Aero Part 2

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Stability vs. controllability

Closer AC to CG: weaker stability, greater controllability

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

Directional Stability

Lateral Stability

Pitch

Yaw

Roll
Directional divergence

Occurs as a/c yaws or rolls into sideslip. Side forces cause increased yaw - directional instability
Spiral divergence

Results from strong directional stability relative to weak lateral stability
Dutch roll

Results from strong lateral stability relative to directional stability
Optimum AOA

17 units AOA
How to improve transonic flight?

Sweep and low thickness to chord ratio
Stall strips

Geometric Twist

1) Cause the root to stall at a lower AOA

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

Combined effect is that the root and tip stall at approximately the same time.
Advantages/disadvantages of swept wing
A: Higher speeds, structurally stronger
- D:
- 1) Less C_L
- 2) Prone to tip stall
- 3) Spanwise flow
- 4) Leading edge vortexing
- 5) High induced drag at low speed
With two pilots, CG moves...

forward. Increased stability
CG Forward Limits

Decreased maneuverability
CG Aft Limits

Decreased Stability
Mach Tuck

AC moves aft
Upper fuselage/center wing to do not move CG (No answer, just know)
Disadvantage of swept wing:

High AOA Stall

Decreased C_L
Tuck Under

Slight nose down pitch Mach 0.8
Second indicator of impending stall

Accelerated stalls with no external stores - 20^o pitch up
Is thrust neutral on longitudinal stability

Yes
Q?

mass air flow in slugs / sec
What happens to T_R in the following?
1) Configuration
2) Weight increase
3) Altitude increase

1) T_R shifts up and left

2) T_R shifts up and right

3) T_R shifts right

Author

Anonymous

177678

Card Set

Aero Part 2

Description

Part 2

Updated

2012-10-15T01:30:09Z

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