The History And Differences Between Airbus And Boeing Winglets

Summary

• Winglets reduce aerodynamic drag by 2-5% on modern jetliners.
• API developed blended winglets leading to a joint venture with Boeing.
• Airbus produced sharklets but faced legal issues with API over the blended winglet design.

The curved edges at the far end of the wings, called winglets, are a common feature on most modern commercial jetliners. Wingtips are used to minimize the intensity of vortices and reduce lift-induced drag on aircraft. Lift-induced drag is generated as a byproduct of downwash from wingtip vortices.

Depending on the type of wing, shape of the winglets, and flight regime, winglets can reduce the total aerodynamic drag by anywhere from 2% to 5%. Airbus and Boeing also offer retrofit wingtip devices for older models that were designed without winglets. This article delves deeper into the history of winglets and the major differences between Airbus and Boeing wingtip devices.

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 Lancaster’s design and came up with the world’s first true winglet.

To test this new device, NASA, the US Air Force (USAF), and Boeing came together and fitted it to a USAF-owned KC-135. This prompted 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.

The very first airliner to roll out of the factory with winglets was the Airbus A310. These were more like wingtip devices, which Airbus called wingtip fences. They functioned similarly to winglets, but the first true winglets were fitted to the Boeing 747-400 which made its maiden flight in 1988. These winglets are known as canted winglets, and they can be found on the Airbus A330 and A340 as well.

Blended winglets

Blended winglets 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, and so, 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). Blended winglets have a much smoother curve than the canted winglets, which reduces the drag by a huge margin, as well as increasing the range and reducings 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.

Boeing enters the show

In 1997, the President of Boeing Business Jets (BBJ), Borge Boeskov, approached API with an 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 increase in range and a payload increase of about 6,000 Ib. Needless to say, Boeing was impressed, and this led to the formation of a joint venture between API and Boeing, called the Aviation Partners Boeing (APB).

It was in the year 2000 when the FAA awarded APB the Supplemental Type Certificate (STC) for the 737 BBJ blended winglets, followed by the 737-800 in 2001.

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, namely Air Berlin.

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

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 are purely intellectual property of Boeing.

Airbus comes into the picture

Airbus approached API in 2006 to test blended winglets on its A320 family of aircraft. During this time, the A320s were fitted with the traditional wingtip fences that first featured on the A310sin 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.

The testing began in 2008, in Toulouse, France on the prototype A320, MSN 0001, and it continued into 2009. However, at this point, Airbus was not too happy with the results from the test flights. API then decided to take matters into its own hands 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 accused 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. Airbus was adamant that sharklets were designed by its own engineers, and that they were 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 it got to keep its sharklet design.

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. Meanwhile, APB continues to hold STCs for winglets fixed to Boeing 737 classics, NGs, 757s, and the 767. As such, the working relationship between API and Boeing remains very strong.

The Boeing 737 MAX's split winglets, however, were independently designed by Boeing and have no connections to APB. This winglet is bit different, 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. Therefore, the AT winglet does not have to be that tall, which reduces parasite drag and the outward and inward lift components give it balance.

Meanwhile, Airbus went from its very distinctly curved sharklets to a winglet that progressively curved rearwards. This can be seen on the wings of its newer A350 and the A330neo models. The seamless curving increases the effective wingspan of the aircraft, and the A330neo’s wings are 4 meters longer than the A330ceo's because of the newly designed sharklets.

What are your thoughts on the history and use of winglets? What is your favorite winglet design? Share your views in the comments section.