Question Issues with sepration from SIV-B

[Bidartarra]

Hello,

I'm having issues with separating from SIV-B and docking with the LM:
I follow the checklist on the MFD but I don't understand what "Thrust + X and hold" means, I've looked online but didn't find anything.

following the checklist I get a separation without CM movement, the 4 panels are jettisonned but the CM just chills there and I'am unable to use the thrusters to complete the docking.

I have spent hours on this so far and cannot seem to crack this nut.

I'm using the Apollo 11 - 05 mission scenario.

 

[indy91]

"Thrust + X and hold" means to use the +X RCS thrusters, with the THC, to thrust away from the S-IVB during separation. The Apollo 11 procedure starts doing that at 59:58 on the event timer, so 2 seconds before sep, and stops it when the EMS counter shows -100.8, so after 0.8 ft/s have been applied. Using the keyboard this would be the 6 key on the numpad, in translation mode.

 

[Bidartarra]

"Thrust + X and hold" means to use the +X RCS thrusters, with the THC, to thrust away from the S-IVB during separation. The Apollo 11 procedure starts doing that at 59:58 on the event timer, so 2 seconds before sep, and stops it when the EMS counter shows -100.8, so after 0.8 ft/s have been applied. Using the keyboard this would be the 6 key on the numpad, in translation mode.

Thanks for your help!

 

[MishutkAviation]

Hi there, I try to comply with procedures in Apollo 7 mission, but I'm unable to use translational RCS - in translational mode numpad keys do nothing. In rotational mode everything works perfectly.
Suprisingly, turning the 2D THC clockwise turned on RCS in forward direction, but still I can't steer properly in other directions. What can I do about this issue?

 

[MrFickles]

Is your TRANS CONTR PWR switch on?

Turning the THC clockwise will translate the CSM forward, this is normal behaviour.

 

[MishutkAviation]

Is your TRANS CONTR PWR switch on?

Yes, it is. I'm following the checklist, so I'm nearly 100% sure that switches are properly prepared for the translation manouver.

Turning the THC clockwise will translate the CSM forward, this is normal behaviour.

Then, why aren't numpad shotcuts working? Also, I was using the 2D THC, so CW turning (as far as I understood NASSP docs) should "transfer spacecraft control from CMC to SCS", and translation controls are avaiable only trough keyboard.

 

[rcflyinghokie]

Yes, it is. I'm following the checklist, so I'm nearly 100% sure that switches are properly prepared for the translation manouver.

Nearly certain =/= certain Did you do the RCS CMD transfer to the SM?

Then, why aren't numpad shotcuts working? Also, I was using the 2D THC, so CW turning (as far as I understood NASSP docs) should "transfer spacecraft control from CMC to SCS", and translation controls are avaiable only trough keyboard.

Turning the THC CW transfers to SCS yes, but this has nothing to do with your issues. The forward translation you had was from turning CCW and is used as a way to separate from the SIVB.

You need to check your DAP, and possibly transfer RCS to the SM again, verify translation controller is on. Also, feel free to post a scenario file I can take a look at the configuration.

 

[indy91]

Does RCS rotations still work if you switch off Direct RCS (the two ROT CONTR PWR - DIRECT switches on panel 1)? If not then I think your Auto RCS relays might not have been automatically switched on at separation from the S-IVB. The RCS thrusters have two coils each to fire the thrusters, the Auto RCS coils and the Direct RCS coils. The automatic +X burn you can do at separation with the THC uses the direct coils and so do rotational commands when the ROT CONTR PWR - DIRECT switches are on. Translation commands never use the direct coils, so that is a clue.

Which method of separating from the S-IVB did you use? You mention the THC, but the Checklist MFD for Apollo 7 uses the CSM/LV SEP button. If you used the button there is actually the possible issue that you have pressed it for too short of a time. That is realistic, you have to press it for more than 0.8 seconds or else the Auto RCS doesn't switch on automatically. It's mentioned in the AOH Volume 2, but it's a bit of an obscurity.

In any case, if this is really the cause of the problem, then you can just use the RCS CMD - ON switch on panel 2 to fix the issue. That does require the two SECS Arm circuit breakers to be pushed in.

 

[MishutkAviation]

If you used the button there is actually the possible issue that you have pressed it for too short of a time. That is realistic, you have to press it for more than 0.8 seconds or else the Auto RCS doesn't switch on automatically. It's mentioned in the AOH Volume 2, but it's a bit of an obscurity.

That actually solved my problem - I've pressed it longer, as you wrote, and all RCS worked perfectly. Thank you very much for help!