Science Behind F1 Aerodynamic Features.

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Table of Contents

.0 Science Behind F1 Aerodynamic Features......................................................1

.1 Bernoulli's Equation.................................................................................1

.2 Drag....................................................................................................2

.3 Downforce.............................................................................................5

2.0 History of Aerodynamic Features - Momentous Design Innovations..............6

3.0 Features of the Front Half of the F1 Vehicle..................................................6

3.1 Front Wing...........................................................................................6

3.2 Wheels.................................................................................................8

3.3 Suspension............................................................................................9

3.4 Barge Boards.......................................................................................10

3.5 Brake Cooling......................................................................................11

4.0 Features of the Rear Half of the F1 Vehicle.................................................11

4.1 Rear Wing...........................................................................................11

4.2 Endplates............................................................................................13

4.3 Diffuser..............................................................................................14

4.4 Chimneys............................................................................................15

4.5 Flip-ups..............................................................................................17

5.0 Testing........................................................................................................17

5.1 Computational Fluid Dynamics (CFD).......................................................17

5.2 Wind-Tunnels......................................................................................18

6.0 Technical Regulations Affecting Aerodynamic Features..............................19

7.0 Concluding Remarks - Predictions for the Future.......................................20

References.............................................................................................................22

.0 Science Behind F1 Aerodynamic Features

Engineered with perfection, the loud and aggressive Formula One (F1) racecar is the ultimate racing machine. Its reputation has been defined by its amazing speed and handling characteristics, which are for the most part, a product of its aerodynamic features. The success of these features relies primarily on the appropriate and efficient harnessing of drag and downforce - both of which are ruled by physical principles explained by Bernoulli's equation.

.1 Bernoulli's Equation

Investigated in the early 1700s by Daniel Bernoulli2, his equation defines the physical laws upon which most aerodynamic concepts exist. This now famous equation is absolutely fundamental to the study of airflows. Every attempt to improve the way an F1 car pushes its way through molecules of air is governed by this natural relationship between fluid (gas or liquid) speed and pressure. There are several forms of Bernoulli's equation, three of which are discussed, in the succeeding paragraphs: flow along a single streamline, flow along many streamlines, and flow along an airfoil. All three equations were derived using several assumptions, perhaps the most significant being that air density does not change with pressure (i.e. air remains incompressible). Therefore they can only be applied to subsonic situations. Being that F1 cars travel much slower than Mach 1, these equations can be used to give very accurate results.1

Low speed fluid flow along single or multiple streamlines is interpreted in Figure 1. The presumptions regarding the application of Bernoulli's equation to this scenario are listed in the figure. In this situation, there exists a relationship between velocity, density and pressure. As a single streamline of fluid flows through a tube with changing cross-sectional area (i.e. an F1 air inlet), its velocity decreases from station one to two and its total pressure equals a constant. With multiple streamlines, the total pressure equals the same constant along each streamline. However, this is only the case if height differences between the streamlines are negligible. Otherwise, each streamline has a unique total pressure.

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Figure 1: Mathematical and pictorial explanation of Bernoulli's Equation as applied to fluid flow through a tube with changing cross-sectional area.2

As applied to flow along low speed airfoils (i.e. F1 downforce wings), airflow is incompressible and its density remains constant. Bernoulli's equation then reduces to a simple relation between velocity static pressure.1

(pressure) + 0.5(density)*(velocity)2 = constant

This equation implies that an increase in pressure must be accompanied by a decrease in velocity, and vice versa. Integrating the static pressure along the entire surface of an airfoil gives the total aerodynamic force on a body. Components of lift and drag can be determined by breaking this force down.

In order to discuss lift and downforce, it may be helpful to provide an additional explanation of the relationship that occurs with the above form of Bernoulli's equation. If a fluid flows around an object at different speeds, the slower moving fluid will exert more pressure on the object than the faster moving fluid. The object will then be forced toward the faster moving fluid.8 A product of this event is either lift or downforce, each of which is dependent upon the positioning of the wing's longer chord length. Lift occurs when the longer chord length is upward and downforce occurs when it is downward. The scenarios for lift and downforce are depicted in Figures 2 and 6, respectively.

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Figure 2: Lift according to the application of Bernoulli's Equation

.2 Drag

The remarkable speed of the F1 racecar is achieved from the careful combination of its powerful engine and expertly crafted aerodynamic body features. In the early years of F1 design, the engine was the primary variable in determining the racing success of a car. Applicable engine technology had far exceeded the maturity of vehicle aerodynamics. Those historic years embodied a simple algorithm. Speed was nearly a direct function of horsepower. Although still improving almost annually, engine performance levels among the cars of each racing season today have comparable performance - record speed achievements now hinge on a different design issue - aerodynamics and drag plays a major role. F1 aerodynamics engineer, Will Gray, has noted that "Top speed is determined other factors [car weight, fuel strategy, and good low-end engine power], but the main factor which separates the victors from the valiants in this area is aerodynamic performance - too much drag and you're pulling unwanted air along with you." 3

One form of drag occurs as air particles pass over a car's surfaces and the layers of particles closest to the surface adhere. The layer above these attached particles slides over them, but is consequently slowed down by the non-moving particles on the surface. The layers above this slowed layer move faster. As the layers get further away from the surface, they slow less and less until they flow at the free-stream speed. The area of slow speed, called the boundary layer, appears on every surface, and causes one of the three types of drag, Skin Friction Drag.
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The force required to shift the molecules out of the way creates a second type of drag, Form Drag. Due to this phenomenon, the smaller the frontal area of a vehicle, the smaller the area of molecules that must be shifted, and thus the less energy required to push through the air. With less engine effort being taken up in the moving air, more will go into moving the car along the track, and for a given engine power, the car will travel faster. Another factor that plays a role in aerodynamic efficiency is the shape of the ...

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