08-20-2002, 06:13 AM
You've probably heard about the old Brabham F1 "fan-car", and wondered why it caused so much controversy, or what the fan did on this remarkable car.
I'll explained. First, we need to understand the principles of aerodynamics. The idea on a modern racing car is to have a low pressure area underneath the car, which produces downforce. The way to achieve this is to have less downforce, underneath the car, and make use of things like venturi tunnels, and spitters, to help expell air from under the car.
The Chapparal-Chevrolet sportscars where the first to start investigating ground effects principles. Designer Jim Hall helped to design a car with venturi tunnels at the front, and back. While, this had big downforce at the back, the only thing keeping the front down was the weight of the engine.. This was countered by putting a big air-dam at the front of the car. This caused the opposite problem. The car had such huge downforce, that the front wheels ground their way through the bodywork! The idea was eventually put aside, as it was not fully understood.
http://www.vicelford.com/gallery/23large.jpg
Eventually, twin fans were tried on the very strange Chapparal 2J sports car, seen above. These fans were designed to pull air out from underneath the car, which would have the effect of creating more downforce, and pulling the car down onto the road.
The idea worked, very well. So well, that it was hurriedly banned!
Before long, Gordon Murray and David North had adopted it for use on the Brabham BT46B F1 "fan-car". Officially, the fan was only used to cool the Alfa Romeo flat-12 engine, which rapidly overheated.
http://www.forix.com/iex/imgz/1978/08001_8W.JPG
The fans supposedly pulled air across the engine, which kept it cool. But, while they pulled air across the engine, the car had venturi tunnels underneath it (designing these was complex, since the Alfa flat-12 engine was very wide), and, the fan also pulled a huge amount of air from under the car. The fan was driven via a complex network of shafts and clutches from the gearbox. The clutches were used to prevent the fan over-driving the gearbox on gearchanges. It wasn't perfect, however. The original plastic fans disintegrated under testing, so glass fibre versions were employed, and then later, magnesium versions were used.
http://8w.forix.com/thething.jpg
The technical problems involved were huge. The whole engine bay was sealed (as shown above), so that air couldn't be drawn through the engine and break the low pressure area beneath the car. Flexible skirts were developed which extended to the road surface, as well as extending back and around the suspension arms. A thermodynamics expert, David Cox, was even employed to work out the number of fan blades, pitch and optimum rotation speed!
Even while the car was at a stand-still, when the engine was revved up, it could be seen to suddenly squat downwards, towards the ground. Flexible rubber skirts were used around the edges of the car, to seal this low pressure region under the car, as well! The front one intially began to wear away, but, once skid was installed on the bottom of the skirt, their were no more problems.
http://www2.zr.ru/friends/f1/Pict/staty/brabhambt46.jpg
http://www2.zr.ru/friends/f1/Pict/staty/m-brbt46b3.jpg
This had rival teams screaming, and very outraged and upset. (Because the use of moving parts for aerodynamic, or downforce benefit was strictly outlawed). Gordon Murray countered that the fans primary purpose was to cool the engine, and any aerodynamic benefits were completely unplanned, and co-incidental. ^_^ This approach was declared legal by the FIA, but, the car would only have a short racing life.
Contrary to popular belief, Bernie Ecclestone, the then boss of the Brabham team, quietly withdrew the car after only 1 race, after all the protests and outrage. In that race, another car dropped oil on the track, through a turn. All the other cars had to slow down for that turn, but the Brabham could speed through, unaffected! A truly remarkable car. It still exists, and holds the record time for the Goodwood hillclimb, I believe.
I'll explained. First, we need to understand the principles of aerodynamics. The idea on a modern racing car is to have a low pressure area underneath the car, which produces downforce. The way to achieve this is to have less downforce, underneath the car, and make use of things like venturi tunnels, and spitters, to help expell air from under the car.
The Chapparal-Chevrolet sportscars where the first to start investigating ground effects principles. Designer Jim Hall helped to design a car with venturi tunnels at the front, and back. While, this had big downforce at the back, the only thing keeping the front down was the weight of the engine.. This was countered by putting a big air-dam at the front of the car. This caused the opposite problem. The car had such huge downforce, that the front wheels ground their way through the bodywork! The idea was eventually put aside, as it was not fully understood.
http://www.vicelford.com/gallery/23large.jpg
Eventually, twin fans were tried on the very strange Chapparal 2J sports car, seen above. These fans were designed to pull air out from underneath the car, which would have the effect of creating more downforce, and pulling the car down onto the road.
The idea worked, very well. So well, that it was hurriedly banned!
Before long, Gordon Murray and David North had adopted it for use on the Brabham BT46B F1 "fan-car". Officially, the fan was only used to cool the Alfa Romeo flat-12 engine, which rapidly overheated.
http://www.forix.com/iex/imgz/1978/08001_8W.JPG
The fans supposedly pulled air across the engine, which kept it cool. But, while they pulled air across the engine, the car had venturi tunnels underneath it (designing these was complex, since the Alfa flat-12 engine was very wide), and, the fan also pulled a huge amount of air from under the car. The fan was driven via a complex network of shafts and clutches from the gearbox. The clutches were used to prevent the fan over-driving the gearbox on gearchanges. It wasn't perfect, however. The original plastic fans disintegrated under testing, so glass fibre versions were employed, and then later, magnesium versions were used.
http://8w.forix.com/thething.jpg
The technical problems involved were huge. The whole engine bay was sealed (as shown above), so that air couldn't be drawn through the engine and break the low pressure area beneath the car. Flexible skirts were developed which extended to the road surface, as well as extending back and around the suspension arms. A thermodynamics expert, David Cox, was even employed to work out the number of fan blades, pitch and optimum rotation speed!
Even while the car was at a stand-still, when the engine was revved up, it could be seen to suddenly squat downwards, towards the ground. Flexible rubber skirts were used around the edges of the car, to seal this low pressure region under the car, as well! The front one intially began to wear away, but, once skid was installed on the bottom of the skirt, their were no more problems.
http://www2.zr.ru/friends/f1/Pict/staty/brabhambt46.jpg
http://www2.zr.ru/friends/f1/Pict/staty/m-brbt46b3.jpg
This had rival teams screaming, and very outraged and upset. (Because the use of moving parts for aerodynamic, or downforce benefit was strictly outlawed). Gordon Murray countered that the fans primary purpose was to cool the engine, and any aerodynamic benefits were completely unplanned, and co-incidental. ^_^ This approach was declared legal by the FIA, but, the car would only have a short racing life.
Contrary to popular belief, Bernie Ecclestone, the then boss of the Brabham team, quietly withdrew the car after only 1 race, after all the protests and outrage. In that race, another car dropped oil on the track, through a turn. All the other cars had to slow down for that turn, but the Brabham could speed through, unaffected! A truly remarkable car. It still exists, and holds the record time for the Goodwood hillclimb, I believe.