Formula 1 Aerodynamics
Formula 1 is home to many trades: drivers, mechanics,
engineers, marketers, managers etc. However, Formula
1 is ruled by one trade...the aerodynamicist.
Aerodynamics is the most important aspect of a
Formula 1 car. The difference between the fastest and
slowest cars on the grid, is rarely down to engine power
or even driver skill or suspension setup. It is down to
how the car handles the air around it.
Initially, the aerodynamics focused on wind resistance
and overcoming drag, the force exerted by the air
against the traveling car body. Beginning in the 1920s
and 1930s car designers began to utilize streamlining to
smooth the outside of a car body such that air flows
virtually undisturbed around it, increasing speeds. In
the 1950s the first decade of Formula 1 as an
established sport, the cars resembled fat cigars with
smooth streamlined shapes and gentle curves allowing
the air to flow smoothly around the cars. This made
the cars fast, but soon enough the limits of these cars
were established.
The problem encountered by a streamlined Formula 1
car is that it doesn't travel in a straight line, or in a wide
oval like indy cars or Nascar stock cars. Formula 1 is
run on a road coarse with corners or left and right turns
of various angles and distances. This means that the
car must abruptly slow down, turn, and then accelerate
over and over, some 10-20 times per lap. Sure
streamlining helps the car accelerate after a corner but
it sure doesn't help it slow down or turn. In fact, how
fast you can take the corners, not your top speed on
the straights, is the determining factor in a road course
race.
The determining factor in how fast you can take a
corner is called grip. The simplest definition of grip we
know is that grip is the car's ability to stick to the road
and go where the driver intends. If the car doesn't go
where the driver intends, the driver is faced with a lack
or deficiency of grip. Grip is what allows a driver to
take a corner faster and faster without running of the
track or losing control.
This valuable commodity-grip occurs in only one place:
where the tire meets the road, the contact patch. The
action between the tire and the road surface determines
grip. A "sticky" or soft compound tire will tend to have
more grip than a comparable harder compound tire.
The softer tire will wear out faster, and a worn tire has
very little grip, so there is a cost to using tires to
maximize grip.
Another way to increase grip is to add weight to the
tire. More weight will push down on the tires contact
patch increasing its grip. For the same reason an
empty pickup truck will have less grip in the snow or
ice, than one with the bed filled with say concrete. The
problem with adding weight is that there is an
associated cost, the added weight on the tire means
that the car can't accelerate as fast or hit the same top
speed. Therefore, car designers needed to find a way
to increase grip without incurring the costs of worn tires
or added vehicle weight. The solution came from
turning an aerospace idea upside down.
Airplane wings through their shape utilize air pressure
differences between the top and the bottom of the
wing to create a force called lift-raising even a heavy
metal airplane. In the 1960s car designers used an
upside down wing to create the opposite of lift, or
downforce. A wing traveling through the air exerts a
powerful force in one direction, and designers aimed
this force in the same direction as added weight to
increase grip, but without the cost of actually adding
the weight. This force is stronger when the car is
traveling faster and more grip is needed, and less when
the car is traveling slower and the need for grip is
reduced.
engineers, marketers, managers etc. However, Formula
1 is ruled by one trade...the aerodynamicist.
Aerodynamics is the most important aspect of a
Formula 1 car. The difference between the fastest and
slowest cars on the grid, is rarely down to engine power
or even driver skill or suspension setup. It is down to
how the car handles the air around it.
Initially, the aerodynamics focused on wind resistance
and overcoming drag, the force exerted by the air
against the traveling car body. Beginning in the 1920s
and 1930s car designers began to utilize streamlining to
smooth the outside of a car body such that air flows
virtually undisturbed around it, increasing speeds. In
the 1950s the first decade of Formula 1 as an
established sport, the cars resembled fat cigars with
smooth streamlined shapes and gentle curves allowing
the air to flow smoothly around the cars. This made
the cars fast, but soon enough the limits of these cars
were established.
The problem encountered by a streamlined Formula 1
car is that it doesn't travel in a straight line, or in a wide
oval like indy cars or Nascar stock cars. Formula 1 is
run on a road coarse with corners or left and right turns
of various angles and distances. This means that the
car must abruptly slow down, turn, and then accelerate
over and over, some 10-20 times per lap. Sure
streamlining helps the car accelerate after a corner but
it sure doesn't help it slow down or turn. In fact, how
fast you can take the corners, not your top speed on
the straights, is the determining factor in a road course
race.
The determining factor in how fast you can take a
corner is called grip. The simplest definition of grip we
know is that grip is the car's ability to stick to the road
and go where the driver intends. If the car doesn't go
where the driver intends, the driver is faced with a lack
or deficiency of grip. Grip is what allows a driver to
take a corner faster and faster without running of the
track or losing control.
This valuable commodity-grip occurs in only one place:
where the tire meets the road, the contact patch. The
action between the tire and the road surface determines
grip. A "sticky" or soft compound tire will tend to have
more grip than a comparable harder compound tire.
The softer tire will wear out faster, and a worn tire has
very little grip, so there is a cost to using tires to
maximize grip.
Another way to increase grip is to add weight to the
tire. More weight will push down on the tires contact
patch increasing its grip. For the same reason an
empty pickup truck will have less grip in the snow or
ice, than one with the bed filled with say concrete. The
problem with adding weight is that there is an
associated cost, the added weight on the tire means
that the car can't accelerate as fast or hit the same top
speed. Therefore, car designers needed to find a way
to increase grip without incurring the costs of worn tires
or added vehicle weight. The solution came from
turning an aerospace idea upside down.
Airplane wings through their shape utilize air pressure
differences between the top and the bottom of the
wing to create a force called lift-raising even a heavy
metal airplane. In the 1960s car designers used an
upside down wing to create the opposite of lift, or
downforce. A wing traveling through the air exerts a
powerful force in one direction, and designers aimed
this force in the same direction as added weight to
increase grip, but without the cost of actually adding
the weight. This force is stronger when the car is
traveling faster and more grip is needed, and less when
the car is traveling slower and the need for grip is
reduced.
As The lift of a wing, or in the race car case downforce is
so powerful that a modern Formula 1 car traveling at
about 100 miles per hour generates enough downforce to
keep it attached to the road even if the road were to
suddenly turn upside down. This is why Formula 1 cars
have two obvious wing assemblies on the front and the
rear of the car, in addition to several less obvious ones
built into the car design.
As the car has front wheels and rear wheels they also
have matching wings producing downforce onto those
wheels. The size and position of these wings is strictly
governed by FIA rules. Teams have the freedom to alter
the shape of the wings within certain areas to extract
aerodynamic benefits. The shape of the rear wing is
strictly regulated but the front wing is given a great deal
of freedom, particularly on either side of the monocoque.
In addition to the two wings the entire floor of the car is
designed to mimic the conditions found under an inverted
wing. Specifically, through the use of a diffuser, a slotted
widening opening of the undercar space at the rear of the
car.
The diffuser speeds up airflow through it creating a low
pressure area just in front of it. This low pressure area
actually acts to "suck" the bottom of the car towards the
ground, or generating more downforce. The bottom of
the floor is smooth to provide the maximum airflow under
the car and through the diffuser. The car is also very low
to the ground which adds to the low pressure effect.
When air or any fliuid travels through a narrowing
passage (like underneath the car) its speed increases and
its pressure decreases. The closer to car is to the ground
the lower the pressure underneath it.
Finally, most of the other elements of the car design, are
there to direct the flow of air to the downforce generating
devices, the wings and the diffuser. The design of the
nose, the sidepods and even the suspension elements is
all to enhance airflow to the rear wing and the diffuser.
In the 2011 season we have seen many teams use the
concept of blowing engine exhaust gases out of the
tailpipes and through the diffuser to enhance the low
pressure created. This was pioneered by Red Bull in 2010
and has made the RB7 the fastest car on the 2011 grid
for the first seven races. Blowing exhaust gas through
the diffuser has some pitfalls, particularly when the driver
is off throttle. When off throttle there is less exhaust flow
through the diffuser and less downforce generated,
resulting in less rear grip or oversteer. Since the driver
must reduce throttle when entering a corner under
braking this would cause the car to spin.
The solution to the off throttle problem is to flow air
continuously through the exhaust and thus diffuser but
moderate engine power through ignition timing. Off
throttle the ECU retards the spark until the exhaust valve
is opening and then sparks as the piston is rising forcing
the combustion of fuel and air to occur in the exhaust
port and header tube. With no combustion occurring
during the power stroke, the engine makes no more
power through the crankshaft, but flows just as much
exhaust gas as under full throttle because the combustion
occurs inside the exhaust.
The cost of using this tactic is burnt or melted exhaust
valves, which must now be made from a more heat
resistant metal like titanium, or in more dramatic fashion,
a flash fire caused by an overheated exhaust header
burning, say a hydraulic line. Lotus-Renault knows this
one quite well as shown below, note the dramatic exit by
German driver Nick Heidfeld, or Herr Heidfeld if you
will...pun intended.
so powerful that a modern Formula 1 car traveling at
about 100 miles per hour generates enough downforce to
keep it attached to the road even if the road were to
suddenly turn upside down. This is why Formula 1 cars
have two obvious wing assemblies on the front and the
rear of the car, in addition to several less obvious ones
built into the car design.
As the car has front wheels and rear wheels they also
have matching wings producing downforce onto those
wheels. The size and position of these wings is strictly
governed by FIA rules. Teams have the freedom to alter
the shape of the wings within certain areas to extract
aerodynamic benefits. The shape of the rear wing is
strictly regulated but the front wing is given a great deal
of freedom, particularly on either side of the monocoque.
In addition to the two wings the entire floor of the car is
designed to mimic the conditions found under an inverted
wing. Specifically, through the use of a diffuser, a slotted
widening opening of the undercar space at the rear of the
car.
The diffuser speeds up airflow through it creating a low
pressure area just in front of it. This low pressure area
actually acts to "suck" the bottom of the car towards the
ground, or generating more downforce. The bottom of
the floor is smooth to provide the maximum airflow under
the car and through the diffuser. The car is also very low
to the ground which adds to the low pressure effect.
When air or any fliuid travels through a narrowing
passage (like underneath the car) its speed increases and
its pressure decreases. The closer to car is to the ground
the lower the pressure underneath it.
Finally, most of the other elements of the car design, are
there to direct the flow of air to the downforce generating
devices, the wings and the diffuser. The design of the
nose, the sidepods and even the suspension elements is
all to enhance airflow to the rear wing and the diffuser.
In the 2011 season we have seen many teams use the
concept of blowing engine exhaust gases out of the
tailpipes and through the diffuser to enhance the low
pressure created. This was pioneered by Red Bull in 2010
and has made the RB7 the fastest car on the 2011 grid
for the first seven races. Blowing exhaust gas through
the diffuser has some pitfalls, particularly when the driver
is off throttle. When off throttle there is less exhaust flow
through the diffuser and less downforce generated,
resulting in less rear grip or oversteer. Since the driver
must reduce throttle when entering a corner under
braking this would cause the car to spin.
The solution to the off throttle problem is to flow air
continuously through the exhaust and thus diffuser but
moderate engine power through ignition timing. Off
throttle the ECU retards the spark until the exhaust valve
is opening and then sparks as the piston is rising forcing
the combustion of fuel and air to occur in the exhaust
port and header tube. With no combustion occurring
during the power stroke, the engine makes no more
power through the crankshaft, but flows just as much
exhaust gas as under full throttle because the combustion
occurs inside the exhaust.
The cost of using this tactic is burnt or melted exhaust
valves, which must now be made from a more heat
resistant metal like titanium, or in more dramatic fashion,
a flash fire caused by an overheated exhaust header
burning, say a hydraulic line. Lotus-Renault knows this
one quite well as shown below, note the dramatic exit by
German driver Nick Heidfeld, or Herr Heidfeld if you
will...pun intended.
