### FILE="Main.annotation" ## Copyright: Public domain. ## Filename: P34.agc ## Purpose: A section of Skylark revision 048. ## It is part of the source code for the Apollo Guidance Computer (AGC) ## for Skylab-2, Skylab-3, Skylab-4, and ASTP. No original listings of ## this software are available; instead, this file was created via ## disassembly of dumps of the core rope modules actually flown on ## Skylab-2. Access to these modules was provided by the New Mexico ## Museum of Space History. ## Assembler: yaYUL ## Contact: Ron Burkey . ## Website: www.ibiblio.org/apollo/index.html ## Mod history: 2024-02-18 MAS Created. ## 2024-03-05 MAS Finished filling out. ## This log section is derived from Artemis's P32-P33, P72-P73. # CONSTANT DELTA HEIGHT (CDH) PROGRAMS (P33 AND P73) # MOD NO -1 LOG SECTION - P32-P35, P72-P75 # MOD BY WHITE.P DATE 1 JUNE 67 # # PURPOSE # # (1) TO CALCULATE PARAMETERS ASSOCIATED WITH THE CONSTANT DELTA # ALTITUDE MANEUVER (CDH). # # (2) TO CALCULATE THESE PARAMETERS BASED UPON MANEUVER DATA # APPROVED AND KEYED INTO THE DSKY BY THE ASTRONAUT. # # (3) TO DISPLAY TO THE ASTRONAUT AND THE GROUND DEPENDENT VARIABLES # ASSOCIATED WITH THE CDH MANEUVER FOR APPROVAL BY THE # ASTRONAUT/GROUND. # # (4) TO STORE THE CDH TARGET PARAMETERS FOR USE BY THE DESIRED # THRUSTING PROGRAM. # # ASSUMPTIONS # # (1) THIS PROGRAM IS BASED UPON PREVIOUS COMPLETION OF THE # CO-ELLIPTIC SEQUENCE INITIATION (CSI) PROGRAM (P32/P72). # THERFORE - # # (A) AT A SELECTED TPI TIME (NOW IN STORAGE) THE LINE OF SIGHT # BETWEEN THE ACTIVE AND PASSIVE VEHICLES WAS SELECTED TO BE # A PRESCRIBED ANGLE (E) (NOW IN STORAGE) FROM THE # HORIZONTAL PLANE DEFINED BY THE ACTIVE VEHICLE POSITION. # # (B) THE TIME BETWEEN CSI IGNITION AND CDH IGNITION WAS # COMPUTED TO BE GREATER THAN 10 MINUTES. # # (C) THE TIME BETWEEN CDH IGNITION AND TPI IGNITION WAS # COMPUTED TO BE GREATER THAN 10 MINUTES. # # (D) THE VARIATION OF THE ALTITUDE DIFFERENCE BETWEEN THE # ORBITS WAS MINMIZED. # # (E) CSI BURN WAS DEFINED SUCH THAT THE IMPULSIVE DELTA V WAS # IN THE HORIZONTAL PLANE DEFINED BY ACTIVE VEHICLE # POSITION AT CSI IGNITION. # # (F) THE PERICENTER ALTITUDES OF THE ORBITS FOLLOWING CSI AND # CDH WERE COMPUTED TO BE GREATER THAN 35,000 FT FOR LUNAR # ORBIT OR 85 NM FOR EARTH ORBIT. # # (G) THE CSI AND CDH MANEUVERS WERE ASSUMED TO BE PARALLEL TO # THE PLANE OF THE PASSIVE VEHICLE ORBIT. HOWEVER, CREW # MODIFICATION OF DELTA V (LV) COMPONENTS MAY HAVE RESULTED # IN AN OUT-OF-PLANE MANEUVER. # # (2) STATE VECTOR UPDATES BY P27 ARE DISALLOWED DURING AUTOMATIC # STATE VECTOR UPDATING INITIATED BY P20 (SEE ASSUMPTION 4). # # (3) COMPUTED VARIABLES MAY BE STORED FOR LATER VERIFICATION BY # THE GROUND. THESE STORAGE CAPABILITES ARE NORMALLY LIMITED # ONLY TO THE PARAMETERS FOR ONE THRUSTING MANEUVER AT A TIME # EXCEPT FOR CONCENTRIC FLIGHT PLAN MANEUVER SEQUENCES. # # (4) THE RENDEZVOUS RADAR MAY OR MAY NOT BE USED TO UPDATE THE LM # OR CSM STATE VECTORS FOR THIS PROGRAM. IF RADAR USE IS # DESIRED THE RADAR WAS TURNED ON AND LOCKED ON THE CSM BY # PREVIOUS SELECTION OF P20. RADAR SIGHTING MARKS WILL BE MADE # AUTOMATICALLY APPROXIMATELY ONCE A MINUTE WHEN ENABLED BY THE # TRACK AND UPDATE FLAGS (SEE P20). THE RENDEZVOUS TRACKING # MARK COUNTER IS ZEROED BY THE SELECTION OF P20 AND AFTER EACH # THRUSTING MANEUVER. # # (5) THE ISS NEED NOT BE ON TO COMPLETE THIS PROGRAM. # # (6) THE OPERATION OF THE PROGRAM UTILIZES THE FOLLOWING FLAGS - # # ACTIVE VEGICLE FLAG - DESIGNATES THE VEHICLE WHICH IS # DOING RENDEZVOUS THRUSTING MANEUVERS TO THE PROGRAM WHICH # CALCULATES THE MANEUVER PARAMETERS. SET AT THE START OF # EACH RENDEZVOUS PRE-THRUSTING PROGRAM. # # FINAL FLAG - SELECTS FINAL PROGRAM DISPLAYS AFTER CREW HAS # COMPLETED THE FINAL MANEUVER COMPUTATION AND DISPLAY # CYCLE. # # EXTERNAL DELTA V STEERING FLAG - DESIGNATES THE TYPE OF # STEERING REQUIRED FOR EXECUTION OF THIS MANEUVER BY THE # THRUSTING PROGRAM SELECTED AFTER COMPLETION OF THIS # PROGRAM. # # (7) IT IS NORMALLY REQUIRED THAT THE ISS BE ON FOR 1 HOUR PRIOR TO # A THRUSTING MANEUVER. # # (8) THIS PROGRAM IS SELECTED BY THE ASTRONAUT BY DSKY ENTRY - # # P33 IF THIS VEHICLE IS ACTIVE VEHICLE. # # P73 IF THIS VEHICLE IS PASSIVE VEHICLE. # # INPUT # # (1) TTPI0 TIME OF THE TPI MANEUVER - SAVED FROM P32/P72 # (2) ELEV DESIRED LOS ANGLE AT TPI - SAVED FROM P32/P72 # (3) TCDH TIME OF THE CDH MANEUVER # # OUTPUT # # (1) TRKMKCNT NUMBER OF MARKS # (2) TTOGO TIME TO GO # (3) +MGA MIDDLE GIMBAL ANGLE # (4) DIFFALT DELTA ALTITUDE AT CDH # (5) T2TOT3 DELTA TIME FROM CDH TO COMPUTED TPI # (6) NOMTPI DELTA TIME FROM NOMINAL TPI TO COMPUTED TPI # (7) DELVLVC DELTA VELOCITY AT CDH - LOCAL VERTICAL COORDINATES # # DOWNLINK # # (1) TCDH TIME OF THE CDH MANEUVER # (2) TTPI TIME OF THE TPI MANEUVER # (3) TIG TIME OF THE CDH MANEUVER # (4) DELVEET2 DELTA VELOCITY AT CDH - REFERENCE COORDINATES # (5) DIFFALT DELTA ALTITUDE AT CDH # (6) ELEV DESIRED LOS ANGLE AT TPI # # COMMUNICATION TO THRUSTING PROGRAMS # # (1) TIG TIME OF THE CDH MANEUVER # (2) RTIG POSITION OF ACTIVE VEHICLE AT CDH - BEFORE ROTATION # INTO PLANE OF PASSIVE VEHICLE # (3) VTIG VELOCITY OF ACTIVE VEHICLE AT CDH - BEFORE ROTATION # INTO PLANE OF PASSIVE VEHICLE # (4) DELVSIN DELTA VELOCITY AT CDH - REFERENCE COORDINATES # (5) DELVSAB MAGNITUDE OF DELTA VELOCITY AT CDH # (6) XDELVFLG SET TO INDICATE EXTERNAL DELTA V VG COMPUTATION # # SUBROUTINES USED # # P20FLGON # VNPOOH # ADVANCE # CDHMVR # INTINT3P # ACTIVE # PASSIVE # S33/34.1 # ALARM # BANKCALL # GOFLASH # GOTOPOOH # S32/33.1 # VN1645 SETLOC CSI/CDH1 BANK EBANK= SUBEXIT COUNT* $$/P34 P34 TC P20FLGON CAF V06N13 # TCDH TC VNFLASH TC INTPRET DLOAD CLEAR TTPI FINALFLG STODL TTPI0 TCDH STCALL TIG VN1645 P33/P73B DLOAD CALL TIG ADVANCE CALL CDHMVR STORE DELVEET1 # CDH DV TO USE DISDVLVC SUB FOR N81 DISP SETPD VLOAD 0D VACT3 PDVL CALL RACT2 INTINT3P CALL ACTIVE SETPD VLOAD 0D VPASS2 PDVL CALL RPASS2 INTINT3P CALL PASSIVE DLOAD SET ZEROVECS ITSWICH STCALL NOMTPI S33/34.1 BZE EXIT P33/P73C TC ALARM OCT 611 CAF V05N09 TC BANKCALL CADR GOFLASH TC GOTOPOOH TC +2 TC P34 TC INTPRET DLOAD ZEROVECS STORE NOMTPI P33/P73C BON SET FINALFLG P33/P73D UPDATFLG P33/P73D DLOAD DAD NOMTPI TTPI STORE TTPI DSU TCDH P33/P73E DSU BPL 60MIN P33/P73E DAD 60MIN STCALL T1TOT2 P33/73F EXIT CAF V06N75 TC VNFLASH TC INTPRET SKIP75 CALL DISDVLVC # PUT UP N81, COMPUTE DELVSIN CALL VN1645 GOTO P33/P73B 60MIN 2DEC 360000 B-28 SETLOC FFTAG12 BANK COUNT* $$/P34 V06N11 VN 0611 V06N13 VN 0613 V06N75 VN 0675 # ..... DISDVLVC ..... # # SUBROUTINES USED # # S32/33.X # VNPOOH SETLOC CDHTAG3 BANK COUNT* $$/CSI DISDVLVC STQ CALL NORMEX S32/33.X VLOAD MXV DELVEET1 0D VSL1 STCALL DELVLVC # REF TO L V DISPN90 CALL S32/33.X VLOAD VXM DELVLVC 0D VSL1 STCALL DELVSIN # L V TO REF NORMEX # ..... ADVANCE ..... # # SUBROUTINES USED # PRECSET # ROTATE SETLOC CDHTAG3 BANK COUNT* $$/CDH ADVANCE STQ SUBEXIT STCALL TDEC1 PRECSET SET VLOAD XDELVFLG VPASS3 STOVL VPASS2 RPASS3 STOVL RPASS2 RACT3 STCALL RTIG ROTATE STOVL RACT2 VACT3 STCALL VTIG ROTATE STCALL VACT2 SUBEXIT # ..... ROTATE ..... SETLOC CSIPROG6 BANK COUNT* $$/CSI ROTATE PUSH PUSH DOT VXSC UP1 UP1 VSL2 BVSU UNIT PDVL ABVAL VXSC VSL1 RVQ # .... DISPN90 ..... SETLOC CSIPROG BANK COUNT* $$/CSI DISPN90 STQ ANEXIT VLOAD VCOMP AUTOY STODL YCSM # COMPLEMENT VALUES FOR N90 DISPLAYS. CMYDOT STORE DELVLVC +2 BOFF ABS PCFLAG OKN81 # NOT IN P36 DSU BPL # IS YDOT LESS THAN .1 FPS 1/10FPS OKN81 # NO VLOAD # YES - FORCE DSKY DISPLAY TO BE 0 ZEROVEC STORE DELVLVC OKN81 EXIT CAF V06N81 TC VNFLASH TC INTPRET GOTO ANEXIT 1/10FPS 2DEC .0003048 B-7 # .1 FPS # ..... INTINTNA ..... SETLOC CDHTAG2 BANK COUNT* $$/CDH INTINT3P PDDL PDDL TCDH TTPI PDDL PUSH TWOPI # FOR CONIC INTEGRATION GOTO INTINT # ..... S32/33.X ..... SETLOC CDHTAGS BANK COUNT* $$/CDH S32/33.X SETPD VLOAD 6D UP1 VCOMP PDVL RACT2 UNIT VCOMP PUSH VXV UP1 VSL1 STORE 0D RVQ SETLOC CDHTAG BANK COUNT* $$/CDH # The name of the following label is a guess. P33/73F DLOAD DSU TTPI TTPI0 PUSH P33/P73F ABS DSU 60MINH BPL DAD P33/P73F 60MINH SIGN STADR STORE T2TOT3 RVQ # ..... CDHMVR ..... # # SUBROUTINES USED # TIMETHET CDHMVR STQ VLOAD SUBEXIT RACT2 PUSH UNIT STOVL UNVEC # UR SUB A RPASS2 UNIT DOT UNVEC PUSH SL1 STODL CSTH DSQ PDDL DP1/4TH SR2 DSU SQRT SL1 PDVL VCOMP VXV RPASS2 DOT PDDL UP1 SIGN STADR STOVL SNTH RPASS2 STOVL RVEC VPASS2 CLEAR RVSW STCALL VVEC TIMETHET STORE 18D DOT SL1R UNVEC PDVL ABVAL # 0D = V SUB PV PDVL RACT2 ABVAL PDDL # 2D = LENGTH OF R SUB A DSU 02D STODL DIFFALT # DELTA H IN METERS B+29 R1A NORM PDDL # 2 - R V**/MU 04D X1 R1 SR1R DDV SL* PUSH 0 -5,1 DSU PDDL # A SUB A B+29 04D DIFFALT SR2 DDV # A SUB P B+31 04D # B+2 PUSH SQRT # A SUB P/A SUB A 06D DMPR DMP 06D 00D SL3R PDDL # V SUB AV METERS/CS B+7 08D 02D # R SUB A MAGNITUDE B+29 NORM PDDL X1 RTMU SR1 DDV # 2MU B+38 SL* PDDL # 2 MU/R SUBAA B+14 10D 0 -5,1 04D # ASUBA B+29 NORM PDDL X2 RTMU SR1 DDV SL* BDSU 0 -6,2 # 2U/R - U/A B+14 (METERS/CS)SQ PDDL DSQ # 10D 08D BDSU SQRT PDVL VXV # SQRT(MU(2/R SUB A-1/A SUB A)-VSUBA2) 10D UP1 UNVEC UNIT VXSC 10D PDVL VXSC UNVEC 08D VAD VSL1 STADR STORE VACT3 VSU VACT2 STCALL DELVEET2 # DELTA VCDH - REFERENCE COORDINATES SUBEXIT RTMU 2DEC* 3.986032 E10 B-36*