Editing Dutch roll (section)

{{short description|Aircraft motion combining rolling and yawing}}
{{More citations needed|article|date=July 2012}}
[[File:DutchRoll AnimGIF 01.gif|right|200px|thumb|An animated illustration of the two motions which combine into a Dutch roll]]
[[File:Dutch Roll Damping Technique.jpg|upright=1.35|thumb|Dutch roll damping technique, scanned from U.S. Air Force flight manual]]

'''Dutch roll''' is an [[aircraft]] motion consisting of an out-of-[[Phase (waves)|phase]] combination of "tail-wagging" (yaw) and rocking from side to side (roll). This [[yaw (rotation)|yaw]]-roll coupling is one of the basic [[Flight dynamics (fixed-wing aircraft)|flight dynamic]] modes (others include [[phugoid]], [[short period]], and [[spiral divergence]]). This mode resembles the motion of a skier who is simultaneously yawing and rolling from side to side.<ref>{{Cite book |last=Çelik |first=Harun |title=Flight Dynamics and Control (tr. Uçuş Dinamiği ve Kontrolü) |publisher=Nobel Publishing |year=2024 |isbn=978-625-371-938-8}}</ref> This motion is normally well damped in most light aircraft, though some aircraft with well-damped Dutch roll modes can experience a degradation in [[Damping ratio|damping]] as [[airspeed]] decreases and [[altitude]] increases. Dutch roll stability can be artificially increased by the installation of a [[yaw damper]].<ref>{{Cite book |last=Stengel |first=Robert F. |title=Flight dynamics |publisher=Princeton university press |year=2005}}</ref> Wings placed well above the center of gravity, [[swept wing]]s, and [[dihedral (aircraft)|dihedral]] wings tend to increase the roll restoring force, and therefore increase the Dutch roll tendencies; this is why high-winged aircraft often are slightly [[Dihedral (aircraft)#Anhedral|anhedral]], and transport-category swept-wing aircraft are equipped with yaw dampers. A similar phenomenon can happen in a trailer pulled by a car.