How do you know 'when' an aircraft has stalled?

[Tomo]

This question was asked by Mr DJP and I have really enjoyed thinking about it. Just wish I had more time to research and study more on the subject.

 

But what a good question - so I thought it would be something worth while discussing, hope you don't mind me pinching your question DJ!

 

 

[turboplanner]

W

 

 

[Guest Maj Millard]

Pull the stick back..the houses get smaller....pull it back some more and the houses get bigger real quick !!!..............................................................Maj...

 

 

[facthunter]

You usually get buffetting, you lose lift and get lots of drag. Your wing has stopped working, as a wing. Nev

 

 

[turboplanner]

You usually get buffetting, you lose lift and get lots of drag. Your wing has stopped working, as a wing. Nev

Yes, but DJ is a cunning so and so. He's out to trick us, so the answer will be a lot more subtle. Think steep turns, abrupt manoeuvres.

 

 

[turboplanner]

And maybe don't even think that!

 

 

[Guernsey]

How do you know when an aircraft is stalled?

 

Simple visual observation.

 

It will be parked in a stall at the back of the shearing shed.

 

Cor stone de crows he's at it again.

 

Alan the Guern.

 

 

[turboplanner]

Yes but that's a pommy aircraft.

 

 

[winsor68]

When the airflow separates from the wing?

 

 

[David Isaac]

When the aircraft will no longer respond in upward pitch to any further application of the elevator.

 

 

[turboplanner]

When the airflow separates from the wing?

Yes but how do you know when that is happening.

 

One thing a certain instructor did with me was make me fly with the stall warning buzzing - it became steady flight.

 

 

[Guest davidh10]

I like David Isaac's response, however the term "stall" is very generic and simple too. It is used to generically refer to the loss of lift due to the boundary layer of the airflow breaking away from the upper surface of the wing, however it can occur differently in different situations and the perceived behaviour will be different in some of them. Depending on wing shape, a stall may start at the wing root and gradually extend outward and backward across the wing surface (wings with wash-out), or be more general:-

 

• Full stall, both wings in horizontal flight with no gusts. Nose drops. Altitude loss.
   
   
  
• Partial stall both wings in horizontal flight with no gusts. Cannot climb. May lose altitude. Aircraft feels unstable (mush).
   
   
  
• Either of the above to different degrees with each wing. Will cause an uncommanded turn in combination with the above symptoms.
   
   
  
• Gusty. One wing may stall and the other not. May be full stall but only for a second or two.
   
   
  
• Fly through the edge of a dust devil. One wing may stall momentarily, resulting in an uncommanded turn.
   
   
  
• A stall in a turn will result in both altitude loss and increase in the radius of the turn, as some of the lift is providing the centripetal force. Due to differing AOA of each wing in a turn, one wing is likely going to have a more pronounced stall than the other.
   
   
  

 

 

I don't have a tailplane, so has no effect.

 

The centre of lift will move aft with respect to the centre of gravity.

 

 

[Guest ozzie]

When your pax starts screaming loud and people on the ground under you start running for cover!

 

serious.

 

buffeting at high AoA indicates onset of a stall ( a turbulent airflow over the wing) followed by break of airflow over the wing that leads to loss of lift. The design of the wing section, weight and CoG position all contribute to the stalling characteristics of the aircraft.

 

Trying to find a true and correct answer to this question is like asking how long is a bit of string, what came first egg or the chicken etc.

 

 

[dazza 38]

When the Stick or control column is moved passed the stall stick position and aircraft deviates from its intended path.

 

 

[turboplanner]

DJ will know Ozzie

 

 

[Guernsey]

When your coffee ends up in your lap. the overhead locker opens and the excess baggage follows the coffee, the person next to you grabs your hand and breaks it, the air hostess ends up flat on the floor, people sitting on the toilet end up on the ceiling, and the Captain confirms that we have experienced a minor incident.

 

Alan.

 

 

[Guernsey]

You know the aircraft has stalled when it is no longer flying, rather, falling to the ground; If you fail to recover, it will most likely hurt.[/font]

I prefer this condensed version.

 

Alan.

[facthunter]

But you can actually fly some planes when they are stalled. ( And I'm not talking about an upwards flick roll) Nev

 

 

[dazza 38]

Hang on fellas, the question is when a aircraft is STALLED.Buffeting, sloppy controls, etc are a precursor to a Stall.The question says stalled, which means the stall has already happened.Im sticking to my post #17. Also I better add, because I dont think peeps have got what im saying in #17.When I say aircraft deviates from its intended path.That means the aircraft , is not reacting in relation to the stick input. Eg-Nose drops towards the ground, even if it is pulled back, beyond stall stick position. If inverted, stick pushed too far forward. Past the forward stall stick postion.Aircraft is stalled inverted and heads toward the ground.etc.Also a aircraft can stall at any airspeed.

 

 

[poteroo]

When weight exceeds lift and drag exceeds thrust?

 

happy days

 

 

[Guest Howard Hughes]

If you are flying a Beechcraft twin (with power on), then you are more than likely upside down...

 

 

[djpacro]

When weight exceeds lift and drag exceeds thrust?happy days

[kaz3g]

*Note: This is in no way an answer; it is merely getting you thinking about the question. But I suppose I should add my thoughts on an answer: You know the aircraft has stalled when it is no longer flying, rather, falling to the ground; If you fail to recover, it will most likely hurt.

There are different types of stall but they all occur when the critical angle of attack is exceeded and the wings lose lift (dynamic stall). While the traditional check ride stall will result in the aircraft losing height because there is not enough lift to sustain hozontal flight, you can also stall your aircraft while performing a zoom upwards to near vertical if you pull back too hard (accelerated stall - lots of power can compensate for loss of lift even in this situation, too).

 

The Air France thingy was the result of a deep stall as far as I recall --- I think the wings were blanking the tail and the pilot held it in the stall because he was descending but his ASI wasn't working. He should had been adding power and flown it out of the stall.

 

So I think you know when a stall has occurred because the elevators will have lost their authority

 

kaz...fingers crossed

 

 

[Powerin]

Geez that's a mind-bender of a question DJP. I can't think of a definitive answer which will be true for all situations. Being a student I've only stalled an aircraft about 20 times and you never get to explore the situation beyond about the first second.

 

So (only theoretically in my mind) Dazza's answer seems best to me...when an aircraft departs from an expected flightpath given a particular stick position.

 

But that stalled stick position would have to be maintained to continue the stall...unless the horizontal stab has also stalled in which case forward stick would worsen the HS stall and probably continue the main wing stall??

 

Aft CofG would exacerbate this. Is there anything else that causes the HS to stall?

 

 

[Mazda]

Who says the stick has to be back for the aircraft to be stalled?