If you have some in-depth knowledge of aviation, you are pilot or student of aviation, or even like simulators, you have heard of a phenomenon called stall. Theoretically, every pilot should be able to detect the symptoms of a stall, and make the corrections before it even occurs. But do you remember how it occurs?
Studies of the National Transportation Safety Board (NTSB) indicate that most stall and spin accidents are associated with inattentiveness and distraction of the pilot’s primary function: to fly the plane.
With the evolution of increasingly sophisticated aircraft, on-board equipment or even cabin procedures make more professionals feel pressured or overwhelmed, and prefer to let the autopilot take care of things while taking care of other tasks. But in an atypical situation, where ‘back to the basics’ is not optional, one should understand:
A stall occurs when the angle of attack corresponds to the maximum lift coefficient, that is, the stall angle is exceeded. This can occur at any speed, and especially in any attitude. However, although the stall occurs at any speed, we should not conclude that speed has nothing to do with it, with its prevention and recovery.
Many factors can affect stall speed. For example: a fully loaded airplane, or even with large load factor stalls at a faster speed than a lightly loaded aircraft. Likewise, a plane with center of gravity (cg) ahead stole with speed superior to that of an airplane with cg behind.
Another factor linked to stall speed is the position of the flap. In addition, turbulence, coordination, snow and ice on the wing can increase stall speed. Believe, even improper maintenance adversely affects stall speed.
In the flight school
It is part of every pilot training, the stall maneuver practice. Basically, divided into 3 types, and we do the procedure with and without the use of engine.
We set our aircraft at 30 degrees above the horizon, we reduced the engine to 2,000 RPM (or idle), so we wait for the recovery speed of 50kt, and then we ceded the nose of the aircraft to the recovery attitude, while we apply all power. When crossing 70kt, we return to the horizontal flight.
45 degrees and 60 degrees
We set the pitch 45 degrees above the horizon, we reduce the engine, and wait for the recovery speed of 40kt. When reached, we start the recovery. At 60 degree loss, the recovery speed is 35kt.
Stall Recognition and Recovery
The stall recognition characteristics change from aircraft to aircraft. The most common in light aircraft is the ‘stall horn’. On more sophisticated aircraft, we may receive this warning with the vibration of the stick, or even with a frightening mechanical voice telling you ‘stall .. stall’.
The secret is that these warning systems are usually programmed to warn us about 5 to 10 knots above the actual stall speed. The horn system still has an aggravating effect: most are only in one wing. Thus, in an asymmetric stall, the signal may not act.
Then again: ‘back to the basics’. Reducing the sound of air passing through the fuselage is one of its greatest allies. The stall still has a fantastic feature … It has its own ‘stick shaker’ called buffet. As efficient as an ultra-sophisticated system, it is a generalized vibration of the aircraft when it is about to stall.
A characteristic common to all types is the loss of effectiveness of the controls, also due to the reduction of the air flow on the control surfaces. All these alerts are for the pilot to do two things: increase speed and reduce the angle of attack.
Anyway: 600 words to remind you that stall is the detachment of the boundary layer. That is to say, the air fillet the wing takes off to the point of the wing can no longer produce lift.
Okay, so far nothing surprising. We passed the ruler, and we are sure to know the seven types of stall. But above I only spoke of three, did not I? Yeah. You remember these other four?
So you think you’re a Red Bull Air Race rider right? Caution cpt… The abrupt or excessive use of commands, in addition to high load factors, high-slope maneuvers, or recoveries involving abrupt changes in the flight path (such as diverting a bird, aircraft, UFO, or anything else should not be in your bow …) can cause this type of stall. He is in the first position because it is the most dangerous, and unexpected (since you are at speed).
So you do not stall an aircraft for a good years right? Alas the inattention, the pressure of the boss, or even the stress takes away your focus from your flight … You stall, and performs an improper recovery of any kind of stall … Cpt .. Welcome to the stall and funky show .. The most common case is attempting to speed up the recovery of a stall before decreasing the angle of attack and gaining enough speed.
Elevator Trim Stall
Then you were landing, and a aircraft entered the runway. We are cautious pilots, are not we? Let’s hurl then. The compensator was set at a slow speed, and when the power is applied to the rush, the nose rises abruptly. You do not pull the stick, and the angle of attack continues to rise. His angle of attack rises violently, and the speed … well … was already completely wrong, right? On top of all this, the plane tends to drift to the left, resulting in an uncoordinated flight.
Fly safe, folks.