A Quick Guide to Improving Tractor Trailer Aerodynamics

semi truck aerodynamics

Did you know that improving trailer aerodynamics can significantly impact drag and fuel efficiency?

Aerodynamic drag is responsible for 65% of the energy used while pulling a trailer. That’s why more fleets are turning to products like trailer aerodynamic products to help reduce drag and save money on fuel costs.

But what are trailer aerodynamics, exactly?

And which product is right for your fleet?

Answering these questions requires understanding the effects of aerodynamic drag on tractor-trailers and the different types of products available to reduce it.

What Are Trailer Aerodynamics?

Trailer aerodynamics refers to the study of how air flows around and over a trailer.

When a truck moves, air resistance (or drag) slows it down and uses up fuel. Reducing drag can lower fuel consumption by up to 12%. This would save more than $10 billion in diesel fuel per year.

The Main Points of Drag on Tractor Trailers

To understand how to reduce drag, it’s essential to know where it comes from.

There are three main points of drag on tractor-trailers:

  • Back of the trailer near the doors: When air circulates around a trailer, it forms a vortex behind the rear door, causing a significant decrease in air pressure.

Addressing these areas can significantly improve trailer aerodynamics.

Airflow Simulation

Products and Devices to Reduce Tractor-Trailer Drag

Aerodynamic devices are effective at reducing drag and improving fuel efficiency.

And the faster the speed, the more efficient they become. Many products and devices on the market can help reduce drag.

  • Trailer fairings: The trailer fairings (or skirts) keep the wind from blowing under the trailer and into the bogie. They work best when they start from the landing gear and end at the front face of the front trailer axle, close to the ground.
  • Wheel covers and mud flaps: Wheel covers are devices inserted into the wheel that help direct airflow around the tires. Mudflaps are installed behind the wheels and help deflect air away from the undercarriage.

When choosing an aerodynamic device, it’s important to remember that many will complement each other. For example, using trailer tails with wheel covers further reduces drag.

Of course, fleet owners must consider the unique needs of their operation when choosing products.

Trailers Are Only Part of the Equation

While trailer aerodynamics are important, they account for only some of the drag that impacts fuel efficiency.

The front tractor section also accounts for a significant amount of drag (about 25%). To address this, some truck manufacturers are exploring a more aerodynamic design for the front of the truck.

Some solutions include adding pedestal door mirrors and sloped-front windshields.

The gap between the cab and trailer also accounts for about 25% of the overall drag. High-speed air rushing in causes a low-pressure area which then drags on the tractor and decreases fuel economy.

Closing the gap would result in a decrease in airspeed and less turbulence downstream. Increased pressure at the back of the cab would decrease overall drag, especially where crosswinds are strong.

For fleet owners, this could mean a significant decrease in fuel consumption and savings amounting to millions of dollars each year.

Learn how Ryder Systems saved 4.1% on fuel with TruckWings.

Improve Trailer Aerodynamics and Fuel Efficiency

Cutting emissions and fuel costs is a high priority for trucking fleets.

That’s why many fleet owners are investing in trailer aerodynamic devices.

There are two types of trailer aerodynamic devices:

  • Hardware-only devices that require driver interaction.
  • Smart products that are automated and require no driver interaction.

TruckWings and TrailerTails are two devices that are sometimes confused, but there are key differences between them. TrailerTail (discontinued) was a hardware-only device installed on the back of the trailer that required the driver to close it manually. TruckWings is the only fully automated, tractor-mounted device that works without interaction, allowing for the best driver experience.

By automatically closing the gap between the cab and trailer, the device:

  • Improves stability
  • Increases fuel efficiency
  • Reduces drag

TruckWings also:

  • Operates in two positions — closed when the truck travels fast on an open highway and open when going slow or making turns
  • Uses smart sensors to track carbon and fuel savings
  • Provides uptime reporting

If you want to improve fuel efficiency, contact us to learn more about TruckWings.

FAQ

How do I reduce drag on my truck trailer?

There are several ways to reduce drag on your trailer, including:

  • Adding trailer fairings (or trailer skirts) to keep the wind from blowing under the trailer and into the bogie.
  • Installing mudflaps and wheel covers to help direct airflow around the tires.
  • Adding a trailer tail to alter the airflow as it leaves the trailing edge of a truck’s side and top surfaces.

Why do truck trailers have wings?

Wings help keep the trailer more stable and improve fuel economy.

Do truck wings work?

Yes, they are an effective way to reduce drag and fuel costs. In fact, TruckWings provides potential fuel savings of 3-6% mpg with 12-18 months ROI resulting in millions of dollars saved per fleet.

Learn how Ryder Systems saved 4.1% on fuel with TruckWings.

5 Ways to Improve Semi-Truck Aerodynamics and Reduce Fuel Costs

Rising fuel prices – topping off at more than 75 percent higher than last year – have left the trucking industry scrambling for solutions to reduce fuel costs and improve the efficiency of their fleets.

Diesel prices have reached record levels and not since the 1970s has there been a tougher time to manage fuel hikes and keep trucks running.

The seemingly endless trend in the wrong direction has trucking operators turning their attention from the inside of the tank to the outside of the truck, reconsidering truck aerodynamics and new advances in products and devices that curb their losses.

The Impact of Aerodynamics on Fuel Economy

Semi-truck aerodynamics plays a large role in how fuel efficient a truck can be when traveling at high speeds along an interstate highway.

At highway speeds, a semi-truck consumes more than half of its fuel by pushing through air resistance created by the size and shape of the semi-truck and trailer. This so-called aerodynamic drag decreases fuel efficiency.

That drag is created along multiple points of the truck and trailer, including the front of the truck, the gap between the trailer and the tractor, the sides and underbody of the trailer, and the back of the trailer. The smoother the airflow around those points, the lower the drag.

Improving aerodynamics can deliver significant fuel cost savings. In fact, industry reports indicate that using multiple devices to reduce aerodynamic drag can reduce trucking industry fuel consumption by more than 12 percent – or some $10 billion in diesel fuel costs.

The Most Common Drags

Trucking companies have popularized many products over the years that improve semi-truck aerodynamics, including streamlined shields, trailer skirts, trailer tails, and devices that cover the gap between the tractor and trailer.

All are directed at reducing the percentage of drag created by each aerodynamic-resistant component of a truck and trailer.

Among the leading offenders on a truck, when it comes to wind resistance, is the gap between the tractor and the trailer, which can produce 25 percent of the overall drag. Any gap of 18 inches or more between the tractor and trailer can produce increased air resistance, researchers say. Covering the gap can reduce drag by as much as 9 percent.

The front end of a tractor also produces a significant amount of drag or about 25 percent. Many truck manufacturers are eyeing the front of the truck for more aerodynamic design, including sloped front windshields and pedestal door mirrors.

All along the side of a semi-trailer, aerodynamics are impacted, along with the underbody. Combined, that’s another 25 percent of overall drag created by a tractor-trailer rolling down a highway.

Finally, the back of the trailer creates yet another point of drag when air gets trapped around the tail.

5 Easy Ways to Improve Semi-Truck Aerodynamics

Devices on the market today can create much-improved aerodynamics on semi-trucks and are readily available. Here are five leading ways to boost fuel efficiency.

  1. Reduce the gap between truck and trailer: Using an aerodynamic device to cover the gap can significantly reduce drag and improve fuel efficiency. Trucking industry giant Ryder System, Inc. partnered with us to use our TruckWings device, which delivered them a fuel saving of 4.1 percent. TruckWings automatically deploys at speeds above 52 mph, covering the gap without any distraction to the driver, and retracts when speeds drop below 50 mph, allowing for safe maneuverability on surface streets.
  2. Reduce airflow underneath: Side skirts reduce airflow underneath trailers, leading to fuel savings of more than 4 percent, according to manufacturers.
  3. Minimize tail drag: Trailer tails, or “boat tails” that reduce turbulence can knock fuel costs down by around 6 percent for semi-trucks traveling at 65 miles per hour
  4. Check your wheels: Wheel covers allow air to flow past the tires, reducing aerodynamic drag.
  5. Make mud flaps aerodynamic: Switch from heavy, solid rubber flaps to slotted mudflaps, which allow air to pass through them.

Improve Aerodynamics, Cut Fuel Costs

In the face of unprecedented fuel costs, fleet owners are finding a growing number of options on the market for improving truck trailer aerodynamics and creating fuel-efficient designs.

Leading the way in preventing costly wind resistance is TruckWings, providing an accessible, automated aerodynamic option that can significantly trim fuel costs across an entire fleet.

Ready to face down fuel inflation? Get in touch today and learn more.

How to Harness Aerodynamics to Reduce Drag, Improve Fuel Efficiency for Fleets

Automation, Targeted Design Boost Performance by Closing the Gap

Improving fleet performance, reducing emissions and reducing fuel costs are top priorities for the trucking industry, especially as fuel costs soar and green policy pressures increase. Fleet operators searching for innovations and solutions have eyed better aerodynamics as an easy answer.

The pocket of air between the tractor and trailer – or gap – is the most common cause for drag, which costs money and wastes fuel. How to close the gap while a truck is at highway speeds, yet maintain maneuverability on surface streets has posed a challenge for operators.

Extra long, static cab extenders have provided some relief. But, while they help close the gap and reduce drag, they interfere with trailer clearance for tight turns, making them a potential nightmare for in-town driving conditions.

Automated design has uncovered a better way to close the gap. Closing the gap reduces buffeting and trailer sway in cross-winds outperforming even the longest side-extenders on the market today.

Automation in Aerodynamics Delivers New Option
Introduced by TruckLabs in 2015, TruckWings is a tractor-mounted device that has unlocked a new frontier in Class 8 efficiency through the use of active aerodynamics. Developed by hardware engineers, software developers, and data scientists to systematically manage the gap in all conditions, TruckWings is innovating the industry.
Closing the gap reduces buffeting and trailer sway in cross-winds outperforming even the longest side-extenders on the market today.

The TruckWings device requires zero driver input to deploy or retract, delivering an automated solution that keeps people and property safe, while achieving the savings and sustainability improvements fleet owners are seeking.

How Do TruckWings Work?
TruckWings is the only fully automated solution that works without driver interaction.
As a smart device, TruckWings receives real-time information about the speed of a tractor-trailer to determine when to open and close. When the vehicle reaches 52 mph, a signal is sent from the cab to automatically deploy the TruckWings. When speed dips to 50 mph or below, TruckWings automatically retract before the truck needs to make sharp turns.
The standalone TruckWings controller is installed on the truck’s CAN J1939 data link. Additionally, a sensor scans the area behind the TruckWings to ensure adequate clearance to the trailer exists.

Five of the 10 largest fleets in North America have installed TruckWings on their trucks, logging over 400 million miles. Each one makes the savings and sustainability impact of taking two vehicles off the road every year.

TruckWings reduces the energy lost in the tractor-trailer gap, lowering wind drag, improving fuel economy and reducing carbon emissions. Most fleets see 3-6% improvement in fuel efficiency. Each TruckWings device reduces 20,000 lbs/yr in carbon emissions. Analysis and customer reviews also confirm an improvement in vehicle stability at higher crosswinds by reducing the side forces acting on the trailer. This leads to improved safety and vehicle control.

As more fleet operators turn to solutions that drive down fuel costs and improve emissions rates, TruckWings automation is delivering a powerful boost to fuel efficiency and sustainability efforts.