How the F1 rules changes for 2009 are meant to improve racing (part 1/3)

Posted on | Author John Beamer

Christian Klien tests BMW's 2009 F1 prototype
Christian Klien tests BMW's 2009 F1 prototype

Over the last three years the rules that govern F1 have remained remarkably stable. In recent times the slowest car on the track (usually a Force India) has often been within 1.5s of the fastest. Ten years ago such a slim margin was unheard of.

However, that will all change as the FIA has overhauled the technical regulations for 2009, which promises to cause havoc in F1 design studios across the globe. Some teams are salivating at the prospect of using the revised technical baseline to leap up the grid. Who knows what will happen. Perhaps the only certainty is that the spread in lap times will increase.

In this series of three articles we will explore why F1 has decided to revamp its technical rules and what will change for 2009.

Why the change?

Despite an often dramatic 2008 season, it is widely acknowledged that F1 as a spectacle is often quite dull. Overtaking is tricky at the best of times and non-existent at the worst – winning from pole is common. Watch the breathless overtaking in GP2 or MotoGP and the challenge F1 faces is apparent.

The problem is that over time F1 cars have become finely tuned aerodynamic locomotives. With the homologation of power plants and imposition of control tyres, the majority of performance gain in recent times is from aerodynamic innovation. Teams can quite comfortably employ 200 people to man a couple of wind tunnels or a bank of supercomputers, just to shave that last hundredth of a second from a lap.

Unsurprisingly if an F1 car operates outside of its optimal aerodynamic band (e.g., when following another car) performance severely drops off. To understand why this is we must explore how air interacts between two cars close together. Two phenomena mostly explain why it is difficult for one car to follow another: upwash and turbulence.

Upwash is more pernicious and is mostly generated by the rear wing and diffuser. The diffuser is designed to help pressure recovery of the floor and as such is angled upwards. In modern F1 the rear aerofoil is coupled with the diffuser and acts as pump by creating a low pressure zone above the diffuser. The diffuser/wing combination creates a sizeable updraft. In addition, the rear wing endplates produce two, large, counter-rotating vortices that usually combine to enhance the upwash (depending on the design of the wing). A wing travelling in upwash faces a lower angle of attack, which reduces pressure on the skyward side and hence downforce.

Whereas upwash causes the airflow to change direction, turbulence is characterised by chaotic, stochastic property changes in a fluid. Typically, turbulence in an F1 car is generated by either a slipstream or a vortex burst. In both instances the outcome is the same: lower total pressure and flow velocity, which reduces the effective camber of a wing and makes it less efficient.

It isn?t only aerofoils that suffer; flow conditioners are badly affected too. These devices are designed to work in stable air so upwash and turbulence disturbs the geometry of the free air flow and the efficacy of the conditioner (usually translating to a loss of grip at the rear).

The 2009 regulations have two objectives in mind. First, is to curtail the car?s wake and control upwash; and second, is to reduce the aerodynamic sensitivity of the car (particularly for the benefit of flow conditioners) so it suffers less in turbulence.

With that in mind let?s take a tour around an F1 car and look at the aerodynamic differences we can expect in 2009.

Front wing

Felipe Massa in the 2009 Ferrari F60
Felipe Massa in the 2009 Ferrari F60

Changes: The front wing is widened from 1,400mm to 1,800mm and now spans the width of the car. After being raised in 2005 to cut downforce, the wing is lowered from 150mm above the reference plane to 75mm above it. Also its leading edge is brought forward by 100mm.

Interestingly the central 500mm section is an FIA specified single-element profile and the shape and size of the non-specified section is partly restricted. At a point 750mm from the centre line to the edge of the wing various area requirements must be met. Also the zone 840mm to the edge must only consist of a single section when viewed from beneath, which allows flicks and channels on the endplate to manage airflow to the front wheels. However, the section spanning 400mm to 750mm from the car centre line is relatively free from restriction although must be less than 550mm long and 200mm deep.

Perhaps the most significant change is the presence of driver adjustable flaps in the zone 250mm to 750mm from the car centre line. These flaps must form a single closed section and can be adjusted by the driver twice a lap up to an angle of six degrees. Finally bodywork over and on top of the nose (i.e., dumbo ears or bridge wings) are banned, although Renault-style cascade flaps are allowed.

Performance implications: All things being equal, by widening the wing plan area is made greater and so is downforce. In addition, lowering the device induces a ground effect, which works better in turbulence, is less susceptible to upwash and also supplements downforce.

Moving the front wing forward improves its efficiency and shifts the aerodynamic balance of the car forward to the benefit of front grip. Although the imposition of a standard central section sparks worries about the sport becoming a spec series it should see the wing operate across a wider tolerance band.

The driver adjustable flaps are the first moveable aerodynamic devices allowed in F1 for over 40 years. The idea is that the driver of a car in dirty air can raise his flaps to increase the angle of attack of the front wing and generate more downforce. When passing the driver lowers the flaps to cut drag to increase the odds of a successful manoeuvre. However the drivers may only alter the positions of these flaps twice per lap.

Marks 7/10: The push to make the front wing less sensitive and increase the ground effective is welcome and will up the aerodynamic efficiency of a car in dirty air. As a result, cars will be able to travel closer together, which makes overtaking easier.

The driver adjustable section is a wild card. It adds a lot of cost and complexity to the wing and the performance benefits are uncertain ?ǣ teams could waste a lot of cash for little gain. It also feels a little arbitrary and archaic ?ǣ what?s wrong with adjusting it automatically and why only six degrees? There is a good argument for the reintroduction of movable devices into F1 as they could be tuned to the amount of turbulence, although the cost implications are significant. The FIA?s manual solution sacrifices efficiency and probably won?t improve racing.

The logic for widening the front wing is to add downforce but it may turn out to be folly. The interaction between the endplates and the front wheel is complicated and reducing drag in this region sucks up a lot of resource. Managing this interaction will continue to be subject to heavy (and costly) development, especially as the reintroduction of slicks alters the aerodynamic characteristics of the tyres. A wider front wing also increases the odds of bodywork flying around the track after prangs ?ǣ at least it will keep pit crews busy.

This series continues tomorrow with a look at the rear wing and barge boards. This is a guest article by John Beamer. If you want to write a guest article for F1 Fanatic you can find all the information you need here.

How the F1 rules changes for 2009 are meant to improve racing

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