For the Formula One fanatics, this term ‘adjustable rear wing’ might not be a surprise since this is a prominent technical rule that will make it to F1 in 2011. The idea has been put forward to cure the long discussed issue of little overtaking seen in the sport. The actual effect of it is still unknown and we wont know it till 4-5 races have taken place this season when it kicks off in Melbourne on 27 March 2011.
The Trick Explained
Before we go on to briefly explain this thingy, what actually will happen is that drivers will now have a button available which will change the angle of rear wing (or spoiler for some who are not familiar with this term) while the car is traveling at high speeds. This option will only be available when a car is within a certain distance of the leading car. The notification will be given to driver by FIA Race Control via a light on steering wheel indicating that the driver is now well within the distance allowed of the leading car to use this feature.
How Change of Angle Can Help Overtaking ?
To understand this, we first explain a bit of basic physics behind the fast moving car.
Whenever an object travels through a fluid (air in this case), it counters a resistance offered by the fluid the value of which varies with (1)Speed of the traveling object (alternatively a fluid traveling and object stationary will have same effect) (2) Shape of object (3)Viscosity of the fluid. So when a F1 car travels through the road, the air puts up a resistance against the car the effect of which is to stop it. This can result in increased power requirement from the engine which of course we dont want to happen.
So we are left with an option to try out to reduce this resistive force known as “aerodynamic drag”. The basic theory in easy language can be found in any basic fluid mechanics textbook. Race cars use wings and other aerodynamic bits & construction of car body to reduce this drag. These wings reduce this resistive force by either decreasing the area that faces the stream of air coming in or making the flow take a certain path along it which imposes a uniform pressure rather than concentrated pressure and the drag somewhat reduces.
A formula one rear wing is designed to do this job. When it is laid parallel to the direction of velocity, it reduces the drag but also causes loss of downforce (which we also generate using these wings for ease of handling, the turns taken at speeds like 150 km/h are only possible due to downforce). So we conclude two things here:
- When wing angle is less (i.e parallel to air stream), the drag reduces, downforce reduces resulting in increased speed
- When wing angle is more (i.e perpendicular to air stream), the drag increases but downforce increases resulting in less speed but increased stability
So we want less angle when we want our car to hit more speed and handling isnt our main issue (this happens on straights in a track). Now the wings are usually set up for a value that is trade-off between this high speed and better handling setup. Sometimes we wish we could keep the wing less for reduced drag and more speed but we have to look at our downforce requirement too. This somewhat hinders the advantage we could gain by keeping the wing low
What’s the Solution ?
So what if we changed the angle as per the location and situation. That is we could change the wing angle to less on straights or when following another car (which actually HUGELY increases drag). This is what adjustable rear wing is about. The wing, which has ‘elements’ and gaps known as ‘slots’ will change its formation while the car is being driven when the driver presses button. The slot gap increases when the wing angle is reduced (as you can see in the images below) and hence reduces drag, which suddenly increases speed of the following car since the resistance against which it had to work has reduced. Increase in speed = Overtaking opportunity
So this is the essence of how it works. The mechanism that triggers the change in angle may vary from team to team. Probably hydraulics and even mechanical linkages are the favourite options to trigger the change.
The idea behind this wing is not new. Aerodynamicists have known this potential for long time, it’s just the rules which prevented such ideas from being implemented.