(CNN) – What was the last time you looked out of your plane window? It could be a winglet, now ubiquitous at the end of each wing, often used by airlines to display their logos and put their branding in your travel pictures.
Winging: The curves at the ends of the wings of a modern aircraft are about efficiency.
Pascal Pigeon / Masterfilms
As air flows around the wings of the aircraft, it produces high pressure on the lower surface and low pressure on the upper surface, creating a lift. But once the air flowing at the bottom reaches the top of the wing, it turns upwards and meets the low pressure air at the top, which is essentially a small tornado. This drag extends behind the generating aircraft, which is equivalent to a loss of energy.
“The energy that is being released into the air is coming from the plane,” says Al Bowers, a former chief scientist at NASA’s Neil Armstrong Flight Research Center. “If there is a way to get more energy and keep it on the aircraft, it will result in less energy wastage.”
In 1897, the British aerodynamist Frederick W. Lancaster patented “wing endplates”, with vertical surfaces placed at the ends of the wings to prevent airflow from meeting the bottom and top, reducing stretch marks. “Endplates act like winglets in many ways, but the lift improvement is poor, because the flat plates themselves are not very good aerodynamic surfaces,” Bowers explains.
“It was Whitecomb who developed the idea that these should be much more aerodynamic surfaces, actually wing-shaped,” says Bowers. “They realized that setting the right angle on them would reduce the tension dramatically.” The name Winglet, meaning small wing, is naturally followed.
Winglets were originally the brainchild of NASA engineer Richard Whitcomb.
Despite the encouraging results, the Winglets did not immediately attract interest from the airlines, as they were still adding extra weight to the plane and were expensive to install.
“In the early days, even after Whitcomb, the engineering tools used to design them were not so good and the mantra was ‘Winglets help at low speeds but they hurt faster’,” said Mark D. Moghmar, says the expert. Professor of Winglet Design and Aerospace Engineering at Penn State.
“So they didn’t get their way on commercial transport at the time because the airlines didn’t want a Winglet penalty.”
Things changed when a company called Aviation Partners created the “Blended” Winglet. Founded in 1991, it hired former Boeing aerodynamist Louis Gretzer, who in 1994 obtained a patent for a new type of winglet design that offers a significant increase in functionality compared to previous, more angular versions that flow easily beyond the wingtip.
The first aircraft to use a mixed winglet was the Gulfstream II, a twin-engine business jet with a maximum capacity of 19 passengers. Soon, aviation partners considered expanding into larger aircraft and began working with Boeing, which first showed interest in 1988 by placing winglets on the 747.
“The entry point with Boeing was the Boeing business jet, which is basically the 737,” says Mike Stowell, CEO of Boeing, a joint venture between Boeing and Aviation Partners. Designed in 1999, Boeing designs factory-installed winglets on new aircraft, and retrofits existing Boeing aircraft with mixed winglets (the 737 retrofit usually costs $ 750,000).
According to Stowell, some of the charms of mixed winglets are based on their attractive appearance, not just on fuel savings.
Split Schemeter Winglet on Boeing 737 MAX 8.
Stephen Brassier / Getty Images
“I think some [early business customers] They wanted a different look – they didn’t want their plane to look like a commercial aircraft. For business people, maybe not.
“We asked a major airline about the exact shape we were looking at, and the airline CEO’s quote was ‘You can put a piano on the edge of the wing – if it saves fuel, we don’t mind.'”
Aviation Partners says it has fitted 10,000 aircraft with their winglets – in 737, 757 and 767 households, as well as in business jets – which they estimate has saved a total of 13 billion gallons of fuel.
Since then they’ve created updated designs, including a “split schemer” and a “spiroid” winglet designed for the 737, used on some business jets, including loops. All design is to further improve efficiency and reduce fuel burn.
The latest Boeing aircraft have rack or backward-sweeping wingtops instead of winglets.
Unlike Boeing, Airbus was a late adopter of winglets and remained unreliable in its advantages in the 2000s. He first flew his own winglet design in 2011, calling it the “Sharklet”. “Airbus was late in the game, but they got caught quickly,” says Moghmer.
Winglets are now found on almost every small and medium-sized jet in the world, although their effectiveness on larger aircraft is less clear.
“They help climb, but they hurt the cruise,” Moughmer summarizes, why most long-haul aircraft, so spending most of their time on the cruise, may benefit less from the winglets.
As a result, models like the Boeing 787 and 777 do not have winglets, but racked wingtips or wingtips that have a more backward sweep than the rest of the wing – a design that is more efficient for pressing the wingtip during a cruise. Whirlpool fuel savings are comparable to winglets.
If you’re a frequent flyer, you’ll also like to know that winglets can make turbulence a little more tolerable, according to Bowers: “They improve the directional stability of the aircraft,” he says.
“I once flew two different 737s on a trip, and one had winglets while the other didn’t. The difference was dramatic: a person without winglets rode a little harder in turmoil. It was like riding in a sports car. On. “
Top Image: Airbus A320neo Winglet. Credit: Airbus