Which force is responsible for opposing the weight of the aircraft?

The force responsible for opposing the weight of the aircraft is lift. Lift is generated by the wings as air flows over and under them, creating a pressure difference. This pressure difference is a result of the wings' shape and the angle at which they are oriented relative to oncoming air, known as the angle of attack.

When an aircraft is in flight, lift must not only overcome the weight, which is the force due to gravity acting on the aircraft, but it must also provide enough additional force to allow for climbing or maneuvering. These dynamics are essential for stable flight and performance changes during different phases of a flight, such as takeoff, cruising, and landing.

The other forces mentioned play different roles in flight dynamics; for example, thrust is the forward force that propels the aircraft, drag is the resistance force that opposes motion through the air, and roll refers to the aircraft's rotation about its longitudinal axis, often related to the control surfaces like ailerons. However, it is specifically lift that directly counteracts the weight of the aircraft, allowing it to become airborne and maintain altitude.