Theory of Flight 6 06 Loads and Load

Theory of Flight 6. 06 Loads and Load Factor References: FTGU pages 17 -18, 34 -35

Review 1. Where is the centre of pressure in straight flight, just before a stall and after a stall? 2. What are some factors that increase stalling speed? 3. What are the symptoms of a stall? 4. When can an aircraft stall?

6. 06 Loads and Load Factor MTPs: • Definitions • Load Factor changes • Load Factor in Turns • Forces in a turn

Weight 1. What is weight? • The downward FORCE due to gravity that acts opposed to lift • Acts through the centre of gravity

Weight What happens if… • Weight is greater than lift? • Lift is greater than weight?

Loading • Gross weight of the aircraft divided by the area of lifting surfaces (wings) = Load • 2 Types – Live Load – Dead Load

Dead Load vs Live Load Dead Load • The load put on the aircraft when it is sitting on the ground. Weight due to gravity. Live Load • Additional loads are added in flight due to acceleration or change in direction associated with manoeuvres

Load Factor • Ratio of the actual load acting on the wings to the gross weight of the airplane • Live Load : Dead Load • In straight and level flight the load factor is 1

Load Factor Changes • The load factor is increased any time the aircraft is not in straight and level flight • Due to: – Performing aircraft manoeuvre – Wind Gusts – Turbulence

Load Factor Is loading a bad thing? . . No but it could cause problems 1. Structural Limitation • Each aircraft is designed with a max load factor that should not be exceeded as permanent damage may occur SGS 2 -33 a Max Load = 4. 67 G C 152 Max Load = 4. 4 G

Load Factor 2. Increased Stall speed • Increased load factor during manoeuvres in flight requires increased lift to maintain level flight • Critical angle of attack is reached at an increased speed • Stall speed increases • More on stalls in 6. 07 Load factor during flight Speed to reach critical angle of attack Stall speed

Load Factors in Turns • As angle of bank is increased in a turn the load factor and amount of lift required also increases • Load factor increases exponentially with angle of bank Angle of Bank Load Factor 15° 1. 04 G 30° 1. 15 G 45° 1. 41 G 60° 2 G

Forces in a Turn • In a turn… • Lift is divided into two components = vertical and horizontal

Forces in a Turn • Vertical component opposes weight • Horizontal component causes airplane to turn – This horizontal component is known as centripetal force

Forces in a Turn Pulls plane into the centre of the turn Resulting lift due to added horizontal components Pulls plane to outside of the turn

Forces in a Turn Centripetal versus Centrifugal Force Centripetal Force Centrifugal Force Pulls INTO the turn Pushes AWAY from turn Genuine force Inertial (fictitious) force This is the force you feel going around a corner in a vehicle. It pulls in the opposite direction of a turn.

Confirmation Fill in the blanks: Load factor = What is the difference between live load and dead load?

Confirmation Label where the centripetal and centrifugal forces are. If this aircraft is doing a 60 degree of bank turn, how many Gs is it experiencing? When does an aircraft experience a 1 G force?

CP 140 Aurora