This document provides an overview of basic aerodynamic principles and aircraft flight theory. It covers key topics such as the atmosphere, Newton's laws of motion, Bernoulli's principle, airfoils, the four forces of flight, stability and control surfaces. The presentation introduces fundamental concepts including pressure, density, humidity, inertia, lift, drag, thrust, weight, angles of attack and incidence, and the three axes of movement. It also explains how stability is achieved through aircraft design elements like dihedral wings, sweepback, and keel effect.

1. Basic Aerodynamic and Theory of Flight

3. Aerodynamics Aerodynamics is the study of objects in motion through the air and the forces that produce or change such motion. INTRODUCTION It is unnecessary that a mechanic be totally versed on Aerodynamics and Theory of Flight . However he must understand the relationships between the atmosphere, the aircraft and the forces acting on it in flight, in order to make intelligent decisions affecting the flight safety of both airplanes and helicopters.

4. The Atmosphere Air is a mixture of gases composed principally of nitrogen and oxygen. An aircraft operates in the air, therefore, the properties of air that affect aircraft control and performance must be understood. Pressure – Atmospheric pressure varies with altitude. The higher an object rises above sea level, the lower the pressure. Density – It varies directly with the pressure and inversely with the temperature. With the same horse power, an aircraft can fly faster at high altitude because of less resistance of air at there. Humidity – Humidity is the amount of water vapor in the air. It varies directly with temperature.

5. Newton's First Law of Motion According to Newton's first law of motion (inertia), an object at rest will remain at rest, or an object in motion will continue in motion at the same speed and in the same direction, until an outside force acts on it. For an aircraft to taxi or fly, a force must be applied to it. It would remain at rest without an outside force. Once the aircraft is moving, another force must act on it to bring it to a stop. It would continue in motion without an outside force. This willingness of an object to remain at rest or to continue in motion is referred to as inertia .

6. Newton's Second Law of Motion The second law of motion (force) states that if a object moving with uniform speed is acted upon by an external force, the change of motion (acceleration) will be directly proportional to the amount of force and inversely proportional to the mass of the object being moved. The motion will take place in the direction in which the force acts. Simply stated, this means that an object being pushed by 10 pounds of force will travel faster than it would if it were pushed by 5 pounds of force. A heavier object will accelerate more slowly than a lighter object when an equal force is applied. F = m × a

7. Newton's Third Law of Motion The third law of motion (action and reaction) states that for every action (force) there is an equal and opposite reaction (force). This law can be demonstrated with a balloon. If you inflate a balloon with air and release it without securing the neck, as the air is expelled the balloon moves in the opposite direction of the air rushing out of it. Figure shows this law of motion. Action Reaction Balloon Air

8. BERNOULLI'S PRINCIPLE Bernoulli's principle states that when a fluid flowing through a tube reaches a constriction or narrowing of the tube, the speed of the fluid passing through the constriction is increased and its pressure is decreased. Pressure Drop in Venturi Tube

10. kinetic energy (velocity) potential energy (pressure) velocity increases pressure decreases Airfoil as a Venturi Tube Lift force appear

12. Parts of An Airplane

13. The forces acting on an airplane in flight are lift , weight , thrust , and drag . These forces are in equilibrium during straight-and-level, unaccelerated flight. The Four Forces of Flight DRAG WEIGHT THRUST LIFT

15. Newton’s Third Law and Lift

16. Newton’s Second Law and Lift

17. Lift: Wing Section Lift Equation: L=C L × ½ ρ × A × V 2

19. Angle of Attack and Lift Force High velocity Low pressure Low velocity High pressure

21. Horizontal Component of Lift

24. Wing Shapes

28. Example of Drag Formation

29. Skin Friction Drag

30. Three Axes of Movement Axis of Roll (Longitudinal Axis) Axis of Pitch (Lateral Axis) Axis of Yaw (Vertical Axis)

31. Pitch Around the Lateral Axis

32. Roll Around Longitudinal Axis

33. Yaw Around the vertical Axis

35. Static Stability Positive-Neutral-Negative

37. Natural Dynamic Stability

38. Negative Dynamic Stability

39. Stability recover by a dihedral wing Larger wing area More lift Smaller wing area Less lift

40. Stability recover by a sweep back wing

41. Stability recover by keel effect

42. CONTROL To achieve the best performance, the aircraft must have the proper response to the movement of the controls. Control is the action taken to make the aircraft follow any desired flight path. Different Control surfaces are used to control the aircraft about each of the three axes. Flight Control Surfaces – Hinged or moveable airfoils designed to change the attitude of the aircraft during flight. 1. Primary group - ailerons - elevators - rudder 2. Secondary group - trim tab, spring tab - servo tab, balance tab 3. Auxiliary group - wing flaps - spoilers - speed brakes - slats - leading edge flaps - slots

43. Flight Control Surfaces Flap Flap Spoiler Spoiler

44. wing flaps spoilers leading edge slats leading edge slots speed brakes

45. Ailerons – The ailerons form a part of the wing and are located in the trailing edge of the wing towards the tips. The control stick is connected by means of wires or hydraulics to the wings’ ailerons. By turning the stick, the pilot can change the positions of the ailerons. ROLLING Control around the Longitudinal Axis

46. Rudder – The rudder is a moveable control surface attached to the trailing edge of the vertical stabilizer. The foot pedals are connected by means of wires or hydraulics to the rudder of the tail section. The rudder can also be used in controlling a bank or turn in flight. YAWING Control around the Vertical Axis Moving rudder to the right forces tail to the left, nose to the right Moving rudder to the left forces tail to the right, nose to the left.

47. Elevators – Elevators are the movable control surfaces hinged to the trailing edge of the horizontal stabilizer. The control stick is connected by means of wires or hydraulics to the tail section’s elevators. - Stabilator - Ruddervator PITCHING Control around the Lateral Axis

48. End of Presentation Thanks for your time