Flight Investigations TEXT BOOK CHAPTER 16 PAGE

Flight – the beginning The Wright Brothers Failures / Early Attempts

Newton’s laws of motion

Forces acting on an aircraft The main forces acting on an aircraft in level flight can be identified as vertical and horizontal pairs. Vertical Pair – Lift and Weight Horizontal Pair – Thrust and Drag

Forces acting on an aircraft Lift is the upward- acting force created by a wing moving through the air Weight is the force applied to an object due to gravity Thrust is the forward force that drives an aircraft through the air Drag is the rearward- acting force that resists the motion of an aircraft through the air

Lift Force Acts upwards, at right angles to the airflow direction. Lift force is generated over the entire wing, although it is usually thought of as acting at one position along the wing. This position is known as the centre of lift or the centre of pressure (CP). Weight Force The weight force is considered to act through the centre of gravity (COG) - This is the point where the mass of the aircraft is considered to be concentrated and is the point of balance. If an aircraft were hung from a cable attached to its centre of gravity, it would hang level and perfectly balanced. The location of an aircrafts COG depends on the load it carries (fuel, cargo, passengers etc) In level flight the Lift Force and Weight Force are equal in size and opposite in direction.

Drag Force As an aircraft moves through the air in flight, it experiences air friction or drag. The faster the aircraft moves, the greater the resultant drag force. There are several different types of drag forces that act on different parts of the aircraft when in flight. The arrow used to represent the drag, refers to the resultant of all the drag forces that act on every part of the aircraft.

Forces acting on an aircraft In level flight, Thrust = Drag ∴ Drag = 10,000 N

Forces acting on an aircraft If the net force acting on an aircraft in flight is zero, it maintains constant velocity. If the net force acting on an aircraft is not zero, the magnitude and direction of the net force determines the magnitude and direction of the acceleration of the aircraft. Describe the direction of the resulting motion (acceleration) if an aircraft has the following forces acting upon it in flight: a) Lift = 5000 N, Drag = 800 N, Weight = 5000 N, Thrust = 1200 N Net Force 400 Forward – Plane accelerates Forward b) Lift = 6000 N, Drag = 900 N, Weight = 5000 N, Thrust = 900 N Net Force 1000 Upward – Plane accelerates Upward

Forces acting on an aircraft The Aerodynamics of Flight

Now Do Text Book - Chapter 16 Questions 1 – 3 Pg 376 ( Applying Newton’s laws to Aircraft)

Moving through fluids Aeronautics is concerned with the motion of aircraft through gases – in particular, air. To understand how lift in an aircraft occurs, we need to understand a little about movement through fluids. All liquids and gases are fluids. Fluids, like solids, are composed of small particles. Particles are packed less tightly in fluids than in solids, allowing movement of particles more freely.

Moving through fluids

eg1. In the diagram pictured, A1 is larger than A2. Using the equation of continuity, explain the difference in V1 and V2 in this scenario. V1 < V2 Wider pipe, slower speed Narrower pipe, faster speed

Moving through fluids

Now Do Text Book - Chapter 16 Questions 4, 5, 6, 7a Pg 376 ( Moving through fluids and Bernoulli’s Equation)

Fluid Speed and Pressure