Aircraft often encounter atmospheric turbulence, such as rapid differences in wind speed and/or direction from an average or a mean flow of air. For example, atmospheric turbulence may include, but is not limited to, wind shear, wind gradients, clear-air turbulence, wake turbulence, air pockets, and the like. Atmospheric turbulence may include vertical and horizontal wind shears or gusts of wind. Vertical shear or gusts of wind typically occur at higher levels in the atmosphere and above or near a vertical surface, such as a mountain. Horizontal shear may occur near weather fronts or near a coastal region. Pilots try to avoid flying in turbulent conditions whenever possible.
During flight, a commercial transport aircraft often operates in a normal cruising configuration that minimizes or otherwise reduces fuel consumption. In the normal cruising configuration, various control surfaces of the aircraft may be in a retracted or other such position that minimizes or otherwise reduces drag. However, the cruising configuration may not be well-suited to compensate for structural loads on wings and other aircraft surfaces caused by gusts.
Aerodynamically efficient control surface configurations may not be well-suited to handle a gust. Aircraft are required to meet discrete gust load criteria, as specified by the Federal Aviation Administration (FAA). As such, when an aircraft encounters a gust, one or more control surfaces are deflected. In short, certain wing configurations are preferable for redistributing gust loads. In this manner, instead of adding structural weight to an aircraft to provide adequate design margin for gust loads, less structure may be required when and control surfaces are reconfigured to compensate for the gust loads. However, while flying an aircraft with deflected control surfaces is structurally weight-efficient with respect to gust loads, the gust configuration is not fuel efficient, as the deflected surfaces cause drag.
In general, the total load on the aircraft includes: a “1 g load” which represents the forces and moments normally sustained in straight, level, unaccelerated flight; a maneuver load which is the result of temporary, pilot-commanded deviations from straight, level, unaccelerated flight; and a gust load that is the result of atmospheric disturbances.
Further, an aircraft may include one or more monitoring systems that detect gusts for the purpose of load alleviation. For example, a load factor may be used as an indicator of a gust and used to reconfigure control surfaces of the aircraft. However, such signals do not differentiate between intentional aircraft maneuvers and gusts. Further, using the load factor typically requires the aircraft to penetrate the gust and respond to the gust before the control surfaces are able to be reconfigured. As such, using the load factor as a feedback signal does not provide sufficient time for the control surfaces to be optimally reconfigured before a time of peak load.
Accordingly, a need exists for a system and method for efficiently configuring an aircraft to compensate for gusts. A need exists for a system and method for withstanding wind gusts that do not increase an overall structural weight of an aircraft.