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Aerodynamic Upgrades

Car Aerodynamics Upgrades

Aerodynamic upgrades come in many different forms and have evolved mostly from the early days of ground effects, deployed by lotus and Colin Chapman and used to win many F1 races. These technologies dramatically changed the face of racing forever and aerodynamic upgrades are still at the very top of Motorsports team abilities to win races.Read on to find out about the various components and how they affect race and road cars ability to keep on the tyres planted on the tarmac and maximising traction.  

Front Wing

front wing

The main function of a front wing, is to create downforce that enhances the grip of the front tires. This aids turning ability in fast corners normally above 60 MPH and can amount to up to 25-30% of total downforce, depending on the regulations for that given season. 

The front wings especially in F1 and other open-wheeled cars undergo constant modification and race developments due to data gathering from race to race. Adjustments to fine tune the angle of these devices to create less or more downforce is needed to suit each race course. In most series, the wings are even designed for adjustment during the race itself when the car is serviced on a pit stop. Following Driver instruction and tyre/ tire wear considerations or the demands of the race course.

There can be in car adjustments to maximise top speed and aerodynamic downforce, especially if a race car is fully loaded with fuel at the beginning of a race. The car will be lower to the ground, as the race progresses and more and more fuel is consumed. The car will slowly raise it's ride height at the front, normally creating understeer. With a in car adjustable front wing, this helps to counter act this troublesome problem and the associated handling imbalances this might cause.

Another problem engineers face is the fact that front wings are designed to function properly with clean undisturbed air, F1 for example has struggled in recent years with this problem, when the car behind has decreased downforce levels when following a lead car. This reduced downforce and associated drag is good for slip streaming and top speed, but totally unsettles the car for fast sweeping corners. Figures suggest that this could be up to 70% reduction at a distance of 20m behind the lead car.

The basic design of a front wing has evolved over the years, but is generally a aerofoil suspended from the from nose cone, with movable flaps incorporated in the design to adjust the angle of attack (downforce setting). End plates are also mounted at either end to help the airflow to be forced over or under the wing, also to help with the turbulences generated by the front wheels. The design of the front wing is critical in controlling the flow of air over the rest of the car and is constantly being refined in a given race series to yield a competitive edge over the competition. 

Canards

carnards

Carnards are small wings which are attached to the front of the bumper in a aid to increase downforce and air flow dynamics. They can create vortices, these can been normally seen on fighter jets wing tips during flight. These are basically spiraling jets of low pressure air. 

With Carnards located at the front of the car, it is possible to generate Vortices which run along the length of the vehicle, helping in reducing drag and making for a more slip stream design. Normally only seen on high performance modified road cars or race series, they will not create huge amounts of downforce, but are useful in improving front to rear aerodynamic balance.

They also generate a small amount of downforce by directing airflow upwards over the front of the car aiding in it cutting through the air. Strategically placed, they can also aid in clearing high drag areas on kit cars or open wheelers, or by helping to increase aerodynamic efficiency on cars not designed specifically for for Motorsport use and from stock origins.

Carnards are normally constructed of Carbon Fibre reinforced plastics, due to the high strength to weight ration. Normally designed in a flat triangle shaped, but sometimes with a curved edge to aid airflow direction. Sometimes supplied in two sets, one smaller and one larger, the smaller is normally located lower and the larger above. 

Front Splitter/Air Dam

Front Splitter/ Air Dam Diagram

The main aim of a front splitter and air dam is to aid in the optimisation of the flow of air to the rest of the car and reduce drag, while creating negative lift ( downforce). The main balance is to achieve minimum drag and maximum downforce, aiding the front tyres to get more grip and reduce understeer tendencies.

 The front splitter is attached to the bottom of the air dam , it serves to increase the amount of downforce at the front of the car. Air flow is brought to stagnation above the splitter by an air dam, causing an area of high pressure. Below, the front splitter redirects air away from this stagnation point and accelerates air under the car, which in turn causes a low pressure. High pressure over the splitter caused by the air dam, and low pressure by the airflow under the car creates downforce by ways of Bernoulli's effect. (high pressure is drawn to low pressure areas ).

This helps to minimise the affects of understeer and gives the front end more turn in response on entering corners at speed. Like most racing applications, adjustable angle of attacks maybe possible to adjust for different applications and tracks.

front splitter

Some bodykits can also generate downforce, but most are just cosmetic. Some of the top brands do go through Research and Development and offer a fully functional aerodynamic package. After market manufacture packages are a good example ( BMW'S M sports kits), or fitting a higher spec bodykit from with in the same family of vehicle. 

In a standard stock car or in modifications for specialist race series, cars will undergo dynamic development to help increase these downforce levels. Normally lowering the car to a certain ride height level as well as a lower frontal area will help to increase the desired downforce requirements.

Also it is generally known that a increase in front downforce while entering the turn in for a corner will help to combat understeer. This can help to balance a car more and having more grip to maximise steering inputs to hit the apex. letting you come on the power more quickly, producing better lap times.

A front splitter and air dam combination is normally added to help in this situation and can be made from a number of different materials, including fibre glass, carbon fibre and plastics.


 

Rear Diffuser

rear diffuser

The rear diffuser has a lot of jobs to do, firstly it acts as a way of speeding up airflow (lowering pressure) and then slowing down airflow (increasing pressure), in an aid to create downforce and smooth out turbulent air exiting the rear of the car, matching the outside high pressure air while minimising drag.By providing what is essentially an expansion chamber at the diffuser's exit, the airflow has to flow and expand back to ambient pressure in the diffuser. 

The faster you drive, the more downforce is generated. The easiest way of looking at this is to think of fast moving air being generated by the diffuser and then slowed down at the rear creating a vacuum effect, sucking the underbody to the ground. The faster you drive, the more downforce is generated.

By incorporating the exhaust system into the rear diffuser, you can also help extract the air from the rear of the car more effectively .The exhaust gasses produced effectively energise the airflow, helping to raise the low pressure air .This fast moving air flow returning back to the ambient atmospheric pressure at the exit of the diffuser, reducing drag levels. Hot exhaust gases also aid in expansion, again aiding in the airflow speed transition between fast moving underbody air and slow moving ambient air. Resulting in higher vacuum effect, more downforce and reduced drag.

The diffuser is rather sensitive to engine speed, so if the driver lifts off the throttle, lose of downforce is experienced ( as a result to speed and exhaust gases). The exhaust flow is greatly reduced off throttle and makes the diffuser less effective, robbing the downforce generation effect. This can cause handling issue where the rear of the car might become twitchy and prone to more lift off oversteer , on throttle release. Engine mapping can overcome this by pumping more air out even when off throttle.

Rear diffuser design is evolving constantly and some application don't even require the exhaust system integration to yield beneficial downforce. Also you might of noticed earlier Supercars of the 80's always had big rear wings to generate downforce, but modern designs can generate sufficient required levels without such devices. 

F1 in 2009, there was also a introduction of the double decker rear diffusers in use, the performance increase was some half a second a lap advantage and was be banned for 2011 season. It goes to show how much increase in performance can be had from what might appear to be a device of little significance. 

Chassis/Under Body

Car Underbody Aerodynamics

 While largely hidden from view, chassis and underbody aerodynamics are the secret weapons in an arsenal of aerodynamic features for generating downforce on racing cars. The bodies are designed to slice through the air and minimize wind resistance or drag. In every day driving this will help keep your fuel/gas bills down as well as provide a better top speed. If you can imagine all the nooks and crannys normally expose on a cars under body, by creating a smooth boxed in under tray, drag can be greatly reduced. Maximisation of a cars aerodynamic potential can be achieved with these along with the other aerodynamic devices already discussed.

Detailed pieces of bodywork can be engineered to allow a smooth air flow to reach the downforce-creating elements (wings or spoilers, and underbody tunnels). In recent times more and more work has been undertaken on the underside of the body, similar in shape to an inverted wing ( first used by Colin Chapman's Ground Effects racecars).

The main principal works by the front of the car (splitter/ airdam) creating low pressure fast moving airflow to the underbody of the car. Then the rear of the car's diffuser creates a expansion area, made to slow down the faster moving air, as a result creating additional downforce and vacuum effect (a giant venturis, high pressure air presses down on low pressure air). The Diffuser also aids in smoothing out the airflow at the back of the car, reducing drag and improving aerodynamic efficiency. 

Side Skirts

The main goal of side skirts is to create an area of low pressure between the car and the track, generating increasing pressure as the car increases in speed making the car stick to the road. Lots of different aids have been designed around this area, including side skirts to increase downforce.

 These are a way of channeling the cars low pressure to the rear of the car and directing it to the rear diffuser. It also prevents high pressure air from around the car interfering with the low pressure air underneath the car. Linked closely to the performance of the whole aerodynamic package. 

911 turbo side skirts

Colin Chapman is the founder and designer of Lotus and also the pioneer of Ground Effects in modern motor racing. In 1972 he designed the radical Lotus 72, featuring shovel nose cone in the shape of a wedge, also the radiators were located in the sidepods. Winning both drivers and constructors championships titles that Year. This lead to the Lotus 78, with true side skirt introduction, creating a vacuum effect, sucking the car onto the floor with higher speeds. This lead to another World Driver champion shipped with the driver Mario Andretti.

lotus 79 side skirts

 

Vortex Generators

vortex generator

Vortex generators were firstly developed for the aircraft sector, this technology has made it's way into Motorsport and car design. The main function of this device is to delay air flow separation. 

Air flow separation is when the airflow of a object detaches from the surface and creates eddies and vortexes. This basically means that the car will result in more drag and will reduce top speed and potentially downforce due to the turbulent air entering other aerodynamic device ( rear wing for example) and the wake of air left behind the car.

So by positioning vortex generator over the rear of the roof, you effectively help to reduce drag and increase downforce via the rear wing. This will have the effect of reducing the overall drag created by the car travelling through the air at speed and the faster and faster you drive the more effect this device will have. Especially effective in speeds in excess of 60 mph (100 KMP) speed ranges. 

Rear Wing


rear wing


The flow of air at the rear of the car can be affected by many different influences. This causes the rear wing to be less aerodynamically efficient than the front wing, due to the the disbursed airflow. But typically it must generate more than twice as much downforce as the front wings in order to maintain the handling to balance the car, but this depend on the type of automobile and it's application.

In car designs with the power being delivered via the rear wheels, this is especially vital and the rear wing will not only add acceleration and braking abilities, but also cornering grip.

Generally speaking, when the aim of top speed is the main consideration, race engineers will reduce the angle of attack to minimise drag. Also on some designs, rear wing construction are less pronounced then on F1 for example, due to the need for a more slippery design. 

The rear wing can typically have a larger aspect ratio or angle of attack then would be seen on the front of the car and often uses two or more sections. In a aid to create the amount of downforce needed. Just like the front wings, each of these can often be adjusted when the car is in the pit stop for a race, or via small allen keys to adjust the required downforce. But from 2011 F1 cars will have adjustable rear wings to aid top speed and overtaking abilities.

In the future the idea of active aerodynamic devices will probably raise their heads again and having the ability of these devises to adjust on the go via computer calculations, would yield huge performance gains.This would help to increase fuel economy, while giving maximum performance levels. 

Spoilers

rear spoiler


On normal production cars there is a lot of confusing with rear wings and spoilers. Spoilers are designed to help the flow of air at the back of the car, but normally don't create positive downforce and are primarily deployed for increased fuel efficiency and reducing lift. The bad flow of air at the rear of the car becomes turbulent and a low-pressure zone is created. Increasing drag and instability through the  Bernoulli effect. Some synergy can be made to spoilers and Vortex generators and the advantages of fitting these devices are similar.

Adding a rear spoiler creates a longer, gentler slope or angle of attack from the roof to the aerodynamic aid. This will help delay flow separation of the fast moving air and increase the flow dynamics of the rear airflow. This decreases drag, increases fuel economy, and also can helps keep the rear window clean when rear wipers are not fitted. 

DRS/ Drag Reduction System

A drag reduction system ( DRS) or rear movable wing as some might know it, is a way in which the rear wing's angle of attack can be adjusted for better straight line speed. Essentially a lever which controls one of the rear wing flaps, normally operated during the straights, it's one of the ways in which F1 has adopted new design rules to spice things up in the 2011 season.

The greater the rear wing's angle of attack, the more downforce is generated. By reducing this angle of attack, the wing reduces downforce and drag levels, increasing top speed as a by product and aid overtaking.

In F1 this system is controlled electronically via a FIA approved ECU system and is normally permitted when the leading car is with in a 1 second gap. Speeds of up to 12km per hour are suppose to be the limit of this device, but arguable tracks with more downforce settings could reap larger gains.