Airtabs | A Patented Aerodynamic Drag Reduction System

“The best design is the simplest design that works.” -Albert Einstein

Safety, Stability & Savings

Airtab® is a registered trademark of Aeroserve Technologies Ltd. US and Canadian Patents.

Airtabs™ are patented, unique wishbone shaped vortex generators designed to increase vehicle aerodynamic performance and fuel economy by reducing aerodynamic pressure drag at two key locations; the tractor-trailer gap and the rear facing surface (the base area) of any commercial or private square backed vehicle or trailer that routinely attains highway speeds. Drag reduction and fuel economy benefits from Airtab® application is not limited to commercial trucking operations. Airtabs™ enhance aerodynamic performance equally well on cube vans, straight trucks, expeditors, SUVs, RVs, buses, horse, toy and utility trailers, faired “bob tail” tractors, flat beds and tankers. The results may vary somewhat with vehicle type but the aerodynamic theory and principles are the same for all.

Airtabs™ are mounted 3 per linear foot, or every 4 inches on center. Take the number of feet to be covered and multiply by 3 to give the number of Airtabs™ required. Airtabs™ are approximately (in inches) 3.5 wide, 5 long and 1 high. To purchase Airtabs™ please click on the “Pricing-Buy Airtab” button

Each Airtab® creates two tight swirls of air or vortices that combine to reduce the suction and drag at the rear of vehicles traveling at speeds above approximately 35 mph or 55kmh. Airtabs™ are also effective at the rear roof lines of automobiles that have a rear window slope of greater than 30 degrees.

Airtabs™ offer several safety benefits as well. They improve vehicle stability by altering the airflow at the vehicle’s rear. The large random eddies at the rear surface are changed to an array of small vigorous “stream wise” vortices. The majority of users comment immediately on the improved vehicle handling performance, especially in gusty cross wind conditions or when passing (or being passed by) other vehicles. This increases driver safety margins by reducing wandering and sudden adjacent lane incursions. Mirror visibility in rain or snow is also improved as the Airtabs™ help suppress precipitation and spray patterns. Safety is improved through better mirror visibility yielding safer lane changes as well as improving the visibility conditions for other road users. By reducing the suction and aerodynamic drag at the rear of vehicles, the tendency to accumulate snow and road grime at this location is reduced. This helps to improve corporate image and reduce cleaning time and expense. It also enhances safety by keeping conspicuity tape, tail and brake lights cleaner and helps the bottom line by reducing snow and weight build up in winter.

How Do They Work?

The Tractor-Trailer Gap
The gap size is an important aspect of fuel economy in trucking operations and should be minimized as much as loads allow. If the gap between the trailing edges of the tractor fairing and the front of the trailer is greater than about 18 inches (1/2 meter) increased drag in this region begins to reduce fuel economy. For every additional 10 inches of gap size above about 30 inches, aero drag will increase 2% and fuel economy will decrease by 1%. The operator can reduce this gap with side extenders and/or moving the 5th wheel forward. However, moving the 5th wheel forward can reduce maneuverability and can place more weight on the steering axle increasing steering gear and tire wear. Through the use of side extenders and Airtabs, operators will have the flexibility of setting the 5th wheel more precisely for the load, not add weight to the steering axel and avoid a reduction in fuel economy by using Airtabs to reduce gap turbulence.

The Back of the Trailer

Airtabs™ reduce drag at the trailer rear by changing the dominant flow pattern from vertical to horizontal. Airtabs™ change the airflow from the alternating formation of large vertical eddies to a line of dozens of small vigorous horizontal ones. This reduces vehicle sway, improves stability in gusty cross wind conditions and increases fuel economy. By altering the airflow in this manner, Airtabs™ artificially taper the trailer and make the airflow behave as if the trailer was slightly smaller than it actually is. This results in drag reduction and an increase in fuel economy.

Look closely at the image. This is a very accurate depiction of the airflow behavior surrounding a moving trailer without Airtabs™ as viewed from above. Notice how large vertical eddys of air (like small tornadoes) alternately form and “shed” making room for another to form on the opposite side.

Although not visible here, there is an additional eddy that rolls off the top of the trailer as well. These eddys tumble into the partial vacuum formed by the moving vehicle.

A lack of trailer streamlining causes a partial vacuum to form at the rear of the trailer at highway speeds. This causes turbulent air in the form of large vertical eddies to tumble into the partial vacuum and the large alternating eddies cause the trailer to sway. Disturbances from passing vehicles or obstacles tend to amplify these eddies and increase the trailer’s tendency to sway, increasing driver work load and fatigue, increasing drag and lowering fuel economy. Streamlining the trailer by tapering would be the best solution but is not practical due to a necessary reduction in trailer capacity and massive changes to docking and loading facilities.

Other functional after-market devices that will reduce drag at the rear of trailers do exist. These are usually devices that physically alter the trailer rear by using inflatable sails, fiberglass boat tails or rigid metal panels that extend to taper the trailer rear. However, these devices can be cumbersome, expensive, heavy and prone to collision damage. These devices can also interfere with loading operations.