What exactly is a stall when talking about airplanes?

Question

Ok im doing a report on airplanes from the small ones to the airliner jets and was wondering what exactly it means when a plane stalls. Also are there different type of stalls, and do pilots stall on purpose? And finally can you recover from a stall once it happens?

Answer 1

A stall can happen at fast or slow speeds as it is when the wing exceeds the critical angle of attack, which is the angle between the cord line that goes through the wing from the leading edge to trailing edge and the line that would represent the horizon.

Answer 2

Simply-  it means the air flow over and under the wings have been disrupted.

If you look at a wing from the side, you'll notice how the top is humped and bottom is flat?   As an airplane moves through the air,  the air gets split, some going over, some going under.  That hump causes air going over the wing  to 'move' faster.  The faster moving air creates low pressure on top of the wing.  The high pressure under the wing wants to push up (creating lift) into the low pressure, like a vacuum.  

When you lose that pressure difference, your wing has stalled (no lift).

To recover- simply push the nose of the aircraft down (push the control yoke forward), throttle up and pick up some airspeed.  When your speed is high enough, you can go back to straight and level flight and reduce power, back to what's called 'cruise power'.

This is a very simple explanation. Ok pilot, hope that helps.

Answer 3

A stall happens when the wings no longer make enough lift to support the plane.  They may still make *some* lift, but not enough to sustain flight.

First - a little bit about planes and such:

A wing makes lift because the wing splits the air into 2 masses - one mass goes over the wing, the other under.  The top surface is curved more than the bottom, making that air mass travel further and faster than the mass that goes below.  Venturi's Law says that a fast-moving fluid exerts less pressure on a surface next to it than does a slow-moving fluid.    So there is less pressure on the top of the wing than on the bottom.  So the faster the air flows over the wing, the more lift it makes.  You can see this effect by holding a piece of paper by one edge up to your mouth, and blow gently across just the top side.  The sheet of paper will rise up.   Blow harder, and it will rise more.

Next - the angle of attack is the angle made by the oncoming air, and essentially a line from a point the forwardmost leading edge of the wing to the hindmost, trailing edge directly behind that leading point.

A stall can happen either if the plane slows down, or increases the angle of attack, or both.  Slowing down means less lift.  Increasing the angle of attack means that the airflow separates from the wing surface - it doesn't flow smoothly over the entire surface.  This means that there is less area on top of the wing with low pressure on it, so there is less lift.  If you combine the two, you get much less lift.

A pilot may stall on purpose - stunt pilots do it all the time.  Flight instruction used to teach stall recovery, but I'm told they don't any more unless the student request it.  And yes, a pilot can usually recover from a stall, although some designs make it harder to do so than others.

Answer 4

When there is loss of lift on the wings, it can happen by slow speeds, or or a very short burst of loss of lift. You can recover by pulling back on the nose once you gain speed. When you stall your nose drops down, but not always sometimes you just fall down, in that situation you pull the nose down gain speed and pull the nose up, pilots are taught stall recovery in school. Pilots do stall in school because it is required for a pilot to learn how to stall, but no pilots do not stall on purpose, just in school.

Answer 5

Simply..It is when the wing stops flying

Answer 6

I am a trainee pilot and am just finishing my last exams.

My formal defenition from my trainee handbook says:

A stall is a condition in aerodynamics and aviation where the angle between the wing's chord line and the relative incoming wind (the angle of attack) increases beyond a certain point such that the lift begins to decrease. The angle at which this occurs is called the critical angle of attack. This critical angle is dependant upon the profile of the wing, its planform, and its aspect ratio but is typically in the range of 8 to 20 degrees relative to the incoming wind for most subsonic airfoils. The critical angle of attack is the angle of attack on the lift coefficient versus angle-of-attack curve at which the maximum lift coefficient occurs, and it usually represents the boundary between the wing's linear and nonlinear airflow regimes. Flow separation begins to occur at this point, decreasing lift, increasing drag, and changing the wing's center of pressure. A fixed-wing aircraft during a stall may experience buffeting or a change in attitude (normally nose down in General aviation aircraft). Most aircraft are designed to have a gradual stall with characteristics that will warn the pilot and give the pilot time to react. For example an aircraft that does not buffet before the stall may have an audible alarm or a stick shaker installed to simulate the feel of a buffet by vibrating the stick fore and aft. The "buffet margin" is, for a given set of conditions, the amount of ‘g’, which can be imposed for a given level of buffet. The critical angle of attack in steady straight and level flight can only be attained at low airspeed. Attempts to increase the angle of attack at higher airspeeds can cause a high speed stall or may merely cause the aircraft to climb.

Any yaw of the aircraft as it enters the stall regime can result in autorotation, which is also sometimes referred to as a 'spin'. Because air no longer flows smoothly over the wings during a stall, aileron control of roll becomes less effective, whilst simultaneously the tendency for the ailerons to generate adverse yaw increases. This increases the lift from the advancing wing and accentuates the probability of the aircraft to enter into a spin.

Depending on the aircraft's design, a stall can expose extremely adverse properties of balance and control; particularly in prototype. The ease with which a particular aircraft will recover from a stall depends on the dynamics of the aircraft itself and the training of the pilot.

Hope this helps :)

Answer 7

A stall is when the wing loses lift due to loss of forward airspeed. There are unintentional stall and intentional stalls.  Usually a pilot can regain the lift by nosing the aircraft down to increase speed and thereby increasing the airflow over the wing to recover from a stall. A pilot will probably answer this in more detail, but that is the basics.

Answer 8

Pilots do stall on purpose--full stall landings are often done in single-engine aircraft.

Answer 9

stall is when you are not going fast enough to stay in the air.  Whenever I am landing, I do a stall.  I am 5 feet off the ground or so and cut my engine power.  I lift the nose ceating a stall.  My back wheels falll and touch down then I bring the nose down.

Answer 10

One reason, when the aircraft is not "trimmed" ptoperly.

Consider this.  If all the weight/passengers were to stand in the tail section, imagine the aircraft tilting with the nose upwards and the belly dragging air, trying to push forward.

This could conceivably happen, beyond the control of the pilot.

That's a perfect example of a situation to cause a stall.

Often with sparse passengers, they will be spread around to distribute the weight.

Bear in mind, the constant job of a pilot is to keep the aircraft trimmed as passengers move around the cabin.  He must keep the craft level from front to rear as well as side to side as passengers may move left to right in order to view something on the ground.  That too happens.

As long as the engines have not developed mechanical problems, they shoud be able to pull out of a stall.  The critical thing is not to allow it to happen, as above.

Answer 11

A stall is when the angle of attack, the angle at which the wings meet the onrushing air, is exceeded and the wings lose lift causing the plane to drop. The angle of attack at which this happens can vary depending upon the airspeed. Sufficient flow of air must continue over the wings to maintain lift. A stall can occur very basically speaking when one of two things may happen:

Too steep an angle of attack with insufficient flow of air over the wings causing a stall or

Insufficient airspeed at any angle, again not enough airflow over the wings.

A stall can be easily recovered from providing you have sufficient space between you and anything hard underneath you (like ground).

Pilots are trained to induce stalls thereby learning to recover from them.

Answer 12

A stall is an excessive loss of lift due to the separation of airflow from the upper surface of the wing due to reaching the critical angle of attack

http://i28.tinypic.com/wi5a44.jpg

Angle of attack is the angle between the relative

wind and the imaginary chord line of the wing.

The critical angle of attack remains constant regardless of weight, dynamic pressure, bank angle, and pitch attitude.

It is the stall speed that varies with changes in weight and CG location, load factor, and power settings.

Stall are intentional or unintentional

They are required to be practice in flight training to get your private license, commercial and i'm not sure if your instrument requires it.

Types of Stalls

Power-off

Power-on

Accelerated

Secondary

Cross-control

Elevator trim

Stall Recovery:

Yes you can recover from a stall

Simultaneously reduce angle of attack and maximum power.

Maximum power minimizes altitude loss.

After regaining airspeed, level the wings if necessary and smoothly apply elevator back pressure. Coordinated use of flight control is essential to avoid spins.

Dangers of Stalls:

You can recover or its very hard to recover if you have an aft CG (Your Center of Gravity has shifted back)

It could lead to a spin if you are uncoordinated

You don't want to stall close to the ground or in traffic patterns