Over the next year

I want to share with you the exciting news!

Over the course of the next year we'll slowly be beefing up the F1-Pitlane technical section. This will culminate with an extensive look at many different technical aspects of a Formula 1 car once the 2008 season has closed. With it we'll take a look at the regulation changes for 2009 and what that will mean for the sport.

In the meantime we'll start by developing some primers on the main technical disciplines demanded in F1. Today we'll look specifically at basic aerodynamics but in future we'll cover more specific aerodynamic areas of a car, transmission, engines, tyres, among other.

If you have any specific requests please leave a note in the comment section and we'll put in on the list of to-dos.

Why is aero so important?

To consider this question let's revisit the basic mechanics of a car. The engine supplies power which must overcome the drag forces (friction and air resistance) to propel the car forward. The greater the power and the lower the drag the faster the car goes. Simple eh?

This is all well and good going in a straight line but consider what happens when a car goes round a corner — assume for the minute that this car has no aerodynamic enhancements. The lateral acceleration will exert a force on the car that will try to "push" it off the race track. The car will successfully go round the corner if the mechanical grip is strong enough to resist this force. Mechanical grip is the confluence of weight and grip provided by the tyres.

We know from experience that if we corner too fast then the we'll lose the back end of the car and it will spin off the track. One way we can corner faster is to improve the grip of tyres or increase the weight of the car.

Another way is to add aerodynamic enhancements to the car to increase its effective weight — this is called downforce and is perhaps the most important element of modern Formula One.

To understand why this is so imagine the back of the car sliding because the lateral acceleration overcomes mechanical grip. If we add a hundredweight to the back end of the car it will obviously slide less (and the mathematics confirms this thought experiment).

The mechanics of downforce

So how is downforce generated?

Well, downforce is the opposite of lift is generated by an aerofoil (much like you might see if you look out of the window in seat 42A on the red eye between New York and London). To generate downforce all you need to do is to invert an aircraft wing — and that, in effect, is how the wings on a racing car work.

The mathematical physics behind lift is complicated so for this 101 piece we'll make do with a descriptive explanation.

This phenomenon is most often explained by the Bernoulli principle. If you place a wing in moving air the shape of the wing will cause the air on one side to slow down. Bernoulli's argument (which is correct!) is that by the principle of conservation of energy there must be an accompanying increase in pressure. This creates a pressure differential across the surface area of the wing and gives us downforce!

By varying the angle of the wing we can change the amount of downforce generated — this is called the angle of attack. However, this isn't necessarily the smart thing to do.

We all know one reason why F1 cars look the way they do is to reduce air resistance (called drag). Surprise, surprise, the greater the angle of attack of the wing the higher the drag, which slows the car down. The aerodynamic trade-off is between downforce and drag, and it is the job of the designer to get this right — unsurprisingly the laws of physics (mostly) prohibit us from generating downforce for free; the question is how can we generate downforce for the lowest cost!

(In a future article we'll revisit the mathematical trade-off between these two constituencies and specifically how designers calculate them.)

Downforce and F1

In Formula 1 the car is designed to generate as much downforce as possible within a set of legal constraints put forth by the FIA. The entire car plays a critical role in generating downforce (and reducing drag).

The front wing (where about 20-30% of downforce is generated) is designed to channel the air under and around the car, into the sidepods and around the wheels. This last part is critical because the wheels are responsible for a lot of the drag that the car generates and the end plates on the front wing should divert the airflow away from the wheels.

As the front wing is the first thing that air interfering with the car goes over, it is probably the most important aerodynamic element on the car. Stuff it up and the downforce performance elsewhere will be seriously compromised.

Another 30%-40% of the downforce is generated by the rear wing. Because the airflow is disrupted as it flows over the car the rear wing is less aerodynamically efficient than the front wing is — hence it is much bigger to compensate.

The rear wing must generate more downforce than the front wing in order to maintain the balance of the car. This is especially important if the car has a forward biased weight distribution, which most cars tend to have in the modern era.

The remainder of the downforce is generated by the body of the car, and the diffuser in particular. The diffuser is an inverted wing that sits between the very back of the car and the front of the rear tyres. Because it is wing shaped it slows the air on the top side of the diffuser, which generates downforce and results in more back-end grip. The diffuser is also designed to reduce turbulence, which as we'll see in part 2 of this article is an important part of maximising aerodynamic performance.

One area were the FIA has seriously constrained aerodynamic evolution is in so-called Ground Effect Aerodynamics.

A ground effiect is created if we accelerate the air flowing under the car to create an area of low pressure, which generates downforce. However, this has severe safety implications. If the car jumps while cornering the ground effect could be lost causing the car to career off the track.

The FIA now has stringent regulations for specifying the underside of the car to prohibit ground effect aerodynamics.

The other obvious aerodynamic features of a formula car are the barge boards and winglets. Although these will be outlawed when the 2009 aero regs come into force, for the time being these protrusions play an important aerodynamic role.

The barge boards don't actually play a true aerodynamic role but tidy up the air around the side of the car (making the rest of the car more aerodynamically efficient —especially the underside) and, importantly, channeling air into the sidepods for engine cooling.

The function of the winglets is slightly more obscure. They create mini-vortices, which create regions of local low pressure that increase the overall downforce of the car. They are most common on the tighter circuits like Monaco and Hungary.

In part 2 ...

Hopefully this mini-introduction has been useful.

In part 2, next week, I'll take a look at some of the reasons why overtaking is so damn difficult in today's sport as well as give you a glimpse into the aerodynamic future of F1.