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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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Why doesn't the A330/A340 have a stickshaker?

When an A330/40 is in alternate law1 and approaching a stall, it has a stall warning composed entirely of a cricket chirp and a voice saying "stall, stall". Most other aircraft, in contrast, have a ...
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Why do aircraft stall warning systems use angle-of-attack vanes rather than detecting airflow separation directly?

Stall warning and protection systems on essentially all aircraft work by using several hinged vanes on the side of the fuselage (usually at least three, and preferably more), which align themselves ...
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Is there an increased concern for stall safety in a 1G steep turn?

Most people know the standard, "At a 60 degree bank, an aircraft experiences 2G's" checkpoint for load-factor on an airplane. I assume that this statement has an underlying, unspoken assumption that ...
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What is the difference between static and dynamic stall?

What are the static and dynamic stalls on the aircrafts wing? When would we encounter static and when dynamic one? What is the difference between them?
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How can I tell from the location of flow separation if an airfoil is stalled?

I am in the process of completing a carbon airfoil for my track car (sedan) and I am looking to determine stall angle visually. AKA, wool tufts and highway runs with my GoPro pointed upward from the ...
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Has the Boeing 737 MAX MCAS system successfully prevented a stall or approach to stall condition outside testing?

The Boeing 737 MAX MCAS system has been in the press a lot as it has been implicated as a possible cause of 2 fatal crashes. The MCAS system was put in to prevent a wing stall caused by excessive ...
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In the compressor characteristic, how do I calculate the minimum flow?

I have a small question, how do I determine the minimum flow point on the compressor characteristic? I.e. what is the safety margin on the curve?
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Why do passenger jet manufacturers design their planes with stall prevention systems?

I understand why passenger jets use software that overrides pilot inputs that might cause the jet to exceed the flight envelope. But why do passenger jet manufacturers design their planes with stall ...
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Why is the A330/A340's angle-of-attack protection disabled in alternate law, even if the AoA vanes are operating normally?

Reading about Air France Flight 447, to quote Wikipedia (emphasis added): ... A second consequence of the reconfiguration into alternate law was that stall protection no longer operated. Whereas in ...
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What is a rudder or fin stall?

What is a rudder or fin stall, how will the aircraft behave in that situation, and how should the pilot recognise it? What is the recovery procedure? And what is rudder reversal?
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How do aircraft stall warning systems handle (or not) asymmetric-stall situations?

Most, if not all, new airplanes are required to have stall warning systems to (as the name should make clear) provide the pilots with a warning when the airplane is about to stall. Most stall warning ...
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Why is this video of a G36 Bonanza taking off so scary?

Why is this video of a G36 Bonanza so 'scary'? If they had clipped the top of the trees, would it really have brought the plane down? (And even if yes, it looks pretty ...
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Why don’t aircraft have interlocks to prevent high-lift devices from being retracted when doing so would stall the airplane?

Most aircraft have high-lift devices on the wings (such as flaps, slats, droops, whatevs) to allow them to take off and climb out at a reasonable speed instead of having to accelerate to near ...
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Why does a sharp leading edge result in a larger pressure peak?

I know in the real world the sharp leading edge (LE) will results in a larger pressure peak compared to a large radius LE. And that there are three types of stall. But I want the explanation in ...
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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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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°?
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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 ...