Fa2004 16.3337-5 Lateral modes Roll Damping -well damped As the plane rolls, the wing going down has an increased a (wind is effectively"coming up"more at the wing Opposite effect for other wing There is a difference in the lift generated by both wings more on side going down The differential lift creates a moment that tends to restore the equilibrium. Recall that Lp <0 After a disturbance, the roll rate builds up exponentially until the restoring moment balances the disturbing moment, and a steady roll is established Disturbing rolling moment Restoring rolling moment Port wing Starboard Reduction in incidenceFall 2004 16.333 7–5 Lateral Modes Roll Damping ­ well damped. – As the plane rolls, the wing going down has an increased α (wind is effectively “coming up” more at the wing) – Opposite effect for other wing. – There is a difference in the lift generated by both wings → more on side going down – The differential lift creates a moment that tends to restore the equilibrium. Recall that Lp < 0 – After a disturbance, the roll rate builds up exponentially until the restoring moment balances the disturbing moment, and a steady roll is established. py V0 -py − �' �' Roll Rate p Disturbing rolling moment Restoring rolling moment V0 Port wing Starboard wing Reduction in incidence Reduction in incidence