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RCS Command Lights

The reaction control system command lights on panel F6 are active during the entry and RTLS flight phases. Their primary function is to indicate RCS jet commands by axis and direction; secondary functions are to indicate when more than two yaw jets are commanded and when the elevon drive rate is saturated.

During major modes 301 through 304, up until the roll jets are no longer commanded (dynamic pressure exceeds 10 pounds per square foot), the roll l and r lights indicate that left or right roll commands have been issued by the DAP. The minimum light-on duration is extended so that the light can be seen even during minimum-impulse firings. When dynamic pressure is greater than or equal to 10 pounds per square foot, the roll lights are quiescent until 50 pounds per square foot, after which time both lights are illuminated whenever more than two yaw jets are commanded on.

The pitch u and d lights indicate up and down pitch jet commands until dynamic pressure equals 20 pounds per square foot, after which the pitch jets are no longer used. When dynamic pressure is 50 pounds per square foot or more, the pitch lights, like the roll lights, assume a new function: both light whenever the elevon surface drive rate exceeds 20 degrees per second (10 degrees per second if only one hydraulic system is left).

The yaw l and r lights function as yaw jet command indicators throughout entry until the yaw jets are disabled at Mach 1. The yaw lights have no other functions.

Curator: Kim Dismukes | Responsible NASA Official: John Ira Petty | Updated: 04/07/2002
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