As an expert in the field of aerodynamics, I can provide an in-depth explanation of why planes do not fall from the sky. The phenomenon is governed by the principles of physics, specifically the laws of aerodynamics and Newton's laws of motion.

Step 1: English Explanation

Aerodynamics and the Bernoulli Principle
The primary reason planes stay aloft is due to the principles of aerodynamics. When a plane is in motion, the shape of its wings, known as an airfoil, plays a crucial role. The airfoil is designed in such a way that it causes the air to move faster over the top of the wing than underneath it. This is where the Bernoulli Principle comes into play, which states that an increase in the speed of a fluid (in this case, air) occurs simultaneously with a decrease in pressure. Therefore, the pressure above the wing is lower than the pressure below it, resulting in an upward force known as lift.

Newton's Third Law of Motion
Another fundamental principle that keeps a plane in the air is Newton's Third Law of Motion, which states that for every action, there is an equal and opposite reaction. When a plane's engines push air backwards, the air in turn exerts an equal and opposite force on the plane, propelling it forward. This forward motion generates the lift needed to keep the plane airborne.

Thrust, Lift, Drag, and Weight
A plane remains airborne by balancing four forces: thrust, lift, drag, and weight. The engines provide thrust, which must be sufficient to overcome drag, the resistance that the air exerts on the plane's forward motion. Lift, generated by the wings, must be equal to or greater than the weight of the plane for it to stay in the air.

Wing Design and Angle of Attack
The design of the wing and the angle at which it meets the air, known as the angle of attack, also play significant roles. An optimal angle of attack maximizes lift while minimizing drag. Pilots adjust this angle during takeoff, flight, and landing to maintain control and stability.

Control Surfaces
Aircraft have control surfaces such as ailerons, elevators, and rudders that allow the pilot to control and maneuver the plane. Ailerons on the wings control rolling motion, elevators at the rear of the wing control pitch (up and down movement), and the rudder on the vertical stabilizer controls yaw (side-to-side movement).

Atmospheric Conditions
Atmospheric conditions also affect a plane's ability to stay aloft. Factors such as air density, temperature, and humidity can influence the performance of the wings and the amount of lift they can generate.

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Planes fly because air pushes up on their wings. ... Slower moving air pushes harder on the wing than faster moving air. So, the air under the wing pushes the plane up. That is how planes stay up in the sky.read more >>