Winglets are a common feature found in almost all transport aircraft these days. They help to reduce fuel burn by preventing the formation of wingtip vortices which increases the induced drag on the aircraft.

The winglet or a wing tip device acts like a small wing. When air flows over it, a force is generated that points toward the fuselage of the aircraft. This force bends the streamlines near the wing tip which generates a small forward lift component or a forward thrust component that opposes the induced drag.

The early winglets

The benefits of winglets were first studied by a British aerodynamicist, F.W. Lancaster in the late 1800s. In the 1970s, a NASA engineer called Richard Whitcomb refined the Lancaster’s design and came up with the world’s first true winglet.

To test this new device NASA, US Air Force (USAF), and Boeing came together and fitted it to a USAF-owned KC-135. This began a 48-flight test campaign which involved testing the winglets by attaching them to the wing at different angles of incidence and flying the aircraft in various flight conditions.

KC-135 winglet

Photo: NASA

The very first airliner to roll out of the factory with winglets was the Airbus A310. It was not exactly a winglet. It was more of a wing tip device which Airbus called a wing tip fence. They functioned similar to the winglets. The first true winglets were first fitted to the Boeing 747-400 which made its first flight in 1988. These winglets are known as canted winglets and they can be found on the Airbus A330 and the A340 as well.

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Spanish Air Force A310
Lufthansa B747-400 touching down Orlando

Photo: Orlando International Airport

The blended winglets

This is where the real story of the winglets begins.

It all started with an American entrepreneur named Dennis Washington and his Gulfstream II. The story goes that Dennis was not happy with the range of his Gulfstream. To solve the problem, he teamed up with his friend Joe Clark and a retired Boeing engineer named Dr. Bernie Gratzer. Together, they developed a high aspect ratio winglet which they called a Blended Winglet under a company called Aviation Partners, Inc (API).

The blended winglets have a much smoother curve than the canted winglets, which reduces the drag by a huge margin. This increases the range and reduces fuel burn.

These newly designed winglets were then put on the Gulfstream II owned by Dennis Washington for testing. This was a success, and in 1993, the FAA granted API the approval to produce and market their new blended winglets.

In 1994, the blended winglets were patented by the API.


Photo: API

Boeing enters the show

In 1997, the President of Boeing Business Jets (BBJ), Borge Boeskove approached API with interest in fitting blended winglets to the BBJs. They used a Boeing 737-800 provided by the now-defunct German carrier Hapag-Lloyd to test the winglet. The winglet gave the test 737 a 150 NM increment in range and a payload increment of about 6,000 Ib. Needless to say, Boeing was impressed. This led to the formation of a joint venture between API and Boeing, called the Aviation Partners Boeing (APB).

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It was in the year 2000 when FAA awarded APB the Supplemental Type Certificate (STC) for the 737 BBJ blended winglets. And in the following year, APB was also given the STC for 737-800 blended winglets.

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Interestingly, Hapag-Lloyd, who loaned the Boeing 737-800 for testing, decided to keep the winglets from the test program, and they became the first official airline to operate a 737 with blended winglets. The first Boeing 737-800 to come out of the factory with the blended winglets fixed to the aircraft, belonged to another defunct German airline, Air Berlin.

In the following years, APB gained STCs to fit and retrofit blended winglets to almost all models of the 737s and even the Boeing 757 and the Boeing 767.

The latest winglet model developed by the API is the Split Scimitar Winglet (SSW) which can be fitted to 737 models including the BBJs. However, this winglet should not be confused with the AT winglets found on the Boeing 737 MAX which is purely an intellectual property of Boeing.

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Virgin Australia 737

Airbus comes into the picture

Airbus approached API in 2006 to test blended winglets on their A320 family of aircraft. During this time, the A320s were fitted with the traditional wingtip fences first fitted to the A310s in the mid-80s. Both companies entered a Non-Disclosure Agreement (NDA) under which they shared confidential information related to blended winglet design to produce a winglet specifically for Airbus aircraft.

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A320 wing tip fence

The testing began in 2008, in Toulouse, France in the prototype A320, MSN 0001, and the testing continued to the year 2009. However, at this point, Airbus was not too happy with the results from the test flights. API then decided to take matters into their hand and got an A320 from JetBlue and performed tests without any involvement of Airbus. The test results were later shared with Airbus, and they were impressed.

In 2011, Airbus shared with API its design for winglets, named “sharklets”. When API engineers went through the technical drawings and data for the new sharklets they alleged Airbus of copying the blended winglets of API.

In the same year, Airbus filed a lawsuit against API in the US District Court in Austin, Texas to solve the issue they had with API. In it, Airbus complained that API claims that the “sharklet” is a copy of the “blended winglet” and they want Airbus to pay a royalty for infringing the design. Airbus was adamant that sharklets were designed by Airbus engineers, and it was not a copy of API’s blended winglets.

The case later went to arbitration before the International Chamber of Commerce In London. There are no official comments or reports from either of the parties of what happened. But according to an article written in Puget Sound Business Journal in 2018, Airbus made a large payment to API, and they got to keep their sharklet design.

Eurowings, Airbus A320, Heraklion

Photo: Eurowings

Winglet designs now

Today, API continues to design winglets for aircraft. This includes winglet designs for BBJs, Dassault Falcon 2000, 900, and 50s, and Hawker 800 and 800 XPs.

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Falcon 2000

The APB continues to hold STCs for winglets fixed to Boeing 737 classics, NGs, 757, and the 767. Thus, the relationship between API and Boeing remains very strong.

The Boeing 737 MAX winglets, however, were independently designed by Boeing and have no connections with the APB. This winglet cheats a bit as the lower part of the winglet creates an outward lift component and a forward lift component. The upper part acts like a normal winglet in that it generates a lift towards the fuselage and a forward lift or thrust. So, the AT winglet does not have to be that tall which reduces parasite drag and the outward and inward lift components give it balance.

Screenshot 2022-11-08 at 22.29.09

Photo: Boeing

Airbus went from their very distinctly curved sharklets to a winglet that progressively curved rearwards. This can be seen in the A350 and the A330neo wings. This seamless curving increases the effective wingspan of the aircraft. The A330neo’s wings are 4 meters longer than the A330ceos because of the newly designed sharklets.

Airbus winglet

Photo: Airbus

  • rsz_airbus_50th_years_anniversary_formation_flight_-_air_to_air


    Stock Code:

    Date Founded:

    Guillaume Faury

    Headquarters Location:
    Toulouse, France

    Key Product Lines:
    Airbus A220, Airbus A320, Airbus A330, Airbus A340, Airbus A350, Airbus A380

    Business Type:

  • 787-8 Dreamliner


    Stock Code:

    Date Founded:

    Dave Calhoun

    Headquarters Location:
    Chicago, USA

    Key Product Lines:
    Boeing 737, Boeing 747, Boeing 757, Boeing 767, Boeing 777, Boeing 787

    Business Type:


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