Semi-Truck Aerodynamics

Aerodynamics on a car can easily make or break the bank. Though overlooked, aerodynamics actually plays a huge role in gas consumption and saving fuel, which are very important as a truck driver looking to earn a decent wage. Typically, the average semi-truck settles at around 6 miles to the gallon (mpg), though this number will waver depending on the weight of the load a truck is carrying. The way fuel is consumed has improved at an amazing rate since the 20th century, but this is only by a minute margin! Let’s take a deeper look into semi-truck aerodynamics, how they work, why they matter, and why you should be interested.

Aerodynamics on a Semi-truck: How does it work?

There are 4 main areas that affect the aerodynamics of a Semi, that being:

  • The front of the tractor
  • The gap between the trailer, which hauls the freight, and the tractor
  • The sides, skirts, and underchassis of the trailer
  • The trailer’s rear side

The front of your tractor will face the brunt of the wind pressure as you drive along. Your tractor’s width, boxiness, and overall shape will contribute to how fuel efficient you are when driving. It is a given that the less refined the surfaces, with lesser curvature and flatter surfaces, the greater the drag experienced when driving. A great example of an aerodynamic Semi with great handling on the front end of the tractor is the International ProStar ES, which showcases very fine curvature and exterior design.

You will notice that the most fuel efficient trucks, such as the Freightliner Evolution I have a minimal gap between both the trailer and the tractor. This is the singular most impactful part of a semi-trucks aerodynamics, which causes up to 25% of air drag. Between the trailer and the tractor, a vortex is formed by the wind suction, which in turn, leads to friction. This leads to a reduction in fuel saved.

The skirts of a trailer can be located beneath it, sandwiched by the axles. The purpose of skirts are to direct the airflow and reduce drag caused by wind from the underchassis. This leads to great fuel efficiency because it reduces strain on the drive train, making driving more efficient the faster you go.

Some trucks come with mud flaps that, though not always the case, cuts down on drag aerodynamically and makes long travel safer for those behind your truck.

Lastly, the trailer’s rear side is also a point of observing when it comes to aerodynamics. In a similar fashion to the gap between the tractor and the trailer, the rear of a Semi creates a vortex, albeit a small one. This creates friction which drags your truck when driving, causing poorer fuel efficiency.

When considering getting into trucking, be sure to consider how aerodynamic and fuel efficient your Semi is as well. You will be doing not only your pockets a great favor, but also the environment. Though there have been a lot of improvements in the 21st century over eco-friendly solutions for trucking and fuel consumption, doing a little bit to help the environment, such as picking more fuel efficient trucks will go a long way in helping the planet.