# Questions tagged [angle-of-attack]

Usually refers to the angle between the oncoming air and the wing.

53 questions
Filter by
Sorted by
Tagged with
8k views

### How does the angle of attack vary in turns?

I read somewhere that when the aircraft banks to turn, its angle of attack increases.Since angle of attack is the angle between the relative wind and chord line, how does turning increase it? Is it ...
• 2,349
65k views

### How does an alpha (AoA) vane work?

The alpha vane (also called AoA vane) is an external probe used to measure the angle of attack. I have been trying to understand how exactly it works, but I can't find any clear explanation or ...
• 1,614
11k 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 ...
• 185
3k views

### Are we changing the angle of attack by changing the pitch of an aircraft?

For example: if I pitch the airplane up, but also increase power and am able to maintain the same speed, then no, the AoA hasn’t changed, although it may have varied in the transition between one ...
1k 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°?
• 2,905
1k views

### Do wingtip vortices cause a decrease in the lift component of aerodynamic force, and do planes need to pull more AoA to compensate?

So, from what I know about wingtip vortices, they shift the angle of the relative airflow to where the effective angle of attack of the airfoil is lowered. Since the aerodynamic force is always ...
15k views

### What is the wing angle of attack of a Boeing 737 in cruise?

I would like to know the angle of attack that a 737 flies at during cruise. I am specifically interested in the wing angle of attack (if you know the cruise nose-up attitude and the wing incidence ...
• 303
11k views

### Does lift coefficient vary with the wind velocity for a given angle of attack?

I have this question in my mind. I have been trying to look for this in different books about aerodynamics and I couldn't find the answer. I know I could check the answer experimentally, if I had a ...
• 1,680
3k views

### Does airspeed affect the critical angle of attack on an airfoil?

I understand that the critical angle of attack is mostly affected by the shape of the airfoil. However does the airspeed of the airfoil or the density of the air affect the critical angle of attack? ...
• 5,769
4k views

### How does the relative wind on a propeller, strike the blade from behind (the non camber side)?

This may be a stupid or simple question, although any help is appreciated! :) If possible, please answer without mathematical terminology. So I understand the concept of the blade increasing air ...
• 1,083
2k views

### How does flight control surface authority change with AOA?

I am working on semi-realistic (let's just call it "believable") flight simulation component set for a game engine. One of the topics that I tried to research but could not find reliable information ...
• 223
22k views

### How to calculate the Lift Coefficient for the A320?

I'm trying to figure out the lift coefficient of an A320. What I'm doing is the following: during cruise, the lift is equal to the weight of the aircraft ($mg$) so that I used the cruise table taken ...
• 1,501
711 views

### Why are the positions of an aircraft's angle-of-attack vanes dependent on airspeed?

According to this answer to an earlier question of mine, the positions of the angle-of-attack sensor vanes on the A330/A340 are dependent not only on AoA, but also on airspeed (and, according to @ymb1'...
• 28.1k
3k views

### Why Air France 447 could not reduce angle of attack?

I just finished reading this article and couldn't understand why in 3 minutes and 30 seconds even though there was no reliable speed data, pilot could not level the plane? Isn't the angle of attack ...
• 736
2k views

### Will an Airbus A320 plane go into an unrecoverable nosedive and crash if a single angle of attack sensor fails, like on Lion Air JT610?

For example, has an Airbus gone from cruise flight into an automated unrecoverable nose dive until it hit the ground because an AOA sensor failed in flight? Moreso, are there any cases of an AOA ...
1k views

### What's the theoretical background of the critical angle of attack?

The critical angle of attack seems to be at all (most?) airfoils around 15-20°. Why is that? Why is it in this range and not lower or higher? Is it just the result of optimizing airfoils? Or is it ...
• 3,829
10k views

### How many AOA sensors does the 737 MAX have?

How many AOA sensors does the 737 MAX have? Given that it's reported in the media, that one faulty AOA probe activated the MCAS on the Lion Air flight, I was wondering if anybody also knows how an ...
• 1,021
3k views

### Is induced drag caused because of the tilt of the wing backwards?

In this question: Why is induced drag less on a high span wing? In the answer it was stated that wing tip vortices do not cause induced drag. If this is the case then what causes the induced drag. ...
• 547
26k views

### What is the typical angle of attack aircraft fly at and at what angle of attack do they stall?

At what angles of attack do aircraft typically fly at? How much of a margin is there before aircraft stall due to an increase of an angle attack due to factors such as gusts or rotation of the wing ...
3k views

### How is a sideslip maintained (aerodynamically)?

(Public domain image that I've modified.) The initial rudder deflection to the left creates a side force that points right and yaws the plane to the left. NASA puts it this way: For the vertical ...
625 views

### Are fly-by-wire fighters protected in AoA?

When thinking about fly-by-wire, I always think about civilian aircraft (Dassault Falcon 7X, Airbus A350...) for which protections are implemented to ensure the aircraft stays in its designed flight ...
• 16.4k
556 views

### Twist optimization for a low speed aircraft

I'm currently designing an aircraft with the following specifications- s=1.8m^2, AR=7-8, trapezoidal planform with a taper ratio of about 0.45, a load of 25KGs and a cruising speed of 13-15m/s. I'm ...
• 359
8k views

### How did this Boeing 787 perform this near vertical takeoff? [duplicate]

At angles of attack like this an airliner would stall very easily. The 787 wing would stall at an angle of 30 degrees. The plane would have been flying at speeds of around 200mph(more likely less) at ...
• 9,289
38k views

### Why does the B-52 take off without rotating?

In the answer to this question it is noted that the B-52 takes off without rotating and climbs out in a nose-down attitude. Why was it designed this way?
• 28.4k
2k views

### What were the advantages of the L-1011 AoA sensor design?

The Lockheed L-1011 had an unusual type of AoA sensor. Instead of the usual vanes it used a tube with two rows of holes in it about 90° apart. A diaphragm sensed the pressure differential between the ...
• 28.4k
4k views

### Why are the angle-of-attack sensors on most airplanes mounted on the forward fuselage rather than at the wing roots?

A source of reliable angle-of-attack information is important for airplanes, as flight at an excessively-high angle of attack can cause the airplane to stall, which is generally considered to be an ...
• 28.1k
1k views

### Can variable incidence wings replace ailerons?

If a wing can change its incidence angle, can aileron be omitted in the design? Since aileron are used to increase lift and decrease it. so is the incidence angle. How would the two solutions ...
• 241
1k views

### Why do airliners on autopilot climb during cruise?

Several years ago I was a passenger on a near cross-country flight when the pilot came on the PA and announced that we were climbing towards our cruise altitude, on autopilot, and as our fuel load was ...
• 1,624
3k views

### Is drag coefficient lowest at zero angle of attack?

The drag coefficient of a symmetric airfoil is lowest when its angle of attack is zero. I'm not sure if this is true in general.
• 203
2k views

### What are the definitions of elevator angle of attack and critical angle of attack?

Angle of attack is the angle between the chord line of the wing to the direction of relative wind. So angle of attack helps the aircraft climb. Then what is the angle between the chord line of the ...
• 2,349
871 views

### Could the stick position be used as a Angle of Attack indicator?

True or False: The stick determines elevator position and elevator position determines angle of attack. When the critical angle of attack is exceeded, the wing stalls. So, given a design with enough ...
• 926
12k views

### Is there a simple relationship between angle of attack and lift coefficient?

Is there an equation relating AoA to lift coefficient? I have been searching for a while: there are plenty of discussions about the relation between AoA and Lift, but few of them give an equation ...
3k views

### What happens during a powered descent?

I was having a discussion with my friend about equilibrium condition in flight: Scenario: While going in straight and level flight, say I reduced my airspeed by 30 mph. At the same time keeping the ...
• 2,349
5k views

### Angle of attack difference between outer wing and inner wing during a descending turn and climbing turn

I understand that during an ascending or descending turn the angles of attack of the inner wing and outer wing are different. However, I don't understand why then ascending and turning, the outer ...
• 51
3k views

### What exactly happened with the Flight Computers on XL Airways Germany Flight 888T?

I recently saw a documentation about XL Airways Germany Flight 888T. This made some questions rising in my mind: Two AOA-Sensors failed (freezed) simultaneously. From Wikipedia: Two out of three ...
• 8,982
1k views

### Finding Angle of Attack/Angle of Sideslip using East/North/Up Coordinates

I've got a set of data that includes: x rate, y rate, z rate (all ENU) which I'll call xd, yd, zd. roll, pitch, yaw (which I'll call ϕ, θ, ψ) roll rates, pitch rates, yaw rates I'm looking at some ...
• 131
9k views

### What is the relationship between Angle of Attack and Angle of Incidence?

The Angle of Incidence (AoI) of most GA planes is 6°. Assuming a plane with an Angle of Incidence of 6 degrees-- How do we calculate pitch attitude if we know the direction of the flight path and the ...
• 2,905
1k views

### Is it possible to fly a Straight and Level flight at high speed?

The question arise while discussing with some of my student pilot friends that as we have been performing Slow Flight we have to keep increasing the AOA of the aircraft to compensate for every lose in ...
• 171
4k views

### What is the difference between Angle of Incidence (AoI) and Angle of Attack (AoA)?

Following discussion here, I am still confused about the difference between AoI and AoA. As I read in many references and watched in many YouTube videos especially this one: 1). AoI is tje angle ...
• 4,411
2k views

### How does the Angle of attack vary from the root to the tip of a propeller for a fixed pitch prop?

I came across a video while learning about propellers where it showed the angle of attack increased from the root of the propeller to the tip of propeller whose pitch was fixed. I somehow cannot get ...
362 views

### How are AOA sensors tested after working on them?

If a maintenance or replacement has been done for an AOA sensor, would the mechanic be able to test if the sensor now works correctly? Can such a sensor be tested on the ground? If there is no ...
• 12k
4k views

### What is the relation between the Lift Coefficient and the Angle of Attack?

I'm trying to understand the relation between the Lift Coefficient and the Angle of Attack using PEP software for the A320 IAE. However, I notice that often for a given Angle of Attack, there could be ...
• 1,501
1 vote
247 views

### Do redundant angle of attack and sideslip sensors use a voting mechanism, or do they display data directly?

In civil transport aircrafts (featured with dual/triple redundancy), how does airplane's Airflow angle (AoA/AoSS) sensor measurements read by the pilot? By using voter mechanism as used for airspeeds ...
• 141
1 vote
340 views

### How many Angle of Attack sensor vanes should a commercial passenger airliner have? [closed]

The ill fated MAX of recent news had 2 angle of attack vanes, with the MCAS computer picking the worst one. It seems a "software patch" may not be the only improvement option available. Sensible ...
• 18.9k
1 vote
1k views

### What happens to the pressure differential of airflow under and over the wing as the critical angle of attack is reached?

I've been doing a research project for mathematics which involves calculating the relationship between lift and angle of attack. While this may seem pretty easy, it's not for a 12th-grade student like ...
1 vote
704 views

### What effect does the angle of attack have on lift and drag?

In general, what effect does the angle of attack have on lift and drag? I understand the the B-25 take-off run was normally in excess of 1500 ft, the exact value dependent upon load, density altitude,...
• 21
1 vote
2k views

### Which 737 generations doesn't have Alpha Vane (Angle of Attack sensor)?

I was wondering if all generations have this angle of attack sensor, especially after recent 737 MAX Lion Air accident.
504 views

### How to define pitch angle for a passive variable pitch propeller?

This question is a continuation of the question How to calculate variable pitch propeller parameters? mentioned before. Actually, the theory described as an answer on the question above is the exact ...
• 77
The drag polar of a propeller driven aircraft is $C_{D}=0.039+0.071 C_L^2$. The lift curve slope of the wing ($C_{L_\alpha}$) is 0.09/deg and zero lift angle ($\alpha_{L=0})= -1.5^o$. Stall angle of ...