Editing Flight control surfaces (section)

==Development ==

The [[Wright brothers]] are credited with developing the first practical control surfaces.  It is a main part of their patent on flying.<ref>'''Patents'''
* {{US patent|821393}} — ''Flying machine'' — O. & W. Wright
* [https://patents.google.com/patent/US821393 U.S. Patent 821,393]—for those who do not have USPTO graphics plugin</ref>  Unlike modern control surfaces, they used [[wing warping]].<ref>*[http://www.centennialofflight.gov/essay/Dictionary/wing_warping/DI56.htm Centennial of flight] {{webarchive|url=https://web.archive.org/web/20080505105053/http://www.centennialofflight.gov/essay/Dictionary/wing_warping/DI56.htm |date=2008-05-05 }} - illustration of Wilbur Wright invention of wing warping using a cardboard box</ref>  In an attempt to circumvent the [[Wright brothers patent war|Wright patent]], [[Glenn Curtiss]] made hinged control surfaces, the same type of concept [[M. P. W. Boulton#Later years: career, publications and scientific works|first patented some four decades earlier in the United Kingdom]]. Hinged control surfaces have the advantage of not causing stresses that are a problem of wing warping and are easier to build into structures.

===Axes of motion===
{{main|Aircraft principal axes}}
[[File:Flight dynamics with text.png|thumb|right|Rotation around the three axes|alt="pitch" is a nose-up/nose-down rotation, "roll" is a rotation lifting one wing and lowering the other, "yaw" rotation moves the nose in a left/right direction]]
[[File:Roll_pitch_yaw_mnemonic.svg|thumb|Mnemonics to remember angle names]]
An aircraft is free to rotate around three axes that are perpendicular to each other and intersect at its [[center of gravity]] (CG). To control position and direction a pilot must be able to control rotation about each of them.

===Transverse axis===
The ''transverse axis'', also known as ''lateral axis'',<ref name=MISB>{{cite web|title=MISB Standard 0601|url=http://www.gwg.nga.mil/misb//docs/standards/ST0601.8.pdf|publisher=Motion Imagery Standards Board (MISB)|access-date=1 May 2015|archive-date=24 March 2017|archive-url=https://web.archive.org/web/20170324002900/http://www.gwg.nga.mil/misb//docs/standards/ST0601.8.pdf|url-status=dead}} Also at [[:File:MISB Standard 0601.pdf]].</ref> passes through an aircraft from wingtip to wingtip. Rotation about this axis is called ''pitch''. Pitch changes the vertical direction that the aircraft's nose is pointing. The [[Elevator (aeronautics)|elevators]] are the primary control surfaces for pitch.

===Longitudinal axis===
The longitudinal axis passes through the aircraft from nose to tail. Rotation about this axis is called ''roll''.<ref name=MISB/>  The angular displacement about this axis is called bank.<ref>Clancy, ''L.J. Aerodynamics'', Section 16.6</ref> The pilot changes bank angle by increasing the lift on one wing and decreasing it on the other.  This differential lift causes rotation around the longitudinal axis.  The [[ailerons]] are the primary control of bank, especially on smaller aircraft: larger aircraft often use roll spoilers or [[Spoileron|spoilerons]] on the upper wing surface to reduce lift on one wing to aid rolling. The [[rudder]] also has a secondary effect on bank through moving one wing forward and the other backwards, affecting the lift they produce.

===Vertical axis===
The vertical axis passes through an aircraft from top to bottom.  Rotation about this axis is called ''yaw''.<ref name=MISB/>  Yaw changes the direction the aircraft's nose is pointing, left or right. The primary control of yaw is with the rudder. Ailerons also have a secondary effect on yaw as the wing with more lift experiences more drag.

These axes move with the aircraft and change relative to the earth as the aircraft moves. For example, for an aircraft whose left wing is pointing straight down, its "vertical" axis is parallel with the ground, while its "transverse" axis is perpendicular to the ground.