Grnd-46 Theory of Flight 2 Aerodynamics

Name the major component parts of an aircraft

Fuselage, wings, engines, empennage - horizontal and vertical stabilisers

Name the control surfaces

Ailerons, flaps, rudder, elevators

Name the axes of control

Vertical, lateral, longitudinal

What is movement around the vertical axis?

Yaw, controlled by rudder

What is movement around the lateral axis?

Pitch, controlled by elevators

What is movement around the longitudinal axis

Roll, controlled by ailerons

Label an airfoil

Leading edge, trailing edge, chord line, mean camber line

Where is velocity fastest on an airfoil?

Above the airfoil is fastest, below is second fastest

What is the relationship between velocity and pressure?

Increase velocity = increased P_D and decreased P_S

Lift Force (L)

Pressure distribution vectors produce a sum force perpendicular to the relative airflow (RA)

Aerodynamic Force (AF)

The total force acting on the airfoil. Changes with the AoA and velocity

AoA - Velocity Relationship

To maintain a constant lift force as an aircraft slows down, the pilot must increase the angle of attack

What happens as a stall occurs?

The lift decreases and the drag increases, there is almost always a loss of altitude and control

What are the critical phases of flight?

Takeoff and initial climb, final descent and landing

What is the boundary layer?

The thin layer of air near the surface of the wing

What is an aerodynamic stall?

A separation of the boundary layer from the upper surface of the wing - caused by excessive angle of attack

Stalling AoA

The point where the boundary layer separates has moved too far forward and the loss of the effective area of the wing is too large to be offset by any increases in the pressure differential that may occur

Stalling Speed

The speed at which, for a given set of conditions, the aircraft is at its stalling angle of attack

Stalling Speed vs Stalling AoA

Stalling AoA constant, stalling speed varies

Factors Affecting Stalling Speed

Weight, Altitude, Thrust Effect, Configuration Effect

V_STALL Weight Effect

As weight is reduced the stalling speed is decreased

V_STALL Altitude Effect

Increased altitude increases stall speed

V_STALL Thrust Effect

Angle between thrust vector and relative air flow = AoA, therefore as it is increased the stall speed decreases

V_STALL Configuration Effect

Presence of High Lift Devices obtains required lift forces at lower velocities

Two ways maximum coefficient of lift (C_LMAX) can be increased

Increasing camber of airfoil, delaying boundary layer separation

Two types of high lift devices

Flaps, Boundary layer control

Two types of stall warnings

Aerodynamic warning (stall buffets, stall strips), mechanical warning systems