How Do Airplanes Fly?

Airplanes fly by carefully balancing four forces: lift, weight, thrust, and drag. Lift is generated by the wings' special shape (airfoil). As the plane moves forward, air flows faster over the curved top of the wing than the flatter bottom, creating lower pressure above and higher pressure below, pushing the wing upward (Bernoulli's principle). The engines provide thrust to overcome drag (air resistance) and move the plane forward fast enough to generate sufficient lift. Weight is the force of gravity pulling the plane down. For flight to occur, lift must exceed weight, and thrust must overcome drag. Pilots control the plane using ailerons (roll), elevators (pitch), and rudder (yaw). Modern commercial jets cruise at about 550 mph at altitudes of 35,000-40,000 feet, where the thinner air reduces drag. The Wright Brothers' first flight in 1903 lasted just 12 seconds, but it revolutionized human transportation forever.