All about cars: Spoiler

A spoiler is an automotive aerodynamic device whose intended design function is to 'spoil' unfavorable air movement across a body of a vehicle in motion. Spoilers on the front of a vehicle are often called air dams, because in addition to directing air flow they also reduce the amount of air flowing underneath the vehicle which reduces aerodynamic lift. Spoilers are often fitted to race and high-performance sports cars, although they have become common on passenger vehicles as well. Some spoilers are added to cars primarily for styling purposes and have either little aerodynamic benefit or even make the aerodynamics worse.

Spoilers for cars are often incorrectly confused with, or the term used interchangeably with, wings. Automotive wings are devices whose intended design is to generate downforce as air passes around them, not simply disrupt existing airflow patterns.

The Plymouth Superbird is famous for its giant rear spoiler.

Operation

Since spoiler is a term describing an application, the operation of a spoiler varies depending on the particular effect its trying to spoil. Most common spoiler functions include disrupting some type of airflow passing over and around a moving vehicle. A common spoiler diffuses air by increasing amounts of turbulence flowing over the shape, "spoiling" the laminar flow and providing a cushion for the laminar boundary layer. However, other types of airflow may require the spoiler to operate differently.

Passenger vehicles

The main design goal of a spoiler in passenger vehicles is to reduce drag and increase fuel efficiency. While many often imitate wings and airfoils, these serve mostly decorative purposes. Passenger vehicles can be equipped with front and rear spoilers. Front spoilers, found beneath the bumper, are mainly used to direct air flow away from the tires to the underbody where the drag coefficient is less. Rear spoilers, which modify the transition in shape between the roof and the rear and the trunk and the rear, act to minimize the turbulence at the rear of the vehicle.

Sports cars are most commonly seen with front and rear spoilers. Even though these vehicles typically have a more rigid chassis and a stiffer suspension to aid in high speed maneuverability, a spoiler can still be beneficial. This is because many vehicles have a fairly steep downward angle going from the rear edge of the roof down to the trunk or tail of the car. At high speeds, air flowing across the roof tumbles over this edge, causing air flow separation. The flow of air becomes turbulent and a low-pressure zone is created, increasing drag and instability (see Bernoulli effect). Adding a rear spoiler makes the air "see" a longer, gentler slope from the roof to the spoiler, which helps to delay flow separation. This decreases drag, increases fuel economy, and helps keep the rear window clean.

This Toyota MR2 sports car has a factory-installed rear spoiler.

Material types

Spoilers are usually made of:

ABS plastic – Most original equipment manufacturers create spoilers produced by casting ABS plastic with various admixtures, which bring in plasticity to this inexpensive but fragile material. Frailness is a main disadvantage of plastic, which increases with product age and is caused by the evaporation of volatile phenols.
Fiberglass – Used in car parts production due to the low cost of the materials. Fiberglass spoilers consist of fiberglass cloth infilled with a thermosettting resin . Fiberglass is sufficiently durable and workable, but has become unprofitable for large scale production due to the amount of labor.
Silicon – More recently, many auto accessory manufacturers are using silicon-organic polymers. The main benefit of this material is its phenomenal plasticity. Silicon possesses extra high thermal characteristics and provides a longer product lifetime.
Carbon fiber – Carbon fiber is light weight, durable, but also a very expensive material. Due to the very large amount of manual labor , large scale production cannot widely use carbon fiber in automobile parts production currently.

Spoiler types

These are main types of spoilers:

Front spoilers – A front spoiler, or air dam, is positioned under the front bumper. This type of spoiler originally was designed for racing cars and is shaped to reduce the airflow under the car. Air dams increase the airflow to the radiator, reduce aerodynamic drag and reduce lift. This type of spoilers is popular among owners of high-powered cars.

Factory style spoilers – Most manufacturers of auto parts and accessories produce OE auto accessories. OE is more general referring to any part that came as original equipment on the car. Some of OE car parts and components are not actually made by the car manufacturer but are purchased and assembled by the automakers to create a vehicle. Compared to a universal fit auto part, which can be installed to any vehicle make, year and model, custom aftermarket spoilers are designed to fit only a particular vehicle. Most auto users prefer aftermarket products because they are less expensive than OEM replacements. While it is true that there may be some aftermarket auto parts that do not meet high standards of original equipments, it is not right to say that aftermarket products are generally inferior in terms of quality and style.

Lip spoiler – Lip spoilers are produced in two variants rear and front lip spoilers. Front lip spoiler used in conjunction with side skirts makes the whole car appear much lower. It perfectly reveals a silhouette of your vehicle, extending the length of the bumper cover. Rear lip spoiler is installed on the edge of the trunk lid. Due to its design lip spoiler has more aesthetic value than performance.

Truck cap spoilers – Truck cap spoiler is mounted right on the edge of the trunk lid. Being a stylish accessory this type of spoilers is usually equipped with lights working as third brake lights. So every time the driver hits the brake pedal the lights on the truck cap spoiler ignite.

Cab spoiler – The cab spoilers manufactured for pickup truck owners who want to modify their vehicle. It attaches only to the top of the truck bed rails. It shields the rear window and cargo area from the sun. It also provides cab shade reducing sun glare. The cab spoilers available with xenon lamps for better visibility on the road.

Rear wings – Wings can be described as special wing-like structures. Unlike a plane's wings, which are designed to generate lift, these wings are designed to generate Downforce, literally pushing the car downwards. This increase stability and grip Most of the cars used in car races and other fast action-packed sports have rear wings as well as front spoilers and other aerodynamic modifications. They're available in a number of various designs and colors and it is even possible to have them custom-made. There are readily spoilers available, which can be installed on to the car with ease.

Ridiculous spoilers – There are three main purposes of car spoilers: reduce drag, increase fuel efficiency, decorative purposes. But there is a group of people who create spoilers for their vehicles from anything that is far from being spoiler material. Such ridiculous spoiler fashion is very popular in Japan. There are constantly held competitions among such car enthusiasts.

Other vehicles

Heavy trucks, like long haul tractors, may also have a spoiler on the top of the cab in order to lessen drag caused from air resistance from the trailer it's towing, which may be taller than the cab and reduce the aerodynamics of the vehicle dramatically without the use of this spoiler.

Trains may use spoilers to induce drag (like an air brake). A new prototype Japanese high-speed train, the Fastech 360 is designed to reach speeds of 400 kilometres per hour (250 mph). Its nose is specifically designed to spoil a wind effect associated with passing through tunnels, and it can deploy 'ears' which act to slow the train in case of emergency by increasing its drag.

Some modern race cars employ a situational spoiler called a roof flap. The body of the car is designed to generate downforce while driving forward. These roof flaps deploy when the body of the car is rotated so it is traveling in reverse, a condition where the body instead generates lift. The roof flaps deploy because they are recessed into a pocket in the roof. The low pressure above this pocket will cause the flaps to deploy, and counteract some of the lift generated by the car, making it more resistant to coming out of contact with the ground.

Whale tail

An earlier use of the term whale tail, now used to refer to a visible thong, dates back to August 1974, when the Porsche 911 Turbo debuted with large, flared, rear spoilers that were immediately dubbed whale tails. Designed to reduce rear-end lift and so keep the car from oversteering at high speeds,the rubber-edges of the whale tail spoilers were thought to be "pedestrian friendly". The Turbo, with its whale tail, became an instant hit. It also became one of the world's most recognizable sports cars, remaining in production for the next two decades in one form or another, with more than 23,000 sold by 1989, although from 1978, the rear spoiler was redesigned and dubbed 'teatray' on account of its raised sides. The Porsche 911 whale tails were used in conjunction with a chin spoiler attached to the front valence panel, which, according to some sources, did not enhance aerodynamic stability. It has been found to be less effective in multiplying downforce than newer technologies like an airfoil, "rear wing running across the base of the tailgate window", or "an electronically controlled wing that deploys at about 50 mph".(80 km/h).

Original whale tail as introduced on the 1975 3.0 litre Porsche 930 turbo.

History

The whale tail came on the heels of the 1973 "duck tail" or Bürzel in German (as a part of the E-program), a smaller and less flared rear-spoiler fitted to 911 Carrera RS (meaning Rennsport or race sport in German), optional outside Germany. The whaletail was originally designed for Porsche 930 and Porsche 935 race cars in 1973, and introduced to the Turbo in 1974 (as a part of the H-program), it was also an option on non-turbo Carreras from 1975. Both types of spoilers were designed while Dr. Ernst Fuhrmann was serving as the Technical Director of Porsche AG. In 1976, a rubber front chin spoiler was also introduced to offset the more effective spoiler. By 1978, Porsche introduced another design for the rear spoiler, the 'teatray, a boxier enclosure which accommodated the intercooler, and was also an option for the 911SC.

Duck tail on a 1973 Porsche 911 Carrera RS.

Other vehicles

These whale tail car spoilers of the Porsche 911 caught on as a fashion statement, and the term has been used to refer to large rear spoilers on a number of automobiles, including Ford Sierra RS, Focus, Chevrolet Camaro, and Saab 900. Whale tail spoilers also appear at the rear of tricycles, trucks, boats, and other vehicles.