Which term describes the forward aerodynamic force produced by a propeller, fan, or turbojet engine as it forces air to the rear?

• A. Thrust
• B. Time And Speed Table
• C. Thrust Aerodynamic Force
• D. Thrust Line

Answer: (C)

Thrust is the forward force produced by propulsion devices as they push air rearward, and it happens because of Newton’s third law: the engine or propeller pushes air backward, and the aircraft is pushed forward. A propeller’s blades accelerate air backward, creating a forward reaction on the airplane. A turbojet or turbofan does the same by accelerating exhaust rearward, generating forward thrust. The effect acts along the aircraft’s longitudinal axis and is what actually moves the airplane through the air. Other terms listed are either unrelated or refer to something different—the line of action describes direction, not the force itself, and a phrase like “thrust aerodynamic force” isn’t the standard term used. So the straightforward term for that forward push is thrust.