Before lift-off, how does lift compare to weight?

Before lift-off, lift is less than weight. This situation is crucial for understanding aircraft performance and the principles of flight. When an aircraft is on the ground, it is subject to the force of gravity, which acts downward and is balanced by the aircraft's weight. Since the aircraft is not yet moving and there is no airflow over the wings, the wings are not producing any lift.

Lift is generated when the aircraft moves through the air, causing air to flow over and under the wings, which creates the pressure differential necessary for lift to counteract weight. Therefore, at the moment before the aircraft begins its takeoff roll, the lift produced is zero, making it inherently less than the weight of the aircraft. This relationship is fundamental for ensuring that the aircraft must generate enough lift during the takeoff phase to eventually equal and then exceed its weight to achieve flight.