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for describing the angle of its rotations An
aircraft An aircraft is a vehicle or machine that is able to fly Flies are insect Insects or Insecta (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Lat ...

aircraft
in flight is free to rotate in three dimensions: '' yaw'', nose left or right about an axis running up and down; ''pitch'', nose up or down about an axis running from wing to wing; and ''roll'', rotation about an axis running from nose to tail. The axes are alternatively designated as ''vertical'', ''transverse'', and ''longitudinal'' respectively. These axes move with the vehicle and rotate relative to the Earth along with the craft. These definitions were analogously applied to
spacecraft File:Space Shuttle Columbia launching.jpg, 275px, The US Space Shuttle flew 135 times from 1981 to 2011, supporting Spacelab, ''Mir'', the Hubble Space Telescope, and the ISS. (''Columbia'' STS-1, maiden launch, which had a white external tank, ...

spacecraft
when the first manned spacecraft were designed in the late 1950s. These rotations are produced by
torque In physics and mechanics Mechanics (Ancient Greek, Greek: ) is the area of physics concerned with the motions of physical objects, more specifically the relationships among force, matter, and motion. Forces applied to objects result in Dis ...

torque
s (or moments) about the principal axes. On an aircraft, these are intentionally produced by means of moving control surfaces, which vary the distribution of the net
aerodynamic study at Wallops Flight Facility, Wallops Island in 1990. A vortex is created by passage of an aircraft wing, revealed by smoke. Vortices are one of the many phenomena associated with the study of aerodynamics. Aerodynamics, from Greek language, ...
force about the vehicle's
center of gravity In physics, the center of mass of a distribution of mass in space (sometimes referred to as the balance point) is the unique point where the weight function, weighted relative position (vector), position of the distributed mass sums to zero. This ...

center of gravity
.
Elevator Berlin U-Bahn, U-Bahn station in Berlin is built with glass walls and doors, exposing the inner workings. An elevator (North American English) or lift (Commonwealth English) is a type of wire rope, cable-assisted, hydraulic cylinder-assi ...
s (moving flaps on the horizontal tail) produce pitch, a
rudder A rudder is a primary control surface used to steer a ship, boat, submarine, hovercraft, aircraft, or other conveyance that moves through a fluid medium (generally air or water). On an aircraft the rudder is used primarily to counter adverse yaw ...

rudder
on the vertical tail produces yaw, and
aileron An aileron (French for "little wing" or "fin") is a hinged flight control surface Aircraft flight control surfaces are aerodynamic devices allowing a pilot to adjust and control the aircraft's flight attitude. Development of an effective se ...

aileron
s (flaps on the wings that move in opposing directions) produce roll. On a spacecraft, the moments are usually produced by a
reaction control system A reaction control system (RCS) is a spacecraft system that uses thrusters and reaction control wheels to provide attitude control Attitude control is the process of controlling the orientation of an aerospace Aerospace is a term used to c ...
consisting of small rocket thrusters used to apply asymmetrical thrust on the vehicle.


Principal axes

* Normal axis, or yaw axis — an axis drawn from top to bottom, and perpendicular to the other two axes, parallel to the fuselage station. * Transverse axis, lateral axis, or pitch axis — an axis running from the pilot's left to right in piloted aircraft, and parallel to the wings of a winged aircraft, parallel to the buttock line. * Longitudinal axis, or roll axis — an axis drawn through the body of the vehicle from tail to nose in the normal direction of flight, or the direction the pilot faces, similar to a ship's
waterline The waterline is the line where the hull of a ship meets the surface of the water Water is an Inorganic compound, inorganic, Transparency and translucency, transparent, tasteless, odorless, and Color of water, nearly colorless chemical ...
. Normally, these axes are represented by the letters X, Y and Z in order to compare them with some reference frame, usually named x, y, z. Normally, this is made in such a way that the X is used for the longitudinal axis, but there are other possibilities to do it.


Vertical axis (yaw)

The yaw axis has its origin at the center of gravity and is directed towards the bottom of the aircraft,
perpendicular In elementary geometry Geometry (from the grc, γεωμετρία; ''wikt:γῆ, geo-'' "earth", ''wikt:μέτρον, -metron'' "measurement") is, with arithmetic, one of the oldest branches of mathematics. It is concerned with propertie ...

perpendicular
to the wings and to the fuselage reference line. Motion about this axis is called yaw. A positive yawing motion moves the nose of the aircraft to the right. The
rudder A rudder is a primary control surface used to steer a ship, boat, submarine, hovercraft, aircraft, or other conveyance that moves through a fluid medium (generally air or water). On an aircraft the rudder is used primarily to counter adverse yaw ...
is the primary control of yaw. The term ''yaw'' was originally applied in sailing, and referred to the motion of an unsteady ship rotating about its vertical axis. Its
etymology Etymology ()The New Oxford Dictionary of English (1998) – p. 633 "Etymology /ˌɛtɪˈmɒlədʒi/ the study of the class in words and the way their meanings have changed throughout time". is the study of the history of words. By extension, th ...
is uncertain.


Transverse axis (pitch)

The pitch axis (also called transverse or lateral axis Also at :File:MISB Standard 0601.pdf.) has its origin at the center of gravity and is directed to the right,
parallel Parallel may refer to: Computing * Parallel algorithm In computer science Computer science deals with the theoretical foundations of information, algorithms and the architectures of its computation as well as practical techniques for their a ...
to a line drawn from wingtip to wingtip. Motion about this axis is called pitch. A positive pitching motion raises the nose of the aircraft and lowers the tail. The
elevator Berlin U-Bahn, U-Bahn station in Berlin is built with glass walls and doors, exposing the inner workings. An elevator (North American English) or lift (Commonwealth English) is a type of wire rope, cable-assisted, hydraulic cylinder-assi ...
s are the primary control of pitch.


Longitudinal axis (roll)

The roll axis (or longitudinal axis) has its origin at the center of gravity and is directed forward, parallel to the fuselage reference line. Motion about this axis is called roll. An angular displacement about this axis is called bank.Clancy, L.J. (1975) ''Aerodynamics'' Pitman Publishing Limited, London , Section 16.6 A positive rolling motion lifts the left wing and lowers the right wing. The pilot rolls by increasing the lift on one wing and decreasing it on the other. This changes the bank angle. The
aileron An aileron (French for "little wing" or "fin") is a hinged flight control surface Aircraft flight control surfaces are aerodynamic devices allowing a pilot to adjust and control the aircraft's flight attitude. Development of an effective se ...

aileron
s are the primary control of bank. The rudder also has a secondary effect on bank.


Relationship with other systems of axes

These axes are related to the principal axes of inertia, but are not the same. They are geometrical symmetry axes, regardless of the mass distribution of the aircraft. In aeronautical and aerospace engineering intrinsic rotations around these axes are often called
Euler angles The Euler angles are three angles introduced by Leonhard Euler Leonhard Euler ( ; ; 15 April 170718 September 1783) was a Swiss mathematician, physicist, astronomer, geographer, logician and engineer who made important and influential dis ...
, but this conflicts with existing usage elsewhere. The calculus behind them is similar to the
Frenet–Serret formulas spanned by T and N In differential geometry Differential geometry is a Mathematics, mathematical discipline that uses the techniques of differential calculus, integral calculus, linear algebra and multilinear algebra to study problems in geomet ...
. Performing a rotation in an intrinsic reference frame is equivalent to right-multiplying its characteristic matrix (the matrix that has the vectors of the reference frame as columns) by the matrix of the rotation.


History

The first aircraft to demonstrate active control about all three axes was the ' 1902 glider.


See also

*
Aerodynamics study at Wallops Island Wallops Island is a island in Accomack County, Virginia, part of the Virginia Barrier Islands that stretch along the East coast of the United States, eastern seaboard of the United States of America. It is just south of ...
*
Aircraft flight control system A conventional fixed-wing aircraft flight control system consists of flight control surfaces, the respective cockpit controls, connecting linkages, and the necessary operating mechanisms to control an aircraft's direction in flight. Aircraft ...
*
Euler angles The Euler angles are three angles introduced by Leonhard Euler Leonhard Euler ( ; ; 15 April 170718 September 1783) was a Swiss mathematician, physicist, astronomer, geographer, logician and engineer who made important and influential dis ...
*
Fixed-wing aircraft A fixed-wing aircraft is a heavier-than-air Aircraft, flying machine, such as an airplane, which is capable of flight using wings that generate Lift (force), lift caused by the aircraft's forward airspeed and the wing configuration, shape of t ...
*
Flight control surfaces Aircraft flight control surfaces are aerodynamic devices allowing a pilot to adjust and control the aircraft's flight attitude Attitude may refer to: Philosophy and psychology * Attitude (psychology) In psychology Psychology is the ...
*
Flight dynamics Flight dynamics is the study of the performance, stability, and control of vehicles flying through the air or in outer space. It is concerned with how forces acting on the vehicle determine its velocity and attitude with respect to time. For a ...

Flight dynamics
*
Flight dynamics (fixed-wing aircraft) Flight dynamics is the science of air vehicle orientation and control in three dimensions. The three critical flight dynamics parameters are the angles of rotation in three dimensions about the vehicle's center of gravity In physics, the ...
* Moving frame *
Panning (camera) Overview from above, looking down on the camera panning left and right of the subject In cinematography Cinematography (from ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the classic ...
*
Six degrees of freedom Six degrees of freedom (6DoF) refers to the freedom of movement of a rigid body in three-dimensional space. Specifically, the body is free to change position as forward/backward (surge), up/down (heave), left/right (sway) translation in th ...

Six degrees of freedom
*
Screw theory Screw theory is the algebraic calculation of pairs of vectors, such as force In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natu ...
*
Triad method Triad is one of the earliest and simplest solutions to the spacecraft attitude determination problem, due to Harold Black. Black played a key role in the development of the guidance, navigation and control of the U.S. Navy's Transit satellite system ...


References

{{Reflist


External links


Yaw Axis Control as a Means of Improving V/STOL Aircraft Performance.3D fast walking simulation of biped robot by yaw axis moment compensation
Aerodynamics Attitude control