Aero Part 2

  1. Stability vs. controllability
    Closer AC to CG: weaker stability, greater controllability

    Further AC from CG: stronger stabiliy, reduced controllability
  2. Longitudinal Stability

    Directional Stability

    Lateral Stability


  3. Directional divergence
    Occurs as a/c yaws or rolls into sideslip. Side forces cause increased yaw - directional instability
  4. Spiral divergence
    Results from strong directional stability relative to weak lateral stability
  5. Dutch roll
    Results from strong lateral stability relative to directional stability
  6. Optimum AOA
    17 units AOA
  7. How to improve transonic flight?
    Sweep and low thickness to chord ratio
  8. Stall strips

    Geometric Twist
    1) Cause the root to stall at a lower AOA

    2) 3.5o causes the tip to stall at a higher AOA

    Combined effect is that the root and tip stall at approximately the same time.
  9. Advantages/disadvantages of swept wing
    A: Higher speeds, structurally stronger

    • D:
    • 1) Less CL 
    • 2) Prone to tip stall
    • 3) Spanwise flow
    • 4) Leading edge vortexing
    • 5) High induced drag at low speed
  10. With two pilots, CG moves...
    forward. Increased stability
  11. CG Forward Limits
    Decreased maneuverability
  12. CG Aft Limits
    Decreased Stability
  13. Mach Tuck
    AC moves aft
  14. Upper fuselage/center wing to do not move CG (No answer, just know)
  15. Disadvantage of swept wing:
    High AOA Stall

    Decreased CL
  16. Tuck Under
    Slight nose down pitch Mach 0.8
  17. Second indicator of impending stall
    Accelerated stalls with no external stores - 20o pitch up
  18. Is thrust neutral on longitudinal stability
  19. Q?
    mass air flow in slugs / sec
  20. What happens to TR in the following?
    1) Configuration
    2) Weight increase
    3) Altitude increase
    1) TR shifts up and left

    2) TR shifts up and right

    3) TR shifts right
Card Set
Aero Part 2
Part 2