Winglets reduce CO2 emissions

Paul Bishop adds the last folds to a paper airplane, bending the wingtips upwards. As the airplane soars through Bishop's office, the Managing Director of DHL Air explains why he is excited about winglets, a technology which was recently certified for use on Boeing 767s.

It comes down to fuel savings. Big fuel savings. On a Leipzig to New York return flight, a Boeing 767 will use 4,000 liters less fuel than the same aircraft without winglets, Bishop notes. Those kind of fuel savings add up fast. Over the course of the year, DHL estimates it will save more than 1 million liters of fuel per aircraft.

It might seem impossible that such a small addition to an airplane's wing can make such a big difference. But winglets actually aren't small at all, Bishop says.

"They really are enormous. Each winglet is 3.4 meters high and adds more than 3 meters to the width of the aircraft," Bishop explains. "Winglets might look small when you see them on the runway, but that is only because aircraft are so large. The Boeing B767 winglets are a highly impressive sight when you get up close."

Reducing drag

Bishop, a former pilot with DHL, is impressed not just by the winglets' size, but also by the science behind the aerodynamic aid.

It is important to remember that wings create lift. When an airplane is propelled forward by its engines, the wing slices through the air, displacing it. Air moves more quickly over the curved top surface of the wing, creating a difference in air pressure between the top and bottom of the wing which in turn creates the lift necessary to support the weight of the aircraft.

Yet this unequal pressure causes problems at each wingtip, where it creates trailing vortices. The vortices, which look like a horizontal tornado funnel, increase drag and reduce lift. Research has found that winglets, far from being a mere stylish accessory, cut down on these vortices and dramatically improve the efficiency of the wing.

Less fuel, less CO2

With a list price of $2.2 million, the blended winglets used by the Boeing 767 had been viewed as an expensive extra by many buyers. But as jet fuel costs have continued to increase, that attitude is rapidly changing. According to Aviation Partners Boeing, which produces the winglets for Boeing aircraft, winglets will improve fuel efficiency by 4.6 percent on a Boeing 767. DHL estimates it will be able to recoup its investment in winglets in less than three years.

But Bishop says the industry's interest in winglets goes far beyond monetary concerns. Less fuel not only brings down costs, but also means fewer harmful greenhouse gas emissions. Each DHL aircraft with winglets is expected to produce 3,150 tonnes less of CO2 annually compared to the same airplane without winglets.

The aviation industry is very aware of its environmental responsibilities. While airplanes cause only an estimated 2-3 percent of man-made CO2 emissions, it consumes 13 percent of fossil fuel used in transportation.

Ambitious climate protection program

DHL Express now has the company's first two winglet-enhanced aircraft in service. By the end of 2012, DHL Express will have taken delivery of all six of its new winglet-fitted Boeing 767Fs.

The winglets are just one small part of Deutsche Post DHL's ambitious GoGreen climate protection program. The Group has set itself the goal of achieving a 30 percent improvement in carbon efficiency by 2020. As a first step, Deutsche Post DHL aims to improve the carbon efficiency of its operations by 10 percent by 2012.

As Bishop picks up the paper airplane that has landed in the corner of his office, the pilot remarks that modern cargo airplanes are nothing like their heavy, hulking counterparts from the 1970s and 1980s. New airplanes are being built with lighter and stronger materials. Kevlar, carbon, fiber, titanium and ceramics are replacing steel. These lighter materials reduce the amount of required fuel. Additionally, the race is on to find cleaner and more efficient mixes of fuel with promising advances in the production of bio-fuels suitable for use in aircraft.