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Old 31st May 2013, 18:58
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WeekendFlyer
 
Join Date: Sep 2002
Location: Hampshire
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Well, there are some misconceptions going on here!

Lateral stability summary:

- Wing sweep, high wing, dihedral and the vertical tail are stabilising influences

- Low wing, anhedral and keel area are destabilising influences

- A laterally stable aircraft ALWAYS rolls away from sideslip

Lateral stability will only come into effect when there is sideslip present. This will happen whenever the lift force is not directly aligned with (and opposite to) the resultant of the weight force and any centrifugal force present. Weight ALWAYS acts vertically down, regardless of aircraft attitude, but lift will roll and pitch with the aircraft. Therefore if the aircraft has a non-zero roll angle, the lift force will be at an angle to the weight force and thus there will be a sideways component of lift. This causes the aircraft to fly slightly sideways as well as forwards, leading to sideslip.

Sideslip will cause the wing on that side to experience a higher AOA than the other wing, leading to a difference in lift that rolls the aircraft level.
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