Universal Pointing MFD question

[jgrillo2002]

Hi I read the readme of the STS-124 scenarios and it says that you should use the universal pointing MFD for TORVA procedure. my question is how do you exactly to that with the UP. I know how to do it with the GPC MFD but I just wanted to know

 

[Belisarius]

I still haven't figured out how to do it right with the GPC-DAP. I just eyeball it.

 

[SiameseCat]

Set the ROT RATE to 0.13 and set the BODY VECT to 2. Then enter ITEM 19 to start the rotation. In theory, you can leave the autopilot on through docking, although I'd recommend disengaging the autopilot (ITEM 21) once you are in the correct attitude, since UP is not good at holding tight deadbands.

 

[jgrillo2002]

UnivPTG question

I did that but it is rotating relative to the earth. how can I possibly rotate it to the harmony docking port. It rotates the other way.

 

[flying coffin]

get the RNDZ checklist http://www.nasa.gov/centers/johnson/pdf/229565main_RNDZ_124_F_1.pdf

Step 20B at the bottom left of page 4-20 describes the beginning of the procedure. Establish yourself underneat the station on the R-Bar.

in the UNVPTG display enter ITEM 14, DATA 5 (Body vector)
then ITEM 15 DATA 270 (Pitch)
then ITEM 19 (trk)

This establishes the proper attitude to start. Keep the ISS centered in
the docking port centerline camera using translational thrusters only.

When ready to start the TORVA, click on ITEM 21 to disable tracking.
Then click on MOD to get to the DAP page, then
ITEM 10 DATA 0.075
ITEM 23 DATA 0.075
click on MOD again (maybe twice) to get back to UNVPTG display (NOT UNVPTG2!)

enter
ITEM 14 DATA 5 (body vector)
ITEM 15 DATA 179 (pitch)
ITEM 19 (trk)

keep the ISS centered in the centerline docking port camera using translational thrusters only.

when less that 5 meters away from docking, click on ITEM 21
to disable tracking.

See page CC 9-7 of the RNDZ checklist.

Hope this helps.

-Chris
(BTW this is mostly from memory so hopefully I haven't missed anything)

 

[SiameseCat]

I just tried it and it seems to work, assuming you start from the correct attitude. The ROT RATE number I posted above was incorrect; it should be 0.13 deg/sec.

flying coffin:
Your post above looks good, except the DAP ITEM 10 and ITEM 23 entries should be 0.13, not 0.075. Also, in Orbiter, ITEM 15 DATA 180 seems to work better for aligning the shuttle with the docking port than ITEM 15 DATA 179.

 

[flying coffin]

OK I'm curious... where did the 0.13 number for the rotation rate come from?

I've only seen the 0.075 number in the checklists. I know that will speed things up a bit. Nasa also seems to use the 179 degree angle for docking approach instead of 180. It's only one degree but they must have a reason?

-Chris

 

[SiameseCat]

The 0.13 rotation rate is because the rotation rate is measured for an inertial frame, not a horizon-relative frame. If you look at the checklists, ths is also the value used by the shuttle DAP.

 

[flying coffin]

OK I see it now, on page 6-2 of the STS-124 RNDZ checklist.

Thanks for clearing up my confusion!

 

[BenSisko]

A question. The UNVPT MFD freezes in the v4.0.1 Shuttle when changing views in the virtual cockpit. It seems stable in the 2-D panel view and ODS camera view. Has anyone else noted this?

Ben

 

[SiameseCat]

A question. The UNVPT MFD freezes in the v4.0.1 Shuttle when changing views in the virtual cockpit. It seems stable in the 2-D panel view and ODS camera view. Has anyone else noted this?

Ben

Have you tried it with the default shuttle? Also, what exactly do you mean by 'freeze'? Does it just stop updating or does it actually freeze Orbiter?

 

[BenSisko]

Sorry, I wasn't clear. I haven't tried the default shuttle but I will. In the v4.0.1 shuttle virtual cockpit, the UNVPT MFD stops updating after changing views. It responds to item and mode inputs but doesn't effect rotation commands (as in starting the RPM). If you switch to the 2-D panel view full functionality returns but not in the VC. Orbiter doesn't freeze.

 

[SiameseCat]

This sounds like an MFD bug; it doesn't handle views changing very well. For the rotation commands, you could try entering ITEM 21, them ITEM18/19.

 

[BenSisko]

I'll give it a try. I'm still working through the RPM/TORVA with this MFD.

Thanks!

 

[BenSisko]

The RPM and TORVA maneuvers work fine using the UNVPTG from the ODS camera view. Thanks for the help!

 

[PriestLizard]

How come that the UNIVPTG usually do not do anything after all? I set it up like its stated in the manual:

- About 180m below the ISS on the stations RBar
- Switch view to ODS and center station, keep a distance of ~180m
- Select MOD, switch to DAP and perform the commands:
ITEM 10 DATA 0.13
ITEM 11 DATA 2.00
- Select MOD two times more for UNIVPTG (1, not2!) Then:
ITEM 15 DATA 270
ITEM 14 BODY VECT 5
ITEM 19

Then... nothing... nothing happens at all. I just spend like ten minutes waiting, keeping the station centered and at a distance of 180m and nothing happens. Frustrating again.

I dont see what I do wrong - already searched the forums etc. .. no info, so sorry to ask again.

 

[BenSisko]

PriestLizard,
I assume you're using SSU v1.25. If your initial position is as you've stated, try the following to perform TORVA using the CRT MFD not UNIVPTG:

In CRT MFD you should have MM201 as the starting screen
SPEC 20 PRO to bring up the DAP screen
ITEM 10 +0.13 EXEC
ITEM 23 +0.13 EXEC
CLEAR
RESUME to return to MM201
ITEM 14 +5 EXEC
ITEM 15 +179.0 EXEC

At this point check the Orbital DAP console (Panel C3 or A6U). Select AUTO and VERN. At this point its helpful to have the Docking MFD active in the aft docking CRT (starboard).

At the keypad enter ITEM 19 EXEC.This should begin a twice orbital rotation pitch up of the shuttle.

Move to the aft docking position. Guided by the Docking MFD, use thrusters in translation to keep TVEL and CVEL at 0.00.

Check your progress through the ODS camers view. Once aligned with the docking port on the V-bar use your thrusters in translation to approach the ISS. At ~5 meters from the ISS set the Orbital DAP to FREE and continue on to docking.

I think your problem was that you were using UNIVPTG instead of CRT MFD.

Ben

 

[SiameseCat]

Nothing happens because you're already in the target attitude. What you need to do is target an intermediate attitude by entering ITEM 15 DATA 145 to start the RPM. Turn the DAP off (ITEM 19) as you pass through 80 degreees, then enter ITEM 15 DATA 270. You can turn the DAP on again once you pass through 180 degrees.

 

[BenSisko]

Nothing happens because you're already in the target attitude. What you need to do is target an intermediate attitude by entering ITEM 15 DATA 145 to start the RPM. Turn the DAP off (ITEM 19) as you pass through 80 degreees, then enter ITEM 15 DATA 270. You can turn the DAP on again once you pass through 180 degrees.

It sounds like PriestLizard is using UNIVPTG for David413's shuttle fleet. His comment about "Select MOD two times more for UNIVPTG (1, not2!)" is unique to UNIVPTG MFD and not a feature of the UP mode of CRT MFD.

Ben

 

[PriestLizard]

Yes, I was talking about Shuttle Fleet. I'll try to follow your guys hints.

I want to perform the TORVA, not the RPM actually. I also watched the tutorial in the playback folder. I dont know why my UNIVPTG is not rotating though like in the playback. I thought UNIVPTG controls the pitch angle while I manually translate to keep the ISS centered. Both movements together then lead to a position on the stations VBAR, with the ODS in direction of the docking port.

My problem is mostly about how to control the MFD. There is also an item for "Start time", I don't know whats the correct syntax to enter a time. Do I have to use this item?

Then again I wonder why its working in the playback with the procedure I posted above... its very confusing for a newbie.