- Oct 26, 2011
- Reaction score
ok, sorry I was not clear. What I mean is/was the following:
Each FDAI can show attitude w.r.t. the PGNS (IMU) or AGS (ASA) and I select from which source I want to see the attitude by the ATTITUDE MON sw;
suppose I have FDAI 1 (CDR side) on PGNS and FDAI 2 (LMP side) on AGS, my question is: what about the error attitude needles? Who drive them?
Will the error needles on FDAI 1 be driven ONLY by the PGNS and the ones on FDAI 2 be driven ONLY by the AGS?
Or are they “driven in BOTH FDAIs" – showing same errors (under the hypothesis that IMU and ASA are aligned) - by the PGNS (or AGS) when the GUID CONT sw is in PGNS (or AGS) mode?
It depends on two switches, RATE/ERR MON and ATTITUDE MON. They both exist twice, for the left and right FDAI. If RATE/ERR MON is set to RNDZ RADAR then the attitude error needles show the RR attitude. With the switch in LDG RDR/CMPTR the attitude error needles are driven by the computer. So with the ATTITUDE MON switch set to PGNS then the attitude and attitude error comes from the PGNS, otherwise it comes from the AGS. The left ATTITUDE MON switch is used for the left FDAI, the right switch for the right FDAI. Attitude rate always comes from the rate gyro assembly, never from the PGNS. That's the same as in the CSM where attitude rate needles are always driven by the BMAGs of the SCS.
I have another question, concerning the CSM Separation burn.
Upon inserting the PAD values for the burn and doing P41 I am in the situation as photo 1 before and at cut off.
The MFD checklist says “thrust +X” … if I do so I got DVc=0.0 and DVx=0.6 in DSKY, which I brought down to almost 0.0 by trimming resulting in an orbit very close the one predicted by the PAD (see photo 2, N85, V82E and PAD values).
But reading the CSM rendezvous pdf (photo 3) it says to “thrust –X” (AFT) to see the DSKY VGx go from 2.5 to 5.0 -> so it seems I did exactly the opposite, thrusting FWD +X dir going from 2.5 to 0.0 in the DVc.
Where is the catch? Is the P41 checklist “generic” so in this case “I should know to thrust in –X direction (AFT) - Numpad 9” ? (without caring to bring the DVc to 0.0 and later on to trim the values in N85 as "far away from 00000" ) or my burn was correct, as instructed by the MFD checklist (as the resulting HA, HP seems to imply)?
Ah that seems like an oversight to use the generic P41 checklist for that burn, you definitely have to thrust aft, towards -X. We need to fix that in the Checklist MFD. Here have a look in the detailed procedures for all of this: https://history.nasa.gov/afj/ap10fj/pdf/19700026734_mission-f-csm-rendezvous-procedures-19690429.pdf And also for the LM: https://history.nasa.gov/afj/ap10fj/pdf/19700025408_mission-f-lm-rendezvous-procedures-19690428.pdf As you can see there you are supposed to get from 2.5 to 5.0 DV remaining on the DSKY. But check that you are in the right attitude. In P30 you have to enter +0.0 +0.0 -2.5 and the attitude is 0° roll, about 14° pitch, 0° yaw.