What you should know about…winglets and wingtips

Adding winglets tilted upward at the tips, either to new aircraft or as retrofits to existing models, has delivered 3-5% reductions in fuel burn, depending on the length of the flight and type of aircraft. Winglets reduce induced drag without needing a significant increase in horizontal span.

Although there are several types of wing tip device, which function in different manners, the effect is always the same. Because the wing tip shape influences the size and drag of the wingtip vortices, tip design has produced a diversity of shapes, including:

• Squared-off
• Aluminium tube bow
• Rounded
• Hoerner style
• Winglets
• Drooped tips
• Raked wingtips
• Tip tanks
• Sails
• Fences
• End plates

Wing tips are also an expression of aircraft design style, so their shape may be influenced by marketing considerations as well as by aerodynamic requirements.

Reduced spacing requirements between aircraft operations at airports

The winglet converts some of the otherwise-wasted energy in the wingtip vortex to an apparent thrust. This small contribution can be worthwhile over the aircraft's lifetime, provided the benefit offsets the cost of installing and maintaining the winglets. Another potential benefit of winglets is that they reduce the intensity of wake vortices. Those trail behind the plane and pose a hazard to other aircraft. Minimum spacing requirements between aircraft operations at airports are largely dictated by these factors. Aircraft are classified by weight (e.g. "Light," "Heavy," etc.) because the vortex strength grows with the aircraft lift coefficient, and thus, the associated turbulence is greatest at low speed and high weight, which produced a high angle of attack.

First winglets on commercial aircraft – the B747

Boeing announced a new version of the 747 in October 1985, the 747-400 introduced in 1989, with an extended range and capacity, using a combination of winglets and increased span to carry the additional load. The winglets increased the 747-400's range by 3.5% over the 747-300, which is otherwise aerodynamically identical but has no winglets.

Blended winglets and sharklets reduce fuel consumption and CO2 emission

In 2001, blended winglets were introduced as an option for the Boeing 737-800. The Boeing extensions decrease fuel consumption by 4% for long-range flights and increase range 240 for the 737-800. In 2009 Airbus launched its "Sharklet" blended winglet, designed to enhance the payload-range of its A320 family and reduce fuel burn by up to 4% over longer sectors.] This corresponds to an annual CO2 reduction of 700 tonnes per aircraft. The A320s fitted with Sharklets were to be delivered from 2012.

Improved takeoff and climb performance with raked wingtips

Raked wingtips, where the tip has a greater wing sweep than the rest of the wing, are featured on some Boeing Commercial Airplanes to improve fuel efficiency, takeoff and climb performance. Like winglets, they increase the effective wing aspect ratio and diminish wingtip vortices, decreasing lift-induced drag. In testing by Boeing and NASA, they reduce drag by as much as 5.5%, compared to 3.5% to 4.5% for conventional winglets. Raked wingtips are installed on the Boeing 767-400ER the Boeing 777-200LR/ 300ER/ Freighter, the Boeing 787-8/ 9/ 10, or the Embraer E-jet E2 for example.

Hybrid between wingtip and winglet delivers additional 1.5% fuel savings

The Boeing 737 MAX uses a new type of wingtip device. Resembling a three-way hybrid between a winglet, wingtip fence, and raked wingtip, Boeing claims that this new design should deliver an additional 1.5% improvement in fuel economy over the 10-12% improvement already expected from the 737 MAX.

Next generation: Foldable wingtips

The Boeing 777X will feature 3.5 m (11 ft) folding wingtips. The mechanism was demonstrated for Aviation Week at the Boeing Everett Factory in October 2016. The folding takes 20 seconds to complete and will be on the Boeing 777X planned for summer 2020.

Since several months HYDRO is supporting Boeing in their prototyping of new folding wing and control surface tools for the 777x. We have already started preparing for 777-X EIS in the summer of 2020.
We are also supporting Airbus aircraft with installation and removing tool kits for their aircraft winglets, including e.g. slings. Aircraft include e.g. the A350, A320neo, and A330neo.