In aviation, a strake is an aerodynamic surface generally mounted on the fuselage of an aircraft to improve the flight characteristics either by controlling the airflow or by simple stabilising effect. In general a strake is longer than it is wide, in contrast to a winglet or a moustache. Leading edge root extensions are also sometimes referred to as wing strakes.
Nose strakes
On both supersonic and subsonic types, smaller strakes are sometimes applied to the forward fuselage to control the fuselage flow at high angles of attack; for example, the Concorde SST had small nose strakes "to get a better directional stability".
Wing strakes
Double delta wing aircraft featured a forward extended leading edge that may be considered as a wing strake; it provides the same additional vortex lift at high angle of attack by leading edge suction.
Nacelle strakes
On jet aircraft where the engines are mounted in nacelles slung under the wings, strakes may be added to one or both sides of each nacelle to produce vortices that energize the airflow over the wings in times of high angle of attack, such as during takeoff and landing, thus improving wing effectiveness.
One or two large fins or strakes are sometimes positioned under the rear fuselage or below the empennage, to provide adequate stability at high angles of attack when the tail fin is shielded from the main airstream by the fuselage and/or the wing wake. Typical examples can be seen on the Piaggio P.180 Avanti, Learjet 60 and Beechcraft 1900D. The Grumman X-29 research aircraft had rear fuselage lateral fins or "Tail fins", sometimes called strakes, continuous with the trailing edge of the main wing. This allowed the positioning of a rear control surface at the end of each fin. Together with the main and forward wing control surfaces, this effectively gave it a three-surface configuration.
Certain air-deployed munitions, particularly "dumb" or unguided bombs, are often retrofitted with bolt-on strake sets. Designed as an open collar with strakes fitted to the outside face, these strake sets are used to alter and normalize the aerodynamics of the weapon, yielding greater accuracy. As most such munitions were manufactured with only tail-mounted stabilizer fins, the addition of longitudinal strakes proves a much cleaner flow of air around the weapon during its glide, reducing the tendency to yaw and improving terminal accuracy. Strakes are also often found on "smart" or guided munitions as an aid to the guidance system. By stabilizing the slipstream of air traveling over the weapon, the actions of control surfaces are much more predictable and precise, again improving the accuracy of the weapon.
