## Subsystem pqrdot

pqrdot computes the time-derivatives of the angular body-axes velocities p, q, and r. The block pqrdot is contained in the block 12 ODEs of the subsystem Aircraft Equations of Motion in the Beaver model. The remaining nine differential equations are stored in the subsystems Vabdot, Eulerdot, and xyHdot, which are all contained in 12 ODEs.

### Inputvector: upqr

      upqr = [x' Ftot' Mtot' yhlp'],

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

      Ftot = [Fx Fy Fz]'           (total forces along the body-axes,
                                        computed in the block FMsort)

      Mtot = [L M N]'             (total moments along the body-axes,
                                        computed in the block FMsort)

      yhlp = [cos(alpha) sin(alpha) cos(beta) sin(beta) ...
              ... tan(beta) sin(psi) cos(psi) sin(theta) ...
              ... cos(theta) sin(phi) cos(phi)]'
                    (sines and cosines, coming from the block Hlpfcn)

     {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]                            }

     {Fx, Fy, Fz: total forces along the aircraft's body-axes [N]    }
      L, M, N   : total moments along the aircraft's body-axes [Nm]

The inputvariables which are not actually used by pqrdot have been displayed between curly braces. None of the elements of yhlp are used by pqrdot.

### Outputvector: ypqr

      ypqr = [pdot qdot rdot]'

      pdot : dp/dt [rad/s^2]
      qdot : dq/dt [rad/s^2]
      rdot : dr/dt [rad/s^2]

### Parameters to be defined in the Matlab workspace

GM2: matrix with inertia parameters of the 'Beaver' aircraft (which is assumed to be constant during the motions of interest). GM2 can be loaded into the workspace by calling the routine DATLOAD. Use MODBUILD if the datafile with model parameters does not yet exist.