What Are the Aerodynamics of a Ground Effect?

Ground effects influence and control air to stabilize a car body in motion. The ground effect concept started in race cars and passenger cars currently use those concepts. Sports cars such as Jim Hall's Chaparral began using spoilers in the 1960s to hold the car to the road and give it more stability in the corners.

  1. Ground Effect

    • The first attempts for ground effect used spoilers, which resemble an airplane wing turned upside down. Putting spoilers on the rear made the front end light and reduced front-wheel traction. Spoilers added to the front cured this problem. The next step was the Chaparral sucker car. This car had plastic panels around the bottom of the car and perpendicular to the pavement. A motor sucked air from around the car and created a vacuum. This pulled the car down and the panels contacted the pavement. Other race cars tried the concept, and eventually all were ruled illegal.

    The Bernoulli Effect

    • The Bernoulli effect is the basis for the next innovation. By forcing fluids through a restriction, a low-pressure area forms behind the restriction. Plastic panels along the length of the car will keep from leaking out the sides. A flat bottom with a slight curve in the middle creates a low pressure point behind the curve. This forces the vehicle down and creates traction and stability. Lotus used this concept, but put a tunnel on each side of the car with a flat section down the middle. The Lotus won the 1978 Formula One World Championship for Mario Andretti and the 1979 Indianapolis 500 for Jim Hall's Chaparral and Johnny Rutherford.

    Modern Gound Effect

    • Current ground effects use two tunnels under the car, one on each side. These start at the middle of the car and slope toward the rear. This produces the most down force and diffuses into a wider area near the rear to produce the vortex. Along with rear and front wings, this gives the car a great deal of stability.

    Street Car Ground Effect

    • Streetcars use front air dams to direct the air to the side of the car. This keeps it from going under the car and causing lift. Side skirts keep the air from going under the car from the side. Automobile manufacturers put these features on as extras, or after-market producers sell them as kits that can be added.