Airplane Normal Stall

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Normal, Power-off Stall
Before you practice any flight maneuver, be sure to execute clearing turns to ensure that the airspace you are flying in is clear. You will not only want to check for traffic at your altitude, but also above and below your altitude. You may have a tendency to gain or lose altitude as you practice, and it is important to verify that no other airplanes are in your vicinity. After reaching a safe altitude and clearing the area, slowly ease the throttle to idle. The reason we do this slowly is to prevent rapid cooling of the engine. After a long climb to altitude, the engine has heated up as a result of generating more power and the reduced airflow around it due to the increased angle of climb. If the engine is cooled too rapidly, this can result in excessive engine wear or damage to engine components.

You will start the maneuver at a specific altitude. Maintain that altitude as the plane slows by easing back on the control yoke, just as you did during slow flight practice. But rather than maintain a given airspeed, you will want to bleed off speed until the airplane stalls. When the stall takes place, you should have the control yoke at or near its aft stop. As the stall approaches, you should notice the same sensations we discussed in the slow flight section: soft control feel, reduced engine noise, and the sound of airflow around the plane will become quieter.

Most planes experience a certain amount of buffet as the plane nears stall speed, but the amount will vary for each plane. As the plane stalls it will normally experience a nose-down movement known as the “break.” The break signals that the stall has occurred and is a pitch-down movement. The amount of break will also be different from plane to plane. In some cases the break can be sharp and very noticeable, while in others the plane may wallow along without a significant pitch down.

While the plane is approaching the stall, or as it stalls, it may have a tendency to drop off on a wing. This can be the result of how the airplane is rigged, or minor differences in the plane’s wings’ angles of attack. For many pilots the first response is to use the ailerons to maintain wings level during the stall. This should be avoided, instead using the rudder to keep the wings level. Ailerons generate their roll ability by changing the shape of the airfoil. When a plane stalls, this can result in a deeper stall of a wing and a more aggravated stall situation. In some cases this can cause the plane to enter a spin. The use of rudders to hold the wings level as the plane stalls helps prevent this from taking place. If the left wing of the plane drops, you will want to use right rudder to help lift it back up. If the right wing drops, use left rudder to keep it level. Make sure you neutralize the rudder once the wings are level again, and don’t overcontrol the amount of rudder you input. Practice with a plane will help you get used to how much rudder should be used.

As the plane stalls, you will initiate stall recovery procedures. For normal stalls this will include relaxing backpressure on the control yoke to reduce the angle of attack and adding full power. Reducing elevator backpressure will result in a nose-down attitude, which puts the angle of attack less than the critical angle of attack. In most cases you only need to drop the nose of the plane slightly below the horizon. Figures illustrate the position of the nose just prior to stall entry and as the plane recovers from the stall. In this case the nose of the plane has been lowered only a small distance below the horizon.

The use of engine power will help the plane recover more quickly from the stall and reduce the amount of altitude the plane loses. Make sure you use full power when you apply the throttle. Some pilots have a habit of easing in only a small amount of power, which results in greater altitude loss. As the plane achieves flying speed, ease the elevator back to produce a positive rate of climb. Avoid pulling the nose up too quickly; this could result in a secondary stall and the need to recover from the stall again with an associated altitude loss.

One of the most common errors is not causing the plane to stall completely. This is normally the result of a timid use of the elevator and not getting it back quickly enough, or all the way to the back stop. The results will vary, but the plane may wallow, not getting a clean break. The use of ailerons to hold the wings level during the stall is also common as pilots begin to learn this maneuver. They have been trained to use the ailerons to control the roll of the plane, and now they must learn to use the rudder in place of the ailerons.

As the plane stalls, some pilots will shove forward on the control yoke too aggressively, resulting in a significant nose-down attitude. Not only does this pin you against the seat belt and cause all the dirt to float up from the floor, but it also results in excessive altitude loss. In most cases gently releasing backpressure and lowering the nose to just below the horizon is sufficient to break the stall and let the wings start to fly again. Regarding the use of the engine during power-off stall recovery, pilots may forget to add engine power and only use partial power as they recover from the stall. Always add full power in a smooth, constant application. Finally, some pilots will then use too much elevator or apply it too rapidly as they attempt to establish a positive rate of climb. As we discussed, this can cause the airplane to stall again and result in even more altitude loss. Smoothly ease the nose of the plane up as flying speed is increased until the descent is stopped.

Normal, power-on stall
Power-on stalls are very similar to the power-off stalls just covered. Flight control use is the same to enter and recover from both stalls, the major difference being that full power is being produced by the engine during entry into a power-on stall.

There are a number of different ways to enter a power-on stall, but this discussion concerns entry from cruise power settings. First ease the nose of the plane up, letting airspeed bleed off to the best angle of climb speed. At that point advance the throttle smoothly to full power. Keep pulling back on the control yoke in a firm, constant motion to keep the nose of the plane coming up and bleeding off airspeed. As with the power-off stall, you will notice that the flight controls become less effective. The sound of the engine will seem to change as the plane slows.

The plane will begin to buffet, as with the power-off stall. The additional airflow generated by the propeller tends to increase the amount of air flowing around the wings and fuselage, and this causes a stronger buffet. The strength of the buffet will be different in each plane and may be more pronounced in some models than in others.

As the plane stalls it will once again have a tendency to pitch nose down. As the plane stalls, release backpressure on the elevators and allow the nose to drop just below the horizon to reduce the angle of attack. The amount of nose-down attitude you will need to achieve to break the stall will differ for each plane, and some planes may require a greater pitch-down attitude than others.

Since power should already be set at full power, you will not need to advance the throttle during the stall recovery. It is a good idea to keep your free hand on the throttle to make sure it doesn’t creep back during the stall. Once your airspeed has increased sufficiently, ease the nose up and establish a positive rate of climb.

Pilots seem to feel less comfortable with the pitch angles the plane achieves during power-on stalls and how much elevator it takes to get many airplanes to stall when the throttle is at full power. Figure shows the pitch angles just before a power-on stall, then after the plane stalls. Compare these to the pitch angles in the power-off stall, and you can see how much steeper the angles are. Because the engine is producing full power, it also takes a considerable amount of right rudder to keep the ball centered as the plane’s airspeed drops. Because the nose rises so much, it is often difficult to see the horizon over the nose of the plane, adding to the disorientation that is common for pilots learning the maneuver.

Most of the errors discussed in power-off stalls apply to power-on stalls as well. Remember to use the rudder to hold the wings level during a power-on stall. If a plane has a tendency to drop a wing during power-off stalls, you may find that it is more exaggerated in the power-on stall configuration.

The nose of the plane can drop more rapidly due to the sharper break during the stall and may have a tendency to sink lower below the horizon. Try not to aggravate the situation by adding too much forward elevator input, which can drop the nose even further below the horizon. Every plane will react differently during a stall, but stall recovery is a task that requires that you are light and smooth with flight control inputs. You will also want to make sure you do not set yourself up for a secondary stall by raising the nose too abruptly after your initial stall recovery. The airspeed will have a tendency to build more quickly since the power was on during the entire stall and there can be greater altitude loss as a result of this.

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