Maximum pitch and roll
When vertical profilers and gliders start their profile, there may be considerable pitching and rolling of the vehicle before it settles into a more consistent flight. Thus, these parameters can also be used to exclude regions that produce poor data. There are no hard criterion for pitching and rolling. In quiesent water, the principal axis of a vertical profiler typically pitches and rolls about [math]\displaystyle{ 1\, ^{\circ} }[/math] about their mean values. In waters that are vigorously turbulent, the large eddies may make a vertical profiler pitch and roll by about [math]\displaystyle{ 5\, ^{\circ} }[/math] . Gliders pitch and roll similarly around their typical flight angle of [math]\displaystyle{ 30^{\circ} }[/math]. Pitch and roll angles must not be confused with the angle-of-attack (aoa). The aoa is the angle of the flow relative to the angle of the principal axis of the vehicle (vertical profiler, glider, AUV, etc.) and may be much smaller than the pitch or roll angles. For example, a glider typically has a pitch of [math]\displaystyle{ 30^{\circ} }[/math] with respect to the horizontal plane. However, once it is gliding stably, the angle of the incoming flow is about [math]\displaystyle{ 3^{\circ} }[/math] with respect to the longitudinal axis of the glider. The aoa produces lift on the glider which is required for "flight".
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