## Subsystem Engmod (Beaver)

Engmod (Beaver) computes the dimensionless force and moment coefficients due to operation of the powerplant, using the engine forces & moments model of the DHC-2 'Beaver' aircraft from ref.[1]. The block is contained in the subsystem Engine Group of the Beaver model. It uses the outputs from the block Power (Beaver) and its outputs are sent to the block FMdims, which are both also contained in the subsystem Engine Group.

### Inputvectors: x and ypow

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

      ypow = [dpt P]'    (dimensionless pressure increase across the
                           propeller and engine power, both computed
                                         in the block Power (Beaver))

     {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]                           }

      dpt  : dimensionless pressure increase across the propeller [-]
     {P    : engine power [Nm/s]                                    }

The input variables which are not actually used by Engmod (Beaver) have been displayed between curly braces.

### Outputvector: Cprop (prop = 'propulsion')

      Cprop = [CXp CYp CZp Clp Cmp Cnp]'

      CXp, CYp, CZp: force coefficients due to engine operation [-]
      Clp, Cmp, Cnp: moment coefficients due to engine operation [-]

### Parameters to be defined in the Matlab Workspace.

- EM: matrix with stability and control derivatives of the 'Beaver' that take into account the engine operation (including slipstream effects of the propeller. The matrix EM can be loaded into the workspace from file by running the routine DATLOAD. Run MODBUILD first if the datafile does not yet exist.

### References

1. R.T.H. Tjee and J.A. Mulder. Stability and Control Derivatives of the De Havilland DHC-2 "Beaver" aircraft. Report LR-556, Delft University of Technology, 1988.