Adjustable rear wings Explained
February 08, 2011
Posted by: Rahul Sampath
Along with the arrival of adjustable rear wings is the departure ofadjustable front wings - a concept that never really delivered what was expected of it, as Renault Technical Director, James Allison, explains: “The moveable front flap was brought in to try and assist with overtaking, but in practice it didn’t really make a difference. Instead it was used as a device to optimise car balance as the tyres degraded and the fuel load reduced. That’s why the teams voted to remove adjustable front wings and try a new initiative with the rear wings with the intention of generating better overtaking opportunities.
The concept
If adjustable front wings didn't help overtaking, why will adjustable rear wings fare any better? Well, it all comes down to the different way that changing the angle of the front and rear wings affects the overall drag of the car. If you change the angle of the front wing, you change the car balance, but the overall drag of the car remains about the same and hence straight-line speed is largely unaffected. However, changing the rear wing angle changes the drag of the car, and therefore the straight-line speed dramatically. "If you allow the rear wing to reduce its angle, you lose drag, rather like an f-duct system last year," explains Allison. "So if two cars are racing each other, the car that has adjusted its rear wing angle will be able to go faster down a straight than the car that hasn't."
Use During Race
As for the mechanics of moveable wings, the adjustments that can be made relate to the two elements of the wing: the main plane and the flap. While the main plane remains fixed, the rules allow the flap to rotate away from the main plane up to a maximum distance of 50mm. This creates a situation where the two elements of the wing stop acting in harmony and the airflow around the wing separates from the surface of the wing. This condition of separated flow is called a "stall" and it is accompanied by a large drop in both downforce and drag on the car. The overall effect on straight-line speed is a bit like an f-duct, but much more powerful.
http://www.youtube.com/watch?v=edEx4nXdIlY&feature=player_embedded
If adjustable front wings didn't help overtaking, why will adjustable rear wings fare any better? Well, it all comes down to the different way that changing the angle of the front and rear wings affects the overall drag of the car. If you change the angle of the front wing, you change the car balance, but the overall drag of the car remains about the same and hence straight-line speed is largely unaffected. However, changing the rear wing angle changes the drag of the car, and therefore the straight-line speed dramatically. "If you allow the rear wing to reduce its angle, you lose drag, rather like an f-duct system last year," explains Allison. "So if two cars are racing each other, the car that has adjusted its rear wing angle will be able to go faster down a straight than the car that hasn't."
Use During Race
As for the mechanics of moveable wings, the adjustments that can be made relate to the two elements of the wing: the main plane and the flap. While the main plane remains fixed, the rules allow the flap to rotate away from the main plane up to a maximum distance of 50mm. This creates a situation where the two elements of the wing stop acting in harmony and the airflow around the wing separates from the surface of the wing. This condition of separated flow is called a "stall" and it is accompanied by a large drop in both downforce and drag on the car. The overall effect on straight-line speed is a bit like an f-duct, but much more powerful.
http://www.youtube.com/watch?v=edEx4nXdIlY&feature=player_embedded
