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   Generate linear models of an airship at a range of flight conditions.
   The angle of attack is set to zero.
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   Form:
   GenerateAirshipLinMods( d, h, V, thteta )
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   Inputs
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   d           (.)       Airship model data structure.
   h          (1,:)      Altitude                          [m]
   V          (1,:)      Total velocity                    [m/s]
   theta      (1,:)      Pitch                             [rad]

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   Outputs
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   none

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