My understanding is that ground effect works when the ground or other surface interrupts the downdraft thereby reducing aerodynamic drag.

With cars, it seems that the explanations I've found describe using the car's body itself as a wing and creating a venturi between the bottom surface of the car and the track. However, with a car the aerofoil's "downdraft" is going upwards so there's no surface to interact with it. In this case there wouldn't be any ground effect.

Am I misunderstanding this? How does ground effect work in a car which is producing downforce rather than a aircraft where it produces additional lift?

1 Answer 1


A simplistic way to think about this is that the wing is shoving air from one side to the other. This creates higher and lower pressure regions around the wing that cause lift (higher pressure below on a plane, higher pressure above on a car).

If you put the ground under an airplane wing, the air "builds up" under the wing because it can't disperse as easily. This allows the pressure to build up higher than it would otherwise. The greater difference means greater lift over the area of the wing.

If you put the ground under a car wing, the low-pressure region can't be filled in by air easily because the ground is in the way. This lets the pressure be lower than it would in a free-stream flow. The "lift" generated from the pressure differential is greater.

  • That all makes sense but in the example of a car it's not "ground effect" as I understand it. Commented May 12, 2022 at 17:13
  • Airplane ground effect is when the wing is within a wingspan of the ground and the non-freestream effects are significant. I've got no problem describing a F1 car's aerodynamics as being in ground effect. Not sure if there's some technical reason that someone wouldn't like that description.
    – BowlOfRed
    Commented May 12, 2022 at 20:32
  • I get that but I thought the whole point was the air displacement had to be TOWARD the ground for it to work? Commented May 13, 2022 at 11:38
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    No, I don't think so. It can help in either direction. If toward the ground, the air can't "get out of the way" and the high pressure is increased. If away from the ground the air can't flow in to replace, and the low pressure is made lower. If someone wants to give the other direction a different name on principle, fine, but I don't see a reason they can't both be called "ground effect". This seems more like a point of language than one of physics or one of sport.
    – BowlOfRed
    Commented May 13, 2022 at 16:34
  • if the effect is empirically equal in both directions that answers my question I think Commented May 13, 2022 at 22:59

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