What is the use of flaps during landing?

Question

well, i have noticed that everytime before landing,the pilot will put down flaps from the wings and the surface area of the wing will be enlarged, but what is the purpose of using the flaps?

Answer 1

Flaps reduce the stalling speed by increasing the camber of the wing and thereby increasing the maximum lift coefficient.

Answer 2

The flaps help you to slow down for landing or deciding. Later

Answer 3

to add drag at landing and lift at take off.

Answer 4

Flaps increase the lift that the wing is producing and lower the stall speed.  In larger airplanes there are usually Slats and sometimes Krueger Flaps on the leading edge of the wing to do the same thing.  

Flaps do not always add surface area to a wing.  Sometimes they simply change the shape of the wing to add more lift.

Along with lift comes extra drag.  This is why airplanes have flaps.  Greater lift at a slower speed during the takeoff and landing phase, then a clean wing with less drag for higher climb and cruise speeds.

Take a look at the link to flaps in the sources to see examples.

Also look at Bernoulli's Principle.  That will show you how a wing gets lift.  Look under Real World Application for the aircraft example.

Answer 5

Flaps create more drag so the plane lands at a certain speed in order for it to not over speed.

Answer 6

Flaps are the most common high-lift devices used on

practically all airplanes. These surfaces, which are

attached to the trailing edge of the wing, increase both

lift and induced drag for any given angle of attack.

Flaps allow a compromise between high cruising speed

and low landing speed, because they may be extended

when needed, and retracted into the wing’s structure

when not needed. There are four common types

of flaps: plain, split, slotted, and Fowler flaps.

The plain flap is the simplest of the four types. It

increases the airfoil camber, resulting in a significant

increase in the coefficient of lift at a given angle of

attack. At the same time, it greatly increases drag and

moves the center of pressure aft on the airfoil, resulting

in a nose-down pitching moment.

The split flap is deflected from the lower surface of the

airfoil and produces a slightly greater increase in lift

than does the plain flap. However, more drag is created

because of the turbulent air pattern produced behind

the airfoil. When fully extended, both plain and split

flaps produce high drag with little additional lift.

The most popular flap on airplanes today is the slotted

flap. Variations of this design are used for small

airplanes as well as for large ones. Slotted flaps

increase the lift coefficient significantly more than

plain or spilt flaps. On small airplanes, the hinge is

located below the lower surface of the flap, and when

the flap is lowered, it forms a duct between the flap

well in the wing and the leading edge of the flap.

When the slotted flap is lowered, high-energy air from

the lower surface is ducted to the flap’s upper surface.

The high-energy air from the slot accelerates the upper

surface boundary layer and delays airflow separation,

providing a higher coefficient of lift. Thus, the slotted

flap produces much greater increases in CLmax than the

plain or split flap. While there are many types of

slotted flaps, large airplanes often have double- and even

triple-slotted flaps. These allow the maximum increase in

drag without the airflow over the flaps separating and

destroying the lift they produce.

Fowler flaps are a type of slotted flap. This flap design

not only changes the camber of the wing, it also

increases the wing area. Instead of rotating down on a

hinge, it slides backwards on tracks. In the first portion

of its extension, it increases the drag very little, but

increases the lift a great deal as it increases both the

area and camber. As the extension continues, the flap

deflects downward, and during the last portion of its

travel, it increases the drag with little additional

increase in lift.

Answer 7

Up to a point, they increase lift.  After that, they increase drag.  They are also used on takeoff (at a minimum deflection) to add lift.

There are times when I use them, and times when it's best not to use them.  The stronger the crosswind component, the less flaps you would use.

Answer 8

You answered your own question.  it increases the surface area and because they go downward the profile increases lift.  The other part of the equation is you can only buy lift at the cost of drag.  Slow speed is nicer for landing.  

I'm impressed you have a better answer in your question than the impressio's that tried to snow you.

Answer 9

The simple answer: Flaps allow the plane to descend at a steeper angle without gaining as much airspeed as they would without flaps.

Flaps add lift and drag. The additional drag slows you down directly, and the additional lift means that you can stay in the air at a lower speed.

Answer 10

The flaps help increase lift at slower speeds which helps reduce the stall speed and also helps slow the plane down.  When you put the flaps out it increases the surface area of the wing and creates more lift.  At the same time it also creates more drag shich slows the aircraft down.  If you notice they also put the flaps out during take off.  It is not as much flap as landing flaps, but it is the same idea.  An aircraft with that much weight needs a little extra help on take off.  Even some some small planes such as a Mooney use take off flaps since it has such a thin wing.

Answer 11

To increase lift at slower speeds so the plane can be stable. Thats all, flaps increase as speed decreases. Obviously there is a limit though, because in order for flaps to work, air must be moving over and under them at a very high speed.

Answer 12

They increase lift at low speeds, thus reducing the stall speed, and allowing the plane to land safely at lower speeds.