Advanced Aerodynamics Features Applied to Mustang

March 3, 2014

Bruce Morey

Vertical slots direct air to vents in the wheel wells, reducing turbulence and drag.

Spending twice as much in aerodynamics development compared to previous Mustangs resulted in innovations such as front-wheel aero curtains and active grille shutters. Showing how important aerodynamic CFD is to the engineering process, Carl Widmann, Aerodynamics Engineering Manager for Ford, noted that major advances in Ford’s CFD capabilities let them test the effect of design changes and give feedback to the studio in less than 48 h. More time means more design options are explored.

The Mustang EcoBoost will get active grille shutters, sending air into the engine compartment when more cooling is needed, closing when not to reduce drag.

Rotating wheels are a major source of aerodynamic drag. They can account for 30% of total drag, or more, depending on how streamlined the rest of the car is. This is because the wheels themselves are not streamlined; they rotate within the wheel housings, and the airflow spreads from the underbody and wheel well and so it hits the wheels on a yaw angle. These three factors interact, causing turbulence and drag.

One solution is to enclose the wheels with a skirt, a design feature dismissed by Ford for a performance sports car such as the Mustang. Instead, the development team adopted air curtains. These are vertical slots in the outer edge of the front fascia. These channel air from the front of the car to openings in the wheel wells, directing it across the outer surface of the wheel and tire. Mustang joins the likes of BMW with this design feature.

This feature also helps cool the brakes, according to Kemal Curic, Mustang Exterior Design Manager. Ford addresses drag from the rear wheels by using small blades attached to the front of the rear wheel housing.

Another feature Curic pointed to was the shark-nose front end that helps cut the air, separate it, and attach the airflow to the body, again for efficiency. New Mustangs are equipped with splitters and air dams below the front fascia that help to minimize air under the car. Integrated rear deck spoilers are slightly different for different models.

For Mustangs outfitted with the 2.3-L EcoBoost gasoline direct-injection, turbocharged engine active grille shutters will further reduce drag at high speeds. The shutters can completely close off the grille, sending air over and around the car instead of through the engine compartment. Other engine options will get static grilles.

All together, Ford claims the overall drag force is reduced by 3%, without providing a specific overall drag coefficient (Cd) at present.

The top speed is 155 mph (249 km/h), slated for the V8, 420-hp (313-kW) Mustang GT. At such speeds, vehicle dynamics and handling matter as much as efficiency. New Mustangs are equipped with splitters and air dams below the front fascia that help to minimize air under the car. The Mustang GT version (alone) also features a pair of vents in the hood that also contribute to front-end downforce.