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Questions tagged [angle-of-attack]

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

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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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What is the glide ratio on the CE-S550 Citation S-II?

I couldn't find it in the AFM. Is it different then the square winged citation II?
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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 ...
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135 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.
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168 views

Can quadcopters still fly with propellers at an angle?

Can quadcopters still fly with propellers at an angle? By this I mean like the whole motor mounts will be situated along a certain slope (so as to be neither horizontal nor vertical). UPDATE I meant ...
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Airbus A320 angle of attack protection priority

The A320 FCOM chapter 27 flight controls, normal law, protections, shows a diagram how the sidestick input is used when protections are active. When high angle of attack protection is active the side ...
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181 views

Does headwind on takeoff affect g force?

I'm aware that headwind or tailwind does not affect rate of climb or descent but only the angle. I'm not sure if it affects the g force or not. I'd assume it affects g force because using trignometry, ...
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Different 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 ...
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239 views

Why does the angle of descent increase in a constant headwind while decreases in a sudden encounter with a headwind, in a descend?

I'm currently studying aerodynamics. I have realized that a sudden encounter with a headwind during descent will result in the aircraft generating more lift, thus angle of descent decreases. I haven'...
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Can airplane performance be increased by cruising “on step”?

Old timers swear aircraft performance can be increased by getting an aircraft "on step" similar to how boats are operated. They claimed a couple extra miles per hour (airspeed was in MPH then) were ...
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Why does the stagnation point on airfoil move with the angle of attack?

What is the physical explanation for the reason the stagnation point is where it is? And, why does it move further down the lower side of the airfoil with an increase in angle of attack?
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Why did this A320 stall protection demo not hold Valpha max?

This video is about the Airbus A320 High angle of attack protection At 4:54 - 5:13 why did it pitch down? I know it is trying to maintain Valpha max but if it would ...
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2answers
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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?
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106 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 ...
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What is the average angle of attack of GA airplanes during takeoff?

What is the average angle of attack of GA airplanes during takeoff?
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Do negative angles-of-attack create lift?

(wikimedia.org) A typical curve showing section lift coefficient versus angle of attack for a cambered airfoil. Based on the graph above, do negative angle-of-attack values create lift? How?
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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? ...
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397 views

Why do aerobatic planes have symmetrical wings?

Besides the fact that symmetrical wings fly the same inverted as upright are there any other reasons why aerobatic planes prefer symmetrical wings? Can symmetrical wings achieve a higher critical ...
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189 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 ...
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2answers
157 views

Does wing sweep affect the direction of lift?

Given both a straight and swept wing (identical otherwise), exposed to the same airflow, would the direction of lift be the same? Please see below a crudely drawn example of my thinking. Additionally,...
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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 ...
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Could a spinning disk disperse heat better?

Could a spinning disk dropped from orbit survive speeds faster than conventional aircraft in our atmosphere? How fast would the disk have to spin to keep it stable along with heat dispersion? Can it ...
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What's the pattern of airflow over the airfoil at high angle of attack?

When at high angle of attack the boundary layer tends to: A. stagnate and stop B. loop around the upper camber line C. decrease air pressure along the chord The answer is A, but as I see ...
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226 views

How to find trim condition of a sectional airfoil without knowing the angle of attack?

I am using a reflexed airfoil designed for positive pitching moments to achieve a pitching angle matched to the changing of free-stream velocity (Aerodynamically tailored). I ended up with a pitching ...
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Does zero-lift angle of attack depend on Reynolds number?

In this post I read that, due to viscous effects, the $C_{l}$ at a given angle of attack increases slightly with the Reynolds number but it seems that it just happens near the stall angle of attack. ...
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319 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 ...
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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. ...
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How does change in airspeed affect pitching moment?

In aircraft with conventional elevator control, if I increase the speed, the horizontal tail sees higher velocity and hence higher lift. Does it mean that increasing airspeed creates nose down ...
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3answers
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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 ...
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163 views

Is it possible to get into a spin situation while coordinated?

Is there any possibility of spinning while coordinated? Of course, any CFI would tell you no, but I wonder if the the following situation could result in a spin while coordinated: Slow level flight ...
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3answers
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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 ...
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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 ...
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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 ...
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558 views

For a flying wing airfoil, which AOA is to consider when selecting Cl?

I'm in the process of designing a flying wing. I'm trying to keep it a small as possible, so the lift coefficient is very crucial for me. I'm currently looking at some airfoils but most of them ...
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Can a taildragger land tail first?

Inspired by this question... How does a taildragger take off? Does it rotate? I imagine if a taildragger has to land front wheels first it has a very limited range of Angle of Attack (if the pilot ...
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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 ...
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Is this angle of attack animation backwards?

Is this animation of the angle of attack sensor in this video from 25:30 to 25:50 correct? It seems like motion of the sensor is the opposite of what it should be based on the angle of the aircraft. ...
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Is it possible to fly horizontally with zero angle of attack?

If an aircraft has a zero angle of attack and the wing doesn't, is it possible to fly horizontally? Because as the book says, there is no lift in this condition, Is this zero angle of attack of the ...
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2answers
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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 ...
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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 ...
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2answers
5k views

How does centre of pressure change with angle of attack?

I've been given the distance of centre of pressure from the leading edge with a certain angle of attack and was wondering if it's possible to calculate the new position when the angle of attack ...
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2answers
401 views

Why doesn't the flight path angle increase beyond a certain angle even if the angle of attack is increased?

From level flight, when the angle of attack is increased the flight path angle increases (the aircraft starts to climb). What causes the aircraft to stop to increase its angle of climb (angle between ...
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1answer
528 views

Does angle of attack change in a sustained climb?

I saw this question on a closed Facebook group, generating wildly differing answers. So I thought I would ask it here. You're in a C172 flying straight and level at 5000 feet and 100 knots IAS. You ...
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2answers
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What does it mean when pitch numbers move all over the HUD screen?

In this video from an F-16: You can see pitch angle move out of screen or be on the side at the end.
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3answers
3k 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 ...
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2answers
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Do airliners adjust altitude for latitude?

According to this NASA article, the troposphere extends from about 5 miles at the poles to about 9 miles at the equator. Though the height of the troposphere is defined by the height of the tropopause ...
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5answers
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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 ...
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What is the significance of stall speed [duplicate]

Irrespective of the stall speed, the only reason aircraft stalls is when its control surface (elevator, aileron) exceeds critical AOA. Then what is the significance of the stall speed? Does the ...