Which four forces affect an aircraft in flight?

The four forces that affect an aircraft in flight are lift, weight, drag, and thrust.

Lift is the upward force created by the movement of air over the wings, allowing the aircraft to rise into the sky. Weight is the force due to gravity pulling the aircraft down towards the Earth. Drag is the resistance that opposes the aircraft's forward motion, caused by the friction of air particles against the surface of the aircraft. Thrust is the forward force produced by the engines, propelling the aircraft in the direction of travel.

Understanding these four forces is crucial for comprehending how an aircraft operates in the air. They interact with one another during flight; for example, lift must overcome weight for the aircraft to ascend, while thrust must surpass drag to maintain speed. This interplay is fundamental to the principles of flight and is essential knowledge for anyone involved in aviation or unmanned air systems.