Change the drag coefficient for fuselages along the Y and Z axes
(i.e. perpendicular to the fuselage's main axis) to use a fixed
value of 0.5. (The value can still be adjusted using the fuselage's
"cy" and "cz" XML attributes.)
For the Y-axis and Z-axis drag on fuselages, YASim originally used
a drag coefficient equal to:
(solver drag factor) * (fuselage length/width ratio)
This value turns out to be way too small for well-streamlined
aircraft, even those with long, narrow fuselages, and especially
so for those with short, stubby fuselages. Such fuselages are
streamlined in the X direction, but not along Y or Z.
0.5 is only a ballpark estimate, but it's reasonably close for the
common case of a fairly long fuselage with a round cross section. For
flat-sided fuselages, a larger value should be used, up to a maximum
of 2 for a slab-sided block. For short fuselages, the value should be
reduced to account for end effects. The fuselage's "cy" and "cz" XML
attributes can be modified to make such adjustments.
This fix won't affect straight flight much, but it should have a strong
impact on some maneuvers. For example, it will make slips more
effective and may make knife-edge flight easier on aerobatic aircraft
which should be capable of it.
Only aircraft which specify version="YASIM_VERSION_32" or newer are
affected.
user attribute "version" of the airplane element of the YASim config file
to define the version this config uses.
Example:
<airplane mass="1344" version="YASIM_VERSION_CURRENT">
Initially, the following can be used:
YASIM_VERSION_ORIGINAL - The original version of YASim as implemented up to
FlightGear 3.0.0
YASIM_VERSION_32 - The version of YASim implemented in FlightGear 3.2.x
(and the development version 3.1.x)
YASIM_VERSION_CURRENT - The current and latest version of YASim.
isn't well-constrained by the solution process is the drag-vs-aoa curve.
The default value that YASim picked was very steep, and resulted in most
of the jets flying their approaches *way* behind the power curve. This
changes the default to be more forgiving, and adds an "idrag" tunable
to the configuration file for tweakers.
Also, change the default gear springiness to be less stiff.
the amount of drag that the produced lift *would* have produced given an
unflapped air surface. A nifty trick involving the assumption that AoA is
small works for this, and produces plausible results in the high AoA case
as well.
Also, trim for approach using the elevator-trim control, not elevator.
Just cosmetic for current planes, but future ones might have differing
implementations of trim.
Dynamics (Sim)ulator. Basically, this is a rough, first cut of a "different
take" on FDM design. It's intended to be very simple to use,
producing reasonable results for aircraft of all sorts and sizes,
while maintaining simulation plausibility even in odd flight
conditions like spins and aerobatics. It's at the point now where one
can actually fly the planes around.
