# Copyright: Public domain. # Filename: ENTRY_LEXICON.agc # Purpose: Part of the source code for Comanche, build 055. It # is part of the source code for the Command Module's # (CM) Apollo Guidance Computer (AGC), Apollo 11. # Assembler: yaYUL # Reference: pp. 837-843 # Contact: Ron Burkey # Website: http://www.ibiblio.org/apollo. # Mod history: 2009-05-12 RSB Adapted from Colossus249 file of the same # name and Comanche 055 page images. # # The contents of the "Comanche055" files, in general, are transcribed # from scanned documents. # # Assemble revision 055 of AGC program Comanche by NASA # 2021113-051. April 1, 1969. # # This AGC program shall also be referred to as Colossus 2A # # Prepared by # Massachusetts Institute of Technology # 75 Cambridge Parkway # Cambridge, Massachusetts # # under NASA contract NAS 9-4065. # # Refer directly to the online document mentioned above for further # information. Please report any errors to info@sandroid.org. # Page 837 # VARIABLE DESCRIPTION MAXIMUM VALUE * COMPUTER NAME # -------- ----------- ------- ------- -------- ---- # # _ # URT0 INITIAL TARGET VECTOR 2 (UNIT VECTOR) = RTINIT # _ # UZ UNIT VECTOR NORTH 1 = UNITW # _ # V VELOCITY VECTOR 2 VSAT = VEL # _ # R POSITION VECTOR 2 EXP 29 METERS = RN # _ # VI INERTIAL VELOCITY 128 M/CENTISEC = VN # _ # RTE VECTOR EAST AT INITIAL TARGET 2 = RTEAST # _ # UTR NORMAL TO RTE AND UZ 2 = RTNORM # _ # URT TARGET VECTOR 2 = RT # _ # UNI UNIT NORMAL TO TRAJECTORY PLANE 2 # _ # DELV INTEGRATED ACCEL. FROM PIPAS 5.85 16384 CM/S # _ # G GRAVITY VECTOR 128 M/CENTISEC = GDT/2 # # A0 INITIAL DRAG FOR UPCONTRL 805 FPSS FPSS=FT/SEC/SEC # AHOOKDV TERM IN GAMMAL CALC. = AHOOK DVL 16 # A1 DRAG VALUE IN FACTOR CALCULATION 805 FPSS # ALP CONST FOR UPCONTRL 1 # ASKEP KEPLER RANGE 21600 NM NM = NAUTICAL MILE # ASP1 FINAL PHASE RANGE 21600 NM # ASPUP UP-RANGE 21600 NM # ASP3 GAMMA CORRECTION 21600 NM # ASPDWN RANGE DOWN TO PULL-UP 21600 NM # ASP PREDICTED RANGE 21600 NM NOT STORED # COSG COSINE(GAMMAL) 2 = COSG/2 # C/D0 RECIPROCAL DRAG, -4/D0 B-8 64/FPSS # D TOTAL ACCELERATION 805 FPSS # D0 CONTROLLED CONSTANT D 805 FPSS # DHOOK TERM IN GAMMAL COMPUTATION 805 FPSS # DIFF THETNM-ASP (RANGE DIFFERENCE) 21600 NM # DIFFOLD PREVIOUS VALUE OF DIFF 21600 NM # DLEWD CHANGE IN LEWD 1 # DR REFERENCE DRAG FOR DOWNCONTROL 805 FPSS NOT STORED # DREFR REFERENCE DRAG 805 FPSS NOT STORED # DVL VS1-VL 2 VSAT # E ECCENTRICITY 4 NOT STORED # F1 DRANGE/D DRAG (FINAL PHASE) 2700/805 = FX +5 # F2 DRANGE/D RDOT (FINAL PHASE) 2700/2VS NM/FPS = FX +4 # Page 838 # F3 DRANGE/D (L/D) 2700 NM = FX # FACT1 CONST FOR UPCONTRL 805 FPSS # FACT2 CONST FOR UPCONTRL 1/805 FPSS # FACTOR USED IN UPCONTRL 1 * MAXIMUM VALUE DENOTES UNSCALED # GAMMAL FLIGHT PATH ANGLE AT VL 1 RADIAN VARIABLE VALUE WHEN SCALED # GAMMAL1 SIMPLE FORM OF GAMMAL 1 RADIAN VARIABLE HAS MAXIMUM VALUE OF ONE. # Page 839 # # HEADSUP INDICATOR FOR INITIAL ROLL 1 # KA DRAG TO LIFT UP IF DOWN 805 FPSS = KAT # KLAT LATERAL SWITCH GAIN 1 (NOM = .0125) # K2ROLL INDICATOR FOR ROLL SWITCH # LAD MAX L/D (MIN ACTUAL VEHICLE L/D) 1 # LADPAD NOMINAL VEHICLE L/D, SP PAD LOAD 1 (NOM = 0.3) # LATANG LATERAL RANGE 4 RADIANS # LEQ EXCESS C.F. OVER GRAV=(VSQ-1)GS 128.8 FPSS # LEWD UPCONTROL REFERENCE L/D 1 # LOD FINAL PHASE L/D 1 (NOM = 0.18) # LODPAD FINAL PHASE L/D, SP PAD LOAD 1 # L/D DESIRED LIFT TO DRAG RATIO 1 # (VERTICAL PLANE) # L/D1 TEMP STORAGE FOR L/D IN LATERAL 1 # L/DCMINR LAD COS(15DEG) 1 (NOM = 0.2895) # PREDANGL PREDICTED RANGE (FINAL PHASE) 2700 NM = PREDANG # Q2 FINAL PHASE RANGE -23500 Q3 21600 NM # Q2 = FCN(LAD) # Q7 MINIMUM DRAG FOR UPCONTROL 805 FPSS # RDOT ALTITUDE RATE 2 VSAT # RDOTREF REFERENCE RDOT FOR UPCONTROL 2 VSAT # RDTR REFERENCE RDOT FOR DOWNCONT 2 VSAT NOT SAVED # ROLLC ROLL COMMAND 1 REVOLUTION # RTOGO RANGE TO GO (FINAL PHASE) 2700 NM = FX +2 # SL SINE OF LATITUDE 1 NOT SAVED # T TIME B 28 CENTISEC = TIME2,TIME1 # THETA DESIRED RANGE (RADIANS) 2 PI RADIANS = THETAH # THETNM DESIRED RANGE (NM) 21600 NM NON EXISTENT # V VELOCITY MAGNITUDE 2 VSAT # V1 INITIAL VELOCITY FOR UPCONTROL 2 VSAT # VL EXIT VELOCITY FOR UPCONTROL 2 VSAT # VREF REFERENCE VELOCITY FOR UPCONTROL 2 VSAT # VS1 VSAT OR V1, WHICHEVER IS SMALLER 2 VSAT # 2 2 # VBARS VL /VSAT 4 # 2 2 # VSQ NORMALISED VEL. SQUARED = V /VSAT 4 = VSQUARE # WT EARTH RATE TIMES TIME 1 REVOLUTION NOT SAVED # = WIE (DTEAROT) # X INTERMEDIATE VARIABLE IN G-LIMITER 2 VSAT NOT SAVED # Y LATERAL MISS LIMIT 4 RADIANS NOT SAVED # Page 840 # EXTRA COMPUTER ERASABLE LOCATIONS NOT SHOWN ON FLOW CHARTS # ---------------------------------------------------------- # # VARIABLE DESCRIPTION MAXIMUM VALUE # -------- ----------- ------------- # # GOTOADDR ADDRESS SELECTED BY SEQUENCER # XPIPBUF BUFFER TO STORE X PIPA COUNTS # YPIPBUF BUFFER TO STORE Y PIPA COUNTS # ZPIPBUF BUFFER TO STORE Z PIPA COUNTS # PIPCTR COUNTS PASSES THRU PIPA READ ROUTINE # JJ INDEX IN FINAL PHASE TABLE LOOK-UP # MM INDEX IN FINAL PHASE TABLE LOOK-UP # GRAD INTERPOLATION FACTOR IN FINAL PHASE # FX DRANGE/D L/D = F3 2700 NM # FX +1 AREF 805 FPSS # FX +2 RTOGO 2700 NM # FX +3 RDOTREF VSAT/4 # FX +4 DRANGE/D RDOT = F2 21600/2VS NM/FPS # FX +5 DRANGE/D DRAG = F1 2700/805 NM/FPSS # TEM1B TEMPORARY LOCATION # TIME/RTO TIME OF INITIAL TARGET RTINIT B 28 CENTISEC # DTEAROT EST TIME BETWEEN RTINIT AND RT B 28 CENTISEC # # _ # UNITV UNIT V VECTOR 2 # _ # UNITR UNIT R VECTOR 2 # _ # -VREL NEGATIVE VELOCITY REL TO ATMOSP 2 VSAT # # COMPUTER SWITCHES INITIAL STATE CM/FLAGS = STATE +6 # ----------------- ------------- ------------------- # # ENTRYDSP DO ENTRY DISPLAY, IF SET NON-BRANCH (1) 92D, BIT13 # GONEPAST INDICATES OVERSHOOT OF TARGET NON-BRANCH (0) 95D, BIT10 # RELVELSW RELATIVE VELOCITY SWITCH NON-BRANCH (0) 96D, BIT 9 # EGSW FINAL PHASE SWITCH NON-BRANCH (0) 97D, BIT 8 # FIRSTPAS INITIAL PASS THRU HUNTEST NON-BRANCH (0) 98D, BIT 7 # HIND INDICATES ITERATION IN HUNTEST NON-BRANCH (0) 99D, BIT 6 # INRLSW INDICATES INIT ROLL ATTITUDE SET NON-BRANCH (0) 100D, BIT 5 # LATSW INHIBIT DOWNLIFT SWITCH IF NOT SET BRANCH (1) 101D, BIT 4 # .05GSW INDICATES DRAG EXCEEDS .05 GS BRANCH (0) 102D, BIT 3 # # GONEBY INDICATES GONE PAST TARGET (SET) SELF-INITIALIZING 112D, BIT 8 # Page 841 # CONSTANTS AND GAINS VALUE # ------------------- ----- # # C1 FACTOR IN ALP COMPUTATION 1.25 # C16 CONSTD GAIN ON DRAG .01 # C17 CONSTD GAIN ON RDOT .001 # C18 BIAS VEL. FOR FINAL PHASE START 500 FPS # C20 MAX DRAG FOR DOWN-LIFT 175 FPSS # CHOOK FACTOR IN AHOOK COMPUTATION .25 # CH1 FACTOR IN GAMMAL COMPUTATION 1.0 # COS15 COS( 15 DEG) .965 # DLEWD0 INITIAL VARIATION IN LEWD -.05 # D2 DRAG TO CHANGE LEWD 175 FPSS # DT COMPUTATION CYCLE TIME INTERVAL 2 SEC. # GMAX MAXIMUM ACCELERATION 257.6 FPSS (8 G-S) # KA1 FACTOR IN KA CALC 1.3 GS # KA2 FACTOR IN KA CALC .2 GS # KA3 FACTOR IN D0 CALC 90 FPSS # KA4 FACTOR IN D0 CALC 40 FPSS # KB1 OPTIMIZED UPCONTROL GAIN 3.4 # KB2 OPTIMIZED UPCONTROL GAIN .0034 # KDMIN INCREMENT ON Q7 TO DETECT END OF KEPLER PHASE .5 FPSS # KTETA TIME OF FLIGHT CONSTANT 1000 # KLAT1 FACTOR IN KLAT CALC 1/24 # K44 GAIN USED IN INITIAL ROLL SECTION 19749550 FPS # LATBIAS LATERAL SWITCH BIAS TERM .41252961 NM # LEWD1 NOMINAL UPCONTROL L/D .15 # POINT1 FACTOR TO REDUCE UPCONTROL GAIN .1 # Q2 FINAL PHASE RANGE - 23500 Q3 -1002 NM # Q3 FINAL PHASE DRANGE/D V .07 NM/FPS # Q5 FINAL PHASE DRANGE/D GAMMA 7050 NM/RAD # Q6 FINAL PHASE INITIAL FLIGHT PATH ANGLE .0349 RAD # Q7F MIN DRAG FOR UPCONTROL 6 FPSS # Q7MIN MIN VALUE FOR Q7 IN FACTOR CALCULATION 40 FPSS # Q19 FACTOR IN GAMMAL1 CALCULATION .5 # Q21 FACTOR IN Q2 CALCULATION. 1000 NM # Q22 FACTOR IN Q2 CALCULATION. -1302 NM # VFINAL1 VELOCITY TO START FINAL PHASE ON INITIAL ENTRY 27000 FPS # VFINAL FACTOR IN INITIAL UP-DOWN CALC 26600 FPS # VLMIN MINIMUM VL 18000 FPS # VMIN VELOCITY TO SWITCH TO RELATIVE VEL VSAT/2 # VRCONTRL RDOT TO START INTO HUNTEST 700 FPS # VRCONT = COMPUTER NAME # 25NM TOLERANCE TO STOP RANGE ITERATION 25 NM # VQUIT VELOCITY TO STOP STEERING 1000 FPS # Page 842 # CONVERSION FACTORS AND SCALING CONSTANTS # ---------- ------- --- ------- --------- # # ATK ANGLE IN RAD TO NM 3437.7468 NM/RAD # G5 NOMINAL G VALUE FOR SCALING 32.2 FPSS # H5 ATMOSPHERE SCALE HEIGHT 28500 FT # J GRAVITY HARMONIC COEFFICIENT .00162346 # KWE EQUATORIAL EARTH RATE 1546.70168 FPS # MUE EARTH GRAVITATIONAL CONSTANT 3.986032233 E 14 CUBIC M/ SEC SEC # RE EARTH RADIUS 21202900 FT # REQ EARTH EQUATORIAL RADIUS 20925738.2 FT # VSAT SATELLITE VELOCITY AT RE 25766.1973 FPS # WIE EARTH RATE .0000729211505 RAD/SEC # # (END GSOP AS-278, VOL 1, FIG. 5.6-3 CONSTANTS,GAINS, ETC.) # # # DISPLAY QUANTITIES # ------------------ # # (SEE SECTION 4 OF THE GSOP FOR SIGN CONVENTIONS.) # # VARIABLE DESCRIPTION MAXIMUM VALUE # -------- ----------- ------------- # # GMAX PREDICTED MAXIMUM ENTRY ACCEL 163.84 GS N 60 # VPRED PREDICTED VELOCITY AT ALTITUDE 128 M/CENTISEC N 60 # 400K FT ABOVE FISCHER RADIUS. # GAMMAEI PREDICTED GAMMA AT ALTITUDE 1 REVOLUTION N 60 # 400K FT ABOVE FISCHER RADIUS. # D DRAG ACCELERATION 805 FPSS N 64 # VMAGI INERTIAL VELOCITY MAGNITUDE 128 M/CENTISEC N 64, N 68 # THETAH DESIRED RANGE ANGLE NM 1 REVOLUTION N 64, N 67 # LAT PRESENT LATITUDE 1 REVOLUTION N 67 # LONG PRESENT LONGITUDE 1 REVOLUTION N 67 # RTOGO RANGE ANGLE TO SPLASH FROM 1 REVOLUTION N 63 # EMSALT FT ABOVE FISCHER RADIUS. (IN NM) # VIO PREDICTED VELOCITY AT ALTITUDE 128 M/CENTISEC N 63 # EMSALT FT ABOVE FISCHER RADIUS. # TTE TIME OF FREE FALL TO ALT B 28 CENTISEC N 63 # EMSALT FT ABOVE FISCHER RADIUS. # ROLLC ROLL COMMAND 1 REVOLUTION N 66, N 68, N 69 # LATANG CROSS-RANGE ERROR (XRNGERR) 4 RADIANS N 66 # DNRNGERR DOWN RANGE ERROR 1 REVOLUTION N 66 # (PREDANG - THETAH IN NM) # HDOT ALTITUDE RATE 128 M/CENTISEC N 68 # Q7 MINIMUM DRAG FOR UPCONTROL 805 FPSS N 69 # VL EXIT VELOCITY FOR UP-CONTROL 2 VSAT N 69 # Page 843 # BODY ATTITUDE QUANTITIES (CM/POSE) # ---------------------------------- # # VARIABLE DESCRIPTION MAXIMUM VALUE # -------- ---------- ------- ----- # # _ # -VREL NEGATIVE VELOCITY REL TO ATMOS. 2 VSAT # _ # OLDUYA USED FOR UYA BELOW 1000 FPS 2 # _ # UXA/2 UNIT VECTOR TRIAD 2 # _ # UYA/2 BASED ON 2 # _ # UZA/2 THE TRAJECTORY. 2 # _ # UBX/2 UNIT VECTOR 2 # _ # UBY/2 BODY TRIAD 2 # _ # UBZ/2 FOR CM. 2