For safety, speed and fuel efficiency, when designing recreation and transportation vehicles, engineers take into account all forces acting on the object. Engineers consider drag forces when they design land, air and water vehicles. When prototyping objects such as wings, windshields, propellers, helmets, sports equipment, or even an athlete's position, engineers use a wind tunnel to see the drag forces that are created around an object when air moves by, and they adjust their designs to minimize the amount of drag.