russia
Number built 2
Developed from Su-35

The Sukhoi Su-37
Sailing is the art of controlling a sailing vessel. By adjusting the rigging, rudder and dagger or centre board, a sailor manages the force of the wind on the sails (main and/or jib) in order to change the direction and speed of a boat.
Points of sail is the term used to describe a sailing boat's course in relation to the wind direction.

First, there is a distinction between the port tack and the starboard tack. If the wind is coming from anywhere on the port side, the boat is on port tack.
airfoil (in American English, or aerofoil in British English) is the shape of a wing or blade (of a propeller, rotor or turbine) or sail as seen in cross-section.

An airfoil shaped body moved through a fluid produces a force perpendicular to the motion called lift.
Angle of incidence is a measure of deviation of something from "straight on", for example in the approach of a ray to a surface, or the direction of an airfoil with respect to the direction of an airplane.
Bernoulli's equation redirects here; see Bernoulli differential equation for an unrelated topic in ordinary differential equations.

Bernoulli's Principle
Camber, in aerospace engineering, is the asymmetry between the top and the bottom curves of an airfoil in cross-section.

## Overview

Camber is often added to an airfoil to reduce aerodynamic drag and/or increase the critical angle of attack (the angle at which the