On Fri, 2004-01-09 at 12:30, David Culp wrote: > > Take the A320 (on FG) and watch the ball. All I want to know, which > > property to use for trigger function to keep the ball centered. > > since you discussed this topic so deeply, I'm sure someone can name me the > > property... > > > Here's the yaw section from the T-38 FCS: > > > <!-- YAW FCS *********************************************************** > --> > <COMPONENT NAME="Rudder Command Sum" TYPE="SUMMER"> > INPUT fcs/rudder-cmd-norm > INPUT fcs/yaw-trim-cmd-norm > CLIPTO -1 1 > </COMPONENT> > <COMPONENT NAME="Yaw SAS Rate" TYPE="SCHEDULED_GAIN"> > INPUT velocities/r-aero-rad_sec > SCHEDULED_BY velocities/ve-kts > ROWS 3 > 30 0.00 > 60 5.00 > 220 3.00 > </COMPONENT> > <COMPONENT NAME="Yaw SAS Beta" TYPE="SCHEDULED_GAIN"> > INPUT aero/beta-rad > SCHEDULED_BY velocities/ve-kts > ROWS 2 > 30 0.00 > 60 0.00 > </COMPONENT> > <COMPONENT NAME="Yaw SAS Sum" TYPE="SUMMER"> > INPUT fcs/yaw-sas-rate > INPUT fcs/yaw-sas-beta > CLIPTO -0.2 0.2 > </COMPONENT> > <COMPONENT NAME="Rudder Sum" TYPE="SUMMER"> > INPUT fcs/rudder-command-sum > INPUT fcs/yaw-sas-sum > CLIPTO -1 1 > </COMPONENT> > <COMPONENT NAME="Rudder Control" TYPE="AEROSURFACE_SCALE"> > INPUT fcs/rudder-sum > MIN -0.35 > MAX 0.35 > OUTPUT fcs/rudder-pos-rad > </COMPONENT> > > > The component called "Yaw SAS Rate" is what one would call a yaw damper. It's > job is to provide an extra "Yaw_moment_due_to_yaw_rate" for airplanes that > are defficient in this quality. The component looks at beta rate (in JSBSim > it is called "velocities/r-aero-rad_sec").
That is yaw rate, which is different from beta rate in a similar way that angle of attack rate is different from pitch rate. Beta rate (or betadot, as it's more commonly called) is aero/betadot-rad_sec in JSBSim. > > The component called "Yaw SAS Beta" is what you are looking for. It could be > called an "auto-coordinator", because it is based on the beta angle. In this > case I have the component turned off. To turn the component on you simply > change the scheduling gains from zero. For instance, look at the yaw damper. > At and below 30 knots the yaw damper gain is zero (off). Between 30 knots > and 60 knots the gain is interpolated from zero to 5.0. Between 60 knots and > 220 knots the gain is interpolated from 5.0 to 3.0. I recommend this > component be turned off at low speeds, otherwise it will fight a crosswind > even when the airplane is stationary. > > The outputs of the yaw damper and auto-coordinator are summed, then limited to > %20 rudder in order to prevent it from overpowering the pilot's input. > > This is just one way of building a yaw SAS. > > Dave -- Tony Peden <[EMAIL PROTECTED]> _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
