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flaps

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if flaps give you lift why do you need them if you want to come down? can you land without flaps? how do you know when to set flaps? when landing do you have to fully retract flaps?

Pro Member Chief Captain
pilotwannabe Chief Captain

1. Flaps give you greater lift at lower speeds so they are used on landing so the aircraft can slow down without stalling.

2. I don't think there is any set speed for deploying flaps, there are limits however on which speed you cannot set flaps. I just generally deploy them when I am slowing down and feel the nose tilting up slightly.

3. You dont have to fully deploy flaps on landing. On the 737 for example, most pilots will only use 30 degress of flaps when 40 degrees is available. Deploy them according to how the aircraft is performing is the best advise I can give.

I hope that helps Wink

Pro Member Chief Captain
Jonathan (99jolegg) Chief Captain

Anonymous wrote:

if flaps give you lift why do you need them if you want to come down? can you land without flaps? how do you know when to set flaps? when landing do you have to fully retract flaps?

Flaps do provide lift. The reason you use flaps on approach is because it is velocity combined with the effect of the wings that create lift. For example, if you travel at 90KIAS in a large jet engine aircraft, there isn't sufficient velocity to render the wings effective. Travel at 150KIAS and yes, there is enough velocity to allow the wings to produce enough lift, thus an aircraft takes off.

Imagine an approach of an aircraft, where flaps are not used. As stated above, a certain amount of velocity is needed to render the wings effective in creating lift, so a determined speed is arranged where if the aircraft falls below this on approach, little lift will be made and the aircraft will crash. Generally, this speed will be fairly high, similar to take off speed. A higher speed (to maintain lift) on approach means a higher speed on landing, which means if something goes wrong, there is more chance of a problem being a major problem at high speed. In short, a slower landing speed is safer.

Flaps, however, extend the surface area of the wing. This means that at the same speed of around 150KIAS a lot more lift is produced, so if an aircrafts speed falls below a high speed, enough lift is still maintained. This is how aircraft are able to fly on approach at speeds of around 130KIAS.

Basically, flaps extend the surface area of the wing which allows an aircraft to fly at similar speeds without a marked reduction in lift.

Yes you can land without flaps (especially in small GA aircraft) but you place more pressure on the gear and tyres as well as making the landing slightly unsafe, in a jet aircraft. Flaps are there for a reason and are always used (to some extent).

The flap extension speeds can be found in the kneeboard under the references section.

When landing, you retract the flaps fully because they are no longer needed.

Hope that answers your questions Wink

Pro Member Chief Captain
Jonathan (99jolegg) Chief Captain

Oops! I was too slow PW Embarassed

Wink

Pro Member Chief Captain
pilotwannabe Chief Captain

99jolegg wrote:

Oops! I was too slow PW Embarassed

Wink

Yes but your explanation is soooo much better than mine Embarassed Wink

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