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kasheee

Plane stalling

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Could you kindly check my understanding of the concept of stalling as below so that I can explain it to my 10-year-old nephew who is new to the game. 
 
******
If the engine speed is considerably lowered, the nose of the plane will start to fall due to gravity when one or both wings
 
make too sharp an angle with the air flow.
 
       On the other hand, if you increase the engine speed, the nose rises because more air is flowing over the wings, creating lift. 
 
Both situations lead to stalling. The goal is to return as quickly as possible to having a level flight. So if you want to rise, you increase 
 
the engine speed, the nose rises up, and you then gently pull back on the stick to reduce engine speed until you achieve level flight
 
Similar situation (but with the action reversed) when you start to descend.
 
        In summary, too little or too much air flow over the wings without compensating action by the pilot leads to stalling. 
 
Thanksin advance.

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Nothing to do with engine speed. It's about air speed (i.e. your engine can be dead, and you can still fly perfectly ... think of gliders). When the airspeed gets too low then the air flower over the upper surface of the wing will separate, typically briefly giving asymmetric forces on the wing, and the stalled wing tip will drop (because the other wing tip is still producing some lift, so continues to lift). With careful flying both wingtips can be stalled simultaneously and the airframe will either mush (nose drop then semi-recover from increased airflow) or still drop a wing and enter a spiral or spin. In half a nutshell. 

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@kasheee

I would say you are basically correct, and it is no good talking more detailed aerodynamics than this with a 10 year old, or giving a boring long-winded explanation.  I dare say he just wants to fly!  :laugh:

To a 10 year old I would summarise it as this: -

1.  To fly, the wing needs airflow around it at a certain speed.  If the airspeed falls too low, the wing will not function properly (stall) and you will start to drop out of the sky.  That speed is different for different aircraft.  A jet fighter or jet airliner will stall at a higher speed than a Cessna 152 / 172 for example.

2.  If you alter the angle of the aircraft too briskly (like pulling up to hard or too quickly), the airflow can also break away from the wing, and once again you stop flying (stall).

3.  To recover from a stall (if you can catch it quickly), then more power to bring back your speed, and maybe lower the nose to gain more speed quicker, if you have enough altitude.

4.  If the stall is bad, you can go into a spin or downward spiral, but if you have enough altitude, the plane can pick up enough speed to get control back and recover.  If you don't have enough altitude to recover, just try not to crash into any buildings or school playgrounds!  That is the decent thing to do!  :biggrin:


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45 minutes ago, lupedelupe said:

Nothing to do with engine speed. It's about air speed (i.e. your engine can be dead, and you can still fly perfectly ... think of gliders). When the airspeed gets too low then the air flower over the upper surface of the wing will separate, typically briefly giving asymmetric forces on the wing, and the stalled wing tip will drop (because the other wing tip is still producing some lift, so continues to lift). With careful flying both wingtips can be stalled simultaneously and the airframe will either mush (nose drop then semi-recover from increased airflow) or still drop a wing and enter a spiral or spin. In half a nutshell. 

It has nothing to do with airspeed,  you can stall a fighter jet at 600 mph. It is angle of attack, period. 

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Bob Cardone         MSFS 2020 , Fenix A320, Milviz C 310 , Kodiak , Simple Traffic  

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From a FL450 level, the slower you get, the more the upper wing airflow separates. You actually hear it and feel it as it happens. It's that buffeting sound you hear and feel that increases as the air continues to separate. In fact, these are the poor man's indicator that you are approaching the stall. You will also hear it in an accelerated stall where you increase the load factor and stall speed through large abrupt control inputs or steep turns. To get out of the stall, you want to break the stall. As you stated, power in and lower the nose some to recover. They used to teach us to minimize altitude loss, but that's not much of a concern anymore. Many people were entering secondary stalls because they would raise the nose too early worried about altitude loss. If you are stalling due to unusual attitudes, you have to correct the unusual attitude and then break the stall. If it's accelerated, stop the yanking lol. The key point is to know the impending stall situations and avoid them. Recognize the indicators and prevent the stall.

Now have fun converting that to 10 year old speak🤣. Actually, kids these days have a lot more understanding than we did at that age. Don't dumb it down too much, just kiss it.     

Rick

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3 hours ago, kasheee said:
 
Could you kindly check my understanding of the concept of stalling as below so that I can explain it to my 10-year-old nephew who is new to the game. 
 
 

You stall because your wing reaches critical angle of attack . You can stall at any airspeed.

angle-of-attack-1.jpg

Critical-angle-of-attack-AOA-and-stall-A

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7 minutes ago, sd_flyer said:

You stall because your wing reaches critical angle of attack . You can stall at any airspeed.

angle-of-attack-1.jpg

Critical-angle-of-attack-AOA-and-stall-A

I am always amazed at the number of pilots that don't understand what AOA is and how it relates to a stall, and many of them  die each year in GA accidents because of it. 


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Bob Cardone         MSFS 2020 , Fenix A320, Milviz C 310 , Kodiak , Simple Traffic  

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3 hours ago, kasheee said:
Could you kindly check my understanding of the concept of stalling as below so that I can explain it to my 10-year-old nephew who is new to the game.

Show pictures or videos. The concept makes much more sense than trying to discribe it verbally, in my opinion.
 

 

@sd_flyer's post is a good one to use.

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When you increase your AOA, you eventually hit the "Critical Angle of Attack" which the point at which air separates from the airfoil.  It is at that point that a stall occurs.


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17 minutes ago, andyjohnston.net said:

When you increase your AOA, you eventually hit the "Critical Angle of Attack" which the point at which air separates from the airfoil.  It is at that point that a stall occurs.

And if you are in a steep turn, the AOA on your inside wing may be higher than the outside wing, and if it stalls, welcome to the world of a spin. 

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Bob Cardone         MSFS 2020 , Fenix A320, Milviz C 310 , Kodiak , Simple Traffic  

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28 minutes ago, andyjohnston.net said:

I'm not an expert, but I don't think your turn even has to be that steep.

60 degree banked turn increases the stall speed dramatically (40%), pilots that overshoot the turn to final, and then try and salvage the approach by a steep turn, wind up often killing everyone on board the aircraft. 

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Bob Cardone         MSFS 2020 , Fenix A320, Milviz C 310 , Kodiak , Simple Traffic  

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8 minutes ago, andyjohnston.net said:

I'm not an expert, but I don't think your turn even has to be that steep

When I flew KC-10s, we had a load factor chart that accounted for bank and it's impact on stall speed. You go in at your beginning weight and ending weight to calculate your stall speeds at a specific bank. You wouldn't go over 20 degrees and 15 degrees was the nice bank angle when refueling. For the most part though, the tanker will just let it accelerate naturally as they offloaded so that your speed increased during the onload. That way you didn't have to worry about getting too slow with those large onloads. The DC10 has those low lift high speed wings that will give you some tickle even though you were not close to stalling. She would buffet during steep turns. Those ants stomping on the wings were you first indicator that you are getting to slow. In fact story time.

So during war, I had this guy in the left seat and we had just come up on station. Suddenly, we were contacted and directed to re-establish at this random point at a lower altitude for a high priority receiver. So of course, I state/go heads down, checking the map for threats/bingo and hand jamming in the refueling pattern. The pilot flying clicked off the auto throttles, ripped out the boards and started a rapid descent. I gave him an initial heading as I hand jammed like a mad man. Once I got it all loaded, I started cross checking everything and making sure the pattern was correct after giving him a direct to. As I flowed through, I started feeling that slight rhythmic shudder in the air frame. I looked up and saw the airspeed needle lower than where it should have been. I yelled out power! Boards! He shoved the throttles forward and retracted the speed brakes. Once he had the auto throttles back on, I continued my cross check. Even with the speed brakes out, I was still able to feel and notice that we were getting slow. That jet was very forgiving.

Rick     

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Take the kid for a drive in the car and have him roll down the window and stick his hand in the airstream, then experiment with what angles and speeds work to make his hand "fly" as opposed to being blown backwards or dropping.  When the car is moving too slow the air won't keep his hand up.  Too much angle and his hand will be blown backward instead of flying.  Both are examples of different kind of stalls. 

That's the way I think we figured it out as kids in the days when our parents let us stick our hand out the window.  It enough of an understanding until he gets into the finer details and understanding Flight Levels etc...

Edited by Stoopy

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