Aircraft flight mechanics

An aeroplane (airplane in US usage), is defined in ICAO Document 9110 as, "a power-driven heavier than air aircraft, deriving its lift chiefly from aerodynamic reactions on surface which remain fixed under given conditions of flight".

Technically, both of these could be said to experience "flight mechanics" in the more general sense of physical forces acting on a body moving through air; but they operate very differently, and are normally outside the scope of this term.

When flying straight upwards the aircraft can reach zero airspeed before falling earthwards; the wing is generating no lift and so does not stall.

In turning flight, lift exceeds weight and produces a load factor greater than one, determined by the aircraft's angle of bank.

On a large aircraft there may be several independent rudders on the single fin for both safety and to control the inter-linked yaw and roll actions.

A precise combination of bank and lift must be generated to cause the required centripetal forces without producing a sideslip.

In early attempts, as pilots exceeded the critical Mach number, a strange phenomenon made their control surfaces useless, and their aircraft uncontrollable.

Also, in supersonic flight the change in camber has less effect on lift and a stabilator produces less drag[citation needed].

Aircraft that need control at extreme angles of attack are sometimes fitted with a canard configuration, in which pitching movement is created using a forward foreplane (roughly level with the cockpit).

A combination tri-surface aircraft uses both a canard and an aft tail (in addition to the main wing) to achieve advantages of both configurations.

A further design of tailplane is the V-tail, so named because that instead of the standard inverted T or T-tail, there are two fins angled away from each other in a V. The control surfaces then act both as rudders and elevators, moving in the appropriate direction as needed.

As well as ailerons, there are sometimes also spoilers—small hinged plates on the upper surface of the wing, originally used to produce drag to slow the aircraft down and to reduce lift when descending.