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The PC-SIG Library 10
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The PC-Sig Library - Shareware for the IBM PC and Compatibles (PC-SIG)(Tenth Edition Disks 1-2804)(1991).iso
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13.CMT
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1989-03-24
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4KB
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131 lines
*** BEGIN TUTORIAL # 1-3 ***
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Tutorial # 1-3 covers the plane change maneuvers
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..through Descent Orbit Insertion (DOI)
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..and ends before Powered Descent Initiation (PDI)
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The first plane change maneuver takes place as the LV passes
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..directly south of the landing site
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..and uses the RCS down thruster to cancel the northward velocity
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The first plane change burn begins
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The LV was moving north at about 0.2m/s
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At an acceleration of 0.011m/s², a 0.2m/s change takes about 20s
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The first plane change maneuver is complete
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The LV up body axis must be pointed south
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..to be in the correct attitude for the second plane change burn
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..since the landing site is in the northern hemisphere
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Therefore, the LV must be pitched by 180°
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The pitch program begins
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The pitch program is halfway complete
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The pitch program is complete
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The second plane change occurs when the LV is 87° west of the landing site
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..at MET 1:21:00
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The plane change burn is so minor (only about 0.01°)
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..that it can be performed using the RCS thrusters alone
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The INS display is switched to "ORBABS" to monitor the course of the burn
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The second plane change burn begins by turning on the RCS up thruster
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*** LOOK at the INS orbit display
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*** WATCH the north component of the angular momentum angle
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The burn is complete when the north component is (90 - 0.02)° = 89.98°
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The second plane change maneuver is complete
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The LV attitude is adjusted for the DOI burn
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The RCS yaw control is used to point the LV left body axis due south
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Yaw program start
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Yaw program complete
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The RCS pitch control is used to point the LV face body axis so that
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..it points straight up during the DOI burn at 165° west of the landing site
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Pitch program start
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Pitch program complete
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The DOI burn begins when the LV is 165° west of the landing site
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..at MET 2:07:00
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The DOI burn reduces the perilune to approximately 20km
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..at 15° east of the landing site near the beginning of PDI
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Four minutes to PDI
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The DOI burn requires a change in velocity of about 29.5 m/s
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..and takes about 12s at 50% throttle
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Three minutes to PDI
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Two minutes to PDI
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Note that the LV face body axis is nearly vertical
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One minute to PDI
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During the PDI burn, LOOK first at the consumables display at the lower left
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A "" appears by "THR" indicating that the main engine is on at 50% throttle
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Then LOOK at the clocks display to the right
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..the burn timer (BUR) will count to 12s at the completion of the burn
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Also LOOK at the perilune in the INS display
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The DOI burn begins by igniting the main engine
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*** LOOK at the throttle display .. it says the main engine is on at 50%
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*** LOOK at the clocks display .. the burn timer has started
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*** WATCH the perilune display .. the burn stops when it nears 20km
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The main DOI burn is complete .. the burn timer says it lasted 12s as required
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The RCS up thruster is used to adjust the perilune to about 20km
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The descent orbit is 20.4km by 149.6km
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The LV is put into the proper orientation for the PDI burn
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..at 15° east of the landing site
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Pitch program start
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Pitch program complete
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This concludes TUTORIAL # 1-3 .. the mission continues with TUTORIAL # 1-4
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