windage

Windage is a term used in several technical fields to describe the effect of air resistance on moving objects and the allowances made to compensate for that effect. In ballistics, windage refers to the horizontal deviation of a projectile caused by cross‑winds or imperfections in the launch environment. Shooters adjust windage by moving the rear sight or the rifle’s turrets left or right, aiming to align the point of aim with the point of impact. Windage corrections are also incorporated into firing tables and ballistic calculators, which estimate the necessary adjustments based on wind speed, direction, distance, and projectile characteristics.

In machining, windage denotes the clearance between a rotating workpiece and a stationary tool or between adjacent rotating parts, allowing for thermal expansion and preventing contact that could cause damage or excessive wear. This clearance is critical in high‑speed turning, grinding, and turbine blade manufacturing, where minute variations can affect dimensional accuracy and surface finish.

The concept also appears in fluid dynamics and engineering, where windage loss describes the energy dissipated as air flowing over moving surfaces, such as the rotor of an electric motor or the moving armature of a generator. Designers calculate windage drag to predict efficiency losses and to size cooling systems, often employing streamlined shapes or seals to minimize the effect.

Across its uses, windage emphasizes the need to anticipate and compensate for the influence of air on motion, whether to improve precision in shooting, maintain tolerances in machining, or enhance the performance of mechanical systems.