The Class 8 Vehicle - Fuel Efficiency & Aerodynamics

As I travel around and speak to many customers who operate heavy equipment and Class 8 vehicles, my goal is to determine how much fuel they burn annually and provide the best price and service based on those estimates. 

I'm always curious on how much fuel is burned or consumed on an annual basis by all sorts of contractors and transportation companies. This information is obviously helpful in my work, however it brings me back to the cockpit of an airplane or helicopter where fuel burn is a crucial element in flight. Burn rates are critical in calculating flight performance and range. So, I wanted to find out how much these industrial machines burn and what contributes to the amount of fuel, operating under various conditions, these Class 8 vehicles actually consume. 

The two factors affecting the average annual fuel use of a vehicle are the average miles per year and the fuel economy of the vehicle. Transit buses or Refuse trucks for instance are relatively inefficient due to their stop-and-go drive cycles and heavy loads, consume more fuel on average than any other vehicle type. Class 8 trucks, which typically travel long distances carrying heavy loads use less fuel, naturally. And, lastly, To give it some perspective, the vehicles you and I use  use a fraction of the fuel used by fleet-based vehicles, on a per-vehicle basis. However, many additional factors like type of use, wear and tear and other humanely-induced usage can affect the vehicles burn rate. 

Similar to aircraft traveling through the air, trucks also travel through the air (relatively speaking)  with additional force acting upon it. The main force that affects fuel economy with larger, Class 8 vehicles is drag. (And let me tell you, it's a drag). In some studies, research has shown that Class 8 vehicles can burn up to 13,000 gallons per year. Not to mention the cost the business' investment in fuel annually, but emissions and environmental regulations, operators have now started to seriously consider how to manage these costs and run cleaner.

With the onset of fleet technologies and tractor-trailer "sculpting", operators are finding creative ways to eliminate drag as did the aircraft industry. Forces on the tractor trailer moving down the road are again similar to the (4) forces of flight (lift, thrust, drag and gravity) experienced in an aircraft. You can see from the picture below that there are a number of trouble spots that add to the drag and inefficiency of the vehicle.

Nothing has transformed the ability of on-highway Class 8 tractors to get better fuel economy more than the use of aerodynamics to sculpt and guide the flow of air around the truck and trailer in order to cut through the air more efficiently. But because airflow is invisible, aerodynamics can be frustrating for many fleet managers.

A full suite of aerodynamic devices have been adopted on vehicles including FlowBelow’s undercarriage system, wheel covers, Fleet Engineers AeroSaver Classic side skirts that cover the landing gear, Stemco TrailerTail, a nose cone, Fleet Engineers AeroFlap mudflaps, and cross-member shields. Some operators also are finding solutions of their own from taking a power saw to a set of mud flaps sticking too far into the slipstream around the truck. Some truck features include relocated and recessed license plate, or even rain gutters that are plated over to smooth out airflow. Other trucks and trailers with application-specific aerodynamics, including aerodynamic skirts on regional haul trailers reduce wind drag under the rear tandems of the trailer. Concept trucks like the Super-Walmart transport vehicle below are those designs that will re-invent manufacturing process to eliminate drag and provide a great deal of fuel efficiency for transport vehicles. 

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