A wing works by creating a pressure difference between air flowing over the top and air flowing underneath . More pressure on the top than the bottom makes downforce , the reverse makes lift . In order to make downforce as opposed to lift on an airplane , the underside is curved more than the top , forcing air to travel a greater distance and thus be moving faster than the air above the wing . Faster moving air is at a lower pressure , and this effect is increased with the wing angled downwards , as that further slows the air above the wing thus increasing pressure ontop . The benefit to mounting the wing from the top is that the bottom surface is free from any obstructions to the flow which could slow the air down and cause bits of turbulence . The top mointing points do affect the air going over top , but you want that flow to be slower anyways .