# Copyright: Public domain. # Filename: CSM_GEOMETRY.agc # Purpose: Part of the source code for Colossus 2A, AKA Comanche 055. # It is part of the source code for the Command Module's (CM) # Apollo Guidance Computer (AGC), for Apollo 11. # Assembler: yaYUL # Contact: Ron Burkey . # Website: www.ibiblio.org/apollo. # Pages: 285-296 # Mod history: 2009-05-08 RSB Adapted from the Colossus249/ file of the # same name, using Comanche055 page images. # # This source code has been transcribed or otherwise adapted from digitized # images of a hardcopy from the MIT Museum. The digitization was performed # by Paul Fjeld, and arranged for by Deborah Douglas of the Museum. Many # thanks to both. The images (with suitable reduction in storage size and # consequent reduction in image quality as well) are available online at # www.ibiblio.org/apollo. If for some reason you find that the images are # illegible, contact me at info@sandroid.org about getting access to the # (much) higher-quality images which Paul actually created. # # Notations on the hardcopy document read, in part: # # Assemble revision 055 of AGC program Comanche by NASA # 2021113-051. 10:28 APR. 1, 1969 # # This AGC program shall also be referred to as # Colossus 2A # Page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age 286 # CALCSXA COMPUTES THE SEXTANT SHAFT AND TRUNNION ANGLES REQUIRED TO POSITION THE OPTICS SUCH THAT A STAR LINE- # OF-SIGHT LIES ALONG THE STAR VECTOR. THE ROUTINE TAKES THE GIVEN STAR VECTOR AND EXPRESSES IT AS A VECTOR REF- # ERENCED TO THE OPTICS COORDINATE SYSTEM. IN ADDITION IT SETS UP THREE UNIT VECTORS DEFINING THE X,Y, AND Z AXES # REFERENCED TO THE OPTICS COORDINATE SYSTEM. # # THE INPUTS ARE 1) THE STAR VECTOR REFERRED TO PRESENT STABLE MEMBER COORDINATES STORED AT STAR. 2) SAME ANGLE # INPUT AS *SMNB*, I.E. SINES AND COSINES OF THE CDU ANGLES, IN THE ORDER Y Z X, AT SINCDU AND COSCDU. A CALL # TO CDUTRIG WILL PROVIDE THIS INPUT. # # THE OUTPUTS ARE THE SEXTANT SHAFT AND TRUNNION ANGLES STORED DP AT SAC AND PAC RESPECTIVELY. (LOW ORDER PART # EQUAL TO ZERO). CALCSXA ITA VLOAD # PUSHDOWN 00-26D,28D,30D,32D-36D 28D STAR CALL *SMNB* MXV VSL1 NB2NB1 STOVL STAR HIUNITX STOVL XNB1 HIUNITY STOVL YNB1 HIUNITZ STCALL ZNB1 SXTANG1 # Page 287 # SXTANG COMPUTES THE SEXTANT SHAFT AND TRUNNION ANGLES REQUIRED TO POSITION THE OPTICS SUCH THAT A STAR LINE-OF- # SIGHT LIES ALONG THE STAR VECTOR. # # THE INPUTS ARE 1) THE STAR VECTOR REFERRED TO ANY COORDINATE SYSTEM STORED AT STAR. 2) THE NAVIGATION BASE # COORDINATES REFERRED TO THE SAME COORDINATE SYSTEM. THESE THREE HALF-UNIT VECTORS ARE STORED AT XNB, YNB, AND # ZNB. # # THE OUTPUTS ARE THE SEXTANT SHAFT AND TRUNNION ANGLES STORED DP AT SAC AND PAC RESPECTIVELY. (LOW ORDER PART # EQUAL TO ZERO). SXTANG ITA RTB # PUSHDOWN 16D,18D,22D-26D,28D 28D TRANSP1 # EREF WRT NB2 VLOAD MXV XNB NB2NB1 VSL1 STOVL XNB1 YNB MXV VSL1 NB2NB1 STOVL YNB1 ZNB MXV VSL1 NB2NB1 STORE ZNB1 RTB RTB TRANSP1 TRANSP2 SXTANG1 VLOAD VXV ZNB1 STAR BOV +1 UNIT BOV ZNB=S1 STORE PDA # PDA = UNIT(ZNB X S) DOT DCOMP XNB1 STOVL SINTH # SIN(SA) = PDA . -XNB PDA DOT YNB1 STCALL COSTH # COS(SA) = PDA . YNB ARCTRIG # Page 288 RTB 1STO2S STOVL SAC STAR BOV +1 DOT SL1 ZNB1 ACOS BMN SL2 SXTALARM # TRUNNION ANGLE NEGATIVE BOV DSU SXTALARM # TRUNNION ANGLE GREATER THAN 90 DEGREES 20DEG- RTB 1STO2S STORE PAC # FOR FLIGHT USE, CULTFLAG IS ON IF CLRGO # TRUNION IS GREATER THAN 90 DEG CULTFLAG 28D SXTALARM SETGO # ALARM HAS BEEN REMOVED FROM THIS CULTFLAG 28D # SUBROUTINE,ALARM WILL BE SET BY MPI ZNB=S1 DLOAD 270DEG STODL SAC 20DEGS- STORE PAC CLRGO CULTFLAG 28D # Page 289 # THESE TWO ROUTINES COMPUTE THE ACTUAL STATE VECTOR FOR LM, CSM BY ADDING # THE CONIC R,V AND THE DEVIATIONSR,V. THE STATE VECTORS ARE CONVERTED TO # METERS B-29 AND METERS/CSEC B-7 AND STORED APPROPRIATELY IN RN,VN OR # R-OTHER , V-OTHER FOR DOWNLINK. THE ROUTINES NAMES ARE SWITCHED IN THE # OTHER VEHICLES COMPUTER. # # INPUT # STATE VECTOR IN TEMPORARY STORAGE AREA # IF STATE VECTOR IS SCALED POS B27 AND VEL B5 # SET X2 TO +2 # IF STATE VECTOR IS SCALED POS B29 AND VEL B7 # SET X2 TO 0 # # OUTPUT # R(T) IN RN, V(T) IN VN, T IN PIPTIME # OR # R(T) IN R-OTHER, V(T) IN V-OTHER (T IS DEFINED BY T-OTHER) BANK 23 SETLOC COMGEOM2 BANK COUNT 10/GEOM SVDWN1 BOF RVQ # SW=1=AVETOMID DOING W-MATRIX INTEG AVEMIDSW +1 VLOAD VSL* TDELTAV 0 -7,2 VAD VSL* RCV 0,2 STOVL RN TNUV VSL* VAD 0 -4,2 VCV VSL* 0,2 STODL VN TET STORE PIPTIME RVQ SVDWN2 VLOAD VSL* TDELTAV 0 -7,2 VAD VSL* RCV # Page 290 0,2 STOVL R-OTHER TNUV VSL* VAD 0 -4,2 VCV VSL* 0,2 STORE V-OTHER RVQ # Page 291 # SUBROUTINE TO COMPUTE THE NATURAL LOG OF C(MPAC, MPAC +1). # # ENTRY: CALL # LOG # # SUBROUTINE RETURNS WITH -LOG IN DP MPAC. # # EBANK IS ARBITRARY.. BANK 14 SETLOC POWFLIT2 BANK COUNT 23/GEOM LOG NORM BDSU # GENERATES LOG BY SHIFTING ARG MPAC +3 # UNTIL IT LIES BETWEEN .5 AND 1. NEARLY1 # THE LOG OF THIS PART IS FOUND AND THE EXIT # LOG OF THE SHIFTED PART IS COMPUTED TC POLY # AND ADDED IN. SHIFT COUNT STORED DEC 2 # (N-1, SUPPLIED BY SMERZH) 2DEC 0 # IN MPAC +3. 2DEC .031335467 2DEC .0130145859 2DEC .0215738898 CAF ZERO TS MPAC +2 EXTEND DCA CLOG2/32 DXCH MPAC DXCH MPAC +3 COM # LOAD POSITIVE SHIFT COUNT IN A. TC SHORTMP # MULTIPLY BY SHIFT COUNT. DXCH MPAC +1 DXCH MPAC DXCH MPAC +3 DAS MPAC TC INTPRET # RESULT IN MPAC, MPAC +1 RVQ NEARLY1 2DEC .999999999 # Page 292 CLOG2/32 2DEC .0216608494 # Page 293 # SUBROUTINE NAME: EARTH ROTATOR (EARROT1 OR EARROT2) DATE: 15 FEB 67 # MOD NO: N +1 LOG SECTION: POWERED FLIGHT SUBROS # MOD BY: ENTRY GROUP (BAIRNSFATHER) # FUNCTIONAL DESCRIPTION: THIS ROUTINE PROJECTS THE INITIAL EARTH TARGET VECTOR RTINIT AHEAD THROUGH # THE ESTIMATED TIME OF FLIGHT. INITIAL CALL RESOLVES THE INITIAL TARGET VECTOR RTINIT INTO EASTERLY # AND NORMAL COMPONENTS RTEAST AND RTNORM . INITIAL AND SUBSEQUENT CALLS ROTATE THIS VECTOR # ABOUT THE (FULL) UNIT POLAR AXIS UNITW THROUGH THE ANGLE WIE DTEAROT TO OBTAIN THE ROTATED # TARGET VECTOR RT . ALL VECTORS EXCEPT UNITW ARE HALF UNIT. # THE EQUATIONS ARE # - - - - # RT = RTINIT + RTNORM (COS(WT) - 1) + RTEAST SIN(WT) # WHERE WT = WIE DTEAROT # RTINIT = INITIAL TARGET VECTOR # - - - # RTEAST = UNITW*RTINIT # - - - # RTNORM = RTEAST*UNITW # # FOR CONTINUOUS UPDATING, ONLY ONE ENTRY TO EARROT1 IS REQUIRED, WITH SUBSEQUENT ENTRIES AT EARROT2. # CALLING SEQUENCE: FIRST CALL SUBSEQUENT CALL # STCALL DTEAROT STCALL DTEAROT # EARROT1 EARROT2 # C(MPAC) UNSPECIFIED C(MPAC) = DTEAROT # PUSHLOC = PDL+0, ARBITRARY. 6 LOCATIONS USED. # # SUBROUTINES USED: NONE # NORMAL EXIT MODES: RVQ # ALARMS: NONE # OUTPUT: RTEAST (-1) .5 UNIT VECTOR EAST, COMPNT OF RTINIT LEFT BY FIRST CALL # RTNORM (-1) .5 UNIT VECTOR NORML, COMPNT OF RTINIT LEFT BY FIRST CALL # RT (-1) .5 UNIT TARGET VECTOR, ROTATED LEFT BY ALL CALLS # DTEAROT (-28) CS MAY BE CHANGED BY EARROT2, IF OVER 1 DAY # ERASABLE INITIALIZATION REQUIRED: # UNITW (0) UNIT POLAR VECTOR PAD LOADED # RTINIT (-1) .5 UNIT INITIAL TARGET VECTOR LEFT BY ENTRY # DTEAROT (-28) CS TIME OF FLIGHT LEFT BY CALLER # DEBRIS: QPRET, PDL+0 ... PDL+5 # Page 294 EBANK= RTINIT EARROT1 VLOAD VXV UNITW # FULL UNIT VECTOR RTINIT # .5 UNIT STORE RTEAST # .5 UNIT VXV UNITW # FULL UNIT STODL RTNORM # .5 UNIT DTEAROT # (-28) CS EARROT2 BOVB DDV TCDANZIG # RESET OVFIND, IF ON 1/WIE BOV PUSH OVERADAY COS DSU HIDPHALF VXSC PDDL # XCH W PUSH LIST RTNORM # .5 UNIT SIN VXSC RTEAST # .5 UNIT VAD VSL1 VAD UNIT # INSURE THAT RT IS 'UNIT'. RTINIT # .5 UNIT STORE RT # .5 UNIT TARGET VECTOR RVQ OVERADAY DLOAD SIGN 1/WIE DTEAROT BDSU DTEAROT STORE DTEAROT GOTO EARROT2 #WIE 2DEC .1901487997 1/WIE 2DEC 8616410 NB2NB1 2DEC +.8431756920 B-1 2DEC 0 2DEC -.5376381241 B-1 # Page 295 ZERINFLT 2DEC 0 HALFNFLT 2DEC .5 2DEC 0 2DEC +.5376381241 B-1 2DEC 0 2DEC +.8431756920 B-1 NB1NB2 2DEC +.8431756920 B-1 2DEC 0 2DEC +.5376381241 B-1 2DEC 0 2DEC .5 2DEC 0 2DEC -.5376381241 B-1 2DEC 0 2DEC +.8431756920 B-1 # Page 296 10DEGS- DEC 3600 270DEG OCT 60000 # SHAFT 270 DEGREES 2S COMP. OCT 00000 20DEGS- DEC -07199 DEC -00000 20DEG- DEC 03600 DEC 00000