Stick your hand out of a moving car and tilt it. The force that pushes up or down is aerodynamics at work, and the same physics keeps a 400-tonne aircraft in the sky. The field studies how air moves around solid objects and what forces that motion produces.

Four forces dominate. Lift holds an aircraft up. Weight pulls it down. Thrust pushes it forward, and drag holds it back. Every design decision, from wing shape to rivet placement, shifts the balance between them.

Where the numbers matter

• Wing profile and camber
• Angle of attack at different speeds
• Surface smoothness and boundary layers
• Compressibility effects near the speed of sound

Engineers test designs in wind tunnels before anything flies. Computer simulations handle much of the work now, but physical testing still catches surprises that models miss.