why do modern aeroplane wings have a vertical tip?

Question

airliners didn't use to have a vertical tip but now they all do. what does this extra bit do? Is it to reduce turbulence?

Answer 1

The concept of using winglets has been studied since the 1800's and a patent was even filed in 1897 by Frederick Lanchester for what was then called the endplate concept. The drag penalty was found to be too high in cruise to be of any benefit at the time.

In conventional wing design, the cambered upper surface of the wing creates a low pressure or suction effect, while the more flat lower surface creates a higher pressure than the upper surface. The air flowing around these two surfaces remains divided until the wing tip where the airflow from the lower surface gets sucked up and rearward by the low pressure created on the upper surface. It begins to swirl and creates a lot of drag. It's called wingtip vortices, much like a mini-tornado. This effect creates a wake consisting of two counter-rotating cylindrical vortices, called wake turbulence. Flight tests have shown that the vortices from larger aircraft sink at a rate of several hundred feet per minute in calm air about 1000 feet lower and dissipate after several minutes. Trailing aircraft have to be careful not to get too close.

In the 1970s Richard Whitcomb and his team at Langley Research were developing new wing designs called the supercritical wing. Whitcomb coined the term "winglet" to describe the vertical extension of the wingtip. In 1977 design evaluations indicated that the winglet could increase lift by 7 percent and reduce drag by 20 percent at the cruise condition, by somewhat blocking and supressing the wingtip vortices, but they would not provide adequate economic return to airlines for the cost of fabrication.

The first aircraft to fly with winglets was the Burt Rutan designed Vari-Eze in 1974. In 1977, the Lear Model 28 prototype employed the first winglets ever used on a jet and a production aircraft and refered to the new wing as the longhorn. Flight tests showed that winglets increased range by 6.5 percent. In 1985, Boeing announced the 747-400 with winglets, with a 3 percent increase in range.

Answer 2

It reduces wake turbulence yes, but it primarily reduces induced drag (drag due to lift) by reducing the wingtip vortices, which are caused by the high pressure air on the bottom of the wing trying to escape to the low pressure area above the wing.

Winglets (as they are called) perform the same function as an extended length wing, but without adding much for wingspan so the aircraft can still fit in existing hangars and boarding gates. They also increase the wing tip visibility for taxiing and they look cool.

There is no aerodynamic advantage to having winglets compared to an increased wingspan. In fact, winglets add a considerable amount of weight because a huge uranium 235 counterweight has to be installed on the wing leading edge to prevent the winglet from increasing the wing angle (incidence angle) due to it's drag.

The winglet's primary function is to save fuel, which it does, but only a very small amount. I have talked to pilots who have flown the 747-400 with and without winglets and they say there is virtually no difference in fuel burn per trip.

Answer 3

indeed as many have said, they are on the wings to reduce wing vortices's, the effect most noticeable to the naked eye when landing due to dust etc in the ground custom. Interestingly enough, the biggest producers of wake turbulence as it is called are helicopters, they also suffer from the greatest problems from wake turbulence, it's called vortex ring, when the aircraft in in a slow forward speed, high rate of decent and power applied the vortex will increase across the blades and upset the low pressure above the wing/blade and reduce effectiveness until the vortex becomes so great the wing/blade will fail to provide any lift at all, and as such the helicopter fall's out of the sky, in lay mans terms you are chopping you own down wash, thankfully it is taught to all pilots at lesson 7 or 8 of there flying instruction and it is very easy to recover......

I know of one case where an army pilot was testing vortex ring at 7000ft and the air craft was in such a bad state of vorte that the puma had to make an emergency auto rotation to the ground....

Answer 4

The turbulence that other people speak about above is called "wingtip vortices". These little vertical tips, called winglets, help eliminate wingtip vortices. Wingtip vortices add drag onto an airplane, which resists its forward movement. Furthermore, air that is trying to rush from the bottom to the top of the wings at the tips instead strikes the winglets. This adds lift.

So to summarize, winglets add lift and reduce drag. This decreases fuel consumption.

Answer 5

My answer from about 3 weeks ago to the same question:

To prevent Vortexes...

A wing creates lift by creating a lower air pressure over the wing than the pressure under the wing (by making the air move faster over a curve). This difference in pressure causes lift, as the higher pressure wants to get to the lower pressure and equalise it. At the wingtips, the high pressure air can slip around the wingtip and mix with the lower pressure air, creating an air swirl or vortex. this increases the aircraft's drag and hence reduces the aircraft's efficiency, needing more fuel to get to it's destination. Bending the wingtips greatly reduces the ability of the air to form vortexes.

Answer 6

Its reduces the turbulence that the edge of the wing produces as it produces lift.
They are called winglets and they reduces the drag that this turbulence produces, and they make the wing more effective (less fuel consumption)
Regards from Argentina

Answer 7

It's to reduce turbulence. The wing-tip vortices from large aircraft can extend back miles and can be quite strong enough to flip a light aircraft coming in behind.

Answer 8

It reduces turbulence at the wing tips, allowing for better airflow and reduced resistance. This lets the plane be more fuel efficient, and handle easier.

Answer 9

These are called 'Winglets'..This causes reduced drag induced by wingtip vortices. This applies vortex pressure which translates to thrust. A more efficient wing and lift. Actually may save some fuel, less drag....Wingtip vortices are a hazard to following small aircraft also.

Answer 10

According to a documentary I saw on the Airbus A380, it's to reduce turbulent air behind the aircraft so that they can stack and land safely close together at airports.