Controls

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 Newtons
  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
Quiz on Chapter 6

• Please take out a sheet of paper
• Include todays date your name

14
Quiz on chapter 6

• List and explain three considerations in lateral
  stability.