It's a simple little piece created by the legendary American driver that increases the downforce on cars.
Dan Gurney (13/4 / 1931-14 / 1/2018) has been one of the great legends of American motorsport. Ran into the F1 in 87 Grands Prix and achieved four victories. In addition, he stood out in the 24 Hours of Le Mans, a competition that he won in 1967 with his compatriot AJ Foyt about one of the mythical Ford GT40.
Once retired he put all his effort into All American Racer, his competition team with which he won races and championships in the IMSA and participated in the Champ car. In addition, in his time as a F.1 pilot he was encouraged to enlist his own team, which he baptized as Eagle.
Although many may not know it, Gurney has a permanent presence in every race that is disputed thanks to a very simple piece that he created himself and that took aerodynamic development in racing cars to another level.
The story goes that during the 1971 USAC preseason at the Phoenix circuit, Gurney attached a small rigid strip of metal at right angles to the rear wing of his car in an effort to improve its handling.. This little item was inspired by something he had already experienced Richie ginther in the spoilers of a Ferrari from GT.
Gurney took to the track with that little flap - made by his mechanics in 45 minutes - and after a few laps he returned to the pits. Many thought that the solution had been a fiasco, but no. The little foot was generating so much understeer that Dan couldn't go too fast. The problem was solved by adjusting the downforce of the front wing to achieve the optimal balance of the car.
With the tune-up change, Gurney's vehicle made a substantial improvement. That day the Flap Gurney, an element currently used by all categories whose cars have aerodynamic loads. Although it must be said that its creator kept the secret of its use for many months, but could not avoid - luckily - that over time others imitated it.
The Gurney Flap is simple: it consists of a strip of aluminum or carbon fiber that is placed on the trailing edge of the aerodynamic element in which it is to be used. In essence it causes an improvement in aerodynamic performance by achieving up to 25% additional load.