FLIGHT PRINCIPLES &FLIGHT DIRECTIONAL CONTROL PRINCIPLES

Forces Acting on An Airplane
There are four forces acting on the airplane all the time
during airplane is flying.The four forces are
(1) Lift, (2) Gravity force or Weight, (3) Thrust, and (4)
Drag.
Lift and Drag are considered aerodynamics forces because
they exist due to the movement of the Airplane through the
Air.
Lift: is produced by a lower pressure created on the upper
surface of an airplane's wings compared to the pressure
on the wing's lower surfaces,causing the wing to be
LIFTED upward. The special shape of the airplane wing
(airfoil) is designed so that air flowing over it will have to
travel a greater distance and faster resulting in a lower
pressure area (see illustration) thus lifting the wing
upward. Lift is that force which opposes the force of
gravity (or weight).
Lift depends upon (1) shape of the airfoil (2) the angle of
attack (3) the area of the surface exposed to the airstream
(4) the square of the air speed (5) the air density.
Weight: The weight acts vertically downward from the
center of gravity (CG) of the airplane.
Thrust: is defined as the forward direction pushing or
pulling force developed by aircraft engine . This includes
reciprocating engines , turbojet engines, turboprop
engines.
Drag: is the force which opposes the forward motion of
airplane. specifically, drag is a retarding force acting upon
a body in motion through a fluid, parallel to the direction
of motion of a body. It is the friction of the air as it meets
and passes over an airplane and its components. Drag is
created by air impact force, skin friction, and displacement
of the air.