Fly Lah!

Hi guys... i have a simple question.

How can aircraft stall? It is due to high Angle of Attack or Airspeed?

I've come across this question and the answers i got are:

-->> Aircraft stall due to insufficient airspeed
-->> Aircraft doesn't stall due to high angle of attack
-->> Wing will stall due to high angle of attack

Sorry if my question turn your eyes up high Lets talk about this

Because of the aircraft exceeds its critical angle of attack..Correct me if i'm wrong..huhu

The wing will stall when the AoA is way pass its optimum angle even with maximum thrust applied. But it still depends on the characteristics of that particular aircraft / wing. Aspect Ratio, Swept back, taper ratio etc etc.

For what I know, the more thrust you have the Higher the stalling angle, the Lower the stalling speed. *Correct me If I'm wrong*

[quote="mosumo"]
-->> Aircraft doesn't stall due to high angle of attack
-->> Wing will stall due to high angle of attack
quote]

what is an aircraft without the wings?

aircraft will stall if the aoa of wings exceed its limit.

Next time when you play flight simulator 2004 or X..Read dont just play maa..hehe..Buat penat je Rod Machado tulis u x baca..keke

nazirul87 wrote:

ok..i know what you mean. aircraft must have wings.

what if i say, wings of aircraft wont stall no matter how high the angle of attack providing the aircraft at its correct airspeed? what im trying to explain is; when pilot purposely try to stall(like rotate control stick aft hardly) his aircraft in situation that the airspeed is sufficient, at first few seconds or even faster the A of A is increasing until the moment where the relative airflow back to normal.

I think the best way to study is by observing aircraft that performs aerobatic manuever.

neway, an aircraft must associated with engine. without engine, we only can call it airframe. What i mean by wing stall is , it must be accompanied by the entire airframe exclude engine. Or we can use airframe stall.

take a look at this situation: An aircraft is gliding because its engine fail. In order to maintain the lift force, it cannot lose the airspeed. In order to do that, pilot must descent(nose down to certain angle) which is gravity is the only force available to pull the aircraft thrust component. of course altitude will decrease.

The fact is the engine had failed, so i believe we can assume that there's no engine! In that situation, if the pilot increase the angle of attack, the 'aircraft with dead engine' will stall.

Aircraft will stall when there is an absence of LIFT.
Consider the situations when LIFT is reduced or will be zero.
Yes, one of the situation when you exceed critical angle of attack and goes into stalling angle.
What other factors? THRUST. You reduce thrust, you reduce LIFT until GRAVITY/WEIGHT overcomes LIFT.
Anything else?...

This would be the best answer for the question:
"Wing will stall due to high angle of attack"

Remember the formula of the Lift: you have 2 parameters on which you can work: the speed and the Angle of attack.
you have also a curve Coefficient of Lift function of Angle of Attack. With the Angle of attack, the coefficient of Lift (CL) increases up to a maximum (generally around 18 degrees- depends on the specifications of the airfoil) and then decreases sharply.
To maintain a level flight, you have to maintain constant your Lift. So if you increase your speed, you have to decrease your angle of attack(Attitude of Aircraft). On contrary,when you decrease your speed you have to increase your angle of attack (Attitude of Aircraft), BUT it is true only until you reach the CL max, after the lift is insufficient and you stall....On an aerodynamic point of view, the stall appears when the airflow is lifting from the airfoil and the flow after the separation point is no more in contact with Airfoil.
When the engine is running, there is an airflow acceleration on part of the wing due to the propeller. So the stall appears at a lower speed, but when it occurs it is more rough...There is also a high speed stall due to compressibility effects, but it is another story.
go to your Principles of Flight books ....

A good website for POF initiation:
http://www.allstar.fiu.edu/aero/princ1.htm

-- Sat Jul 04, 2009 3:02 pm --

Stall in turn- stall in turbulence
when you turn one part of the Lift force is going to be used for counteracting the centrifugal force, as consequence you have to increase your speed and angle of attack to avoid stalling in the turn.
Same in turbulence, you have to increase the speed in order to avoid the stall as your A of A varies with the gusts (depending on Direction and force of the gusts): you must have a range of variation of your A of A.
In high altitude (30,000ft and more for a typical Airliner) you have the low speed stall, but you have also the High speed one due to appearance of transonic effects, (the lift decreases with increase in speed). You are working between two limits.
This can be important. As crew when we are "heavy" we have to check what is our maximum altitude taking into account a factor for turn/turbulence: we cannot increase the speed (expressed in mach Number in those altitudes) over the upper limit. So we check what is the factor we can cope with, eventually this can be limitative for climbing.
It is one of the speculations on the Air France A330 accident, the aircraft would have gotten a turbulence higher than what is normally recommanded to cope with, would have stalled and cannot recover from the stall for unknown reasons. I repeat this is a speculation coming from some Air France pilots, but the real thing maybe quite different, just a working hypothesis.....

Terengganu01 wrote:Remember the formula of the Lift: you have 2 parameters on which you can work: the speed and the Angle of attack.
you have also a curve Coefficient of Lift function of Angle of Attack. With the Angle of attack, the coefficient of Lift (CL) increases up to a maximum (generally around 18 degrees- depends on the specifications of the airfoil) and then decreases sharply.
To maintain a level flight, you have to maintain constant your Lift. So if you increase your speed, you have to decrease your angle of attack(Attitude of Aircraft). On contrary,when you decrease your speed you have to increase your angle of attack (Attitude of Aircraft), BUT it is true only until you reach the CL max, after the lift is insufficient and you stall....On an aerodynamic point of view, the stall appears when the airflow is lifting from the airfoil and the flow after the separation point is no more in contact with Airfoil.
When the engine is running, there is an airflow acceleration on part of the wing due to the propeller. So the stall appears at a lower speed, but when it occurs it is more rough...There is also a high speed stall due to compressibility effects, but it is another story.
go to your Principles of Flight books ....

A good website for POF initiation:
http://www.allstar.fiu.edu/aero/princ1.htm

-- Sat Jul 04, 2009 3:02 pm --

Stall in turn- stall in turbulence
when you turn one part of the Lift force is going to be used for counteracting the centrifugal force, as consequence you have to increase your speed and angle of attack to avoid stalling in the turn.
Same in turbulence, you have to increase the speed in order to avoid the stall as your A of A varies with the gusts (depending on Direction and force of the gusts): you must have a range of variation of your A of A.
In high altitude (30,000ft and more for a typical Airliner) you have the low speed stall, but you have also the High speed one due to appearance of transonic effects, (the lift decreases with increase in speed). You are working between two limits.
This can be important. As crew when we are "heavy" we have to check what is our maximum altitude taking into account a factor for turn/turbulence: we cannot increase the speed (expressed in mach Number in those altitudes) over the upper limit. So we check what is the factor we can cope with, eventually this can be limitative for climbing.
It is one of the speculations on the Air France A330 accident, the aircraft would have gotten a turbulence higher than what is normally recommanded to cope with, would have stalled and cannot recover from the stall for unknown reasons. I repeat this is a speculation coming from some Air France pilots, but the real thing maybe quite different, just a working hypothesis.....

The statement "ABOVE" is the most excellent answer to the questions asked. Nuff' said.