On Wed, Dec 8, 2010 at 11:14 PM, Roland Haeder wrote:
> I use the following call to start FGFS:
> --------------------------
> fgfs...
...
> --aircraft=aircrane --enable-fpe
Thanks, that actually always reproduces it.
> And the temperature at EDDL can now really be at 0 deg. Celsius because
> of winter time. :)
Yep, looked like a mix-up of Kelvin vs Celsius at first. But that's
not the problem. It doesn't depend on season or environmental
temperature. The specific calculation failing doesn't even use the
actual temperature. So the aircrane always crashes when using
--enable-fpe.
The trigger is a missing configuration setting in the FDM description.
The YASim FDM seems to rely on a valid "cruise" and an "approach"
configuration. Several things are not properly initialized unless both
configurations are present in the XML file. The aircrane only provides
an "approach" configuration. This results in stupid default values
being used, so it eventually starts calculating with a temperature of
0 Kelvin (where the classic laws of aerodynamics, gas and pressure
seem to fail...).
Adding the following configuration to "aircrane.xml" fixes this issue:
<cruise speed="84" alt="0">
<control-setting axis="/controls/engines/engine[0]/throttle" value="1.0"/>
</cruise>
That's a configuration I copied from a different helicopter. Maybe
helijah/Heiko can comment on the correct FDM settings for the
aircrane.
The underlying problem with YASim should also be fixed. Not nice when
missing config settings result in the FDM going wild. In fact, this
could explain a number of issues why specific YASim aircraft run into
infamous NaN problems (few people use "--enable-fpe" to abort on
floating point exceptions, so divisions by zero result in
"Not-a-Number" results). There maybe more config options (and
aircraft) where YASim goes mad when settings are missing...
cheers,
Thorsten
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