Wind Drift and Crabbing
Crabbing in straight and level flight for the initiated. Good example to use, with ground reference, is a N-S highway. The wind is out of the West at 20 MPH. Remember, this is a mass of air moving which is defined as "wind." You fly at a speed of 100 miles per hour, straight ( nose of the aircraft in a N-S direction) and level for 15 minutes.
Question is, where will you be? You will be exactly 25 miles North of where you started due to your flying through the air and exactly 5 miles East of the N-S highway due to your flying with the air.
Since the airplane is completely immersed in the air it must, simultaneously, move with the air eastward, as well as through the air, northward. This is exactly what happens. To the uninitiated it looks wrong.
To a person familiar to ground-associated eye reference they think the airplane is sliding sideways. This just doesn't seem possible when compared to the ground oriented travel.
Like a visual illusion, the inexperienced pilot has a strong urge to apply left rudder to stop the planes movement to the right. The mistake is the left rudder just makes the nose of the aircraft swing to the left and does nothing to prevent the aircraft from continuing to the right. Continued left rudder pressure will swing the nose further and further to the left and the plane will still exhibit its rightward slide. If this left rudder pressure still continues, as he tries to counteract the drift, the plane will turn completely off its heading and begin to circle. It will still slide to the right.
Now the danger. Cross-controlling. Extreme cross controlling will increase the angle of attack to precipitate a stall. The uninitiated uses right aileron against his left rudder, flying with his right wing low. The two controls cancel each other and the airplane will fly inefficiently in a slight sideslip. The airplane still slides eastward.
Some pilots think the air is blowing at the planes left side and shoving the nose of the plane to the left.(weather-cocking) The pilot then applies right rudder to counteract the imagined tendency to weather-cock.
In reality, the planes sideways movement to the right is pure drift. It is motion with the air mass or wind. It doesn't need any compensating control movement. The plane is behaving as in calm flight.
The experienced pilot knows the eastward flow of the air mass from the west cannot be stopped. He just gently turns the entire plane slightly to the west of north. The longitudinal axis of the plane is changed. The pilot is hoping the eastward movement of the plane in the air mass plus the slight northwest flight of the plane through the air mass will result in a actual flight path over the ground of true north.
You keep adjusting for the drift until it stops. The student flyer must understand clearly that a normal turn is always made to compensate for drift. These compensating turns allow the track of the plane over the ground to follow a true north direction.
