📄 aeromod.htm
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<TITLE>FDC help: Aeromod (Beaver)</TITLE>
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<H2>Subsystem <I><FONT FACE="Arial","Helvetica","Sans Serif">Aeromod (Beaver)</FONT></I></H2>
<I><FONT SIZE=2 FACE="Arial","Helvetica","Sans Serif">Aeromod (Beaver)</FONT></I> is a masked S<SMALL>IMULINK</SMALL> subsystem, used to compute aerodynamic force and moment coefficients for the DHC-2 'Beaver'. The aerodynamic model is aircraft-dependent, hence, this block must be replaced if models of other aircraft are to be implemented in the simulation structure of FDC. Instant replacement of the block <I><FONT SIZE=2 FACE="Arial","Helvetica","Sans Serif">Aeromod (Beaver)</FONT></I> is possible only if the same inputs and outputs to and from this block remain the same. However, the internal structure of a replacement for the current block <I><FONT SIZE=2 FACE="Arial","Helvetica","Sans Serif">Aeromod</FONT></I> may look completely different. For instance, the aerodynamic model of the DHC-2 'Beaver', contained in <I><FONT SIZE=2 FACE="Arial","Helvetica","Sans Serif">Aeromod (Beaver)</FONT></I> determines the force and moment coefficients by means of evaluation of six polynomial equations (<A HREF="#References">see ref.[1]</A>), whereas it is more customary to compute aerodynamic forces and moments by means of interpolation in large multi-dimensional tables. The block <I><FONT SIZE=2 FACE="Arial","Helvetica","Sans Serif">Aeromod</FONT></I> is contained in the subsystem <I><FONT SIZE=2 FACE="Arial","Helvetica","Sans Serif"><A HREF="aerogrp.htm">Aerodynamics Group (Beaver)</A></FONT></I> of the system <I><FONT SIZE=2 FACE="Arial","Helvetica","Sans Serif"><A HREF="beaver.htm">Beaver</A></FONT></I>. Other blocks within that subsystem are: <I><FONT SIZE=2 FACE="Arial","Helvetica","Sans Serif"><A HREF="dimless.htm">Dimless</A></FONT></I>, and <I><FONT SIZE=2 FACE="Arial","Helvetica","Sans Serif"><A HREF="fmdims.htm">FMdims</A></FONT></I>.
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<B>Note:</B> The side-force coefficient with respect to beta-dot has been neglected in the block <I><FONT SIZE=2 FACE="Arial","Helvetica","Sans Serif">Aeromod (Beaver)</FONT></I>, because it would have yielded an algebraic loop. Therefore, the beta-dot equation has been written out as an explicit equation with an aircraft-independent and an aircraft-dependent term. The latter is evaluated in a separate block <I><FONT SIZE=2 FACE="Arial","Helvetica","Sans Serif"><A HREF="xdotcorr.htm">xdotcorr (Beaver)</A></FONT></I>, which is contained in the subsystem <I><FONT SIZE=2 FACE="Arial","Helvetica","Sans Serif"><A HREF="eqmotion.htm">Aircraft Equations of Motion</A></FONT></I>.
<H3>Inputvectors: <I>x</I>, <I>uaero</I>, <I>ydl</I>
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<PRE> x = [V alpha beta p q r psi theta phi xe ye H]' (states)
uaero= [deltae deltaa deltar deltaf]' (aerodynamic inputs)
ydl = [pb/2V qc/V rb/2V]' (dimensionless velocities,
computed in the block <A HREF="dimless.htm">Dimless</A>)
{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] }
deltae: elevator deflection [rad]
deltaa: deflection of the ailerons [rad]
deltar: rudder deflection [rad]
deltaf: flap setting [rad]
pb/2V: dimensionless roll rate [-]
qc/V : dimensionless pitch rate [-]
rb/2V: dimensionless yaw rate [-]
</PRE>
The inputvariables which are not actually used by <I><FONT SIZE=2 FACE="Arial","Helvetica","Sans Serif">Aeromod (Beaver)</FONT></I> have been displayed between accolades.
<H3>Outputvector: <I>Caero</I>
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<PRE> Caero = [CXa CYz CZa Cla Cma Cna]'
CXa, CYa, CZa: dimensionless aerodynamic force coefficients
Cla, Cma, Cna: dimensionless aerodynamic moment coefficients.
</PRE>
<H3>Parameters, which must be defined in the M<SMALL>ATLAB</SMALL> Workspace
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<LI><I>AM</I>: matrix with stability and control derivatives of the 'Beaver' (valid only for the nonlinear aerodynamic model of the DHC-2 'Beaver', see <A HREF="#References">ref.[1]</A>). The matrix <I>AM</I> can be loaded into the M<SMALL>ATLAB</SMALL> workspace from file by running <I><FONT SIZE=2 FACE="Arial","Helvetica","Sans Serif"><A HREF="loader.htm">LOADER</A></FONT></I>. Run <I><FONT SIZE=2 FACE="Arial","Helvetica","Sans Serif"><SMALL><A HREF="modbuild.htm">MODBUILD</A></SMALL></FONT></I> first if this datafile does not yet exist.
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<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 "Beaver" aircraft</I>. Report LR-556, Delft University of Technology, 1988.
</OL>
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