 +_____________________________________________________________________
 ] AUTHOR:            ]                             ] DR:              ]
 ] C. FLETCHER        ]    PASS PROGRAM NOTE        ]    37562         ]
 ]____________________]                             ]__________________]
 ] ORG/PHONE:         ] OPS NOTE ( )  USER NOTE (X) ] DATE: AUG. 1987  ]
 ] ENG/282-7333       ]      RELEASE NOTE( )        ]                  ]
 ]____________________]_____________________________]__________________]
 ] OI/FLIGHT EFFECTIVITY:        ]  USER AFFECTED:                     ]
 ] REL 18 AND SUBS               ]  CREW (X)  GROUND ( )  DUMP ONLY ( )]
 ]_______________________________]_____________________________________]
 ]        MAJOR SOFTWARE AREA:       ] OPS MODES AFFECTED:             ]
 ]SSW ( )  GNC (X)  VU ( )  SM/PL ( )] G1, G2, G3                      ]
 ]_____________________________________________________________________]
 ] SOFTWARE SUB-AREA:  RCS, ADI                                        ]
 ]_____________________________________________________________________]
 ] PRINCIPAL FUNCTIONS: 4.103, 4.169, 4.226, 4.97, 4.168               ]
 ]_____________________________________________________________________]
 ] TITLE:                                                              ]
 ] PITCH ERROR NEEDLE SENSITIVITY FOR RCS MANEUVERS                    ]
 ]_____________________________________________________________________]
 ] DESCRIPTION:                                                        ]
 ]                                                                     ]
 ] THE ADI PITCH ERROR NEEDLE BECOMES VERY SENSITIVE AS TIME-TO-GO     ]
 ] (TGO) BECOMES SMALL DURING +X RCS MANEUVERS. THIS SENSITIVITY       ]
 ] RESULTS BECAUSE THE FLIGHT SOFTWARE NAVIGATION FUNCTION PROPAGATES  ]
 ] THE NAVIGATION BASE STATE RATHER THAN THE CENTER OF GRAVITY (C.G.)  ]
 ] OF THE VEHICLE. CONSEQUENTLY, ANGULAR ACCELERATIONS ABOUT THE       ]
 ] VEHICLE C.G. CAUSE CROSS AXIS (CROSS AXIS TO THE DESIRED GUIDANCE   ]
 ] THRUST DIRECTION) SENSED VELOCITY CHANGES WHICH GUIDANCE ATTEMPTS   ]
 ] TO NULL BY DEFLECTING THE DESIRED GUIDANCE THRUST DIRECTION IN THE  ]
 ] OPPOSITE SENSE. THESE CROSS AXIS VELOCITY CHANGES BECOME MORE       ]
 ] SIGNIFICANT AS VELOCITY-TO-BE-GAINED BECOMES SMALLER (BECAUSE THEY  ]
 ] ARE BECOMING LARGER IN PROPORTION TO VGO) AND CAUSE MORE            ]
 ] SIGNIFICANT DESIRED THRUST ROTATION. ERROR NEEDLE JUMPS OF          ]
 ] SEVERAL DEGREES CAN RESULT BECAUSE OF THESE ANGULAR ACCELERATIONS   ]
 ] AS TIME-TO-GO APPROACHES 6 SECONDS (FINE COUNTDOWN).                ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 ] USER RESPONSE:                                                      ]
 ]                                                                     ]
 ] RESPONSE TO JUMPS IN THE ERROR NEEDLES SHOULD BE MINIMIZED OR THE   ]
 ] JUMPS SHOULD BE IGNORED ENTIRELY AS TGO BECOMES SMALL. NO ATTEMPT   ]
 ] SHOULD BE MADE AT ALL TO CHASE THE NEEDLES SINCE A DIVERGENT        ]
 ] SITUATION CAN BE CREATED.                                           ]
 ]                                                                     ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 ]CONCURRENCE:                           ]APPROVAL:                    ]
 ]IBM: WYATT COOPER         DATE 07/28/88]                             ]
 ]    --------------------      ---------]                             ]
 ]SSD: SAM ANKNEY           DATE 08/02/88]                             ]
 ]    --------------------      ---------] JACK G BOYKIN      08/17/88 ]
 ]PF MGR: ARTHUR HIEMER     DATE 07/29/88]------------------- -------- ]
 ]       -----------------      ---------] CHAIRMAN, SASCB      DATE   ]
 ]_______________________________________]_____________________________]
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 DR37564
