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Aero input and outputs: Difference between revisions
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→Stall hysteresis, normalized:: Added dany93 comment
(→Function outputs: deleted stuff I wrote when I had misunderstood how it worked.) |
(→Stall hysteresis, normalized:: Added dany93 comment) |
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/fdm/jsbsim/aero/stall-hyst-norm | /fdm/jsbsim/aero/stall-hyst-norm | ||
dany93 wrote on the forums about this: | |||
What I have understood at this point: | |||
By setting, say | |||
<code> | |||
<hysteresis_limits unit="DEG"> | |||
<min>5.0</min> | |||
<max>17</max> | |||
</hysteresis_limits> | |||
</code> | |||
stall-hyst-norm, normally at 0, switches to 1 at 17 deg (alpha-deg or corresponding alpha-rad value, different from alpha-wing-rad if wing incidence is not zero). | |||
Later on, it returns back to 0 only when alpha-deg comes down to 5 deg. Close to the usual hysteresis behavior (typically iron magnetization, with magnetic field h corresponding to alpha angle for us), but the delay is not dependent on the max value attained by the variable alpha. A kind of 'rectangular' hysteresis loop, more simple but already good for aerodynamics (linear or turbulent) regimes. | |||
This stall-hyst-norm (0 or 1 values) can then be used as a parameter for tables, to set some command sensitivity, lift coefficient,moment, etc, to hold longer in it's 'bad' condition even when the cause has ceased. Stall holds for a longer time, like turbulent regime in the real case. | |||
Logically, the <max> value is close to the critical AoA for stall, but the lift curve and stall-hyst-norm are used independently. | |||
=== Time rate of change in alpha and sideslip in deg/sec and rad/sec: === | === Time rate of change in alpha and sideslip in deg/sec and rad/sec: === | ||