1.
 The force against the thrust is drag
OR
 The force acting in the direction of relative airflow is drag
OR
 During flight all parts of an aircraft exposed to the airflow
experiences a resistance as aircraft moves through the air,
the force is known as drag

2.
Drag
Parasite
Drag
Profile Drag
Interference
Drag
Induced
Drag
Skin Friction
Drag
Form Drag

3.
 The parts not contributing to lift are called parasite
and the drag they produce is called parasite drag
 The sum of skin friction drag and form drag is
known as profile drag

4.
 Skin friction drag is the reaction to the retardation
of the airflow within boundary layer, it depends
upon the rate at which the air trying to slide
adjacent to the aircraft surface

5.
 Directly proportional to square of speed
 Roughness
 Irregular Shape

6.
 Cruise at optimum efficiency speed
 Polishing
 Aerodynamic shapes

7.
 When streamline air flow passing over an aircraft
separates from the surface and becomes
turbulent, this phenomena is known as form drag

8.
 Directly proportional to square of speed
 Hindrance (e.g. undercarriage)
 Irregular shapes
 Roughness

9.
 Aerodynamic shapes (even, smooth,
well cambered)
 Fairing on undercarriage

10.
 When two differently directed airflows interfere
they produce interference drag e.g. joint between
different aircraft parts such as wing and fuselage,
lights, stabilizers and antennas

11.
 Aerodynamic Joints

12.
 The force that occurs when the aircraft redirects the
airflow coming at it, this drag force occurs due to wings
OR
 Pressure difference from top to bottom of wing (span-
wise flow) causes vortices along the wings particularly
wing tips

13.
 It is a by-product of lift
 Increases with increasing angle of
attack
 inversely proportional to speed
increases

14.
 Increase wing span (Aspect ratio)
 Wing-lets
 Washout

15.
 Fuel tank on wing tips
 Tapered wings
 Wing tips modification