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Questions tagged [stall]

A stall is an aerodynamic condition wherein the angle of attack of a wing increases beyond the "critical angle of attack", causing the wing to cease generating lift.

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Can computer imposed inputs be overridden on the Boeing 737-MAX?

During Lion Air Flight 610, a Boeing 737-MAX, it seems that the angle of attack sensors caused the software to believe the aircraft was stalling, thus initiating a nose-down pitch to recover from the (...
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What prevents BFS from becoming unstable when pitching from horizontal to vertical?

In this video from (SpaceX's BFS landing) there is a point where the ship tilts from horizontal « belly first » terminal velocity freefall, to vertical « engine first » landing position. The graph ...
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Mechanical vs Pneumatic Stall Warning Systems

Light Cessna aircraft - at least the high wing single engine line - have commonly made use of a solid state pneumatic stall warning system. The system is fairly unique to Cessna airplanes and makes ...
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Why does the Ikarus C42 pitch down when stalled?

Apparently, the C42 nose pitches down shortly after stall, like in this video. I know part of the video might be pilot input to recover from the stall, but I've read on various flying forums that this ...
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Is there an abnormal condition that could have caused this fatal accident involving a stall?

In 2009, a Grob 103 glider stalled and crashed at Richmond Field, Michigan, killing the passenger but not the pilot. (NTSB accident report: CEN09LA353) The accident occurred after a failed winch ...
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Difference between Mach buffet and shock stall

What is the difference between Mach buffet and shock stall?
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What is primary cause of shock induced separation (shock stall)?

In the video link above describing Prandtl Meyer Waves, lecturer stated (at 22:40) a very important fact on which he based his first half of the lecture. "Mach wave (mach lines) deflect the flow ...
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Why does a rectangular wing stall first at the root?

Why does a rectangular wing stall first at the root? as opposed to tapering of the wing which causes the stall at the tip and moving inboard?
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Why does a stall decrease lift, rather than increasing it?

A stall occurs when the angle of attack of a wing or other airfoil becomes so high that the airflow over the upper surface of the wing separates from the wing, rather than remaining attached to it; ...
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Can this vane prevent/delay wing stall?

Given that a stall results from the airflow over the top of the wing separating from the wing at high angles of attack, would it be possible to prevent, or at least ameliorate, a stall by deflecting ...
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How can I compute the minimum possible bank angle for a turn with a given radius?

I know that I can find an upper bound for the bank angle for a plane, if I know the maximum sustained load factor of that plane because the roll angle and the load factor $n_z$ in a turn are directly ...
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Definition of a Deep Stall

I've been doing some research for a uni assignment and I noticed that the RQ-11B uses a "deep stall landing" to get back onto the ground. What I don't understand though is how this aircraft gets into ...
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Has a scheduled passenger flight ever stalled because of shifting cargo?

Has any scheduled commercial passenger - not cargo - flight ever experienced a stall due to cargo shifting, like the National Airlines Flight 102 did, back in 2013? Please note I am specifically ...
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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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Controlled stall,aileron or rudder input?

I know aileron input in a stall approach is not adviced, what if vortex generators are placed at the wingtip where the ailerons sit meaning there will still be aileron authority even at stall, at this ...
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Can an aileron stall in-flight?

Horizontal stabilizers stall, so I was wondering, is it possible for an aileron to stall? If yes, at what angle of attack?
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stall with max power

I saw a video of a test flight of a GA plane and it stalled with max power and with a moderate AOA (angle of attack). How can a plane stall with max power (with the wings flying below the critical ...
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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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Did the space shuttle have a stall warning system (such as a stick shaker)?

I've been wondering about this, but I can't find any sources one way or the other: Was the space shuttle equipped with a stick shaker and\or other stall warning system?
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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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What's going on with sudden acceleration/deceleration in mid-air?

I was recently on a flight between LGB and PHX. I've been flying since I was 5, am now 31. After takeoff, as the plane approached cruising altitude, the plane slowed down. A lot. Then accelerated ...
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Why does XKCD say that autogyros will crash if the pilot reacts to a stall as in a normal airplane?

This recent XKCD comic is all about autogyros. Image is copyright XKCD, licensed under CC 2.5 BY-NC The note at the bottom is what got my attention Extremely safe, unless you do the one thing you ...
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How will a prolonged series of steep turns produce a stall in subsequent level flight?

In Stick and Rudder, the author warns pilots against the unreliability of judging airspeed and hence “buoyancy” — his term for how far the airplane is from aerodynamic stall — by throttle position, ...
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Why disable stall warning based only on low airspeed, rather than multiple criteria?

One of the factors that potentially contributed to the Air France 447 crash is that the stall warning was disabled when the airspeed fell below 60 knots. I understand why this is -- you don't want to ...
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What solutions are there against deep stalls?

What solutions are there against deep stalls? According to SKYbrary: Aircraft with a T-tail design are often configured with a Stick Pusher system to help prevent the mainplane angle of attack ...
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On Air France 447, what would have been the lowest altitude to initiate recovery after the stall developed?

What could the lowest altitude of Air France 447 have been to recover the (stalled) flight, where the co-pilot informed the captain that he was pulling up the whole time? The co-pilot didn't inform ...
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Why do zero gravity flights not stall? [duplicate]

Airbus' (A300 / A310) are being used by French companies (i.e. Novespace) that offer zero G flights. Now the airbus seems to risk a stall at a 40 degree angle of attack (i.e.Air France 447). In a ...
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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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Is it possible to maintain horizontal flight with the angle of attack above critical value by increasing speed?

In this video a stall happens at 1:40 upon reaching the critical angle of attack. The air flow is now detached from the upper part of the wing, resulting in higher pressure above the upper part of the ...
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Is there a new “best practices” technique for demonstrating stall recovery?

This is a question that is probably best suited for active flight instructors. I was doing an FBO checkout and the CFI asked me to demonstrate power on and power off stall recoveries, but well before ...
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Does a sudden drop of the velocity of the headwind affect the airspeed by lowering it?

I had a discussion about air speeds with one of my instructors recently. He is claiming that there is a sudden drop in the wind velocity as you get closer to the ground (which is absolutely true, due ...
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Did the F-8 have a stall speed of 1.6x its landing speed?

Wikipedia says that the F-8 was to have a landing speed of no more than 100 mph (160 km/h) This web page says that the F-8 did have Stalling speed 157 mph. The two don't explicitly discuss ...
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Why would one wing stall before the other?

Reading about the Douglas C-133, I see this: The second issue discovered was stall characteristics gave very little warning to the crew. The left wing was found to stall before the right wing. ...
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Will a stalled aircraft fall down like a brick? Or how steep does the Lift-AoA curve fall off after stall?

When an aircraft stalls, do all or most lift forces abruptly disappear or is this transition continuous? Will the aircraft drop from the sky like a brick or can this (losing lift and altitude) happen ...
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What causes a slight increases in indicated stall speed with altitude?

Theorectically, the stall speed in IAS doesn't change with altitude, but this graph above shows the stall speed actually starts to increase a little from above a certain altitude. How can this be ...
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Do airliners stall first at the wing tip?

One of the disadvantages of the sweepback aircraft is the tendency of a stall to occur at the wingtip first. Various high lift devices are added by design to the wings of the sweepback aircraft like ...
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Why does Airbus suppress stall warnings in certain situations?

I was reading about Air France 447 and came across the line: The stall warnings stopped, as all airspeed indications were now considered invalid by the aircraft's computer due to the high angle of ...
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What is the stall speed for the Dassault Rafale?

Looking at this video of a Rafale escorting a high-speed train (TGV) I was wondering what the stall speed for the Rafale is at close to sea level altitude. Is this ...
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What would cause an aircraft (j3 piper cub) to slide backwards when going into a stall?

Fifty years ago, I took lessons at an uncontrolled airport and this happened to me, fortunately my instructor took over and as cool as a cucumber corrected the situation. His detailing of what he was ...
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Can a helicopter be “stalled” by pulling too hard?

In the PC game Arma 3, there is a helicopter-race game mode, in which the player tries to manipulate the helicopter to pass a serious of hoops as fast as possible in an AH-6. In the game, if the ...
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How can hang gliders and paraglider pilots prevent stall?

Aircraft and gliders usually have instruments to measure air speed and angle of attack, which should be monitored to prevent stalling the aircraft. However, it seems that most paragliders and hang-...
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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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Can a Kline-Fogleman airfoil be used for engine turbines?

I am currently working on the Kline-Fogleman airfoil for NACA 23015 variant at Reynolds number 208800 with the configuration of the backward facing step of 50% thickness at 50% chord on the bottom ...
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Do Air Traffic Controllers have to remember stall speeds for different aircraft?

While dealing with Takeoffs and Landings controllers provide speeds to pilots for different phases of the flight, specially during a landing approach. How do they know which speeds are safe for all ...
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How can planes with the same stall speed and power-to-weight ratio have such different takeoff field length, climb rate, glide ratio, etc?

I am interested in better understanding the performance differences between different planes that seem to be similar in many important ways but that differ greatly in performance. For example, take ...
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How can a flying wing style airplane recover from a spin without a vertical stabilizer? [duplicate]

I fly a Cessna C-172, and if I have any bank when stalling, I have to use rudder to level the airplane. If I use aileron, the bank angle will increase and bring the airplane into a spin. My question ...
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How does a nose down stall occur?

Imagine I am in a straight down dive, at terrific speed, and if I wanted upward sharp turn and got the stick back far enough, would I stall (or spin)? Does normal laws apply when the aircraft nose is ...
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Why does the ACS forbid activation of the stall warning during slow flight?

In section VII. Slow Flight and Stalls, page 54 of the Private Airplane ACS, the Skills section contains in part $$\begin{array}{l|l} \bf{Skills} & \text{The applicant demonstrates the ability ...
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AF447 stall and failure to recover [duplicate]

To my knowledge Air France Flight 447 experienced stall. How was the stall detected and why wasn't the crew able to recover?
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Does the expression “stall speed” have a definition?

I read, not only on this site, that the stall speed of an airfoil doesn't exist, and I usually make the effort to stay away from this expression. While an airfoil can stall at any airspeed, it's ...