Windage is a term used in aerodynamics, firearms ballistics, and automobiles.

Usage

Aerodynamics

Windage is a

force In physics, a force is an influence that can change the motion of an object. A force can cause an object with mass to change its velocity (e.g. moving from a state of rest), i.e., to accelerate. Force can also be described intuitively as a ...

created on an object by

friction Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding (motion), sliding against each other. There are several types of friction: *Dry friction is a force that opposes the relative la ...

when there is relative movement between air and the object. Windage loss is the reduction in efficiency due to windage forces. For example, electric motors are affected by friction between the rotor and air. Large

alternator An alternator is an electrical generator that converts mechanical energy to electrical energy in the form of alternating current. For reasons of cost and simplicity, most alternators use a rotating magnetic field with a stationary armature.G ...

s have significant losses due to windage. To reduce losses, hydrogen gas may be used, since it is less dense. There are two causes of windage: # The object is moving and being slowed by

resistance Resistance may refer to: Arts, entertainment, and media Comics * Either of two similarly named but otherwise unrelated comic book series, both published by Wildstorm: ** ''Resistance'' (comics), based on the video game of the same title ** ''T ...

from the air. # A

wind Wind is the natural movement of air or other gases relative to a planet's surface. Winds occur on a range of scales, from thunderstorm flows lasting tens of minutes, to local breezes generated by heating of land surfaces and lasting a few ...

is blowing, producing a

on the object. The term can refer to: * The effect of the force, for example the deflection of a missile or an aircraft by a cross wind. * The area and shape of the object that make it susceptible to friction, for example those parts of a

boat A boat is a watercraft of a large range of types and sizes, but generally smaller than a ship, which is distinguished by its larger size, shape, cargo or passenger capacity, or its ability to carry boats. Small boats are typically found on i ...

that are exposed to the wind.

Aerodynamic Aerodynamics, from grc, ἀήρ ''aero'' (air) + grc, δυναμική (dynamics), is the study of the motion of air, particularly when affected by a solid object, such as an airplane wing. It involves topics covered in the field of fluid dyn ...

streamlining can be used to reduce windage. There is a hydrodynamic effect similar to windage, hydrodynamic drag.

Ballistics

firearms A firearm is any type of gun designed to be readily carried and used by an individual. The term is legally defined further in different countries (see Legal definitions). The first firearms originated in 10th-century China, when bamboo tubes ...

parlance, the word ''windage'' refers to the

sight Visual perception is the ability to interpret the surrounding environment through photopic vision (daytime vision), color vision, scotopic vision (night vision), and mesopic vision (twilight vision), using light in the visible spectrum refl ...

adjustment used to compensate for the horizontal deviation of the

projectile A projectile is an object that is propelled by the application of an external force and then moves freely under the influence of gravity and air resistance. Although any objects in motion through space are projectiles, they are commonly found i ...

trajectory from the intended point of impact due to wind drift or

Coriolis effect In physics, the Coriolis force is an inertial or fictitious force that acts on objects in motion within a frame of reference that rotates with respect to an inertial frame. In a reference frame with clockwise rotation, the force acts to the ...

. By contrast, the adjustment for the vertical deviation is the ''

elevation The elevation of a geographic location is its height above or below a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational surface (see Geodetic datum § ...

''. The colloquial term "Kentucky windage" refers to the practice of holding the aim to the upwind side of the target (also known as deflection shooting or "leading" the wind) to compensate for wind drift, without actually changing the existing adjustment settings on the gunsight. In muzzleloading firearms, ''windage'' also refers to the difference in diameter between the bore and the ball, especially in

musket A musket is a muzzle-loaded long gun that appeared as a smoothbore weapon in the early 16th century, at first as a heavier variant of the arquebus, capable of penetrating plate armour. By the mid-16th century, this type of musket graduall ...

s and

cannon A cannon is a large-caliber gun classified as a type of artillery, which usually launches a projectile using explosive chemical propellant. Gunpowder ("black powder") was the primary propellant before the invention of smokeless powder duri ...

s. The bore gap allows the shot to be loaded quickly, but reduces the efficiency of the weapon’s internal ballistics, as it allows gas to leak past the projectile. It also reduces the accuracy, as the ball takes a zig-zag path along the barrel, emerging out of the muzzle at an unpredictable angle.

Automobiles

In automotive parlance, windage refers to parasitic drag on the crankshaft due to

sump A sump is a low space that collects often undesirable liquids such as water or chemicals. A sump can also be an infiltration basin used to manage surface runoff water and recharge underground aquifers. Sump can also refer to an area in a cav ...

oil splashing on the crank train during rough driving, and/or dissipating energy in turbulence from the crank train moving the crankcase gas and oil mist at high RPM. Windage may also inhibit the migration of oil into the sump and back to the oil pump, creating lubrication problems. Some manufacturers and aftermarket vendors have developed special scrapers to remove excess oil from the counterweights and windage screens to create a barrier between the crankshaft and oil sump.

References

Navigation Ballistics Nautical terminology Engines {{firearms-stub

Usage

Aerodynamics

Ballistics

Automobiles

See also

References