noisebox wrote:Can anyone explain in simple terms what stalling the rear wing means, and how this device does it? I can see that it allows additional when the vent is open, but how does it change things when it is closed? Also, are their any pictures of the slots in the rear wing. Generally I can get my head around most technical innovations in F1, but this one has me.
Now, I'll admit that this is not my area of expertise, but I'll try to give you some idea of what is said to be going on. I'll admit that my explanation would probably be laughed at by somebody who does aeronautics, since I deal with an entirely different branch of fluid dynamics, but I'll try my best.
Imagine that you have a wing, which is initially horizonal, and moving horizontally - for the purpose of this, I'll use an aircraft wing. Now, imagine that you start to angle that wing upwards. Initially, the lift that the wing generates increases, but the airflow over the top surface detatches and becomes turbulent.
![Image](https://upload.wikimedia.org/wikipedia/commons/thumb/6/6d/Angle_of_attack.svg/305px-Angle_of_attack.svg.png)
Eventually, you reach a critical angle at which the airflow over the top surface becomes so disrupted that it detatches completely from the upper surface - at this point, the lift that the wing produces drops dramatically, and the drag increases, due to the difference in air pressure on each side of the wing. Normally, this produces a graph which looks something like this:
![Image](https://upload.wikimedia.org/wikipedia/en/thumb/2/22/Lift_drag_graph.JPG/800px-Lift_drag_graph.JPG)
Note how the lift suddenly drops off, and the drag increases rapidly, once the airflow over the top of the wing detatches.
Now, for an F1 car, this becomes much more difficult. Because F1 cars are trying to create as much downforce as possible, the angle at which the wing is compared to the airflow is very extreme. A conventional airplane wing would stall at about 15º, but F1 cars use something in the order of 50º - so, for an F1 car, the wing would already be starting to stall, although they can get around this by using extreme cambering (the curved profile of the wing) and other tricks.
Now, the idea is that air is injected through a gap into the wake region behind the rear wing. Doing this causes the wing to fully stall. However, by injecting air into the region behind the wing, the pressure difference between each side of the wing reduces, effectively causing the pressure induced drag to drop (or, at least, that is how I understand this works). So, although the wing would produce less downforce, it also produces less drag, which is ideal on the straights.
To do this, air is ducted, supposedly through the vent on the top of the nose, through the shark fin and through a gap in the wing, with the driver supposedly blocking the hole off.
For the gap in the rear wing, I believe that this picture shows it reasonably well:
![Image](http://motorsport.nextgen-auto.com/gallery/pictures/2010/f1/gp-bahrain-11mar/092wri.jpg)
Don't worry about struggling to understand this, though - I've seen pages and pages on various websites discussing how they could get this to work, what sort of effect it would have, and a great deal of debate about points of aerodynamics which you would probably need a MEng in aeronautics to fully understand all of their nuances.