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Controls

Controls. Chapter 6 Lecture 13. Control. Pitch- Trim- Yaw & Roll-. 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.

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Controls

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  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. 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.

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