Windage

Windage is a force created on an object by friction when there is relative movement between air and the object.

There are two causes of windage:

1. The object is moving and being slowed by resistance from the air.
2. A wind is blowing producing a force 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 that are exposed to the wind.
• The difference between the bore and the diameter of the cannonball in a muzzle-loading cannon.

Aerodynamic streamlining can be used to reduce windage.

There is a hydrodynamic effect similar to windage.

In firearms parlance, windage refers to the side-to-side adjustment of a sight used to change the horizontal component of the aiming point. By contrast, the up-down adjustment for the vertical component is the elevation. Kentucky windage refers to the practice of aiming to one side of the target to adjust for wind, rather than adjusting the gun's sights. It can also refer to the difference in diameter between the bore and the shot, especially in muskets and cannons.

In automotive parlance, windage refers to parasitic drag on the crankshaft due to sump oil splashing on the cranktrain during rough driving, and/or dissipating energy in turbulence from the cranktrain 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.

See also

• Deflection (ballistics)
• Drag (physics)