Aircraft fairing

A fairing is a structure whose primary function is to produce a smooth outline and reduce drag.

These structures are generally light-weight shapes and covers for gaps and spaces between parts of an aircraft to reduce form drag and interference drag, and to improve appearance.

Types

Engine cowlings: to reduce parasitic drag by reducing the surface area, having a smooth surface and thus leading to laminar flow, and having a nose cone shape, which prevents early flow separation. The inlet and the nozzle in combination lead to an isotropic speed reduction around the cooling fins and due to the speed-squared law to a reduction in cooling drag.

Tail cones

to reduce the form drag of the fuselage, by recovering the pressure behind it. For the design speed they add no friction drag.

Wheels on fixed gear aircraft

often called "wheel pants", "speed fairings" or in the united kingdoms, "wheel spats". These fairings are a trade-off in advantages, as they increase the frontal and surface area, but also provide a smooth surface, a faired nose and tail for laminar flow, in an attempt to reduce the turbulence created by the round wheel and its associated gear legs and brakes. They also have the important function of preventing mud and stones from being thrown upwards against the wings or fuselage, or into the propeller on a pusher craft.

Wing root: to reduce interference drag. On top and below the wing it consists of small rounded edge to reduce the surface and such friction drag. At the leading and trailing edge it consists of much larger taper and smooths out the pressure differences: High pressure at the leading and trailing edge, low pressure on top of the wing and around the fuselage.