406.08 Loads and Load Factors

1. 406.08Loads and Load Factors 1 X 40 min OCdt Marl-e-a-u

2. Outline • Definitions • Relationship Between Wing Loading and Angle of Bank • Load Factor in Turns • Centripetal and Centrifugal Force • Forces on Aircraft

3. What is weight? • The downward FORCE due to gravity (or other acceleration), that is usually directly opposed to lift • Acts through the centre of gravity

4. What happens if… • Weight is greater than lift? • Aircraft descends • Lift is greater than weight? • Aircraft climbs

5. Wing Loading • Gross weight of the aircraft divided by the area of lifting surfaces (wings) = Wing Loading

6. Dynamic/Live Loading • Additional load due to acceleration or change in direction associated with manoeuvres in flight

7. 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

8. Gust Loads • Load changes imposed on an aircraft due to intense up and down wind gusts

9. Weight, Load Factor and Stalling Speeds • Increased aircraft WEIGHT requires increased lift to maintain level flight • Critical angle of attack is reached at a higher speed • Stall speed increases Speed to reach critical angle of attack Weight Stall speed

10. Weight, Load Factor and Stalling Speeds • 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 Speed to reach critical angle of attack Load factor during flight Stall speed

11. Angle of Bank and Wing Loading • 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

12. Is it easier to stall an aircraft when in a turn or when in straight and level flight? In a turn! Speed to reach critical angle of attack Load factor In a turn Stall speed

13. Structural Limitations • Each aircraft is designed with a max load factor that should not be exceeded as permanent damage may occur • Schweizer 2-33a Max Load Factor = 4.67 G

14. Forces in a Turn • In a turn… • Vertical forces of lift and weight are no longer in balance • Angle of attack must be increased to produce the increased lift needed • Lift is divided into two components = vertical and horizontal

15. Vertical and Horizontal Components of Lift • Vertical component = opposes weight • Horizontal component = causes airplane to turn • This horizontal component is known as centripetal force • Centrifugal force is opposite to centripetal force and pulls the aircraft out of the turn

16. Forces in a Turn Pulls plane into the centre of the turn and counteracts centrifugal force Resulting lift due to added horizontal components Pulls plane to outside of the turn

17. Centripetal vs Centrifugal Force

18. Centripetal vs Centrifugal Force

19. What we have learned… • Definitions • Relationship Between Wing Loading and Angle of Bank • Load Factor in Turns • Centripetal and Centrifugal Force • Forces on Aircraft