Windage
Encyclopedia
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:
The term can refer to either:
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. (The up-down adjustment for the vertical component is the elevation.) 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
caused by oil splashing out of the sump at high rpm. At 6,000 rpm, for example, the crankshaft must rotate 100 times per second. As the crankpins and counterweights rotate at such high speeds, they create a swirling cloud of air around them. Windage is considered to occur when excess oil is caught up in this turbulent air, drawing energy from the engine to spin the oil mist. 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.
Force
In physics, a force is any influence that causes an object to undergo a change in speed, a change in direction, or a change in shape. In other words, a force is that which can cause an object with mass to change its velocity , i.e., to accelerate, or which can cause a flexible object to deform...
created on an object by friction
Friction
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and/or material elements sliding against each other. There are several types of friction:...
when there is relative movement between air and the object.
There are two causes of windage:
- the object is moving and being slowed by resistance from the air
- a windWindWind is the flow of gases on a large scale. On Earth, wind consists of the bulk movement of air. In outer space, solar wind is the movement of gases or charged particles from the sun through space, while planetary wind is the outgassing of light chemical elements from a planet's atmosphere into space...
is blowing producing a forceForceIn physics, a force is any influence that causes an object to undergo a change in speed, a change in direction, or a change in shape. In other words, a force is that which can cause an object with mass to change its velocity , i.e., to accelerate, or which can cause a flexible object to deform...
on the object
The term can refer to either:
- the effect of the force, for example the deflection of a missileMissileThough a missile may be any thrown or launched object, it colloquially almost always refers to a self-propelled guided weapon system.-Etymology:The word missile comes from the Latin verb mittere, meaning "to send"...
or an aircraftAircraftAn aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...
by a cross wind, or - the area and shape of the object that make it susceptible to friction, for example those parts of a boatBoatA boat is a watercraft of any size designed to float or plane, to provide passage across water. Usually this water will be inland or in protected coastal areas. However, boats such as the whaleboat were designed to be operated from a ship in an offshore environment. In naval terms, a boat is a...
that are exposed to the wind.
Aerodynamic streamlining
Streamliner
A streamliner is a vehicle incorporating streamlining in a shape providing reduced air resistance. The term is applied to high-speed railway trainsets of the 1930s to 1950s, and to their successor "bullet trains". Less commonly, the term is applied to fully faired recumbent bicycles...
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. (The up-down adjustment for the vertical component is the elevation.) 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
Crankshaft
The crankshaft, sometimes casually abbreviated to crank, is the part of an engine which translates reciprocating linear piston motion into rotation...
caused by oil splashing out of the sump at high rpm. At 6,000 rpm, for example, the crankshaft must rotate 100 times per second. As the crankpins and counterweights rotate at such high speeds, they create a swirling cloud of air around them. Windage is considered to occur when excess oil is caught up in this turbulent air, drawing energy from the engine to spin the oil mist. 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.