📄 fwind.htm
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<TITLE>FDC help: Fwind</TITLE>
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<H2>Subsystem <I><FONT FACE="Arial","Helvetica","Sans Serif">Fwind</FONT></I></H2>
<I><FONT SIZE=2 FACE="Arial","Helvetica","Sans Serif">Fwind</FONT></I> is a masked S<SMALL>IMULINK</SMALL> subsystem, contained within the system <I><FONT SIZE=2 FACE="Arial","Helvetica","Sans Serif"><A HREF="beaver.htm">Beaver</A></FONT></I>. It is used to compute the contributions to the external forces along the body-axes in non-steady atmosphere (i.e., forces due to non-constant wind and/or atmospheric turbulence).
See the descriptions of <I><FONT SIZE=2 FACE="Arial","Helvetica","Sans Serif"><A HREF="cwind.htm">Cwind</A></FONT></I>, <I><FONT SIZE=2 FACE="Arial","Helvetica","Sans Serif"><A HREF="blwind.htm">BLwind</A></FONT></I>, <I><FONT SIZE=2 FACE="Arial","Helvetica","Sans Serif"><A HREF="turb1.htm">Turb1</A></FONT></I>, and <I><FONT SIZE=2 FACE="Arial","Helvetica","Sans Serif"><A HREF="turb2.htm">Turb2</A></FONT></I> for more information about the generation of the wind and turbulence velocities (and their time-derivatives). The outputs from Fwind are sent to the block <I><FONT SIZE=2 FACE="Arial","Helvetica","Sans Serif"><A HREF="fmsort.htm">FMsort</A></FONT></I>.
<H3>Inputvectors: <I>x</I> and <I>uwind</I></H3>
<PRE> x = [V alpha beta p q r psi theta phi xe ye H]' (states)
uwind = [uw vw ww uwdot vwdot wwdot]' (wind + turbulence velo-
cities and accelerations)
{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] }
uw : wind + turbulence velocity along the XB-axis [m/s]
vw : wind + turbulence velocity along the YB-axis [m/s]
ww : wind + turbulence velocity along the ZB-axis [m/s]
uwdot: d(uw)/dt [m/s^2]
vwdot: d(vw)/dt [m/s^2]
wwdot: d(ww)/dt [m/s^2]
</PRE>
The variables which are not actually needed by <I><FONT SIZE=2 FACE="Arial","Helvetica","Sans Serif">Fwind</FONT></I> have been displayed between accolades.
<H3>Outputvector: <I>Fwind</I></H3>
<PRE> Fwind = [Xw Yw Zw]'.
where:
Xw, Yw, Zw: forces due to non-steady atmosphere, measured along
the aircraft's body-axes [N]
</PRE>
<H3>Parameters which must be defined in the M<SMALL>ATLAB</SMALL> Workspace</H3>
<I>GM1</I>: vector with some important geometrical properties of the 'Beaver' aircraft, and its mass (which is assumed to be constant during the motions of interest). Here, the mass <I>m</I> is extracted from <I>GM1</I>. <I>GM1</I> can be loaded from file by running the utility <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"><A HREF="modbuild.htm">MODBUILD</A></FONT></I> first if the datafile does not yet exist.
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