TO SERVE WITH PRIDE AND DEDICATION PRINCIPLES OF FLIGHT

2) Bernoulli’s Principle 3) Airfoil/Aerofoil Shape TO SERVE WITH PRIDE AND DEDICATION SCOPE….. 1) 4 Forces of Flight 2) Bernoulli’s Principle 3) Airfoil/Aerofoil Shape 4) How a Plane is Controlled

TO SERVE WITH PRIDE AND DEDICATION 4 Forces of Flight... While an aircraft is flying, there are 4 forces acting on it: THRUST, DRAG, LIFT and WEIGHT. Thrust VS Drag while Lift VS Weight. Refer to the pictorial below: Centre of Gravity, cg

TO SERVE WITH PRIDE AND DEDICATION THRUST VS DRAG THRUST A force that is created by the aircraft’s propulsion system, engines. It is a push or pull that moves the aircraft forward. For aircraft to start moving, THRUST = DRAG. For aircraft to accelerate, THRUST > DRAG.

How does the aircraft body contributes to drag? TO SERVE WITH PRIDE AND DEDICATION THRUST VS DRAG DRAG Opposes THRUST and acts the opposite direction of THRUST. It is the resistance of air due to aircraft movement. The aircraft body itself also contributes to drag. Discussion How does the aircraft body contributes to drag?

LIFT VS WEIGHT LIFT Generated by airflow over the aircraft body. TO SERVE WITH PRIDE AND DEDICATION LIFT VS WEIGHT LIFT Generated by airflow over the aircraft body. Wings of aircraft produces most of the aircraft’s lift. To be able to take off / go airborne / pitch up, LIFT > WEIGHT.

LIFT VS WEIGHT WEIGHT Opposite reaction of LIFT. TO SERVE WITH PRIDE AND DEDICATION LIFT VS WEIGHT WEIGHT Opposite reaction of LIFT. It is a vertical downward force towards the ground. Includes mass of aircraft, fuel, cargo or any loads on aircraft. Weight distribution in aircraft is not constant. i.e. Passengers walking about, fuel consumption.

HOW IS THIS APPLICABLE TO FLIGHT? TO SERVE WITH PRIDE AND DEDICATION BERNOULLI'S PRINCIPLE... David Bernoulli is a Swiss scientist in the 18th century. He discovered that as the velocity of fluid increases, its pressure decreases. Venturi Tube As the fluid enters the narrow part of the tube, it speeds up. This decreases the fluid pressure. As the molecules speed up, it uses more energy, thus less energy is used to exert pressure. 1 1 2 The speed of the fluid decreases as it exits the narrow part of the tube. There is more energy to exert pressure as less energy is used for the speed of the molecules. 2 HOW IS THIS APPLICABLE TO FLIGHT?

TO SERVE WITH PRIDE AND DEDICATION THE AIRFOIL SHAPE... In most aircraft, you will see this shape if seen from the wing tip. There’s a lot of different types of airfoil shape, which is designed for the aircraft, depending on its role. To facilitate better understanding of how aircraft wings generate lift for the whole aircraft, we will look at the most common design of airfoil.

Cross-section of the wing… TO SERVE WITH PRIDE AND DEDICATION Cross-section of the wing… For easier understanding, Bernoulli’s principle will be used to explain how airfoil shape generates lift.

HOW A PLANE IS CONTROLLED... TO SERVE WITH PRIDE AND DEDICATION HOW A PLANE IS CONTROLLED... Movements of an aircraft plays along 3 axis. Different movements about or along different axis will bring about different kind of movements. AXIS MOVEMENT Longitudinal Roll Lateral Pitch Vertical Yaw From the above, we get 3 different kinds of moments: Rolling, Pitching and Yawing moments.

Air particles accelerate as it goes along the upper camber, due TO SERVE WITH PRIDE AND DEDICATION How LIFT is produced… Airflow is separated. 1 2 Air particles accelerate as it goes along the upper camber, due to the longer distance it has to travel as compared to that of lower camber. As the velocity of air increases, the pressure against the upper camber decreases. 2 4 1 3 Since pressure against the upper camber is more than that against the lower camber, the wing is being pushed upwards by the higher pressure. 4 Velocity of air remains about the same as before. Thus, pressure exerted against the lower camber would be greater then the pressure exerted on the upper camber. 3

Rolling Moment OUTCOME? TO SERVE WITH PRIDE AND DEDICATION Rolling Moment When the starboard (right side of aircraft) aileron is up: - Port (left side of aircraft) aileron will move downwards. - Greater pressure at the bottom of port wing compared to top; pushing the port wing upwards. - Greater pressure on top of starboard wing compared to bottom; pushing the starboard wing downwards. OUTCOME? Aircraft will roll to the right. It is a rotation about the longitudinal axis Controlled by ailerons

Pitching Moment OUTCOME? When the elevator is up: TO SERVE WITH PRIDE AND DEDICATION Pitching Moment When the elevator is up: - Pressure on top of the tailplane is greater as compared to the bottom. - This pushes the tailplane down. OUTCOME? Aircraft will pitch up. It is a rotation about the lateral axis Controlled by elevator

Yawing Moment OUTCOME? It is a rotation about the vertical axis TO SERVE WITH PRIDE AND DEDICATION Yawing Moment It is a rotation about the vertical axis Controlled by rudder When the rudder is moved to the left: - Pressure on the left of the vertical stabiliser is more as compared to the right. OUTCOME? Aircraft will yaw to the right.

RESEARCH ACTIVITY Find out how these flight controls work: Elevons TO SERVE WITH PRIDE AND DEDICATION RESEARCH ACTIVITY Find out how these flight controls work: Elevons Ruddervator Spoilerons Flaperons

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