How Split Scimitar Wing Tips Increase Fuel Efficiency

While winglets on planes are nothing new, we will try and explain how split Scimitar winglets increase fuel efficiency by up to 2%. Have you ever looked out of a plane’s window and wondered why aircraft nowadays have a strange curved shaped tip at the end of the wing?

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Winglets were developed to increase fuel savings. Photo: Bill Abbott via Flickr

Called winglets the curved shaped metal wingtips, we see today are a direct result of the 1973 oil crisis when Gulf Arab states put an oil embargo on the United States for supplying aid to Israel during the 1973 Arab–Israeli War.

Engineers started looking at ways to make aircraft more fuel-efficient

Causing a huge spike in prices at the pump, engineers in America started looking at ways they could make aircraft more fuel-efficient.

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Enter Richard T. Whitcomb an aeronautical engineer who worked for the National Aeronautics and Space Administration (NASA). Having been an ardent student of flight from a young age, Whitcomb got his inspiration from watching how birds curve the ends of their wings upwards during flight to gain more lift.

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Bird in flight
Birds curve their wings upwards to increase lift. Photo: Public Domain Pictures.

As you are already aware, planes are able to fly by developing high-pressure air under the wings and low-pressure air above the wings.

Air will always flow from high-pressure regions to low-pressure regions. This can cause some problems at the tip of the wings. High-pressure air from below the wing will begin to flow into the low-pressure air above creating what is known as induced drag.

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Winglets help to reduce drag

By producing a vortex or mini-tornado effect at the end of the wing, this drag is reduced. This is what winglets are designed to do. As a result, the aircraft’s fuel consumption reduces, and as we know airlines are always trying to be as fuel-efficient as possible.

SSW on United 737

Adding winglets reduces the pressure gradient. Photo: United Airlines

Split Scimitar winglets are named after a Middle Eastern sword with a distinct curved blades ending with a sharp point. Split Scimitar winglets were developed by Aviation Partners Boeing and are available for the 737-800 and 737-900ER after entering service in 2014.

Weighing 133kg (294Lb) and costing $555,000 when first introduced, the Split Scimitar winglets can produce fuel savings of between 1.6% and 2.2%.

United Airlines was the first to use Split Scimitar winglets

While traditional curved winglets reduce the vortices created at the ends of the wing, by adding another downward-pointing fin, the Split Scimitar winglets will further reduce energy loss.

United Airlines was the first airline to retrofit its fleet of Boeing 737-800s and 737-900ERs

installing SSW

United was the first airline to use SSWs. Photo: United Airlines

When announcing that they would be the first customer to fit Split Scimitar winglets, vice president of fleet operations for United Airlines Ron Baur said, according to website b737.org.uk:

 “We are always looking for opportunities to reduce fuel expenses by improving the efficiency of our fleet. The Next-Generation 737 Split Scimitar Winglet will provide a natural hedge against rising fuel prices while simultaneously reducing carbon emissions.”

United was confident that by fitting the new Split Scimitar winglets on its aircraft they will reduce fuel consumption by 2% leading to a more than $200 million per year saving in jet fuel costs.

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