# Aerodynamics - Key terms

### AERODYNAMICS:

The study of airflow and its principles. Applied aerodynamics is the science of improving man-made objects in light of those principles.

### AIRFOIL:

The design of an airplane's wing when seen from the end, a shape intended to maximize the aircraft's response to airflow.

### ANGLE OF ATTACK:

The orientation of the airfoil with regard to the airflow, or the angle that the chord line forms with the direction of the air stream.

### BERNOULLI'S PRINCIPLE:

A proposition, credited to Swiss mathematician and physicist Daniel Bernoulli (1700-1782), which maintains that slower-moving fluid exerts greater pressure than faster-movingfluid.

### CAMBER:

The enhanced curvature on the upper surface of an airfoil.

### CHORD LINE:

The distance, along an imaginary straight line, from the stagnation point of an airfoil to the rear, or trailing edge.

### DRAG:

The force that opposes the forward motion of an object in airflow.

### LAMINAR:

A term describing a streamlined flow, in which all particles move at the same speed and in the same direction. Its opposite is turbulent flow.

### LIFT:

An aerodynamic force perpendicular to the direction of the wind. For an aircraft, lift is the force that raises it off the ground and keeps it aloft.

### PITCH:

The tendency of an aircraft in flight to rotate forward or backward; see also yaw and roll.

### ROLL:

The tendency of an aircraft in flight to rotate vertically on the axis of its fuselage; see also pitch and yaw.

### STAGNATION POINT:

The spot where airflow hits the leading edge of an airfoil.

### SUPERSONIC:

Faster than Mach 1, or the speed of sound—660 MPH (1,622km/h). Speeds above Mach 5 are referred to as hypersonic.

### TURBULENT:

A term describing a highly irregular form of flow, in which a fluid is subject to continual changes in speed and direction. Its opposite is laminar flow.

### VISCOSITY:

The internal friction in a fluid that makes it resistant to flow.

### YAW:

The tendency of an aircraft in flight to rotate on a horizontal plane; see also Pitch and Roll.