Is passive DRS, authorized in 2013, worth it?

The DRS (Drag Reduction System) continues to make headlines between last season and the upcoming one. First of all, the 2013 regulations have been significantly strengthened regarding this with:

– The ban on “double DRS,” a system that allows for a more balanced loss of downforce between the front and rear of the car.
– Use of DRS limited to the race zone during free practice and qualifying sessions.

As a reminder, the double DRS is an enhancement of the classic DRS, effective at the same moments, aiming to reduce aerodynamic drag on the straight by means of downforce loss. During activation, air recovered from the movable rear wing passes through the car to be expelled towards the back from the front wing. Unlike the classic DRS, the downforce loss is not only located at the rear but is shared with the front of the single-seater. This latter point results in more stable behavior during acceleration, allowing earlier activation upon exiting a corner without compromising grip. The Passive DRS works quite differently. Tested by Mercedes and Lotus last year, it is entirely independent of the classic DRS. It involves collecting air from the engine cooling inlets to activate or not the movable rear wing. The faster the car, the more significant the aerodynamic effort becomes. The idea of the device is therefore to activate after this effort has reached a certain threshold. The downforce loss remains located at the rear. As its name suggests, this system is entirely passive as it is not activated following driver action. Thus, it is not subject to the 2013 regulation restrictions. The Passive DRS is usable only on the straight to avoid a sudden loss of downforce in corners. The triggering speed must therefore be carefully determined and especially higher than the speed of the fastest corner on the circuit. This last point is actually the major weakness of the system.

Indeed, Mercedes and Lotus struggled to develop real confidence in their respective systems mainly due to the speeds necessary for triggering and deactivating the system: because of the aerodynamic characteristics of the car, the deactivation speed is not always the same as the triggering speed. A safety margin is therefore necessary to avoid a loss of control at the end of the straight line. Ross Brawn, director of the Mercedes AMG team, indicates that for optimal operation of the system, a circuit with slow corners is ideal: From the moment there are fast corners, the triggering threshold is too high and the advantage is minimal. […] For now, the DRS can only be used when you are close to the car in front of you, but with passive systems, you can use them all the time, which makes them very attractive.

The two teams continued to study the device this winter and still seem to be evaluating performance gains. Finally, Ross Brawn indicates that even if the 2013 cars are equipped with the passive DRS, it won’t be a ticket to victory. […] The performance gain is there, but it’s not significant […] It’s not like the advantage provided by the F-duct. It’s a system that’s good to have, but it won’t be a determining factor for the team’s competitiveness.