At 3/30/03, Tony Peden wrote:
... snip ...On Sun, 2003-03-30 at 21:16, Michael Selig wrote: > At 3/30/03, you wrote: > >On Sun, 2003-03-30 at 20:05, Michael Selig wrote: > > > At 3/30/03, you wrote: > > > >Michael Selig writes: > > > >
> > > [2] In preferences.xml, I have changed 'eye-heading-deg-path' per below.
> > > The LaRCsim/UIUC code computes this value. The advantage is that in the
> > > second view, the view direction is in the direction of the airplane
> > > ("Gamma" horizontal in effect). The result is that when rudder is
> > applied,
> > > the airplane will yaw, but the view direction will not. It is a much more
> > > natural way to see the airplane and tendency for vertigo is greatly
> > reduced
> > > when things are unsteady. With the ASW-20 landing w/ sideslip
> > > (cross-controls), the 2nd view is down the runway w/ the airplane in a big
> > > sideslip.
> > >
> > > <!-- view 2 -->
> > > <view>
> > > <name>Chase View</name>
> > > <type>lookat</type>
> > > <config>
> > > <from-model type="bool">false</from-model>
> > > <from-model-idx type="int">0</from-model-idx>
> > > <eye-lat-deg-path>/position/latitude-deg</eye-lat-deg-path>
> > > <eye-lon-deg-path>/position/longitude-deg</eye-lon-deg-path>
> > > <eye-alt-ft-path>/position/altitude-ft</eye-alt-ft-path>
> > >
> > <eye-heading-deg-path>/orientation/gamma-horiz-deg</eye-heading-deg-path>
> > >
> > > Frankly, I think this should be applied w/ all FDMs, but JSBSim and YASim
> > > will need to compute gamma-horiz-deg first.
> >
> >Flight path angle is computed by JSBSim. It's probably not passed to
> >FG, however.
>
> I am referring to the "flight path angle" in the horizontal plane, not the
> flight path angle proper (in the vertical plane). I'm not sure if that was
> clear. Does JSBSim compute the "flight path angle" in the horizontal plane?
That would be drift angle, wouldn't it? I think we compute ground track heading and drift = heading - ground track.
Yes, I think so. I get gamma-horiz-deg from this in ls_aux.c (line 421): Gamma_horiz_rad = atan2( V_east_rel_ground, V_north_rel_ground ); I set the property in LaRCsim.cxx.
I'd like people to try this out:
In the preferences.xml, change the line:
<eye-heading-deg-path>/orientation/heading-deg</eye-heading-deg-path> ... line 126, for chase view (view #2)
to
<eye-heading-deg-path>/orientation/gamma-horiz-deg</eye-heading-deg-path>
and fly one of the uiuc planes. Go to the chase view and kick in rudder. The plane yaws immediately but the view does not. I think this is a better way to do the chase view. This gamma-horiz-deg is only set in the uiuc code for now, but if people like this approach the other fdms could compute this angle. Or else we could set a new property for this view angle and the uiuc code would set it to gamma-horiz-deg while the other fdms could still use heading-deg.
Regards, Michael
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