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Space Shuttle: Difference between revisions
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→Lateral stability
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Below approximately Mach 6, the rudder starts to contribute to yaw stability and from Mach 3.5 down to Mach 2 where the yawing moment finally becomes positive only the rudder is used. The roll behavior of the orbiter before any FCS is somewhat skittish as the roll moment as a function of roll rate is not a large damping term over most of the Mach range. The FCS of the Shuttle in FG therefore does not place yaw and roll axis directly under pilot control. The rudder is always commanded to minimize beta and no pilot input for the rudder should be needed or used unless sideslip is explicitly desired. The elevons are commanded to provide a simple roll damper to make control smoother. | Below approximately Mach 6, the rudder starts to contribute to yaw stability and from Mach 3.5 down to Mach 2 where the yawing moment finally becomes positive only the rudder is used. The roll behavior of the orbiter before any FCS is somewhat skittish as the roll moment as a function of roll rate is not a large damping term over most of the Mach range. The FCS of the Shuttle in FG therefore does not place yaw and roll axis directly under pilot control. The rudder is always commanded to minimize beta and no pilot input for the rudder should be needed or used unless sideslip is explicitly desired. The elevons are commanded to provide a simple roll damper to make control smoother. | ||
The real Shuttle has in addition a <b>NO Y JET</b> mode to stabilize the orbiter during entry in which the elevons are used to control yaw. This leads to significantly reduced roll control since roll then needs to be driven by adverse yaw till the rudder picks up sufficient airflow. | The real Shuttle has in addition a <b>NO Y JET</b> mode to stabilize the orbiter during entry in which the elevons are used to control yaw. This leads to significantly reduced roll control since roll then needs to be driven by adverse yaw till the rudder picks up sufficient airflow. This mode has been implemented since dev version of july 2017. | ||
=== A note on thruster efficiency in the atmosphere === | === A note on thruster efficiency in the atmosphere === | ||