Spring 2003 16.61AC3-6 Dutch Roll- damped oscillation in yaw, that couples into roll Frequency similar to longitudinal short period mode, not as well damped (fin less effect than the horizontal tail) Do you know the origins on the name of the mode? Consider a disturbance from straight-level fight Oscillation in yaw y(fin provides the aerodynamic stiffness) Wings moving back and forth due to yaw motion result in oscillatory differential Lift/ Drag(wing moving forward generates more lift +Oscillation in roll o that lags y/ by approximately 900 Forward going wing is low Oscillating roll- sideslip in direction of low wing Path traced by starboard wing tip in one dutch roll cycle a)Starboard wing yaws aft with wing tip high aft yaw angle as aircraft rolls through ooo(c)Starboard wing g tp low yaws forward with yaw angle as aircraft rolls wings level in negative sense Damp the Dutch roll mode with a large tail finSpring 2003 16.61 AC 3–6 Dutch Roll - damped oscillation in yaw, that couples into roll. • Frequency similar to longitudinal short period mode, not as well damped (fin less effect than the horizontal tail). • Do you know the origins on the name of the mode? • Consider a disturbance from straight-level flight → Oscillation in yaw ψ (fin provides the aerodynamic stiffness) → Wings moving back and forth due to yaw motion result in oscillatory differential Lift/Drag (wing moving forward generates more lift) → Oscillation in roll φ that lags ψ by approximately 90◦ ⇒ Forward going wing is low Oscillating roll → sideslip in direction of low wing. • Damp the Dutch roll mode with a large tail fin. 6