On 10/28/2013 02:00 PM, James Turner
Hi, following the discussion after a"fix" for
the reported true air
speed, for jsbsim planes, we've got yet
another case where yasim and
jsbsim diseagre when exporting a property to
the property in cause is:
yasim report it as the mach value, along the
u axis, if wind come from
behind, the value is negative.
jsbsim reported it (before the patch) as the
absolute value, the value
was the same whatever the plane heading, this
was changed to have the
same as the yasim behaviour.
The jsbsim is what I would expect, thus /Mach being the total vector
value. This value is used for any aerodynamic calculation (where
aerodynamic coefficients are made non-dimensional with). Any
projected values (which you might need also) would ideally need a
reference in their names to the axis it is projected on or else you
just dont know what you are dealing with. Like the jsbsim variant
MachU, MachV, MachW for instance (Mach vector projected on body axis
x,y and z respectfully).
next come the question :)
what is supposed to be velocities/mach ?
should we keep the norm of the wind relative
to the plane speed, in case
pitot and other instrument using it should
use alpha and side slip to
give dynamique pressure, or should we use the
yasim one, ie mach being
the mach speed along the u axis?
I can't answer these questions, hopefully Jon / Eric /