Downforce! How does it work?
Hi there! Your favourite pretend engineer is back to incorrectly inform you about science! Jokes aside, today we will be talking about downforce. First I will explain why and where it came from, why it´s so important in modern day race cars and, most importantly, how it works.
Let´s start with a bit of history. When cars where first conceived, people were scheptical about the technology. But as time passed, rich playboys decided to race them. As time passed even further, motorsports was no longer just for the enjoyment of its drivers. Companies sought to make money from it, and the only way to accomplish this is by winning. At this time, especially in the inter-war period, many companies like Auto Union and Alfa Romeo were battling it out in the Targa Florio or the Mille Miglia. Back then, engineers only understood the most basic properties of drag, and were only able to take advantage of what they knew by making their cars more streamlined, thus reducing drag and sometimes gaining better stability at higher speeds.
After the war, wind tunnels were (a little)more popular, thus making the study of the aerodynamics on aircraft and cars easier. Many companies, with the thirst to win more, started to push the limits of the cars and the track to (and sometimes over) the limit, causing horrible crashes like the one in Le Mans in 1955. Back then, there were no organizing bodies to set regulations on cars like there is now,so they made cars with too much power that weren´t particularly controlable until the Le Mans disaster in 1955. Even at the time of the crash, companies were only able to reduce their cars´ drag coefficient to make them faster in a straight line. This changed in the 60´s when F1 cars, and most notably Le Mans cars began to use ground effect(the use of aerodynamic effects to make a car faster).
Porsche was one of the earliest adopters of downfoce. When they designed the Porsche 917, one of their objectives was to make downfoce. This can be seen with the CanAm racing variant, known as the 917/30.
Also known as the TurboPanzer, this version made quite a bit of downforce, at the cost of drag. It still reached a top speed of 246MPH on the Mulsanne straight. This is because, when they were designing it, they only wanted to make downforce regardless of how much drag it made. This is due in part to the fact that it had up to 1500+hp at 8100RPM!
Then, companies started using "skirts" under their cars in F1. What this did is exploit the Venturi effect. What it did is constrict air under the car, reducing it´s pressure, thus increasing the effect of the wings above the car designed to create high pressure over the car. This greater pressure differential between the top and the bottom of the car was a big advantage to the cars that used it. This was a massive discovery, which was soon banned. Most innovative ideas get banned whenever they are used in competitive motorsport. This is either for safety, or simply to make a fairer playing field for all race teams.
Nowadays, there isn´t a craving for more downforce, due to restrcitions in the regulations in most motorsports categories. Now, the challenge is to make the maximum permited downforce with less drag and increasing the efficiency (i.e. fuel consumption, drag...etc).
So, now let´s talk about why every new racecar is so cu cu bananas about downforce.
Downforce is desired in racecars because it creates high pressure over the car and low pressure under the car(with difussers and stuff). What this does is "stick" the car to the track or which ever road surface it is driving on. This "sticking" gives the car more grip, increasing the speed the car can achieve and maintain around corners. This is also helpful because you don´t need increadibly wide tires which would make it impractical(more unsprung mass). It also gives more stability at higher speeds. The major penalty downforce has on cars is that it hinders their top speed.
If you´ve read my article on how wings work, you will find quite a few similarities between lift and downforce. In fact, downforce is also popularly known as negative lift.
Well...that´s it! I hope you´ve enjoyed this article and now understand the basics of downforce.
This post might seem a bit too simple for those who already know quite a lot about racecars, so I will upload more posts about downforce oriented to hardcore racecar enthusiasts. For now, feel free to read this post on Jalopnik:
http://oppositelock.kinja.com/aerodynamics-101-lift-downforce-and-drag-1687401001. I found this article super helpful!
If you´ve found any mistake in my article, please let me now... I am only a pretend engineer you know!
Bye!
Let´s start with a bit of history. When cars where first conceived, people were scheptical about the technology. But as time passed, rich playboys decided to race them. As time passed even further, motorsports was no longer just for the enjoyment of its drivers. Companies sought to make money from it, and the only way to accomplish this is by winning. At this time, especially in the inter-war period, many companies like Auto Union and Alfa Romeo were battling it out in the Targa Florio or the Mille Miglia. Back then, engineers only understood the most basic properties of drag, and were only able to take advantage of what they knew by making their cars more streamlined, thus reducing drag and sometimes gaining better stability at higher speeds.
The Auto Union type C from 1937 is an example of 1930´s aerodynamics: make a car as slippy(through the air) as possible. This was the first car to achieve downforce(accidentally). It later lost control and crashed, killing its driver, Bernd Rosemeyer
After the war, wind tunnels were (a little)more popular, thus making the study of the aerodynamics on aircraft and cars easier. Many companies, with the thirst to win more, started to push the limits of the cars and the track to (and sometimes over) the limit, causing horrible crashes like the one in Le Mans in 1955. Back then, there were no organizing bodies to set regulations on cars like there is now,so they made cars with too much power that weren´t particularly controlable until the Le Mans disaster in 1955. Even at the time of the crash, companies were only able to reduce their cars´ drag coefficient to make them faster in a straight line. This changed in the 60´s when F1 cars, and most notably Le Mans cars began to use ground effect(the use of aerodynamic effects to make a car faster).
Porsche was one of the earliest adopters of downfoce. When they designed the Porsche 917, one of their objectives was to make downfoce. This can be seen with the CanAm racing variant, known as the 917/30.
Also known as the TurboPanzer, this version made quite a bit of downforce, at the cost of drag. It still reached a top speed of 246MPH on the Mulsanne straight. This is because, when they were designing it, they only wanted to make downforce regardless of how much drag it made. This is due in part to the fact that it had up to 1500+hp at 8100RPM!
Then, companies started using "skirts" under their cars in F1. What this did is exploit the Venturi effect. What it did is constrict air under the car, reducing it´s pressure, thus increasing the effect of the wings above the car designed to create high pressure over the car. This greater pressure differential between the top and the bottom of the car was a big advantage to the cars that used it. This was a massive discovery, which was soon banned. Most innovative ideas get banned whenever they are used in competitive motorsport. This is either for safety, or simply to make a fairer playing field for all race teams.
Nowadays, there isn´t a craving for more downforce, due to restrcitions in the regulations in most motorsports categories. Now, the challenge is to make the maximum permited downforce with less drag and increasing the efficiency (i.e. fuel consumption, drag...etc).
The Maserati MC12 Corsa is an example of a successful modern racecar designed and constructed under tight regulations to race at the FIA GT Championship
So, now let´s talk about why every new racecar is so cu cu bananas about downforce.
Downforce is desired in racecars because it creates high pressure over the car and low pressure under the car(with difussers and stuff). What this does is "stick" the car to the track or which ever road surface it is driving on. This "sticking" gives the car more grip, increasing the speed the car can achieve and maintain around corners. This is also helpful because you don´t need increadibly wide tires which would make it impractical(more unsprung mass). It also gives more stability at higher speeds. The major penalty downforce has on cars is that it hinders their top speed.
If you´ve read my article on how wings work, you will find quite a few similarities between lift and downforce. In fact, downforce is also popularly known as negative lift.
Well...that´s it! I hope you´ve enjoyed this article and now understand the basics of downforce.
This post might seem a bit too simple for those who already know quite a lot about racecars, so I will upload more posts about downforce oriented to hardcore racecar enthusiasts. For now, feel free to read this post on Jalopnik:
http://oppositelock.kinja.com/aerodynamics-101-lift-downforce-and-drag-1687401001. I found this article super helpful!
If you´ve found any mistake in my article, please let me now... I am only a pretend engineer you know!
Bye!
Comments
Post a Comment