Results of the Apollo Spacecraft Software Configuration Control Board meeting of April 9

See list belowAPR 16 196868-FM-T-80FM/Deputy ChiefResults of the Apollo Spacecraft Software Configuration Control Board meeting of April 9

This memorandum briefly summarizes the results of the subject meeting. For detail, I would suggest you contact the ?????????????????????? specific program change request you are interested in. You will note that PCR activity doesn't seem to be slacking off any.

A. SUNDANCE ITEMS

1. Several PCR's were approved to reflect changes already in program – to wit.

a. PCR's ??? and 144 affect the delta V monitor.

b. PCR ??? applies to the rendezvous radar search routine. It eliminates the automatic attitude maneuver when the radar angle exceed 30° in order to avoid a DSKY display conflict.

2. There were two PCR's to make the LM software and hardware compatible.

a. PCR 142 was approved to fix a GADC FDAI error and provides full scale deflection for 5° attitude error.

b. PCR 141 would have compensated for some GAEC hardware which doesn't meet specifications but was not approved due to excessive schedule slip. It involves the DPS trim gimbal alarm which has come on when it shouldn't. This is serious and may require a hardware fix. At least such a proposal is being taken to Low's CCB.

3. Finally, we intend to discuss the significance of the “Stage Verify” discreet on the FACT that work at MIT ????????????? but would prevent either DPS or APS maneuver ?????????? wrong. It would be better to just ??? ?? ????????????????? crew to override if necessary.

B. LUMINARY ITEMS

1. The following PCR's were approved:

a. PCR's ??? and ??? to delete the ascent lift off time compu- tations P-10 and P-11.

b. PCR 133 to provide an abort insertion orbit apogee of ?? n.m. prior to high gate and 30 n.m. after high gate (two days.)

c. PCR 140 – an improvement in the rate command attitutde hold capability (two days).

d. PCR 118 to simplify the proceed and inhibit logic in R??.

e. PCR 137 which permits use of landing radar data starting at 35,000 feet rather than 26,000 feet altitude.

f. PCR 124 applies to the rendezvous radar search routine. It eliminates the automatic attitude maneuver when the radar angle exceeds 30° in order to avoid a DSKY display conflict.

g. PCR 134 which adds what may be an outstanding capability deserving a name of its own. It permits pulse torquing the IMU to a new orientation without making star observa- tions. It is said to be accurate of 0.1 to 0.2% of the angle through which the IMU is torqued. Maximum torque rate is ½°/sec. This could be used for example to avoid gimbal lock. It only costs two days.

h. PCR 14? reduces the DSKY update rate in an effort to avoid over- taxing the LGC during descent after high gate.

i. PCR 144 is another adjustment to the delta V monitor already implemented.

2. PCR 141, the DPS trim gimbal alarm fix (???????????????), was not accepted since the cost was seven days. A hardware fix is being taken to Low's CCB.

C. COLOSSUS ITEMS

1. Although rendezvous targeting on the CSI and CDH rendezvous maneuvers are not needed in the earlier ?? flights, MIT was requested to determine the impact for adding the P-3?, P-53, P-73, P-?? programs into Colossus.

2. The following changes were approved:

a. PCR 128 to fix a programming error in the landmark naviga- tion program P-22.

b. PCR 1?0 to permit backward integration across the lunar sphere of influence.

c. PCR 151 to restore the SCS deadband previously set by the crew when the computer exits the P-40 or P-41 thrusting programs.

3. The following were to be held:

a. PCR 1?? to provide a VHF ranging data good discreet light until the DSKY lights are available.

b. PCR 1?4 to provide pulse torque reorientation of the IMU (see Luminary “1g”) until Colossus #2. It would have cost seven days.

4. PCR 129 had the distinction of being the only one turned down! It was to avoid a display confusion in the return-to-earth program (P-37).

And that's it for this week.