This homebuilt plexiglass desk fan wind tunnel simulates the airflow as it travels over bo
Ok we know the aerodynamics of a truck and SUV is like floating a brick upstream. Designing a sleeker-coefficient aero package is every truck manufactures objective with every up-coming model year. After design engineers and technicians have spent hours and hours plotting a multitude of different rendering flavors with an assortment of new tastes, it is not until the artists' sketches become clay model and are actually tested in a wind tunnel to evaluate it's sleek ability as it penetrates through the atmosphere.
When studying aerodynamics we are trying to capture the scientific amenities and characteristics of a moving object as penetrates the earths atmosphere while traveling on the ground.
The basics of aerodynamics are air pressure and how it flows around a moving object, or how the object moves through the air. There are four, major contributors to the effects of aerodynamics of a moving object: drag, down force, lift, and yaw.
Aerodynamic Terminology Drag: Is resistance caused by penetrating the atmosphere with a truck's leading edge creating turbulent airflow over, under, and around a smooth surface area (i.e., a truck's leading edge, grille, front bumper, fenders, hood, cab, bed, tailgate, and rear bumper). Another way to describe drag is, a result of skin friction. Longer truck beds can create a lower drag coefficient.
Down Force: Is the ability of a forward moving truck to create a downward pressure on the topside of its outer skin. Starting with its leading edge the front bumper lip, hood, A-pillar/windshield, cab/SUV roof, and tonneau cover. As the angle of the surface is tilted at the rear, downward pressure is increased. Increasing the down force will increase the load on the tires' contact patches with the road surface without adding weight to the truck. Developing weight to the tires increases the tires adhesion during high-speed acceleration and cornering, improving the suspension-handling performance.
Lift: Affects the trucks handling in the opposite of "down force" at higher speeds. As air travels underneath the trucks chassis and suspension components it causes turbulence. This rough airflow also contributes to creating lift. When the ground clearance is limited (lowered truck) the airflow is limited causing a positive lift. When the ground clearance is greater (lifted truck) the airflow under the truck is increased. On the other hand a lowered truck limits airflow from getting underneath the truck causing negative lift pressure.
Yaw: Yaw is defined as the aerodynamic side load, or pressure effected onto the side panels of the truck: fenders, doors, windows, cab, and bedsides. Yaw or crosswinds tend to create increased pressure causing the truck to yaw in the direction of the crosswind. As the forward speed is increased, it equalizes the yaw wind speed, which causes the forward and yaw speeds to equalize
Ride Height: When a truck is shipped from the manufacture to the dealership its ride height is set to DOT regulations. But after a customer drives his or her newly purchased truck or SUV of the lot they may do what they wish with it ride height. Some lift them to the sky and others drop them to the ground. What is the best ride height for a truck or SUV?
Wind tunnel testing has proved that the lower the vehicle the better its coefficient drag becomes, due to the fact that less air is able to flow underneath the chassis create drag. Elevated trucks and SUV's we see cruising the boulevards or prowling rugged terrain are a mess when it comes to creating a coefficient aero package. The greater the truck or SUV's ride height,the more drag and turbulence it's creating underneath the chassis. Other contributors are the massive wheels/tires that are part of the rugged off-road image. As these redundant rolling spools of aluminum RPMs increase, more turbulence is developed causing incredible drag load. Less air travels underneath causing turbulence.