Private Pilot License (PPL) Aerodynamics Practice Exam

What is the primary function of thrust in an aircraft?

1. To lift the aircraft off the ground

2. To counteract drag

3. To control the aircraft's pitch

4. To stabilize the aircraft during flight

The correct answer is: To counteract drag

The primary function of thrust in an aircraft is to counteract drag. When an aircraft is in motion, it experiences resistance in the form of drag, which acts opposite to the direction of travel. Thrust, generated by the aircraft's engines, must be sufficient to overcome this drag for the aircraft to accelerate, maintain speed, or climb. While thrust plays a critical role in overall flight dynamics, its main purpose is to provide the forward force necessary to overcome drag and ensure sustained flight. The ability to generate enough thrust allows the aircraft to achieve and maintain its desired speed and climb performance effectively. In essence, without sufficient thrust to counteract drag, an aircraft would not be able to move forward efficiently or reach flying speeds. The other functions mentioned, such as lifting the aircraft or controlling pitch, are primarily the results of aerodynamic forces and control surfaces rather than thrust itself.