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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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2answers
63 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
107 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 ...
0
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1answer
104 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, ...
3
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4answers
208 views

Could flaps replace spoilers by deflecting more than 90°?

Could flaps replace spoilers by deflecting more than 90° after touchdown?
4
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1answer
115 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 ...
0
votes
1answer
191 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 ...
5
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1answer
200 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
votes
2answers
423 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?...
2
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2answers
101 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 ...
1
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2answers
100 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
votes
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
votes
1answer
374 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
293 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, ...
2
votes
3answers
307 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
votes
1answer
122 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
vote
2answers
139 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
114 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
735 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
422 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°?
23
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2answers
6k 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
656 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
vote
0answers
200 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
100 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
177 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
votes
1answer
985 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
300 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
439 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
938 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?
10
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2answers
4k 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
272 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
1k 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
votes
1answer
195 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?
4
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2answers
652 views

What kind of flaps are used in gliders?

I'm estimating some wing parameters for an imaginary airplane (simple college project). We are allowed to use coefficients for any basic types of flaps (plain/split/slotted/Fowler etc), but since I'm ...
6
votes
3answers
498 views

What is the purpose of extending one degree of flaps (perhaps with spoilers)?

What would be the use of one degree of flaps? And is there any reason to use both flaps and spoilers combined?
12
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2answers
1k views

Why were the 747SP's trailing-edge flaps so much different than those of the -100/-200?

I read several decades ago about how the 747SP's trailing edge flaps were substantially redesigned from those of the "original" 747-100/-200s. The images on the 747SP Wikipedia page clearly show what ...
13
votes
3answers
916 views

Why are the outboard Krueger Flaps retracted before the others on the B747?

In this video, I noticed that the outboard Krueger Flaps on this Boeing 747 were retracted while the middle and inner sets remained extended (refer to 3:22 - 3:30 in the video). My questions are: ...
4
votes
1answer
162 views

How does the extension of inboard flaps raise the effective critical angle of attack of the outer wing?

I raised a question about this on this post in the comment section and was suggested by Peter Kämpf to create a new question. So here it goes: How does the extension of inboard flaps raise the ...
3
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0answers
876 views

Does the extension of trailing edge flaps increase or decrease the critical angle of attack?

Which graph is the correct representation of the trailing edge flaps' effect on the critical angle of attack? Does their extension increase (as depicted on the first graph) or decrease (as depicted on ...
3
votes
2answers
502 views

How does the flap configuration affect the tailstrike limit?

The configuration that provides the maximum FLEX temperature varies with the runway length. On short runways, CONF 3 usually provides the highest FLEX temperature, and the tail clearance at lift off ...
14
votes
2answers
1k views

Do modern airliners have a flaps warning indication?

Years ago I was on a flight from San Francisco to Los Angeles, a 737 if I remember rightly, and was sitting just behind the wings and could not help noticing the flaps were partly extended for the ...
14
votes
3answers
2k views

Is it normal practice to use 25 degrees of flaps when taking off at max weight in a PA-28-181?

I recently started renting a plane (PA-28-181) from a new flight school and had to get checked out before I had the "OK" to rent. I had brought 2 family members ...
8
votes
2answers
2k views

How are flaps controlled?

I can understand what function(s) the flaps serve, but how are they controlled from an internal perspective? Does flipping the switch send signals to an electrical servo? Or is it hydraulics? How are ...
9
votes
1answer
807 views

How do the uninterrupted and interrupted flaps compare?

(wikimedia.org) Airbus A350. There aren't many wide-bodies out there. Whether it's Douglas, Boeing, or Ilyushin, they all have the high-speed aileron interrupting the flaps. Whereas Airbus uses ...
3
votes
1answer
2k views

Is the A320 family allowed to take off with the flaps retracted?

Is it legal for the A320 family (A318, A319, A320 and A321) to take off without flaps? An answer to this question states that the A300 can take off without flaps. On the other hand, the 737 family of ...
7
votes
2answers
788 views

Could an aircraft like a Boeing 777 take off with flaps fully deployed?

I have wondered this for years. Could an aircraft successfully take off with the flaps fully extended to the landing position? To make this more concrete, let's say a B773-ER at ATL runway 8R.
5
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1answer
1k views

How can you tell what position the flaps are in whilst on a commercial aircraft?

I am flying with thomson soon and want to be able to tell what position the flaps are in. How can i figure this out?
2
votes
1answer
1k views

How does leading edge flap increase camber?

From this post, I've learned that the leading edge flap works by increasing the camber of the airfoil. But how exactly does it work? Since it is a flap, I can guess it works by changing the chord line,...
7
votes
3answers
2k views

Why would a pilot want to land with less than full flaps?

So for example if I am flying the Boeing 737-800, the FMC gives me three flap settings and approach speeds. Why would a pilot want to fly with anything less than full flaps where possible?
3
votes
1answer
649 views

How to calculate the lift coefficient of a multi element airfoil?

How to calculate the lift coefficient of an airfoil section with flaps and slats if we know the Cl for the individual elements, like Cl of wing, Cl of slat and Cl of flap?