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The drag reduction system (or DRS) is a form of driver adjustable bodywork aimed at reducing aerodynamic drag in order to increase top speed and promote overtaking. It is an adjustable rear wing of the car, which moves in response to driver commands. DRS often comes with conditions, such as the pursuing car must be within a second (when both cars cross the detection point) for DRS to be activated.
DRS was introduced in Formula One in 2011. The use of the DRS system is an exception to the rule banning moving parts whose primary purpose is aerodynamic and were introduced in response to the banning of F-ducts, as they were not susceptible to enforceable regulation.
The system is also used in the Formula Renault 3.5 since 2012 and Deutsche Tourenwagen Masters since 2013. An adjustable wing was also used by the Nissan DeltaWing at the 2012 24 Hours of Le Mans, although with free usage.
In Formula One, the DRS opens an adjustable flap on the rear wing of the car to reduce drag, thus giving a pursuing car more speed and thus a greater chance of overtaking a car in front. The FIA estimate the speed increase to be between 10–12 km/h by the end of the activation zone. When the flap is closed it creates more downforce giving better cornering.
The device can only be used during a race once two racing laps have been completed, and when the pursuing car enters a designated "activation" zone defined by the FIA.
In 2011, the FIA increased the number of DRS zones to two on some circuits featuring multiple long straights. In Valencia and in Montreal, two zones were endorsed on consecutive long straights, whilst in Monza and in Buddh, two zones were created on separate parts of the circuit. Two zones had originally been planned for every race with multiple long straights from Montreal onwards (depending on Montreal/Valencia success), but such plans did not materialize. However, at the penultimate round of the 2011 season, two zones on consecutive long straights saw a return at Yas Marina.
The horizontal elements of the rear wing consist of the main plane and the flap. The DRS allows the flap to lift a maximum of 50 mm from the fixed main plane. This reduces opposition (drag) to airflow against the wing and results in less downforce. In the absence of significant lateral forces (straight line), less downforce allows faster acceleration and potential top speed, unless limited by the top gear ratio and engine rev limiter. Sam Michael, technical director of the Williams team (as of early 2011), believes that DRS in qualifying will be worth about half a second per lap.
The effectiveness of the DRS will vary from track to track and to a lesser extent from car to car. The system's effectiveness was reviewed in 2011 to see if overtaking can be made easier, but not to the extent that driver skill is sidelined. The effectiveness of DRS seems likely to be determined by the level of downforce at a given circuit (where the cars are in low drag trim at circuits like Monza, the effects may be smaller), by the length of the activation zone and by the characteristics of the track immediately after the DRS zone.
The usage of DRS is limited by the F1 rules. It is allowed to be used only when:
The drivers are able to use the system without restriction during practice and qualifying (as of the 2013 season, the drivers are only able to use the DRS system in the designated overtaking zone(s)). A dashboard light notifies the driver when the system is enabled. The system is deactivated when the driver releases the button or uses the brakes.
There are lines on the track to show the area where the one-second proximity is being detected and a line later on the track where the drivers whose system is deemed valid to be armed may deploy it. These lines are more commonly referred to as the 'detection point' and the 'activation point'.
There has been a mixed reaction to the introduction of DRS in Formula One amongst both fans and drivers. Some believe that this is the solution to the lack of overtaking in F1 in recent years while others believe this has made overtaking too easy. The principal argument for the opponents of DRS is that the driver in front does not have an equal chance of defending his position because they are not allowed to deploy DRS to defend. The tightening up on the rules for a leading driver defending his position has added to this controversy.