The wings of modern planes are now bent at the tips. Does anyone know why?

Question

It never used to be the case, but all Virgin and Jetstar planes now have bent wing tips.

Answer 1

Whenever lift is created, there is a high pressure zone under the wing and a low pressure zone above the wing.

Remenber, air always wants to travel from high pressure to low pressure.

Air at the wingtips will attempt to spiral around the edge to reach the low pressure and as a result, some of this lift is destroyed as the pressure is being equalized.

When there's less lift, the airplane has to fly at a higher angle of attack, which means the wing meets the incoming air at an greater angle than straight-on, and this increases drag.

The wingtips help stop this airflow from going around the wing and destroying this lift.

Answer 2

They're called winglets, and they help with fuel efficiency.  

Answer 3

Helps with drag, increases fuel economy.  

Answer 4

I dont think anyone knows why they are like that. I think it's a manufacturing mistake.

Answer 5

Those are called winglets.  They reduce the magnitude of vortices at the wingtips, which reduces drag, which reduces fuel consumption by 5% or so.  They are added to aircraft to help them use less fuel, making them more economical to operate.

Answer 6

They also increase lift.

Answer 7

Winglets are vertical extensions of wingtips that improve an aircraft's fuel efficiency and cruising range. Designed as small airfoils, winglets reduce the aerodynamic drag associated with vortices that develop at the wingtips as the airplane moves through the air. By reducing wingtip drag, fuel consumption goes down and range is extended.

Aircraft of all types and sizes are flying with winglets -- from single-seat hang gliders and ultralights to global jumbo jets. Some aircraft are designed and manufactured with sleek upturned winglets that blend smoothly into the outer wing sections. Add-on winglets are also custom made for many types of aircraft.

The concept of winglets originated with a British aerodynamicist in the late 1800s, but the idea remained on the drawing board until rekindled in the early 1970s by Dr. Richard Whitcomb when the price of aviation fuel started spiraling upward.

Whitcomb, a noted aeronautical engineer at the NASA Langley Research Center, refined the winglet concept with wind tunnel tests and computer studies. He then predicted that transport-size aircraft with winglets would realize improved cruising efficiencies of between 6% and 9%. A winglet flight test program at the NASA Dryden Flight Research Center in 1979-80 validated Whitcomb's research when the test aircraft -- a military version of the Boeing 707 jetliner -- recorded an increased fuel mileage rate of 6.5%.

Since the 1970s, when the price of aviation fuel began spiraling upward, airlines and aircraft manufacturers have looked at many ways to improve the operating efficiency of their aircraft. Winglets have become one of the industry's most visible fuel-saving technologies and their use continues to expand.

Winglets increase an aircraft's operating efficiency by reducing what is called induced drag at the tips of the wings. An aircraft's wing is shaped to generate negative pressure on the upper surface and positive pressure on the lower surface as the aircraft moves forward. This unequal pressure creates lift across the upper surface and the aircraft is able to leave the ground and fly.

Unequal pressure, however, also causes air at each wingtip to flow outward along the lower surface, around the tip, and inboard along the upper surface producing a whirlwind of air called a wingtip vortex. The effect of these vortices is increased drag and reduced lift that results in less flight efficiency and higher fuel costs.

Winglets, which are airfoils operating just like a sailboat tacking upwind, produce a forward thrust inside the circulation field of the vortices and reduce their strength. Weaker vortices mean less drag at the wingtips and lift is restored. Improved wing efficiency translates to more payload, reduced fuel consumption, and a longer cruising range that can allow an air carrier to expand routes and destinations.

To produce as much forward thrust as possible, the winglet's airfoil is designed with the same attention as the airfoil of the wings themselves. Performance improvements generated by winglets, however, depend on factors such as the basic design of the aircraft, engine efficiency, and even the weather in which an aircraft is operating.

The shapes and sizes of winglets, and the angles at which they are mounted with respect to the main wings, differ between the many types and sizes of aircraft produced but they all represent improved efficiency. Throughout the aviation industry, winglets are responsible for increased mileage rates of as much as 7%.

Aircraft manufacturers and makers of add-on winglets have also reported improved cruising speeds, time-to-climb rates, and higher operating altitudes.

The use of winglets throughout the aviation industry in the U.S. and overseas is constantly growing. Winglets now appear on powerless hang gliders soaring above mountain ridges and from seaside cliffs. Sailplane builders around the world have included blended winglets to their designs and the sleek, graceful gliders are silently soaring farther than ever Corporate-size Learjet's were the first commercial aircraft to use winglets. Now, several decades later, winglets are incorporated into the designs of many other business jets such as Gulfstreams and the Global Express: a new aircraft built by Lear's parent company, Bombardier.

Retrofitting winglets to existing business jets is also a fast-growing market within the aviation industry itself. Many winglet marketing firms report their products help increase aircraft roll rates and lower approach and takeoff speeds.

Answer 8

I reduces the wing tip vortexes, enhancing both safety related to those, as well as improving fuel economy. It is a relatively recent innovation and costs extra to put on the aircraft. Only a few airlines have actually installed them across their fleets because of the cost.

Answer 9

Winglets increase the wing's effective span, without increasing the actual span.  They also improve fuel efficiency and stability.

Answer 10

The winglets reduce drag thus making the aircraft more efficient and are quieter (perhaps also due to the newer engines on the newer wings)