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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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2
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4answers
254 views

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

I'm considering flying wings as well as airplanes with only vertical stabilizer. As I can't find a working example of such scheme, theoretical explanation is very welcome. To compensate for rear end ...
2
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1answer
54 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 ...
0
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1answer
30 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?
0
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1answer
113 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
192 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 ...
7
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2answers
2k 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
61 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
877 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 ...
6
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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 ...
13
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7answers
1k 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
130 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
595 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 ...
1
vote
1answer
293 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 ...
2
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1answer
169 views

Would adding a slat and a slotted flap increase the max CL of a multi element airfoil to 6.5?

Would adding a slat and a slotted flap increase the of a multi element foil to 6.5? I understand, as a general rule, the max $C_L$ for a classic NACA airfoil is as follows: Base: 1.5 Slat: + 0.7 ...
16
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1answer
3k views

What happens to Cessna electric flaps that are moving when power is lost?

On final in a C182T you move the flap control arm from 20 to FULL, and when halfway there, the breaker pops (or BUS1 fails, a wire falls off, etc.) Does the flap stay where it is, slide back to 20°, ...
17
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2answers
3k views

What is the reason for setting flaps 1 on the ground at high temperatures?

Yesterday I've seen an A320 standing at the gate with flaps 1. While this question answers, why the flaps should be up, is there any reason to retract the flaps to 1 instead of up? In addition it ...
5
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2answers
750 views

Why doesn't extending the flaps on a B-2 send it into an uncontrollable dive?

The Northrop-Grumman B-2, a tailless-flying-delta-wing aircraft, has a set of flaps along its trailing edge, as seen (for instance) in this cutaway diagram: (Image from Funker530.) But tailless ...
-1
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2answers
84 views

Are flaps a good idea for airfoils with a lot of camber?

I have a wing with an airfoil s1223 which is an airfoil with a lot of camber. the take off distance is limited so I want to implement flaps for this issue but I have the doubt if this is a good idea.
0
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1answer
286 views

Why does the DHC-6 pitch down when the flaps are retracted, rather than up?

Air Moorea Flight 1121 crashed because one of its elevator cables broke immediately after the pilot retracted the flaps, but before he could trim out the resulting pitch-down moment - to quote the ...
1
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1answer
165 views

What is the name for a flap that increases the wing's area but not its camber?

Flaps are high-lift devices mounted to the rear portion of an aircraft's wing. Some types of flaps increase lift by increasing the wing's camber, or, at least, that of its lower surface (plain flaps, ...
4
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4answers
281 views

Could flaps replace spoilers by deflecting more than 90°?

Could flaps replace spoilers by deflecting more than 90° after touchdown?
6
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1answer
439 views

Why does the A320’s maximum allowable aileron deflection decrease, rather than increase, when the flaps are extended?

According to this answer to why the A320 uses mainly spoilerons for roll control during landing, rather than conventional ailerons, the ailerons can’t extend as far when the flaps are extended, for ...
1
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1answer
413 views

Is it normal procedure to lower flaps at high altitudes?

I was flying on a Boeing 747-800 today and the pilot opened up flaps at high altitude. This caused sharp descend for about 5 seconds ( Causing slight panic onboard ) , the pilot leveled the flaps ...
9
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1answer
534 views

What are possible causes for the flaps not deploying on a Cessna 172?

I would like to seek some expert opinion on why my flaps failed to deploy when I took it to Flaps 20. I was turning from Downwind to Base when I took flaps 20 and noticed that my speed was creeping ...
4
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2answers
757 views

What is this unusual leading edge flap on a B737-200?

On this video of Air North's gravel runway-equipped B737-200, there's what appears to be a small leading-edge flap (Krueger flap?) inboard of the engine. Refer to the screen shot below. What is this?...
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2answers
270 views

What flaps and throttle settings are used on takeoff, climb, cruise, descent, and landing? [closed]

What degree of flaps and throttle setting are used on takeoff, climb, cruise, descent, and landing? This question is for private and general aviation aircraft. I have looked everywhere for FAA manuals ...
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2answers
139 views

What backup systems are in place for flaps actuated by sliding block guides?

Looking at this video of a 737's flap extension, it looks like there is just one screw per side driving all of the flaps. Are there any systems in place that will allow the flaps to extend in the ...
16
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3answers
4k views

To flap or not to flap?

I am learning to fly an Ikarus-C42. The instructor I have recommends to all students that they land without flaps, because it is less to think about and because it gives you more airspeed, thus less ...
4
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1answer
491 views

Which photo more accurately represents Flaps 1 in a 737-800?

or A recent update in a sim craft changed the visuals from what I'm used to, but from my research it looks to be more realistic. This post clearly reflects the more extended option being more ...
2
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4answers
759 views

How does setting takeoff flaps improve aircraft performance?

A study guide I recently found indicates that Vmc and aircraft performance improve with takeoff flaps set. The Vmc improvement makes sense but the performance improvement does not. At a basic level, ...
3
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3answers
1k views

What does the extending the flaps do (or any high lift device) to the Rate-Of-Descent of an airplane?

I know that deploying flaps will increase both drag and lift, thus increasing L/D ratio. But how exactly does that correlate with the increase/decrease of the rate-of-descent?
0
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1answer
172 views

Is using flaps the same as increasing the AOA? [duplicate]

The purpose of trailing edge flaps is to give the aircraft more lift at lower speeds. But do simple flaps beneficent more than increasing the angle of attack? The image looks like part of the wing ...
1
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2answers
161 views

Why flaps can deflect up to 25°+ without stalling the wings? [duplicate]

According to this graph,plain flaps have their highest Cl at about 2 and stalls at about 15°,my question is how then do airplane flaps reach 25°+ of delflection when this gragh clearly states that ...
3
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2answers
117 views

Is the lift produced by a wing with a 10° flap equal to the lift created by a wing with 10° AOA but with no flap?

After reading this article I would like to know if the lift produced by a wing with a 10° flap is equal to the lift created by a wing with 10° AOA but with no flap?
3
votes
1answer
893 views

Where is the F-4 Phantom II's flap lever?

I'm trying to fly this fighter for the first time in X-Plane 11 but I can't seem to find the flap lever in the cockpit. Where is it on the real plane?
3
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2answers
580 views

Why is the critical AoA of most flaps 40° when most airfoils stall at 15°?

A plain flap deflected 40 degrees is largely stalled (...) Flaps stall at 40° according to an answer on Quora, why is this so when typical airfoils stall at 15°?
25
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2answers
7k views

Why didn't the Concorde have flaps or slats?

It's well known that the Concorde had no flaps or slats. The lack of high-lift devices considerably reduced lift at low speeds, requiring the Concorde to take off and land at higher speeds and angles ...
-1
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4answers
694 views

Why would an aircraft do multiple runway laps before takeoff?

During a recent Ryanair, Boeing 737 flight, the aircraft went up and down the runway several times before takeoff, whilst modifying the flaps. Why would this have been? Usually, I thought flaps and ...
1
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0answers
295 views

Why are Leading Edge Flaps (LEFs) create lift while down at slow speeds but decrease lift while down at higher speeds?

When taking off or landing, both LEFs and trailing edge flaps (TEFs) for fighter aircraft are in the down position to provide more lift. However, when flying around at higher speeds (let's say 500-600 ...
3
votes
1answer
184 views

How are flaps sized in order to give necessary delta CLmax? [duplicate]

Given an airfoil and wing planform, what is the process to find the flap size and deflection necessary to give a certain change in CLmax? Flaps are usually sized as a percentage of the chord, with 0....
4
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2answers
195 views

How do partial- and full flaps compare for gusty approaches?

From an aerodynamic aspect, how do partial flaps and full flaps compare for gusty approaches?
6
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1answer
2k views

How is the area of flaps determined?

While may be possible to look up the dimensions of high lift devices in an aicraft's documentation, there is no information on what the underlying design choices are. Using Wikipedia, I found out ...
0
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1answer
472 views

What is the optimum speed for takeoff flaps?

I took a 737 rating written test yesterday and one of the questions was: What's the optimum speed for takeoff flaps? V2 V2 + 10 V2 + 15 V2 + 20 Anybody knows the answer? I did some research and ...
2
votes
1answer
773 views

Which flap is better suited? Split or Plain?

I’m considering which flap to build onto a home built aircraft, but not exactly sure which flap would best fit the aircraft and which one would be more beneficial. The aircraft has a fighterlike look ...
4
votes
2answers
1k views

Does extension of flaps 1, 2, 5 or 10 increase descent rates?

Let's say you need greater descent rates than you can get with the full use of the speed brake in an airliner. Does it help to use the above flap positions in getting greater descent rates?
12
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2answers
6k views

Why does stall speed decrease when flaps are deployed?

I've been told that deploying the flaps on approach enables the following: Potentially steeper approach Slows down the plane Lower stall speed It's the last one that confuses me. Given the equation ...
4
votes
1answer
396 views

What are the benefits of using thick trailing edge flaps?

I had been reading in numerous articles (see this answer and this one) that there are advantages of using thick trailing edge flaps. In these articles it kept on coming up that Airbus uses thick ...
7
votes
1answer
2k views

Why is deploying speed brakes not recommended with the flaps extended?

I read this in the normal procedures section of the A320 FCOM. Why is it so? When the speed brakes are deployed, extending the flaps beyond FLAPS 1 may induce a slight roll movement, and in calm ...
12
votes
3answers
2k views

When does a 'flaps/slats misconfiguration' warning sound during takeoff roll?

If a flight crew begins their takeoff roll and don't have slats and flaps configured properly, when does the system know when to sound the alarm? If it actually sounds during the roll itself, that ...
7
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1answer
217 views

What operations during preflight and pre-takeoff engine run-up cause a change in engine rpm?

In a Cessna 182, during certain preflight check procedures with the engine running, RPM drops. What are these procedures and why does rpm change?