Why are the ends (tips) of some airplane wings pointed up?

Question

Why are the ends (tips) of some airplane wings pointed up?

Answer 1

those tips save airlines millions of dollars in fuel. they have installed  them on some older planes to help them in fuel savings as well....

Answer 2

the answer has something to do with aerodynamics.maybe the answer needs complex math to describe properly.  my guess is for lateral stability, also probably the tips of wings is where there can be turbulent air coming off of them and these wings help sort that out for a more streamline cut through the air typed thing rather than making "whirlpool" type things like you can make with a paddle in the water except in the air.

Answer 3

They are called Winglets:

http://www.nasa.gov/centers/dryden/image...

Winglets are one of the most successful examples of a NASA aeronautical innovation being utilized around the world on all types of aircraft

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%.

The Benefits of Winglets

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.

Answer 4

If the tips of the wings are down if reduces the airspeed but when the are up it help the plane get more speed

Answer 5

Yea....what Cherokeeflyer_redux said.

Answer 6

to decrease wingtip vortex gereration.

Answer 7

aerospace speaking, the design helps to keep the aircraft aloft, saving more fuel...

Answer 8

They're called "Winglets" they help to stabalize the aircraft and reduce drag and even cut fuel costs, the wings without winglets produce a vortex so dangerous that if another plane flies through it it can actually bring the plane down, however winglets help reduce the vortex

Answer 9

Primarily as a fuel-saving measure...

When lift is generated, there is higher pressure air flowing under the wing than over - so the higher pressure air naturally endeavours to move "up" to equalise the pressure - lifting the wing at the same time.

This works fine except for at the tip where air beneath can move up and over the end of the wing - reducing the lift effect there and requiring more engine power to overcome the lost lift (hence, more fuel used.)

If a curved wingtip is installed, this effect is eliminated - air cannot come up and over, as it is stopped by the wingtip!

Also, the flat wingtip generates spirals of air called vortices behind - these are a form of drag on the plane. A curved wingtip basically heads off the vortices and reduces the drag.

Answer 10

These things are called "splates", - they slow down the flow of air off the tips of the wings, which makes the plane more stable, more easily controlled at all speeds. For some reason, - depending on the shape of wing and other factors, they actually make the plane fly a little faster and therefore more fuel efficient!

There are also wing tips thart curve down, (generally 2 feet or less), - they make the wings look "drooppy".  These also control flow outward from wing tips, increasing the "ground effect" (which is sort of squeezing air underneath wing when closer to the ground than the length of the wings).  This makes the airplane land slower, slow down quicker (from "drag of air" )and makes the airplane become airborne quicker also!  This is called STOL equipment (short take off and landing).   Years ago when I worked for a Piper dealer we had a Catholic Doctor that had a Cherokee with the droopy wingtips, we called it the "Flying Nun"  (you have to be older to know what that is about)!

Answer 11

aeordyanamics and all that stuff, by cutting the air i think it reduces drag, I'm not too sure th0ough