## Subsystem Atmosph

Atmosph computes some atmospheric properties, using the ICAO Standard Atmosphere model (see for instance ref.[1]). The block also computes the acceleration of gravity and the dynamic coefficient of viscosity. The block Atmosph is contained in the subsystem Airdata Group of the Beaver model. Other airdata (-related) variables are computed in the blocks Airdata1, Airdata2, and Airdata3, which also contained in the subsystem Airdata Group.

### Inputvector: x

      x = [V alpha beta p q r psi theta phi xe ye H]'        (states)

     {V    : airspeed [m/s]                                         }
     {alpha: angle of attack [rad]                                  }
     {beta : sideslip angle [rad]                                   }
     {p    : roll rate [rad/s]                                      }
     {q    : pitch rate [rad/s]                                     }
     {r    : yaw rate [rad/s]                                       }
     {psi  : yaw angle [rad]                                        }
     {theta: pitch angle [rad]                                      }
     {phi  : roll angle [rad]                                       }
     {xe   : x-coordinate in Earth-fixed reference frame [m]        }
     {ye   : y-coordinate ''     ''          ''      ''  [m]        }
      H    : altitude above sea-level [m]

The variables which are not actually used by Atmosph have been displayed between curly braces.

### Outputvector: yatm

      yatm = [rho ps T mu g]', (atmospheric properties)

      rho  : airdensity [kg/m^3]
      ps   : static pressure [N/m^2]
      T    : temperature [K]
      mu   : dynamic viscosity [kg/(m*s)]
      g    : acceleration of gravity [m/s^2]

### References

1. Ruijgrok, G.J.J. Elements of airplane performance. Delft University Press, Delft, The Netherlands, 1993.