why is it necessary for the flaps under the airplane wing to give more drag, when an airplane lands?

Answer 1

it increases the lift at lower speeds so they can land slower

Answer 2

Flaps can also be used as an air brake if they are of the very large variety and are used in an extended at severe angles. When flaps are used in the extended mode of between 5 to 25 degrees they give the aircraft two aids for safe flight: 1) Increased lift at a slower airspeed without a significant increase in drag, and 2) They help induce a form of wash-out to the wing. This is seen in the center or inboard portion of the wing now has a relatively higher angle of attack in comparison with the section of the wings where the ailerons are. This feature helps prevent snap rolls at slow airspeeds.

An example:
An airplane that lands at 50 knots with full flaps selected may have a landing speed as fast as 70 knots with flaps up. If a swerve occurs during the landing roll, the centrifugal force unleashed at 70 knots is twice what it would be at 50 knots, since centrifugal force increases as the square of the speed. It follows then, that a slower landing speed reduces the potential for loss of control during the landing roll. It also means less strain on the tires, brakes and landing gear and reduces fatigue on the airframe structure.

Answer 3

While the flaps do add drag to the airplane, their primary function is to increase the lift of the wing so the airplane can land at a lower speed. Low landing speed is always a nice thing.

Flaps increase the lift coefficient of the wing, which is basically the factor that determines how well the wing works. A higher lift coefficient means that less air has to go over the wing to produce the same lift as one of less coefficient. That means the airplane can fly slower without stalling.

Answer 4

you are all incorrect, flaps increase lift and drag, by increasing the wing camber or curvature of the wing, some flaps also increase wing area. As a rule of thumb you can expect the first 50% of flap deployment to increase lift while the drag penalty will be minimal, the other 50% will increase more drag than lift. This is why on takeoff, flaps are only set to 5 to 15 degrees depending on the aircraft (large aircraft only).

the primary purpose of flaps is to decrease the stall speed (to fly slower) and increase the rate of descent without increase in airspeed on landings, and decrease the runway length required for takeoff by increasing lift.

there are 4 types of flaps here is the list on order of complexity:

plain, split, slotted, and Fowler. the latter is the only one that causes an increase in wing area.

ive been talking about trailing edge flaps only, theres also leading edge flaps......

to answer your question the drag is needed to:
1. slow the aircraft down to a managable airspeed, so that the aircraft will be able to land on most runways, if airplanes didnt have flaps you would need much longer runways.

2. for jet aircraft the drag also is used so that the engines can run at high RPM, turbine engines in nature do not do well at low RPM (unlike their piston counterparts) and take a while to spool up, this would be hazardous at low altitudes.

im assuming youre talking about commercial jets, but for the most part the theory is the same small or large...

Answer 5

The purpose of flaps is not to increase drag, but to increase lift and decrease stall speed.

Flaps increase the amount of lift produced by the airfoil as well as decrease the stall speed of the wing. This combines to allow the aircraft to land slower than if the flaps were not deployed. Immediately after landing, pilots will retract the flaps of certain aircraft in order to have more of the aircrafts weight on the wheels to aid in braking.

Some aircraft will take off with flaps partially deployed to increase lift, shorten the takeoff roll and decrease the chance of a low altitude wing stall.

The landing gear WILL NOT be ripped off if an aircraft lands with no flaps. Pilots often practice no-flap (flaps not deployed) landings. I have made several no-flap landings in excess of 120 knots, and at no time were the gear in danger of being ripped off.

In fact, even if the aircraft does too fast through the air with the landing gear down, they will not be ripped off, just damaged.

Answer 6

It is NOT necessary, the extra drag is just the consequence of the added lift, as the flap deflected wing has a higher induced drag component, since it is not as well adapted to optimal lift/drag ratio (the wing is optimized for optimal lift/drag ratio in cruise configuration).
If flaps would add lift without additional drag, that would actually be better, as flaps are used at takeoff although usually at more modest defelction angle, where you want the drag to be as little as possible to allow faster acceleration, while drag can always be provided by spoilers anyway when needed at landing or for rejected takeoff. Lower drag would also be useful in case of rejected landings and missed approaches, when the plane has to pick up speed and altitude to go around, without the possibility of retracting the flaps to a lower setting.

Answer 7

Wing flaps increase the camber , or curvature, of the wing,which increases the lift coefficient allowing slower landing speeds. A byproduct of increasing the lift coefficient is increased
drag during approach, not necessarily unwelcome since that allows easier speed control.

Answer 8

Bubba is right. it is not for to increase the drag. It is for when landing it gives a stable mode. the plane has to land with the rear gear first. but the nose gear shoudnt be really high. it make the nose gear almost equal to the rear gear so when they land they can start to land they will have almost 1 whole of the run way to travel and press on the brake.

Answer 9

............ flaps are designed to increase the area of wing to produce more lift ............ but at the same time it produces more drag also ..... but this is overlooked for landing flaps as it is more important to reduce speed of the plane than worry about drag ........... and after touch down spoilers come into play ....... they are on top of the wing ....... the come up and kill the lift on top of the wing .... thus increasing positive ground contact of the landing gear with efficient traction and braking on runway ........... thus stopping the aircraft ....

Answer 10

I like Bubba's answer. Just like to add that it also allows for a steeper decent without increasing the airspeed. Helps keep the neighbors who purchased a home on final approach from complaining.