What does it mean when an aircraft "stalls"?

Answer 1

Joe S is the only one that has it right, you can stall at ANY speed with powere or not, any one ever heard of a glider?? the reason for stalling is exceed ing the critical angle of attack

edit" apology's to Dennis, he too explains it as well.

to the poster below, while your $100 words
might be correct, any one that has not sudied
aerodynamics would have no idea what the hell you are talking about. Hope fully you impressed your self, Didin't impress me. I could have grabbed my copy of Aerodynamics fort Naval Aviaters and spewed out pages of "how an airfoil stalls", but it would be of no help to the Person that asked the question!

Answer 2

An aircraft stalling has nothing to do with the engines.

Air moving over the wings produces lift. When there is not enough air moving over the wings to lift the aircraft it is called stalling.

This can be affected by different things, the most common is the speed the aircraft is traveling through the air. Imgine you are driving down the highway at 60 mph with your hand out the window. If the front of your hand is raised a little more than the back the wind will try to lift your hand up. If the driver stops the car your hand is no longer being lifted.

Other factors are the shape of the wing, the attitude of the aircraft(if its pointed up or down) and anything that may be disrupting airflow over the wing(example: frost on the wings). All of these affect the speed the aircraft needs to be going to produce enough lift to cary the weigh of the airplane.

If you are flying the airplane and it stalls, the nose will go down and you feel a falling sensation. If you hold the controls back which tells the airplane you want the nose back up, you will continue to stall because you can not gain enough airspeed to fly. Instead if you start to stall you need to push the controles forward and dive towards the earth untill you are going fast enough to fly again. You should also make sure you have the throttle set for more power if you had not already done so.

One method for landing is to fly towards the runway with the power at the minimum setting. Fly untill you are almost touching the runway and then start pulling back on the controlls. As you pull back the nose of the airplane goes up and the airplane slows down. As it slows down you have less lift and need to raise the nose higher. You keep doing this just barely off the runway untill the airplane stalls. You will then fall the foot or few inches to the runway and be going slow enough that you cant fly. This is why you feel a bump when you land sometimes, its from falling the last little bit onto the runway.

Hope this helps,
dennis

Answer 3

Most of the previous answers are close, but basically a stall happens when the engine can not provide enough forward momentum to get the wings to keep the aircraft in the air.

In the days of 40 hp engines (think World War I), a stall was common if you tried too steep a climb -- the engine couldn't pull the plane faster through the maneuver than gravity pulled it down!

Since engines have become more powerful, this is less a cause, and it becomes more a problem of maintaining forward velocity -- keeping the speed up, as others have said.

Stalls occur during landings by trainee pilots because they come in too slowly.

And it certainly wouldn't help if the engine stalled out, as Beez said.

Answer 4

An aircraft will always stall at the same angle of attack regardless of airspeed, weight, & load factor, this angle varies 16-18 degrees for most aircraft. Angle of attack is simply the chord line of the wing to the relative wind. The wing produces low pressure air on top and high pressure on the bottom, as the angle increases so does the pressure differential, but when the critical angle is reached, the wing will stall because the airfow on top of the wing will become turbulent and "unstick" resulting in loss of lift. The only way to remedy this is to lower the nose below the horizon until speed increases above VS.

There are three separate situations where the critical angle of attack can be exceeded: low speed, high speed, and turning flight.

In straight & level flight as speed decreases the AOA must be increased to compensate for the loss of speed, remember that as AOA increaes so does lift.

The wing can stall at any speed, an aircraft can be traveling at 200kts but if the pilot pulls back quickly the AOA will change from very low to very high immediately.

In turning flight lift is split into vertical and horizontal components. as bank increases the AOA must increase to create more lift because of the decrease of the vertical lift component and increase of centrifugal force.

case & point engine has nothing to do with an airplane stalling, even if the engine quits you can fly the plane using best glide speed.

Answer 5

Most people think of an engine stopping when they hear the word stall. When talking about flying,the word stall has an entirely different meaning. It's sometimes called air-stalling.
When a plane passes through the air, it's held up by the slope of the wings pushing the air downward as the plane moves foreward. If the foreward motion is too slow the plane stalls and drops.
Try this- - - When sitting on the passengers side of a car going a good speed, hold your hand out of the window with your palm down. Now slant your hand so that the thumb is slightly higher, The wind passing over the palm of your hand will cause the hand to go upward. Turn the thumb below the level of the palm, and the hand will go down.
Now if you have your hand turned just right it will take no effort to hold it there. Withour changing the position of your hand, have the driver slow down. your hand will drop unless you use muscle power to keep it up. When your hand dropped, it air stalled.

Answer 6

When the airflow over the wings is not enough to generate suitable lift for the aircraft, thn the aircraft falls out of the sky. This is a stall

Answer 7

You can check with any pilot training or flying lesson facility for the FAA definition, but it generally means the speed at which a planes engine when it is operating, will keep from making forward progress in flight. For example only, small single engine Cessnas have stall speeds between 57 and 80 miles per hour. Also an airplane flying horizontally changes to a straight up vertical climb - at some point the engine is not powerful enough to keep the plane climbing. When it hits the 'top', the planes progress will "stall" and the plane will start to descend.

Answer 8

It is all about angle of attck. Stalling has NOTHING to do with the engine. I have stalled many times with the engine at full power.

Due to the curve of the wing, air passing over the top has farther to travel than air passing under the wing. This causes high pressure below and low pressure above the wing, aka lift.

Angle of attack is the angle of the wing relative to the air. When this angle gets too great, the air no longer flows over the top, rather it is deflected away from the wing resulting in a loss of lift.

Answer 9

Stall is actually the situation when lift coefficient is maximum, but after this point lift decrease.
Lift coefficient can be considered proportional to angle of attack:
Cl= α*π (lift coeff = angle of attack *π) for thin airframes.
but this law is valid only when angle of attack is not too big, less than about 10°-15°( α<10°~15°).
When Cl is no longer proportional to α (but is still increasing with α) we are near stall situation(α<α_stall). When Cl is at his max value, it also starts to decrease for α>α_stall.
The big problem is that beyond stall drag is very bigger than in normal flight.
Aerodynamically Stall is almost independent from speed(little Reynolds number influence) but in airplanes there is a minimum flight speed called V_stall because when you fly at minimum speed you need the max Cl(that is stall situation) to have lift-weight equilibrium, and you can't fly slower because Cl can't be bigger.

Answer 10

The sign is to encourage you to obey the law. They aircraft, usually fixed wing patrol the highway. They can see far more roadway than a cruiser on the ground. There are lines painted on the road and the observer in the plane times how long it takes you to go from the first line to the second. They then calculate the speed. If you are speeding they radio ahead for the cruiser to nab your car. Truly the goal is to get you to slow down, not write tickets.