Editing Flight (section)

==== Thrust ====
{{Main|Thrust}}
[[File:aeroforces.svg|thumb|Forces on an [[aerofoil]] cross section]]

A [[fixed-wing aircraft]] generates forward thrust when air is pushed in the direction opposite to flight. This can be done in several ways including by the spinning blades of a [[Propeller (aircraft)|propeller]], or a rotating [[Mechanical fan|fan]] pushing air out from the back of a [[jet engine]], or by ejecting hot gases from a [[rocket engine]].<ref>{{cite web| url = http://www.grc.nasa.gov/WWW/k-12/airplane/newton3.html| url-status = dead| archive-url = https://web.archive.org/web/19991128055408/http://www.grc.nasa.gov/WWW/K-12/airplane/newton3.html| archive-date = 1999-11-28| title = Newtons Third Law}}</ref> The forward thrust is proportional to the [[mass]] of the airstream multiplied by the difference in [[velocity]] of the airstream. Reverse thrust can be generated to aid braking after landing by reversing the pitch of variable-pitch propeller blades, or using a [[Thrust reversal|thrust reverser]] on a jet engine. [[Rotary wing aircraft]] and [[thrust vectoring]] [[V/STOL]] aircraft use engine thrust to support the weight of the aircraft, and vector sum of this thrust fore and aft to control forward speed.