Aerodynamics and Truck Gas Mileage

Semi-trailers are the lifeline of the supply chain, hauling all the products and raw materials Iowans need. Prices of products are dependent on transportation costs and these, in turn, are dependent on how much gas the hauler uses. Gas usage is dependent on many factors including the amount of drag on the vehicle. Drag, or friction, reduces the gas mileage because it is a force that opposes motion. Reducing drag on semi-trailers is an important engineering design problem.

• Can gas mileage be improved by modifying a semi's aerodynamics?

• What are the differences between the cabs seen in the video?
• What are the differences between the trailers seen in the video?
• Which parts of the trailer or cab create the most or least drag? Explain.

Students could:

• Use this to learn about friction or at the end of a unit about force, and design a low-drag semi-trailer as a final product. 
• Investigate factors that affect drag via a variety of activities including the FoilSim program produced by NASA. They can calculate the lift and drag using the information and equations on the NASA website. 
• Develop working definitions for the terms aerodynamics, lift, and Bernoulli’s Principle.
• Investigate the points on a semi that cause the most drag.
• Use research, knowledge and imagination to design a new semi-trailer that would be functional as well as aerodynamic.

• NASA | Student Airfoil Interactive:With this simulator you can investigate how an aircraft wing produces lift and drag by changing the values of different factors that affect lift and the factors that affect drag.
• NASA | Factors That Affect Aerodynamics: Article explaining the factors that affect aerodynamics including those associated with the object, those associated with the motion of the object through the air, and those associated with the air itself.
• Government of Canada | Review of Aerodynamic Drag Reduction for Heavy Trucks and BusesA very thorough document outlining how drag affects fuel usage. In section 7, it examines the various drag reduction devices that can be added to a vehicle.
• Heavy Duty Trucking | Aerodynamic Devices Can Translate into Fast Fuel Savings: This 2017 article is an easy read that discusses drag reduction devices and their cost savings.