Why modern airplanes have winglets

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(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.

But Winglet isn’t for marketing purposes alone – it actually saves fuel. On average, aircraft equipped with them can consume as little as 5% less fuel, and for a typical Boeing 737 commuter plane that could mean 100,000 gallons of fuel a year. According to NASA. Collective savings for airlines are in the billions of dollars.
They do this by reducing the natural vortices formed on the wings, which are so strong that even small planes Flip in mid-air When crossing in the wake of very large planes. The effect is so obvious that the aerodynamists were thinking about it even before the Wright brothers completed their first flight. However, the widespread adoption of winglets is more recent.

Better design

Winging: The curves at the ends of the wings of a modern aircraft are about efficiency.

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.

The idea for modern aircraft was refined in the 1970s by NASA engineer Richard Whitcomb, who envisioned the expansion of the vertical wing. Inspired Birds bend their wings when a lift is needed.

“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.

Whitcomb Thought tested In wind tunnels and found that winglets can achieve a reduction of about 5% of the pull. At the same time, Winglet was being researched independently by NASA, and in 1977, the commercial jet maker LearJet was the first to mount a winglet on a real aircraft. Two years later, NASA flew for the first time an Air Force KC-135 test plane – very different from a Boeing 707 airliner – equipped with nine-foot-high winglets. On more than 47 test flights, NASA confirmed the findings of the Whitcomb Wind Tunnel.

Mixed winglets

Winglets were originally the brainchild of NASA engineer Richard Whitcomb.

Winglets were originally the brainchild of NASA engineer Richard Whitcomb.

NASA

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.

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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.

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“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.

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.

Recorded wingtips

The latest Boeing aircraft have rack or backward-sweeping wingtops instead of winglets.

The latest Boeing aircraft have rack or backward-sweeping wingtops instead of winglets.

Bob Ferguson

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.

The A320 family – currently the world’s best-selling airliner with over 16,000 orders – began having Charcot as an alternative in 2012, while the current A320 has been retrofitted since 2015. Airbus Promised 4% reduction in fuel burn and saving of 900 tons of CO2 per aircraft per year.
In 2013, with the A350, ahead of Airbus Pure Its winglet design, which was no longer a separate appendage but a “simple wing-shaped simple three-dimensional curve.” The new design was also applied to the A320neo, a new version of the popular plane with a superior engine, which now comes with Charcot as standard.

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

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