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   Provide a default aircraft state. 
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   Form:
   x = DefaultACState;
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   Inputs
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   None 

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   Outputs
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   x               Aircraft state vector, consisting of:
                    - r       (3,1) ECI position vector
                    - q       (4,1) Quaternion from ECI to body
                    - w       (3,1) Inertial body rate in body frame
                    - v       (3,1) Velocity of cm wrt air
                    - wR      (:,1) Angular velocity of rotors
                    - mass    (1,1) Mass
                    - inertia (6,1) Inertia
                    - cG      (3,1) Center of mass
                    - engine  (:,1) Engine states
                    - actuator(:,1) Actuator states
                    - sensor  (:,1) Sensor states
                    - flex    (:,1) Flex model states
                    - disturb (:,1) Disturbance model states

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