Questions tagged [flaps]

Surfaces that extend from the wings to increase lift, allowing flight at slower speeds (such as for takeoff and landing).

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14
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6answers
6k views

Why aren't takeoff flaps used all the way up to cruise altitude?

In general aviation aircraft such as Diamond star DA-40, flaps to take-off are used until 500ft AGL and speed before retracting flaps is Vy (best ROC speed)-67kts and after retracting flaps is 80kts. ...
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0answers
18 views

Typical flaps/slats extension chord ratios?

Fowler flaps for example extend the chord of the airfoil by about 25%. So their chord ratio is C'/C = 1.25. Does anyone know similar values for other types of flaps, like double/triple slotted Fowler ...
3
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1answer
277 views

Is all the extra lift from flaps added upstream where the spars sit?

Flaps can significantly increase the lift for a wing, is all that extra lift added upstream where the spars sit? I ask this question because the flaps in airliners seem to be only connected by a few ...
2
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1answer
116 views

Does the A220-300 have krueger flaps or are all of its leading-edge highlift devices slats?

They look like slats to me, but I could be wrong. I'm asking because I know the 737, a very similar airplane, has inboard krueger flaps. Also, what number of slats/krueger flaps does it have?
2
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1answer
179 views

What trailing edge flap design does the A350 use? Is it similar to the A380?

Both Airbuses have similar flap deployment based on some YouTube videos I have watched, just wondering if they both have the same flap design being "Single-Slotted Fowler Flaps".
3
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1answer
131 views

How many Krueger flaps does the 737-700 have?

How many Krueger flaps does the 737-700 have? It has inboard krueger flaps, but I'm trying to make out if it has one or two.
7
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2answers
1k views

What flap design does the A380 use? Is it Fowler flaps, slotted flaps or a combination?

I have looked at maintenance manuals, the Airbus website, and Wikipedia but still could not find a definite answer as to what trailing edge flaps the Airbus A380 uses.
2
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2answers
152 views

What are the approach speeds for each flap setting in a Cessna 152?

I am still trying to understand how the approach speeds for different flap speeds work. I cant find it in the handbook but I want to know the different approach speeds for the following flap settings: ...
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0answers
94 views

How can I design a slotted flap?

I have not been able to find satisfactory methods on design of slotted flaps, or flaps in general. Most of the answers are about eyeballing or experience. Can you guide me on what could be good ...
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0answers
50 views

Comparison between Split and Slotted Flaps

Question 4: As we know, the more complicated design of high lift systems, gives us more maximum lift @ takeoff, such as slotted (single - double) or fowler flaps type. Beside the point of view of ...
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1answer
108 views

Why does the Information Manual say "C172S - Flaps 10 (Preferred) for Normal Takeoff", when the models before S-model do not have this note?

Do Flaps 10 really do anything performance-wise other than reducing ground roll and distance over a 50-foot obstacle? If not worried about clearing an obstacle, does a Flaps UP-normal takeoff make ...
2
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1answer
100 views

Who manufactured the 737 MAX flap track fairings?

I can't seem to find the information online, would anyone of you know where / by who the flap track fairing for the B737 MAX is produced?
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0answers
38 views

Is pitch-flap coupling an aerodynamic effect or an intrinsic property of a delta 3 offset?

I am modelling a propeller, in particularly the equations of motion of the various pitch/lag/flap angles as the propeller is turning around. The blade includes a $\delta_3$ angle, which provides pitch-...
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6answers
2k views

Can flaps be used to perform rotation and flare?

TL; DR using flaps to directly control sink/climb rate near ground = simpler and faster response = easy to fly airplane? Rotating is the pitch up during takeoff that causes the aircraft to leave the ...
2
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2answers
116 views

Is there a cockpit indication if the B737 flap load relief is not working properly?

On a 737, does the pilot get any cockpit indication that his Flap Load Relief is not working properly? Say for instance due to a Flap Lever Position Switch failure?
0
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1answer
519 views

Why does it feel like a plane stops in mid-air during approach?

At some stage while on approach to an airport in a commercial jet, it feels like the plane is almost coming to a complete stop in mid-air. Is this maybe as a result of the flaps engaging or the ...
7
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1answer
343 views

Is it safe to fly if the flaps won't retract on ground?

The Piper Archer (PA-28) i had this morning had issues returning flaps to normal after being fully extended ON THE GROUND. It required a non trivial amount of push on the air-frame itself to restore ...
0
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1answer
115 views

Is flap-asymmetry protection on airliners still active even on the ground?

On aircraft with flaps, a general certification requirement is that it must not be possible for the aircraft to suffer a loss of lateral control secondary to an asymmetric-flap condition. This ...
3
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1answer
164 views

Are overwing exits still useable if the flaps can’t be lowered?

Essentially all narrowbody airliners (except for the very smallest propliners), and many widebodies as well,1 are equipped with one or more overwing exits for use in an emergency evacuation; these ...
18
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1answer
3k views

Why is the DC-9-80 ("MD-80") prohibited from taking off with a flap setting between 13 and 15 degrees?

A bit of digging into the 7Z9363 accident investigation has brought up some interesting information regarding the DC-9-80 ("MD-80")'s flap system: Flaps may be positioned in any of the six ...
5
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1answer
308 views

Why is there an altitude limitation on operating the slats/flaps on the A320?

As per the FCOM limitations chapter there is an altitude limitation of 20000 feet for operating the flaps/slats on the A320? Why this specific altitude?
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1answer
79 views

What is the temperature of flap linkages during takeoff and landing in passenger and fighter aircraft? [closed]

During takeoff and landing, what is the temperature of flap linkages in passenger or fighter jet aircraft?
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0answers
51 views

How can the flap deflect to higher angles (than the wing) without experiencing loss of lift? [duplicate]

For a simple aircraft wing, assume the stall angle of attack of this wing is 16 degrees. Now, if I use the same airfoil as used in the wing for the flaps, I am able to deflect the flap at quite ...
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2answers
289 views

On large aircraft, why do flaperons not run the full length?

This is a 777 flaperon. It looks rather tiny, compared to the flap. There have been air disasters where the airplane rolled uncontrollably for one reason or the other. It seems to me that a larger ...
0
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2answers
158 views

How do airplane designers determine flap deflection angles for flaps of various % wing chords?

How do airplane designers determine flap deflection angles for flap chords of various % wing chords? E.g. flap chord of 30%, 40% or 50% of wing chord. I understand most flaps' chords are about 25% of ...
14
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4answers
5k views

Why not always take off with 10 degree flaps in a Cessna 172?

10 degree flaps increase our lift, reduce stall speed, reduce ground roll. Seems like all advantages with no disadvantages. So why does the Cessna 172 POH say normal take off is 0-10 degree flaps? Why ...
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0answers
125 views

How can a designer deal with a strict requirement when designing an aircraft?

I'm working on designing an aircraft with some specific requirements (Vstall, Vmax, Ceiling, Payload, Range, RoC, Slanding/takeoff etc). I'm following Anderson's and Raymer's ways (trying to find the ...
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1answer
169 views

At which point in scale reduction do slats and flaps become unnecessary?

Imagine some Fi-156 Storch, and reduce its scale down gradually to 10cm span. Let's assume full scale Fiesler Storch is 100% efficient at, for example, minimizing stall speed. During this reduction ...
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5answers
961 views

How does retracting flaps help extend the glide of an aircraft?

As per the video from Smithsonian channel BA flight 38's captain retracted the flaps of the Boeing 777 by 5 degrees to extend glide, to travel further. Why?
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1answer
424 views

Does the flap settings for the best lift/drag ratio change with speed on the Diamond DA20-A?

As I've recently started time building in DA20, I've noticed the AFM suggests flaps at T/O for a glide. Being very intrigued by this I run across this post. Although I appreciate Peter's reply that ...
2
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4answers
2k views

How do slats actually work?

I want to know what is the difference between slats and flaps and the mechanism of the slats This what I know and researched about flaps: Flaps are a kind of high-lift device used to reduce the ...
24
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4answers
5k views

Why are heavy flaps better than just a bigger wing?

Flaps increase lift during landing and T/O. But when retracted, they do nothing. The space needed to stow the common fowler flaps can't be used for anything else - fuel or structure. Extended flaps ...
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4answers
511 views

Why do flaps retract?

Why do flaps retract? I know, it might seem obvious at first, because of drag, but instead of retracting the flaps, can't they just make the flaps flexible enough to get into a reduced drag position, ...
2
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1answer
171 views

Does leading-edge droop increase or decrease lift, other things being equal?

Consider a conventional subsonic airfoil in level flight. Typically it is cambered and with a small positive incidence, both of which features contribute to lift. Now droop the leading edge, as with ...
18
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7answers
2k views

Is lowering V1/VR (and runway length required) the only reason for flaps at take off?

I've read that some aircraft (examples include the Saab 340 and the Fokker 100) can perform flapless take offs, provided there is enough runway available. It's also my understanding that, in terms of ...
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2answers
2k views

A320 flap settings

Can anyone please explain about the 5 types of A320 flap settings - Up, Flap 1, Flap 2 and FULL. What do these mean? I've read that the A320 gives 2 outputs for the corresponding flap settings. What ...
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2answers
811 views

Do MD-11 pilots ever use flaps 50?

I'm curious if there is ever a purpose to use full flaps like that? Was it a bit of an overkill?
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5answers
650 views

Can thrust vectoring be used to enable the use of flaps on tailless delta-winged aircraft?

I'm considering flying wings as well as airplanes with only vertical stabilizer for their compact size, efficiency and high speed. As I can't find a working example of such scheme, theoretical ...
4
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1answer
531 views

Why does lift curve slope increase when Fowler Flaps are deployed?

Below is an image for a Fowler Flap: Notice that as the flap is deployed, both the camber and the area increase. This change in wing shape modifies the lift curve as follows: (source: Development of ...
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1answer
132 views

What does the lift coefficient take into consideration for flaps?

Angle of attack increases lift for two reasons, Camber and increased flow deflection, What reason does the lift coefficient use? Both?
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1answer
5k views

What is the difference between an aileron and a flap?

I have already been searching Google for the difference between an aileron and a flap, but I am not much satisfied, so now I am asking here on SE. What is the difference between an aileron and flap? ...
5
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1answer
563 views

Why do Boeing planes have more flap settings than Airbus planes? [duplicate]

The Boeing 737 and Airbus A320 are similar in size and performance. They are direct competitors. Boeing seems to have eight flap settings (1, 2, 5, 10, 15, 25, 30, 40) whereas Airbus seems to have ...
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2answers
3k views

What does "speed checked" mean?

Here is a Scenario: PF: Flaps one. PM: Speed Checked, Flaps one. What does that mean and why do they have to say "speed checked" every time?
3
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1answer
233 views

Does deploying flap change the aspect ratio of the wing?

Specifically when a Plain flap is defleted the geometry of the wing will be altered (Camber is increased). Does this have any effect on aspect ratio? What's the connection between Camber and aspect ...
11
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2answers
5k views

Why are Krueger flaps called flaps and not slats?

I always thought that flaps are trailing edge high lift devices and slats are leading edge high lift devices. This is also confirmed by the accepted answer for What is the difference between flaps and ...
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2answers
2k views

Is it right to extend flaps only in the white arc?

If the cruise speed is >80kts on the downwind leg but I can only extend flaps in the white arc, am I right in saying I need to get to the white arc, even if I'm on - for example - 100kts? For ...
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8answers
2k views

Could flaps be raised upward to serve as spoilers / lift dumpers?

I should preface that I'm by no means an aviation person. I'm just in a aircraft knowledge obsession phase and daydreaming about designing my own ultralight (will never happen). The idea would be to ...
2
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1answer
462 views

How beneficial are flaps when landing with a tailwind?

I understand that flaps are devices used to increase the amount of lift and drag. When landing with a tailwind your groundspeed will be higher. Therefore, flaps would help reduce this groundspeed, ...
11
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3answers
1k views

How does the A350 variable camber system decrease drag?

Just curious how the A350 reduces drag/fuel burn by extending the flaps ever so slightly during cruise. Everything I've read about extending flaps says that extending them pushes the centre of ...
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1answer
348 views

What is this loose object above the flap fairing? [duplicate]

During my flight, I noticed a loose object above one of the flap fairings. You can see it in this video: https://imgur.com/wCPSEem. Is it normal or should I notify the airline? People pointed out to ...