How do airplanes stay in the air?

Airplanes stay in the air thanks to the interaction between four physical forces: lift, weight (gravity), thrust, and drag.

Here is how they work together to achieve flight:

• Lift (The Core Secret): This is the force that pushes the plane upward. It is primarily generated by the wings. As the plane moves forward, air flows over and under the wing. The shape of the wing (called an airfoil) is curved on top and flatter on the bottom. Because of this shape and the angle at which the wing meets the air, the air pressure becomes lower on the top of the wing and higher on the bottom, creating an upward force that lifts the plane.
• Thrust: To generate lift, the plane must be moving forward. Engines (jet or propeller) provide thrust, which pushes the plane through the air. The faster the air moves over the wings, the more lift is generated.
• Weight (Gravity): This is the force pulling the plane toward the Earth. For an airplane to stay in the air, the lift generated by the wings must be strong enough to balance out the weight of the aircraft.
• Drag: This is the air resistance that tries to slow the plane down. To maintain steady flight, the thrust from the engines must be powerful enough to overcome this drag.

In summary: An airplane achieves "straight and level" flight when the forces are balanced: lift equals weight, and thrust equals drag. If the pilot wants to climb, they increase the thrust and adjust the wing's angle to increase lift until it is greater than the plane's weight. To descend, they reduce thrust or adjust the wing angle to decrease lift.