22k views

### How does stall depend on angle of attack but not speed?

Everyone says that the angle of attack is what determines a stall, not the speed. I understand the theory and understand that it is separation of the airflow that matters for stalling. However, I don’...
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### What is the immediate cause of stall?

The direct cause of stall is unclear to me. I heard about exceeding maximum angle of attack (around 40°) ; I heard about reaching the stall speed in the current configuration (flaps, etc). I heard ...
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### Why are planes slower at higher altitudes?

On many flight simulators, I have noticed that planes tends to get slower with increasing altitude. For example, I can reach 1100 knots just above the sea level in Google Earth flight simulator(F16), ...
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### What is a high speed stall?

I'm told that planes can actually stall when the airflow over the wing goes past Mach 1? Why does this happen and how do you design an aircraft to avoid it?
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### What is the relation between an airplane's altitude and the drag it is experiencing?

The Reynolds-Number $Re$ is defined as $Re = \frac{c \cdot L \cdot \rho}{\mu} = \frac{c \cdot L}{\nu}$, with the velocity $c~\left[ \frac{m}{s} \right]$, the reference length $L~\left[ m \right]$, ...
56k views

### What happens when an aircraft breaks the sound barrier?

What happens when an aircraft breaks the sound barrier? Why can't it break the sound barrier near the ground?
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### How slow could the U-2 fly at 50,000 ft?

How slow could the Lockheed U-2 fly at 50,000 ft? It was surely subsonic as its max speed is 500 mph.
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### Under what conditions do airplanes stall? [duplicate]

I've seen somewhat conflicting information on when planes stall. I've seen references to "stall speed," apparently a speed below which the airplane will stall, but stalling also seems to be ...
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### Is there always a stall if you exceed a specific angle of attack?

So lets consider that the stall angle (=Cl max) of a B747 is at 16° (in clean configuration). Does this mean, that, at whatever speed you are flying (i.e. 500 knots), you would stall if you go on a ...
317 views

### Why would a ram air parachute need less brake input to stall at a higher altitude?

I have some anecdotal evidence that a ram air sport parachute requires less toggle input to stall at higher altitudes. A pilot needed one wrap of the brake lines around the hands to quickly, ...
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937 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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1 vote
579 views

### Does Indicated Stall speed increase with altitude (Coffin Corner)?

It is my understanding that Indicated Stall speed is mostly constant with altitude, the one that increases is True Stall Speed. Given that PFD show speed as IAS, how come the yellow speed range ...
1 vote
35 views

### Can partial flow separation make the effects of Reynolds number on stall more significant?

While discussing this stall differences with altitude question with a skydiving canopy designer, I told him that most people seemed to think Reynolds would not be significant at these altitudes. His ...
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1 vote