1. Controls
Chapter 6
Lecture 13

2. Control
Pitch-
Trim-
Yaw & Roll-

3. Directional Stability
The vertical stabilizer (fin) provides directional stability to the airplane in the same way the horizontal stabilizer acts in the longitudinal case.
Figure 6-13 p. 171
weathercock stability

4. Lateral Stability
Lateral stability- is the stabilizing motion about the roll axis
1. Dihedral- one of the most effective ways of stabilizing against slide-slipping
2. Vertical tail provides some lateral stability
3. Fuselage Effect

5. Considerations for lateral
4. Swept Wing-contributor to lateral stability
figure 6-16 p. 175
figure 6-17 p. 175

6. Directional-Lateral Coupling
Coupling-the interaction between rotating motion in one plane and rotating motion in another plane
Adverse Yaw-
Figure 6-18 p. 177

7. Lateral Dynamic Motion
Spiral Divergence- a yaw will continue gradually until recognized & corrected by the pilot
uncorrected the airplane could be in a significant turn of yaw instability
& gradually increasing turn of decreasing radius or spiral motion.
This motion can end up as a spiral dive called a graveyard spiral

8. Lateral Dynamic Motion
Dutch Roll- oscillating movement from side to side
The resulting motion is a series of uncoordinated turns alternating in opposite directions.
Airplanes with small vertical tails often exhibit significant Dutch roll motion.
Increased dihedral will reduce spiral instability, but will increase Dutch roll tendencies.

9. Anatomy of the Turn The airplane banks through an angle
The lift vector is tilted
Enough lift must be generated for the vertical component of lift to equal the weight & keep the plane in level flight.
Figure 6-20 p. 180
The tilted vector also has a horizontal component of lift
Figure 6-21 p. 181

10. Radius & Rate of Turn
When a body is moving in a circular path, it is subject to a centrifugal force
This force is equal to its mass times the square of the forward velocity at any point, divided by the radius of the circle
The centrifugal force must be equal & opposite to the inward component of the lift, by Newton’s third law
Figure 6-22 p. 182

11. Load Factor & Stall Speed
The total lift on the wing in a bank, must be greater than that in level flight.
This means that the wing is experiencing a G-force greater than one, in a level turn.
Figure 6-23 p. 184
Figure 6-24 p. 185

12. Power Limits on Turn Performance
When the airplane is banked into a turn it requires more power than wing-level condition.
Figure 6-25 p. 186

13. Please take out a sheet of paper Include today’s date & your name
Quiz on Chapter 6
Please take out a sheet of paper
Include today’s date & your name

14. Quiz on chapter 6
List and explain three considerations in lateral stability.