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AERODYNAMIC DOWNFORCE has been used in Formula One for years, the 1978 Lotus 79 being exemplary in dominating the series. Today, an F1 car traveling 130 mpg generates its own weight in downforce.
What’s more, race-team aerodynamicists now work to disrupt downforce of a closely following car. This has evolved into a downforce-vs.-turbulence battle that’s encouraging rule changes to promote closer racing.
“F1 Streamlines for Closer Racing,” by Dan Carney in SAE Automotive Engineering, May 2019, gives a sense of the subtleties of today’s motorsports aerodynamics. It also explains why today’s open-wheel racecars, particularly the F1 variety, have such elaborate (some would say “disfiguring”) aero devices. Here are tidbits from Carney’s article.
Rulings of Millimeters. The Fédération Internationale de l’Automobile’s set of Formula One—Technical Regulations comprises an 111-page PDF, a goodly portion devoted to aerodynamics.
As Dan Carney notes, “Since the current generation of hybrid-electric Formula 1 cars debuted in 2012, the racing has been substantially processional, with every championship won by Mercedes-AMG drivers. Fans have complained about this—and about the hybrid-electric cars’ decidedly uninvigorating sound.”
“In response to these concerns,” Dan writes, “the Fédération Internationale de l’Automobile is plotting a clean slate of new specifications for the 2021 season, aimed at improving the spectacle. But race fans are unhappy now, so the FIA has tweaked the rules for the upcoming  season in a bid to increase the opportunity for cars to race nose-to-tail.” It is genuinely a matter of millimeters.
Front Wings. Front wings generate downforce for increasing front wheel grip, but they also divert the dirty wake these wheels produce. The idea is leave clean air flowing over the rest of the car.
Pat Symonds, F1 chief technical officer, explained to Dan, aerodynamicists “do this by producing specific vortices with the front wings and brake ducts…. Unfortunately, when you start pushing the front wheel wake out a long way, you create a very wide area of low-energy air behind the car, which reduced the downforce of the following car.”
Note, though, what’s unfortunate for the following car is also beneficial to the one in front.
To minimize this advantage, 2019 front wings are considerably wider than before, 2000 mm (78.7 in.) versus the previous 1800. The wing’s front edge is moved forward 25 mm (0.98 in.) and the stack of winglets atop the main plane is raised 20 mm.
Also, now banned is the array of turning vanes seen atop 2018 wings. The array’s purpose was to reduce drag, but it also aided diverting the dirty air aft. Other subtle rule changes involve limiting a front wing’s strakes (longitudinal vanes) from five to two, and reducing the size of front brake ducts which were also diverting air.
In toto, these front wing changes are intended to provide increased downforce, but to encourage pursuers to follow more closely as well.
Midship Barge Boards. The barge-board turning vanes ahead of the sidepods are shorter for 2019, but allowed to be closer to the front wheels. “This,” Dan notes, “reduced their ability to control airflow to the rear wheels.”
Rear Wings. “The rear wing,” Dan writes, “is 100-mm wider, 20-mm taller and has end plates that are 70-mm longer…. Pressure-equalizing slots in the tops of the end plates are also eliminated for 2019.”
“The rear wing,” FIA aerodynamicist Nikolas Tombazis told Dan, “helps us when we’re trying to promote closer racing. It has two strong trailing vortices, which pull the flow up from close to the ground into the ‘mushroom.’ This mushroom is pushed upward quite violently and quickly, allowing clean air to be pulled in from the sides to take the place of the turbulent air being flung upwards.”
“This clean air,” Tombazis notes, “tends to be higher energy which has a beneficial effect on the aerodynamics of the following car.”
Race engineers don’t mind disrupting competitors’ airflow. But FIA officials and F1 fans are all for larger mushrooms—and closer racing.
© Dennis Simanaitis, SimanaitisSays.com, 2019