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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
ID
177678
Card Set
Aero Part 2
Description
Part 2
Updated
2012-10-15T01:30:09Z
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