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      FDC help: Aerodynamics Group (Beaver)
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    <h2>
      Subsystem <i>Aerodynamics Group (Beaver)</i>
    </h2>
    <p>The subsystem <i>Aerodynamics Group (Beaver)</i> of the <i><a href="beaver.htm">Beaver</a></i> model contains blocks that determine the aerodynamic
    forces and moments for the &#39;Beaver&#39; aircraft. The block <i><a href=
    "dimless.htm">Dimless</a></i> first computes the non-dimensional rotational
    velocity components along the aircraft&#39;s body-axes. The dimensionless
    force and moment coefficients are then calculated in the block <i><a href=
    "aeromod.htm">Aeromod (Beaver)</a></i>, which contains the actual
    (aircraft-dependent) aerodynamic model, and finally, the real values of
    these forces and moments are determined by the block <i><a href=
    "fmdims.htm">FMdims</a></i>.</p> 
     <p>As implied by its name, the subsystem <i>Aerodynamics Group (Beaver)</i>
    is only valid for the De Havilland DHC-2 &#39;Beaver&#39;, using the
    aerodynamic model from <a href="#References">ref.[1]</a>. The internal
    structure of similar models for other aircraft may look entirely different.
    For instance, in this case the block <i>Dimless</i> is needed, because the
    dimensionless rotational velocities are used as helpvariables for the
    actual aerodynamic model in <i>Aeromod</i>, whereas aerodynamic models for
    other aircraft may require entirely different helpvariables.</p>
     <p>For this reason, the internal structure of the subsystem <i>Aerodynamics
    Group</i> will <i>always</i> depend upon the aircraft model considered. </p>
    <h3>
      Inputs: <i>x</i>, <i>uaero</i>, <i>yad1</i>
    </h3>
<pre>
  x    = [V alpha beta p q r psi theta phi xe ye H]&#39;     (states)
  uaero= [deltae deltaa deltar deltaf]&#39; (aerodyn. control-inputs)
  yad1 = [a M qdyn]&#39;                   (basic airdata variables,
                                            coming from <a href=
"airdata1.htm">Airdata1</a>)

  V     : true 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, relative to Earth-axes [m]              }
 {ye    : Y-coordinate, relative to Earth-axes [m]              }
 {H     : altitude above sea level [m]                          }

  deltae: deflection of elevator [rad]
  deltaa: deflection of ailerons [rad]
  deltar: deflection of rudder [rad]
  deltaf: deflection of flaps [rad]

 {a     : speed of sound [m/s]                                  }
 {M     : Mach number [-]                                       }
  qdyn  : dynamic pressure [N/m^2]
</pre>
    <p>The variables which are not actually used by any of the masked subsystems
    <i>Dimless</i>, <i>Aeromod (Beaver)</i>, and <i>FMdims</i> have been
    displayed between curly braces. </p>
    <h3>
      Outputs: <i>ydl</i>, <i>Caero</i>, <i>FMaero</i>
    </h3>
<pre>
  ydl   = [pb/2V qc/V rb/2V]&#39;              (outputs from <a href=
"dimless.htm">Dimless</a>)
  Caero = [CXa CYa CZa Cla Cma Cna]&#39;       (outputs from <a href=
"aeromod.htm">Aeromod</a>)
  FMaero= [Xa Ya Za La Ma Na]&#39;              (outputs from <a href=
"fmdims.htm">FMdims</a>)


  CXa, CYa, CZa: dimensionless aerodynamic force coefficients
  Cla, Cma, Cna: dimensionless aerodynamic moment coefficients
  Xa, Ya, Za   : aerodynamic forces [N]
  La, Ma, Na   : aerodynamic moments [Nm]
</pre>
    <h3>
      Parameters to be defined in the Matlab workspace
    </h3>
    <ul>
      <li>
        <i>GM1</i>: vector with some important geometrical properties of the
        &#39;Beaver&#39; aircraft, and the mass of the aircraft (which is
        assumed to be constant during the motions of interest). Here, it is
        needed by <i>Dimless</i> in order to extract geometrical data.
      </li>
      <li>
        <i>AM</i>: matrix with stability and control derivatives of the
        &#39;Beaver&#39; (valid only for the nonlinear aerodynamic model of the
        DHC-2 &#39;Beaver&#39;, see <a href="#References">ref.[1]</a>). This
        matrix is needed by <i>Aeromod (Beaver)</i>.
      </li>
    </ul>
    <p><i>AM</i> and <i>GM1</i> can be loaded into the workspace from datafile by
    running the utility <i><a href="datload.htm">DATLOAD</a></i>. Run <i><a
    href="modbuild.htm">MODBUILD</a></i> first if the datafile does not yet
    exist.</p> 
    <h3>
      <a name="References">References</a>
    </h3>
    <ol>
      <li>
        R.T.H. Tjee and J.A. Mulder. <i>Stability and Control Derivatives of
        the De Havilland DHC-2 &quot;Beaver&quot; aircraft</i>. Report LR-556,
        Delft University of Technology, 1988.
      </li>
    </ol>
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