Car Spoiler or Wing is an easy way to upgrade a performance car or add the aura of speed to an ordinary ride. Spoiler & wing can make a car look better and give more stylish and sporty looking. However, all later modifications on your car may come at a price. Lets start with how spoiler & wing work on a car.
When air passes over a curved surface, it tends to accelerate which is called the Venturi principle. Air that flows faster also has a lower pressure. This is Bernoulli’s principle. Together, these two principles explain how the wings of airplanes work. In the world of cars, this means that the air passing over the roof of the car will tend to generate lift. The lifting is an upward force that while on an airplane is good, in the car it can lead to instability and ultimately loss of control.
Difference between a Car Spoiler and a Car Wing
Before starting, it is also important to note that a car wing and a car spoiler are not the same thing. Both of the material often is referred as the same thing. Here is a very detailed article for understanding thin line between two. To summarize,
- Both wings and spoilers reduce up-lift at the tail of the vehicle, but use different mechanisms.
- Wings are airfoils designed to directly deflect air upwards and thus push the rear of the vehicle down. They generally add quite a bit of drag.
- Spoilers are barricades to undesirable flows, and thus are able to reshape airflow streams around the vehicle. This can help keep the rear of the vehicle down and decrease drag by changing the effective vehicle shape.
- You need computational fluid dynamics and/or wind tunnel testing to quantify spoiler/wing performance.
- Neither have any positive impact whatsoever on straight-line low-speed acceleration. Both are primarily intended to improve stability and cornering at high speeds.
Why Spoilers/wings are usually seen on sport cars?
As is known, Sports cars have stiff suspensions and low aerodynamic resistance. Therefore, they are produced with a streamlined geometry and quite low distance from the ground. This creates a problem of skidding and stability in cars at high speeds. This is because as the speed of the vehicle increases, the pressure of the air passing over the vehicle decreases as a result of excessive acceleration. Also, the air flowing under goes at vehicle speed which apply a lift force. Although the same situation occurs in aircraft wings, the creation of buoyancy is desired there, but not in automobiles.
Sports cars with extremely powerful engines can transmit very high torque to the tires even at high gears. When the speed of the vehicle is high, due to the lifting force, the force exerted on the ground may fall far below the vehicle weight. It is excepted that If you install very powerful engine to a car that is not heavy enough, the car will skid.
The force of the torque on the asphalt will exceed the static friction force between the tires and the road. Therefore it causes dynamic friction and the tire to spin idle (skidding). Since this situation is frequently encountered in first gear especially in front-wheel drive vehicles, there is a system that restricts the engine power or activates the ESP system.
However, this skidding problem starts to occur again at extremely high speeds. This is because the outer structure of the car, which is optimized for aerodynamic efficiency, works like an airplane wing. The aerodynamic creates lift force on the car. With high torque applied on tires, the car cannot hold the road causes both stability and performance problems.
How do car wings work?
To prevent this problem, a wing is added to the rear surface of the vehicles. You can compare this wing to a plane wing, but with a difference. In aircraft wings, the upper surface is curved than the lower surface. Hence, the pressure on the wing is high and the pressure under the wing is low. Therefore, the aircraft takes off. The aircraft wing in the automobile is similar to the inverted version of aircraft wing. In other words, the same force that lifts the plane have opposite force for the cars.
As a result, the lifting force generated by the car’s structure is less felt due to the reverse force applied by the wing. Since the force applied by the tires on the ground will increase, the risk of skidding at high speeds is eliminated.
However, there is only one problem. The wing on the car creates unnecessary friction at low speeds when its lift force is low. To prevent this, luxury car manufacturers have designed the wing to open at speeds above 120 km/h and close at speeds below it.
Does Installing Spoiler/Wing Increase Fuel Consumption?
Finally, wings add drag, which reduce your car top speed and top-end acceleration. However, at high speeds, they push the car down and add traction so you can turn faster. Therefore, wings usually produce down force and create additional fuel consumption. A spoiler breaks up the laminar boundary layer by inducing turbulence, which in turn reduces drag and increases fuel efficiency.
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