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Why does XKCD say that autogyros will crash if the pilot reacts to a stall as in a normal airplane?

That one thing is to unload the rotor too much (i.e. "push on the stick"): From explainxkcd: ... Unfortunately, as soon as the rotor stops spinning, the whole aircraft falls like a brick ...
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60 votes
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What is a 'deep stall' and how can pilots recover from it?

A deep stall or a super stall is a condition where the wake of the wing impinges on the tail surface and renders it almost ineffective. The wing is fully stalled, so the airflow on its upper surface ...
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49 votes
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How do aircraft stall warning systems work?

Audible Warning On light aircraft there is a reed (much like used on a musical wind instrument) mounted on one wing root, which is angled such that at the Angle of Attack which would cause a stall, ...
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47 votes

Is it practical to intentionally stall an aircraft to execute a fast, controlled descent?

It isn't practical for a number of reasons: Intentional stalls are inherently dangerous. Stall-spin accidents are a major cause of accidents, stall recognition and recovery are taught specifically to ...
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44 votes
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Can fighter aircraft glide?

All airplanes can glide, if they couldn't they wouldn't be able to fly in the first place. When you glide an aircraft you are converting height into airspeed, which you can use to move across the ...
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44 votes

Can a large passenger aircraft recover from a stall?

The main thing that is required for a stall recovery is just the ability to drop the nose to decrease angle-of-attack and regain airspeed (and, of course, adding power helps, too.) Except in the case ...
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38 votes
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Why do passenger jet manufacturers design their planes with stall prevention systems?

Why do car manufacturers install seat belts? Shouldn't licensed drivers be well aware that they should slow down when it's raining or snowing and that they shouldn't run through red lights or stop ...
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36 votes
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Why does my wind tunnel experiment give two different stall angles of attack?

This is called stall hysteresis. You have two different situations and the flow reacts differently in each of them. When increasing the AOA The flow is attached to the wing and the boundary layer is ...
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35 votes
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Do airline pilots practice stalls in actual aircraft?

In 727 and 747-100/200 aircraft and their simulators for the two airlines I flew those aircraft for up to my retirement in 1999, all stall training was done in simulators, never in the actual aircraft....
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34 votes
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What is the stall AoA for the space shuttle?

As far as I can tell, NASA has never given a straight-forward answer to this question. The theoretical stall AoA is likely in the 33-40° range (see reason for that guess below). However, at ...
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34 votes

Is a "stalled" aircraft free-falling?

If the cables break on an elevator (and the safety brakes fail), you won't be in true freefall. You'll still have friction from wind resistance, from the guide rollers on the rails, etc. The same is ...
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33 votes

Can fighter aircraft glide?

All airplanes can glide. Some glide better than others. A very old reference I read talked about engine-out landings in military aircraft. Their procedure was arrive at the airfield at X feet, circle ...
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33 votes
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Do Air Traffic Controllers have to remember stall speeds for different aircraft?

No because aircraft are categorized by their speed at the runway threshold (1.3 times stall speed). VAT —Speed at threshold used by ICAO (1.3 times stall speed in the landing configuration at maximum ...
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32 votes
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What is the immediate cause of stall?

The immediate cause of a stall is the detachement of the airflow from the wing: Image from NASA This happens when your Angle of Attack is too high. How can the AoA become too high? --For level ...
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32 votes

How do aircraft stall warning systems work?

Large commercial aircraft typically rely on either Angle of Attack (AoA) Vanes or Differential Pitot Tubes (Smart Probes (PDF)) to supply input to flight computers for the purpose of calculating AoA. ...
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32 votes
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Is a pilot's instinctive reaction to a stall counter-intutive?

The correct way to recover from a stall is counter intuitive, not because pilots are trying to climb, but because the nose of the airplane drops due to the loss of lift and aircraft design. 99.999% ...
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31 votes
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On Air France 447, what would have been the lowest altitude to initiate recovery after the stall developed?

For the stalled flight to recover, the nose needs to be pointed in the airstream, and then the aircraft pulled up with load factor below the ultimate load. From the accident report: The recordings ...
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31 votes

Why do aircraft stall warning systems use angle-of-attack vanes rather than detecting airflow separation directly?

The short answer is that we want to warn the pilots about an impending stall well prior to an actual stall condition. From a safety perspective, waiting until the airflow starts to separate, or at ...
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30 votes
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Does a sudden drop of the velocity of the headwind affect the airspeed by lowering it?

Your airspeed does not remain constant because of inertia: it takes more time for the airplane to adapt to the new relative wind, compared to the time it takes for the wind to change. Example One: ...
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29 votes
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When approaching a stall, is the first priority to apply power or lower nose?

The instinct drilled into a pilot's head from the beginning as the primary response is "lower the nose" to lower AOA. If you learn in a glider, that's the only option, so it's easy to drill the ...
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  • 104k
27 votes

Can fighter aircraft glide?

Yes, all aircraft have a glide ratio. On many of the higher-performance fighters, it's 1:1 at best (1 foot altitude traded for one foot forward gliding). Many of the newer fighter aircraft are ...
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  • 1,257
27 votes

Could an airliner with only one functioning engine recover from a stall?

Yes, but the challenge is managing the asymmetric thrust effects when applying power during the stall recovery. Pilots are trained in the sim for two stall (actually, just stick shaker onset) ...
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26 votes

Why does XKCD say that autogyros will crash if the pilot reacts to a stall as in a normal airplane?

This is a well known problem with gyrocopters. The first answer was partially correct in that the problem was caused by pushing the stick forward and unloading the rotor. However, the problem wasn't a ...
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26 votes
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Why does a stall decrease lift, rather than increasing it?

For a parcel of air to generate a lift force as it flows over the wing requires the wing to tip that air parcel's momentum vector downwards slightly; the reaction force that the wing experiences as it ...
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23 votes

Why does XKCD say that autogyros will crash if the pilot reacts to a stall as in a normal airplane?

I believe what the comic is referencing is Mast Bumping. Rotor blades are very flexible, and for a bunch of reasons, are free to pivot around the mast.(The shaft the blades are spinning around) In ...
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23 votes

Why do passenger jet manufacturers design their planes with stall prevention systems?

To be certifiable, airplanes have to have some kind of cues to warn when you are getting close to a stall, and have decent behaviour during the stall, because nobody is perfect. Airplanes with very ...
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  • 104k
23 votes

Could an airliner with only one functioning engine recover from a stall?

A stall recovery doesn't require engines (although they help, especially if altitude is an issue). To recover from a stall, you need to lower the angle of attack. You can do this by lowering the nose ...
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23 votes

What is the physical explanation for the pre-stall judder in a Spitfire?

It's because aircraft don't stall all at once. A stall occurs when the airflow over the upper surface of the wing separates from the entire upper surface, causing loss of lift. This airflow ...
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22 votes

Can a large passenger aircraft recover from a stall?

An airliner certainly has the ability to recover from a stall, given sufficient height and power. Moreover stall recovery isn't about maneuverability as such. A fighter jet is more difficult to ...
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