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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Will the autopilot raise the AoA above the critical AoA to maintain altitude?

NOTE: This question is regarding commercial airliners (eg: Boeing 737, Airbus A320, etc.. This is for any given configuration of the aircraft) Will the autopilot raise the AoA above the critical AoA ...
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3 votes
4 answers
339 views

Can a plane still climb even if it has exceeded the critical AoA?

According to this answer here, an airplane requires less lift for a climb than horizontal flight because the thrust of the engines will point up. Now if the wing was in a stall condition, could the ...
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-2 votes
1 answer
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Stall speed requirement [closed]

I calculated my stall speed at 22m/s. For this stall speed, would it be a better idea to increase it to use in my calculations later on or leave it as it is? I thought increase it a little to be on ...
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1 vote
1 answer
127 views

Can vane delay flow separation? [closed]

In general is a slat better than a vortex generator to delay flow separation, for high AoA or extremely curvature wing/objects? Does this "roof vane spoiler" works same as slat at wing, ...
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What is max angle of surface without stall?

AoA is by defintion angle between choord line and airflow, here is 25°. But max effective AoA here is 60°, so flow will separate for sure here.. What is max lets call it "effective AoA" that ...
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-1 votes
1 answer
168 views

The stall velocity condition: Exactly what is stall velocity? [closed]

Question: if my stall velocity is 20m/s, then... If the airplane is travelling at a velocity greater than or equal to the stall velocity, can one assume the plane will not stall? Can one assume that ...
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0 votes
3 answers
252 views

What is the AeroVironment Helios' Kármán line?

If it's true that the NASA/AeroVironment Helios maintained level flight 96,000 ft above sea level at a maximum airspeed of 23.5 kts (43.5 km/h) I assume it must have a very high Kármán altitude, the ...
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0 votes
1 answer
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Attack angle in high speed [closed]

I found the above animation; the moving slow air (or wing) will hardly to lead to an aerodynamic stall, but the usual case is a plane in the air running much faster than the animation, so does the ...
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7 votes
1 answer
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What is the difference between Vs and Vs1g?

As the name suggests, what is the difference between Vs1g and Vs? If both of them are referring to the stall condition, why they aren't the same? Which one is usually greater and why? Why do we need a ...
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5 votes
4 answers
711 views

Why does lift decrease and drag increase when approaching the stall condition?

This is an ECQB-PPL question specifically asking what happens before the stall. I do understand that after the critical angle has been reached, the airfoil is no longer generating lift (so obviously ...
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9 votes
2 answers
3k views

What caused this crash landing?

Watching this video, my attention was triggered by the quite firm right rudder deflection, just before the right wing stalls. There's no information about what ...
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6 votes
1 answer
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Can a wing be stalled at a speed larger than its stall speed?

I was told pulling the yoke quickly and all the way back stalls the plane immediately. I believe this is not possible as long as this occurs above the stall speed. I think about a styrofoam plane: ...
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1 vote
1 answer
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How was the AeroVironment Helios able to fly to the edge of space at no more than 23.5 kn?

The NASA/AeroVironment Helios holds the FAI record for the highest sustained horizontal flight at 96,900 ft (29.5 km) MSL. It reportedly spent more than 40 min above 96,000 ft. It could fly no faster ...
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3 votes
2 answers
322 views

Do fighter jets experience angles of attack greater than stall when initiating a zoom climb?

I was just wondering that the fighter jets like F-16, F-35 and Rafale when they are doing a steady flight at a certain airspeed, try to rotate 90 degrees and aim to obtain a vertical motion, so does ...
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2 votes
5 answers
416 views

What do you call a fall that is due to too little engine power, not due to cessation of aerodynamic lift?

If you raise your plane's pitch but the engines can no longer counter the gravity and you begin to fall (because the engines are too weak, not because of too little lift), what do you call that? This ...
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8 votes
4 answers
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What effect does towing a glider have on the stall speed of the tow plane?

I can see that if the tow is perfectly aligned with the axis of the engine thrust, that it is equivalent to pure parasitic drag and similar to some reduction of thrust. However, in the real world the ...
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10 votes
2 answers
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Why doesn't critical angle of attack increase with airspeed? [duplicate]

Critical angle of attack is related to the Coefficient of Lift, which is a function of Reynold's number. Reynold's number depends on the speed of the aircraft. So why doesn't the Critical Angle of ...
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0 answers
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Is the L-39 Albatros able to go above 40,000 ft in steep flight?

The L-39's service ceiling is 36,100 ft / 11 km but would it be able to easily reach and surpass 40,000 ft MSL if flying a parabola?
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1 vote
1 answer
153 views

How to turn inviscid data to viscous?

I have used Panel method to calculate Cp vs x/c graph and CL. But as panel method assumes attached flow it does not give an flow separation and thus in CL vs alpha graph I could not find any stall. My ...
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-5 votes
1 answer
194 views

What is the explanation for the appearance of airplanes hovering? [duplicate]

A few weeks ago, I saw a plane that appeared to be hovering in the air. It was a large commercial airliner. It was not a windy day, land speeds of 24km/h max that day, about 5km/h at the time I saw it ...
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Why is the definition of $V_{S1}$ vague wrt configuration?

The definition of $V_{S1}$ is the stalling speed or the minimum steady flight speed obtained in a specific configuration from 14 CFR §1.2 Abbreviations and symbols. Why is this vague in terms of the ...
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9 votes
1 answer
594 views

Why are there two local maximums on some CL vs AOA curves?

I know what a stall is but I don't understand why there are in some cases two local maximums on the $C_L$ vs AOA curve of some airfoils. What is the reason for the mini stall that occurs before the ...
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12 votes
3 answers
4k views

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

From the book "First Light" by Geoffrey Wellum, where the author describes dog-fight manoeuvres against an Me 109: If you want to shake someone off your tail you have to fly your Spitfire ...
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2 votes
1 answer
140 views

Why are aerodynamic models without stall used in research papers?

Some papers that I'm reading in the Journal of Fluid Mechanics give aerodynamic models in which the lift force appears to not take stall into account -- unless I am misinterpreting the math model, but ...
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3 votes
3 answers
467 views

Why does stalling increase drag?

I understand (I think) why lift reduces in a stall. What I don't understand is why drag increases. I can see that the ratio of drag to lift would increase, but I'm not sure I understand the mechanism ...
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6 votes
2 answers
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What’s the difference between an AIRSPEED LOW warning and a STALL warning?

Just an enthusiast here; pardon the dumb question. Im a little confused between the difference of a stall and airspeed low. “An aircraft Stall Warning System is that system which provides the pilot ...
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2 votes
2 answers
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Why would I want to lower the stall speed?

Why would a cargo pilot for example want to dump fuel to lower the stall speed? I understand that lowering the weight decreases the stall speed, meaning it is "easier" for the plane to reach ...
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4 votes
2 answers
335 views

What's the difference between an accelerated stall and a dynamic stall?

I am a commercial pilot. I always like to understand everything in detail, so here's my question: What's the difference between an accelerated stall and a dynamic stall? For example, in a high-speed ...
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1 vote
2 answers
595 views

Does too big an angle of decalage make the horizontal stabilizer to stall?

This styrofoam airplane has two positions for stabilizer. When put in the upper one, the plane flies in a circle. Is the stabilizer now stalled because the decalage angle is very big?What happens with ...
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13 votes
4 answers
5k views

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

If a modern commercial airplane such as a Boeing 787 would stall with only one functioning engine, is it possible for the pilots to right it or would it require two functioning engines?
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12 votes
2 answers
2k views

In this MD-11 stall test video, are we seeing the tail stalling first?

Watching this short stall test video for the MD-11, one can notice obvious buffeting (starting at about 0:04) of the tail section, while at the same time – at least apparently – there doesn't seem to ...
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4 votes
2 answers
335 views

In this F-104 V-n diagram, why does the stall speed (in terms of IAS) decrease with altitude in some parts of the flight envelope?

(This question has been edited to reflect a change in perspective: based on answers to the related question What is causing these "corners" on this F-104 V-n diagram?, I now believe that the ...
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0 votes
1 answer
189 views

Why did TWA800 not stall?

I believe the NTSB account, but based on this graph, http://twa800.com/lahr/zoom-climb.htm, why did the flight not stall after the nose separated?
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2 votes
1 answer
112 views

Could leading-edge dynamic stall occur for a tripped airfoil?

As far as I know leading-edge dynamic stall is characterized by the formation of a Leading edge vortex. This leading edge vortex forms due to the 'bursting' of the LSB (Laminar separation bubble). ...
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2 votes
1 answer
131 views

Retreating Blade Stall, P-Factor, and Gyroscopic Precession

Most airplane pilots are aware of P-Factor in propeller driven aircraft and that it tends create a torque in phase with the lift imbalance over the blade disc, resulting in a yaw moment about the ...
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0 votes
1 answer
133 views

Impact of centre of gravity position on stall recovery

Can somebody explain what is the impact of CoG position on stall recovery. I heard that stall speed is higher with forward CoG comapared to aft CoG, but does it have influence on stall recovery? Is it ...
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4 votes
3 answers
942 views

Why do tapered wings not stall at the root first?

Why do moderate tapered wings stall first at mid-wing section and high tapered wings stall at tip first? The effective AoA should be always higher close to the root? (considering no geometric or ...
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1 vote
3 answers
212 views

How the pitch of a blade must change along the length so that the blade does not stall?

I have to finish an assignment in the next couple of days. One of the questions asks to show how the pitch of the blade must change along the length so that the blade does not stall. I have no idea ...
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5 votes
1 answer
243 views

Is it possible to stall a stationary helicopter through excessive collective input?

I understand that helicopters can suffer from "retreating blade stall" where the retreating side of the rotor has low airspeed and stalls in a typical way that airplane wings stall. This ...
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1 vote
2 answers
247 views

Can Savannah be stalled with agressive yoke pull?

My friend fly ultra light Savannah, 2 seats plane,wings dont have slats ,it has vortex generators at leading edge. He says that he cant stall plane with agressive yoke pull (I talk about speeds above ...
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0 votes
3 answers
208 views

What would be the challenges for a pilot taking off into a headwind of just under the clean stall speed?

If a strong and fairly steady headwind was coming down the runway at just under the stall speed for a clean configuration/weight, what challenges would a pilot face? Or would it be fairly easy? Is ...
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-1 votes
2 answers
119 views

Is the vertical flight close to a building possible for GA plane?

Is the vertical flight in GA plane, so close to an actual building, as depicted in 67th second of Microsoft Flight Simulator 2020's official commercial, ever possible: Or is there "at least a ...
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0 votes
0 answers
237 views

Using XFOIL to find the angle of attack corresponding to buffet onset and stall

I am trying to find the angle of attack that corresponds to the stall point and buffet onset. I understand for stall this occurs at the maximum lift coefficient? However upon plotting a range of ...
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3 votes
1 answer
193 views

Would a wingtip stall still be bad if there was no aileron there?

If there was no aileron on the wing tip, would a tip stall still be bad compared to a root stall?
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0 votes
1 answer
642 views

Leading edge or trailing edge stall?

As I wrote last week, I'm doing a Benedek 10355 airfoil performance report. At this point of the work I am analyzing the stall of the profile at a fixed Reynolds number. The Benedek 10355 airfoil has ...
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2 votes
4 answers
817 views

What's the relationship between AOA and airspeed?

We know that any aircraft will stall at its stall speed (for a specific weight, CG position, etc.) but also, that the same airplane will always stall at the same angle of attack. I´ve read that IAS is ...
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0 votes
0 answers
60 views

In symmetrical airfoils is the stall angle the same for negative AOAs as for positive ones? [duplicate]

In symmetrical airfoils is the stall angle the same for negative Gs as for positive ones? Let say the stall angle is 17 degrees AOA. Is it the same if you push the nose down?
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10 votes
2 answers
3k views

What does the autopilot do if activated in a stall condition?

I was thinking about Air France 447 recently and had a wonder: What would happen if the pilots had re-engaged the autopilot and stopped all stick input? (If that's even possible in a stall condition). ...
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19 votes
1 answer
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Why does my wind tunnel experiment give two different stall angles of attack?

When I increase the angle of attack from 0 to 20 the stall begins at 18 deg. When I decrease the angle of attack from 20 to 0 the stall ends at 13 deg. Why the difference and what value (13 or 18 deg) ...
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5 votes
7 answers
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Why angle of attack is always shown against the relative wind parallel to horizon?

I have a question about Stall, which I have difficulty to understand. According to the theory, stall happens when : 1- Speed is slow then a certain limit. 2- Angle of attack is greater than a ...
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