Straight and Level Flight with Different Speeds

Chapter 6.3

Objectives

To know the different drag forces

To know the relationship between thrust, drag and angle of attack

To know the influence of the position of the flaps on the flight attitude and the angle of attack

The Parasitic Drag

Parasitic drag depends on the shape and surface of the wing. It increases exponentially with increased airspeed.

INDUCED DRAG

Induced drag depends on the angle of attack in respect to the flightpath. The faster the plane flies, the more the angle of attack decreases and therefore induced drag decreases as well.

TOTAL DRAG

TOTAL DRAG of an airplane in flight, consists of the sum of two factors: INDUCED DRAG and PARASITIC DRAG.

MINIMUM DRAG

A speed for each wing profile can be determined where the mimimum total drag occurs. This indicates the airspeed for maximum endurance.

One Power Setting, Two Speeds

Lift is mainly generated by:

Change of flight attitude with decreasing speed

Change of Flaps Position in a Straight and Level Flight

Configuration change: extend FLAPS

• Check the ASI

• Extending the FLAPS to an intermediate position

Change of Flaps Position in a Straight and Level Flight

Configuration change: retract FLAPS

• Check the ASI
  

• Retract FLAPS completely