Truck News


Aerodynamics: Aero facts

OTTAWA, Ont. - Many of today's truck-tractors look like they've just emerged from aircraft wind tunnels, and most tractors of any kind have some type of streamlining.Experience shows they save money i...

OTTAWA, Ont. – Many of today’s truck-tractors look like they’ve just emerged from aircraft wind tunnels, and most tractors of any kind have some type of streamlining.

Experience shows they save money in fuel, and have since the first fuel crisis caused fairings to sprout from cab roofs in the mid-1970s.

By the mid-’80s, truck builders were designing aerodynamics into many models. Even square-nosed “large cars” will usually mount big deflectors on their roofs to smooth the flow of air over the van or reefer trailer behind.

But behind them, trailers appear to have been riveted together in a box factory. True, they hide behind the tractors’ air deflectors, but some sit too far behind for the fairings to do much good.

Considerable research has shown that aerodynamic trailers can save a lot of fuel and money. However, it’s true that many trailers spend a lot of time sitting in yards and at docks, where aerodynamics do nothing. And whether they work or not, most buyers simply will not spend money on aero improvers.

Maybe that’s changing, as the two companies that produce aerodynamic devices for trailers are getting more interest in their products. One is Aeroserve Technologies Ltd. in Ottawa, Ont. It makes Air Tabs, small air-flow improvers applied to the sides of both tractors and trailers. The other is Nose Cone Manufacturing Co. in Buena Park, Calif., which sells bulbous appendages attached to the front walls of trailers and truck bodies.

Relatively new to the market, wishbone-shaped Air Tabs cause air to swirl and leave the wing’s surface with less friction and without forming a vacuum at the wing’s trailing edge. This increases lift and boosts payload; it also reduces drag and saves fuel.

Air Tabs are vortex generators for trucks, explains Mark Adler, vice-president of sales and marketing for Aeroserve Technologies.

Placed at the trailing edges of a tractor’s sleeper, they swirl the air and cause most of it to flow past the gap between tractor and trailer instead of being sucked into it. Placed at the rear edges of the trailer, they cause air to swirl off instead of being sucked into the vacuum at the doors.

The tractor-trailer gap and the trailer’s rear door area are notorious producers of fuel-wasting turbulence. The busy air remains attached to the vehicle’s skin and pulls on it; this drag has to be overcome by the engine, and that burns fuel.

“The tabs reduce turbulence in the gap by keeping the air from going in,” Adler says. “At the trailer’s rear, the tabs create air swirls well behind the trailer, where it’s no longer attached.”

One operator who’s committed to Air Tabs is Ken Atkinson, part owner and vice-president of operations for Tilbury Mechanical Enterprises (Til-Mech) in Tilbury, Ont

The Atkinsons have documented a three per cent increase in fuel efficiency since applying Air Tabs to the trailing side-edges of the tractor’s fairing. Fuel economy climbed from 2.75 kilometres per liter to 2.85 km/liter, with an average road speed of 100 km-h and a gap of 26 inches between tractor and trailer.

“To really do it right, you have to put the tabs on the trailers, too,” Ken Atkinson says.. With tabs at the rear edges of the trailers, fuel economy went to 2.91 km/liter, or more than five per cent compared to a rig with no tabs at all.

The $350 per unit investment was worth it, paying for itself in about two years.

“However, we have noticed other pluses which help,” said Dale Atkinson, the company’s president, in a testimonial letter. “The driver has better visibility in the rearview mirror in bad weather because of better draft control in stormy weather. We are also noticing what seems to be a 25 per cent increase in steering tire life.”

Dale and Ken also attribute the tread-wear improvement to better control of airflow, because the betterment began when the Air Tabs were put on the tractor. They also find they can increase the tractor-trailer gap by four inches, to 30 inches, to improve ride quality without affecting fuel economy.

Til-Mech’s driver sees reduced water spray in rain, and an operator in Australia can see the tabs swirl the dusty air as his truck goes down a gravel road, relates Adler. Less buildup of dirt and snow on the rear doors is additional proof that they work. When it rains, water spray is cut, improving rearward visibility for truck drivers and improving the view for motorists.

Less sway

“Drivers can feel the difference,” he says. “There is less sway and less pull. One guy in Australia stopped to get out to make sure he still had a full load aboard because it felt like the truck was lighter. And he was one of the skeptics.”

Trailer tires last up to 30 per cent longer in those overseas operations, says Adler. This is a function of reduced sway. Fuel savings – the main point of the devices – will be at least four per cent if the tabs are installed on tractor and trailer. The four per cent is guaranteed, but some operators have seen 10 per cent fuel savings, he says.

Each Air Tab is about 5.5 inches long by 3 inches high and 1 inch deep. It’s molded in tough ABS plastic and comes with an adhesive-backed undersurface, which attaches to the wall of the vehicle. Ordering information is at 800-475-2155. The device is explained further on the company’s Web site, www.airtab. com.

At Nose Cone Manufacturing, recent spikes in fuel prices have sparked a lot of interest, says Jim FitzGerald, son of the company’s founder. Jim joined the business not long after the first fuel crisis in 1973.

“I think people are more aware that the cost of fuel is such a large part of their operating budget, and are now looking at ways to further reduce their costs,” FitzGerald says.

A Nose Cone is hung on the upper-front of a trailer or truck. It will save five to 15 per cent in fuel or buyers can get their money back, the company advertises on its Web site,

Made of reinforced fiberglass, a Nose Cone typically costs $550 to $750, weighs no more than 50 pounds and installs in less than two hours, according to FitzGerald. A trailer version usually pays for itself in less than a year, or about 50,000 miles of operation. Nose Cones come in many configurations and have been around for 20 years plus.


One satisfied customer is Curtis Matthes, president of C.D. Matthes Inc. of Fresno, Calif., which runs high-cube single- and double-trailer combinations.

“We won’t send a trailer out without it,” he says. “In a cross wind, it saves almost a mile per gallon. Our drivers remark that they can feel the difference if they pull a trailer without one – if we run a leased trailer, which isn’t equipped with it.”

The gap between tractor and trailer produces considerable drag which the Nose Cone eliminates, Matthes explains. This is critical with gaps over 36 inches, FitzGerald says, but Matthes gets his fuel economy and vehicle stability gains even with a very tight gap – 12 inches.

“You’re talking to a believer,” Matthes says. “And I have been since 1983.”

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