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Author Topic: ORDEAL Development Thread  (Read 35612 times)
pattersoncr
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« Reply #45 on: July 11, 2008, 04:32:00 AM »

A bit tricky in my mind since the purpose of the ordeal is not to match exactly the local horizon but to rotate the FDAI at a constant rate as close as possible to the orbital rate. That means that the FDAI displays the local horizon only while in near circular orbit. As soon as the orbit becomes elliptical, the FDAI slightly moves away from the horizon periodically.

On the other hand, since the apollo orbits are always very close to circular (look at the orbit MFD while in the initial lunar orbit of 115x320 km and you will see that's it's almost a perfect circle), pattersoncr's idea sounds good because it's simple.
I was talking about the slew switch in order to put the FDAI in the correct position.
dseagrav's talking about the altitude setting.  I think as long as there's a 100nm setting (for LEO) and a 60nm setting (for lunar orbit) we ought to be covered as these are the usual altitudes.  One possible shortcoming is the use of ORDEAL during TLI.  I'll post exactly what I mean later today after I have a chance to dig thru the docs.
« Last Edit: July 11, 2008, 07:27:30 AM by pattersoncr » Logged
pattersoncr
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« Reply #46 on: July 11, 2008, 07:26:57 AM »

The A12 and A15 procedures differ on this but basically, the TLI procedure has you set the ORDEAL for Lunar/300nm at TIG -9min (for FDAI 1 only.  FDAI 2 stays inertial)
you slew the FDAI pitch 1 min before ignition.
at ignition, you start ORDEAL torquing.
I believe this is to setup FDAI 1 to allow a means of monitoring attitude thru the TLI burn.

I think the ability to recreate this is of very low priority compared to getting ORDEAL working for Earth/Lunar orbit but something to think about for the future.
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Swatch
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« Reply #47 on: July 11, 2008, 08:02:50 AM »

I'm not 100% sure, but I think that implementing ORDEAL functionality is relatively minor, as its well documented how it worked and we have a very able set of developers when it comes to creating virtual systems.  The biggest question from what I've gathered is how to interact with it.  Perhaps I'm wrong.
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My Project Apollo Work:
CM Visual
 -VC (~75% complete: texture work beginning again; mesh-78%; texture-70%)
Propulsion Particle Improvements (Focused on S1B right now, BETA 1.0 has been commited)
New Docking Method (~50% complete: research complete; coding partially completed, testing not underway)

Future Work:  (if it's here, it's deemed unnecessary to upcoming release)

Older Work:  (if it's here, it's fair game to whoever wants to improve)
EMS Implementation (committed: minor flaws, but groundwork is there, needs extensive testing)
EMS scrolls (committed: not refined, but usable)
SM Visual (committed: mesh-finished, texture-60%; possibly revisited in future)
J2 Texture (commited: room for improvement)
LRV (committed: mesh-finished, texture-90%; in future a ground up rebuild may be in order, but not on my plans)
pattersoncr
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« Reply #48 on: July 11, 2008, 08:29:26 AM »

My understanding was (and someone please correct me if I'm wrong) that the "normal" attitude while in Earth parking orbit or in lunar orbit was essentially like the standard orbiter "prograde" attitude rolled 90* to the left.  In other words, the nose pointed forward and the "top" of the spacecraft was pointed towards the Earth (or moon as appropriate).  Here is how I think ORDEAL was used;  You put the spacecraft into roughly this attitude, putting the big scribe line in the rendezvous window on the horizon would get you close in pitch.  V83E would more precisely show your angle with local horizontal.  You then set up the ORDEAL.  At this point nulling pitch rate would set the correct pitch rate to keep the "top" of the spacecraft pointed towards the Earth.  BMAG MODE - ATT1/RATE2 would cause SCS to hold this attitude.  I'm sure there was a way to have the CMC hold this attitude as well but I don't know off the top of my head.  Come to think of it, with Artemis, P20 option 2 was used for this on A15 and later.  Perhaps there wasn't a way for the CMC to do it on earlier flights.
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Tschachim
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« Reply #49 on: July 11, 2008, 08:46:51 AM »

At this point nulling pitch rate would set the correct pitch rate to keep the "top" of the spacecraft pointed towards the Earth.  BMAG MODE - ATT1/RATE2 would cause SCS to hold this attitude. 

I'm not sure if I understand that correctly, but this BMAG mode holds the inertial attitude (as CMC MODE - HOLD), not the local horizontal attitude. The ORDEAL doesn't affect the BMAGs, the GDC or anything else, it just slews the FDAI pitch axis.

The biggest question from what I've gathered is how to interact with it.

Swatch, I'm not sure if you're talking about how it was used (this is explained in this thread and here: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19740026211_1974026211.pdf) or how we implement this interaction (but the recent ideas are looking fine for me).

Cheers
Tschachim
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Swatch
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jasonims
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« Reply #50 on: July 11, 2008, 12:25:26 PM »

Tschachim, that's exactly the document I was thinking of.  It gives us the right timings and procession rates to use.

It is similar to how dseagrav implemented the Optics control from the CMC.
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My Project Apollo Work:
CM Visual
 -VC (~75% complete: texture work beginning again; mesh-78%; texture-70%)
Propulsion Particle Improvements (Focused on S1B right now, BETA 1.0 has been commited)
New Docking Method (~50% complete: research complete; coding partially completed, testing not underway)

Future Work:  (if it's here, it's deemed unnecessary to upcoming release)

Older Work:  (if it's here, it's fair game to whoever wants to improve)
EMS Implementation (committed: minor flaws, but groundwork is there, needs extensive testing)
EMS scrolls (committed: not refined, but usable)
SM Visual (committed: mesh-finished, texture-60%; possibly revisited in future)
J2 Texture (commited: room for improvement)
LRV (committed: mesh-finished, texture-90%; in future a ground up rebuild may be in order, but not on my plans)
Christophe
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« Reply #51 on: July 11, 2008, 12:33:13 PM »

My understanding was (and someone please correct me if I'm wrong) that the "normal" attitude while in Earth parking orbit or in lunar orbit was essentially like the standard orbiter "prograde" attitude rolled 90* to the left.  In other words, the nose pointed forward and the "top" of the spacecraft was pointed towards the Earth (or moon as appropriate). 

Not necessary.
The spacecraft does not fly always in "prograde attitude". Looking at the Apollo 8 flight plan i discovered the vessel was turned into different attitudes but almost always with the ordeal reference. For exemple: ordeal 180, 0, 0 which means retrograde heads up, 120,0,0 etc...
Simply the reference commonly used while into a planet orbit (moon or earth) is ordeal, in other words roughly with reference to the local horizon.
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pattersoncr
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« Reply #52 on: July 11, 2008, 12:54:28 PM »

My understanding was (and someone please correct me if I'm wrong) that the "normal" attitude while in Earth parking orbit or in lunar orbit was essentially like the standard orbiter "prograde" attitude rolled 90* to the left.  In other words, the nose pointed forward and the "top" of the spacecraft was pointed towards the Earth (or moon as appropriate). 

Not necessary.
The spacecraft does not fly always in "prograde attitude". Looking at the Apollo 8 flight plan i discovered the vessel was turned into different attitudes but almost always with the ordeal reference. For example: ordeal 180, 0, 0 which means retrograde heads up, 120,0,0 etc...
Simply the reference commonly used while into a planet orbit (moon or earth) is ordeal, in other words roughly with reference to the local horizon.
OK,
To modify my previous post:
put spacecraft into desired attitude (prograde being only one possibility)
null rates on FDAI (which is being driven in pitch at orbital rate by ORDEAL).
And no way to hold this attitude on early flights, A15 and later can use the CMC, P20 option 2.
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Christophe
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« Reply #53 on: July 11, 2008, 01:43:13 PM »

OK I probably misunderstood you first.
Quote
And no way to hold this attitude on early flights, A15 and later can use the CMC, P20 option 2.

As far I as know, there's no other way but to null the rate using the RHC manually, indeed, until the further AGC artemis version.
Old 60's...  things are quite different today when an inoperative FMS is almost a NOGO... Rolling Eyes
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Swatch
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jasonims
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« Reply #54 on: July 11, 2008, 02:21:25 PM »

ORDEAL will also 'spin' both ways....  it can be controlled with the NORMAL switch on it.
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My Project Apollo Work:
CM Visual
 -VC (~75% complete: texture work beginning again; mesh-78%; texture-70%)
Propulsion Particle Improvements (Focused on S1B right now, BETA 1.0 has been commited)
New Docking Method (~50% complete: research complete; coding partially completed, testing not underway)

Future Work:  (if it's here, it's deemed unnecessary to upcoming release)

Older Work:  (if it's here, it's fair game to whoever wants to improve)
EMS Implementation (committed: minor flaws, but groundwork is there, needs extensive testing)
EMS scrolls (committed: not refined, but usable)
SM Visual (committed: mesh-finished, texture-60%; possibly revisited in future)
J2 Texture (commited: room for improvement)
LRV (committed: mesh-finished, texture-90%; in future a ground up rebuild may be in order, but not on my plans)
pattersoncr
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« Reply #55 on: July 11, 2008, 02:32:06 PM »

ORDEAL will also 'spin' both ways....  it can be controlled with the NORMAL switch on it.

Huh?
I don't see the NORMAL switch.
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GauthierH
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« Reply #56 on: September 01, 2009, 05:11:57 PM »

Hello,

no news about this one?
 Cool
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Tschachim
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« Reply #57 on: February 05, 2010, 01:34:20 PM »

Sometimes, it takes a little bit longer...  Wink

The ORDEAL is done and committed to CVS, a couple of comments:

  • I added an ORDEAL Initialization checklist to ChecklistMFD to set up the ORDEAL.
  • You can display the ORDEAL on MDC 1, too, because you need to see the ORDEAL, the DSKY and the FDAI simultaneously for setup, click on the panel area above the EMS to enable it(or use the checklist).
  • All switches are as usual except the ALT SET switch: Click and hold the left mouse button and you see the actual value. Move the mouse to the left/right with pressed button to change the value. The knob itself is changed in coarse steps of 50 nm only.

Cheers
Tschachim


* ordeal.jpg (42.3 KB, 595x319 - viewed 721 times.)
« Last Edit: February 05, 2010, 07:06:16 PM by Tschachim » Logged

NoName
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« Reply #58 on: February 06, 2010, 03:51:52 PM »

Thanks a lof Tschachim for all your efforts Thumbs Up

Great news.
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Gunner_CAF
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« Reply #59 on: February 06, 2010, 08:31:24 PM »

Nice work!  I ran the ORDEAL checklist on an A7 save in orbit, it worked fine.  The location work good.

Gunner
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