Questions tagged [angle-of-attack]

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

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Does thin airfoil theory work at very high angles of attack?

Thin airfoil theory says that lift coefficient is directly proportional to the angle of attack in radians. I haven't been able to find any limit, short of stall, for applying this theory. It would ...
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What is the average angle planes wings they need to fly? [duplicate]

The planes I am talking about are everyday passenger plane's, not fighters. Do you know what the angle needs to be for it to create enough lift so the plane can fly?
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Why does pitching moment coefficient decrease with an increase in the angle of attack?

Slope of Cm vs alpha graph is negative, why it is so? The attached graph is from https://en.m.wikipedia.org/wiki/Pitching_moment , this graph is for cambered airfoil, as pitching moment is zero for ...
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Is it possible to have an angle of incidence for a vertical stabilizer?

horizontal surfaces in airplane have small angle of incidence in general, Is it possible to have an angle of incidence for a vertical stabilizer? Please help me to find it. Thanks!!
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Does this web page really correctly depict the angle that is called “incidence” in the French language in the aviation context?

Does this web page really correctly depict the most common usage of the term "incidence" in the French language in the aviation context, in the context of speaking of an entire aircraft and not just ...
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A question about the exact meaning of one British usage of the term “Angle of Incidence”

This answer to a related question stated: Most anything can have an angle of attack. If you must be specific, you mention 'angle of attack of ...' ... When we talk about airplane as a whole, ...
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Is the lift vector reversed during inverted flight?

Heard a physics professor say that when an aircraft flies inverted, the wing assumes a significant angle of attack (by pushing the stick forward) to continue to generate the necessary "upward" lift ...
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Can lift be increased by increasing the angle of incidence of the wing? [closed]

Can the lift of a plane be increased by increasing the Angle of Incidence (angle between the chord line of the main wing and the axis of the fuselage)? Meaning, can more lift be generated while the ...
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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 ...
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What is the stall AoA for the space shuttle?

Once flying as (fast) glider in order to land, what was the angle of attack it would have stalled? I'm really interested in the angle of attack for such wings and not the speed.
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How does increasing the RPM result in a higher AOA for the blades?

I know that an increase in velocity (TAS) reduces the AOA and that makes sense. But how just simply increasing the blade rotation (RPM) results in higher AOA?
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What 's the difference between Angle of Attack and Pitch? [duplicate]

I am interested in knowing the theoretical and practical differences between the Angle of Attack (AoA) and Pitch: Graphical definitions How are they related? In what circumstances these angles are ...
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Why aren't angle-of-attack data sanity-checked before being fed to other aircraft systems?

For most fixed-wing aircraft, accurate angle-of-attack information is utterly essential for safe flight, due primarily to the risk of stalling the aircraft if the AoA of one or both of its wings ...
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Difference between symmetrical and cambered airofoil?

I have seen images of cambered and symmetrical wings but apart from that what are the major differences between them? I have also read that symmetric wings don't produce any lift at 0° AOA whereas ...
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136 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 ...
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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 ...
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What happens to the high pressure below an airfoil when the angle of attack increases?

I recently came across this question in a principles of flight exam: When the angle of attack of an airfoil increases the high pressure below the airfoil increases, the induced drag increases the ...
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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 ...
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How to calculate aerodynamic efficiency at minimum power conditions?

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 ...
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Is the highly optimized high subsonic cruise airfoil less safe for higher AOA flight? [duplicate]

An examination of the 737 airliner wing profile and that of a blue whale leads to the question of whether the high Reynolds number subsonic cruising airfoil and the low speed, high AOA airfoil are ...
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Does the AOA and G-Force increase if a fighter uses the afterburner during a max G level turn?

My understanding is that if you apply power (increase the thrust) for a jet in level flight, it will momentarily pitch up, and then gain some speed. So, if a fighter pilot lights their afterburner ...
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How does the critical Angle of attack changes with Increasing Reynolds Number?

I am simulating NACA 2415 Airfoil for different Reynolds Number i.e. 2 million,3 million and 4 million on ANSYS Fluent. The difference between the critical Angle of attack is quite vast. For the 4 ...
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“Snowglobe”-type attitude indicator [duplicate]

I'm an aviation enthusiast (I do not, nor have I ever worked in the industry), and after researching several various emergencies (reading text documents, reviewing CVR transcripts and watching ...
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Does flying an airplane upside down imply negative AoA? Why?

I saw the statement below in this answer: Note that for normal level unaccelerated flight $C_L$ is always > 0. The minimum $C_L$ is a negative value for negative AoA, and would mean that the ...
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What material and shape should be used for angle of attack sensors?

Does the material and shape of the vane for an angle of attack sensor have to be identical to the material and shape of the wing? What properties should I consider?
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Why does RPM for a fixed-pitch propeller change with an aircraft's pitch?

Talking bout a C-152 - If I pitch the aircraft down, and without adjusting the throttle, the RPM would show an increase. Pitch up, and without adjusting the throttle, the RPM shows a decrease. I've ...
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Is it more efficient to use inlet guide vanes or variable pitch blades

Again, its all in the question. two scenarios for a ducted prop in hover: inlet guide vanes close to the prop to control the angle of attack just a prop with a variable pitch mechanism. obviously, ...
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Sideslip vs Freestream Azimuth Angle

Why is the sideslip angle, $\beta$, defined as $$\beta=sin^{-1}\left(\frac{v}{|{\bf v}|} \right)$$ and not the same as freestream azimuth angle $\psi$ $$\psi=tan^{-1}\left(\frac{v}{u} \right)$$ ...
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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 ...
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274 views

Why is the angle of attack not proportional to the stagnation point?

While I was studying my PPL today, I've encountered a question right below and I wasn't really satisfied with the answer. Which statement about the airflow around an aerofoil is correct if the angle ...
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551 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 ...
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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 ...
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Why does an increase of airspeed result in a decrease of angle of attack?

In Chapter 02: Aerodynamics of Flight of Helicopter Flying Handbook, on page 10, it says: Induced flow velocity is increased, resulting in a decrease in AOA. I don't understand how airspeed can ...
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How are airliners AoA-Sensors calibrated?

Airflow around the fuselage is not free, even near the aircraft nose. I assume some correction is applied to the measured angle to get the corresponding freeflow angle. How is the reponse curve for ...
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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 ...
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Why is airspeed different in climbs and descents although the AoA doesn't change?

Here are the background facts: This excercise has the objective to familiarise the student with the slow flight characteristics. The steps are: 1)Establish straight and level, 90% RPM, 15 units ...
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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.
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Why are the AOA sensors placed outside the aircraft?

Why should the AOA sensors be placed outside the aircraft? Is it not the angle between the chord line of a wing and a vector representing the relative motion between the aircraft and the surrounding ...
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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 ...
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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 ...
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What is being depicted w.r.t. AoA in this video?

I was looking at this video of the AF447 crash simulation and at about 4:45 the angle of attack diagram shows a few things I don't understand (frame above). I get the orientation of the airplane, ...
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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 ...
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Has the number of angle of attack sensors been reduced in Boeing 737 Max, in comparison to the older models?

Boeing 737 is flying since 1967. I would like to know first how many ' angle of attack sensors' does it have, and has they number been reduced for Boeing 737 Max, in comparison to the older models ...
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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 ...
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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,...
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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'...
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Wind shear questions

I had a discussion and I'm curious on an experienced pilots knowledge. When taking off, let's say from telluride. You have a tailwind, but when you get off the ground you experience and windshear ...
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Why does the rotor thrust decrease at smaller tip clearance for shrouded rotor?

Consider this system, rotor with shroud: From this research, we see that: at the same rpm, the rotor thrust decreases,the shroud thrust increases as tip clearance decreases. But why does the rotor ...
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Wing pitching moment decomposition into two terms

Summary: Assuming constant angle of attack $\alpha$, speed $V$, and lift $L$ applied at the center of pressure CP (whose position is $x_{CP}$), the distance $(x_{CP} - x_O)$ between the moment ...
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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 ...