[Project] Shuttle FDO MFD

[Donamy]

What was your favorite Orbiter ?

[RamjetFDO]

Quote:

Originally Posted by Donamy

 What was your favorite Orbiter ?

Hard to pick between Discovery and Atlantis.

Disco was my best girl early on, but Atlantis was my girl for Mir missions. So, kinda liked 'em both!

[Donamy]

Quote:

Originally Posted by RamjetFDO

 Hard to pick between Discovery and Atlantis.

Disco was my best girl early on, but Atlantis was my girl for Mir missions. So, kinda liked 'em both!

Never heard her referred to as Disco before.

[Wolf]

So I finally had some time to practice some Rendezvous with SSU and FDO MFD. So far I have succesfully completed STS-114, STS-121 and STS-115. I am still very far from mastering FDO MFD but Indy's walkthrough was very helpful. In all 3 cases I made it to the ISS though the Ti TIGs were not exactly the same as in real life (and in the original FDO MFD plan). In order to keep the Lighting and the vertical velocity within the desired constraints I had to modify the Terminal Initiation TIGs. Long way to go but I am very happy so far.
This tool has been in my wish list since ages and IMHO it brings SSU realism to different level.

Some pics from STS-121 RBar arrival just prior to orbital sunset on July 6th 2006

Discovery 600 feet below the ISS


View of the PB and the Docking Camera in the monitor


A bit of sci-fi with the ISS clearly visible against the darkness of space with the camera switched in Night Vision mode

[indy91]

Quote:

Originally Posted by Wolf

 BTW since a good starting point in order to work with FDO MFD is to have the original STS mission plans available (details about phasing and rendezvous burns) we have the "Attitude Timeline" in the Flight Plan only for some of the missions (if I remember well STS-114 to STS-118 only). Do you know if the same info are available for the other STS missions (I searched on the web but could not find anything really useful)?

Flight plans and mission reports have been my main source so far. The mission reports usually have a full list of OMS burns, although that's not the case for some early missions. A lot of 80s/90s missions were deploy and retrieval, so they deployed some payload and then rendezvoused with it again after 2-3 days. And lots of those rendezvous maneuvers were done with the RCS, which unfortunately don't have a actual TIG and DV listed in the mission report. So those missions would work well with the OMP, but might be tricky to get right with the lack of numbers.

There has been another release: https://github.com/indy91/Shuttle-FD...ag/0.1.9-alpha

A few more things can now take non-spherical gravity into account:

-Circularization (CIRC) maneuvers
-Height adjustment (HA) maneuvers
-apogee and perigee altitude on the evaluation table

From the FDO Handbook it seems that the HA and HP on the evaluation table should at least somewhat take non-spherical gravity into account, although the accuracy is not super high (in one example the targeted height is 88.0 NM and the evaluation table says 88.92 NM). So I chose the most simple calculation method for this, just doing a simple J2 approximation. Found a nice subroutine for that in one of the Apollo RTCC documents.

OMS-2 is actually interesting as a height adjustment burn. The onboard PEG-4 targeting is not taking non-spherical gravity into account, so the HT value you input would have to be biased. For the standard 51.6° inclination, ascending node ascent and orbit that bias is almost a constant, about 6.2 NM (as per FDO Handbook). Minimum HP after OMS-2 is 105 NM (85 NM with special approval) and the 105 NM biased by the 6.2 NM is about 111 NM. So that is probably why the ascent checklists have 111 NM by default.

[Donamy]

Quote:

Originally Posted by Wolf

 So I finally had some time to practice some Rendezvous with SSU and FDO MFD. So far I have succesfully completed STS-114, STS-121 and STS-115. I am still very far from mastering FDO MFD but Indy's walkthrough was very helpful. In all 3 cases I made it to the ISS though the Ti TIGs were not exactly the same as in real life (and in the original FDO MFD plan). In order to keep the Lighting and the vertical velocity within the desired constraints I had to modify the Terminal Initiation TIGs. Long way to go but I am very happy so far.
This tool has been in my wish list since ages and IMHO it brings SSU realism to different level.

Some pics from STS-121 RBar arrival just prior to orbital sunset on July 6th 2006

Discovery 600 feet below the ISS


View of the PB and the Docking Camera in the monitor


A bit of sci-fi with the ISS clearly visible against the darkness of space with the camera switched in Night Vision mode

Nice to see the ISS in the correct config.


Show more.

[Wolf]

Quote:

Originally Posted by Donamy

 Nice to see the ISS in the correct config.


Show more.

I will . With a bit of patience so far I was able to reproduce the ISS AtoZ from 1A to 12A (basically from STS-88 to STS-114)

[indy91]

Quote:

Originally Posted by Wolf

 So I finally had some time to practice some Rendezvous with SSU and FDO MFD. So far I have succesfully completed STS-114, STS-121 and STS-115. I am still very far from mastering FDO MFD but Indy's walkthrough was very helpful. In all 3 cases I made it to the ISS though the Ti TIGs were not exactly the same as in real life (and in the original FDO MFD plan). In order to keep the Lighting and the vertical velocity within the desired constraints I had to modify the Terminal Initiation TIGs.

A bunch of things have to come together for TI to happen at the same time as it happened in reality. Most importantly non-spherical gravity has to be enabled in Orbiter (and the MFD of course). From launch to rendezvous the lighting could be off by a few minutes already due to that. And then very important of course an accurate initial ISS state vector in the launch scenario. In the one or two rendezvous I have flown where those conditions were fulfilled I had TI TIGs that were less than a minute off from reality. And moving it by a few seconds off the ideal lighting doesn't hurt much and was probably done in reality to optimize some of the previous maneuvers.

There also is the case of a low beta angle, in which case TI isn't set at SS - 36 minutes, but SS - 38.5 minutes. I had that with STS-129 but noticed too late that I should have used 38.5min, only when I checked the Execute Packages. The result is the sun right in the face during the TORVA. Definitely was undesirable in reality. So a few missions (not that many probably) will have the lighting at TI moved to 38.5 minutes to avoid that.

[DaveS]

Quote:

Originally Posted by Wolf

 I will . With a bit of patience so far I was able to reproduce the ISS AtoZ from 1A to 12A (basically from STS-88 to STS-114)

You mean 11A, 12A was STS-115. STS-113 brought it to 11A with the addition of the P1 ITS in December 2002, the last ISS mission prior to the fateful STS-107 mission. STS-114 was LF1. Also, the inboard/outboard radiators on S1/P1 were deployed after STS-120/10A. Up until then, only the center radiators had been deployed. The reason for waiting to deploy the remaining radiators was that the FGB solar arrays had to be retracted to provide enough clearance as the Thermal Radiator Rotary Joints (TRRJ, pronounced "targ") rotates the radiators to keep them mostly shaded for optimal cooling performance.

[Wolf]

Quote:

Originally Posted by DaveS

 You mean 11A, 12A was STS-115. STS-113 brought it to 11A with the addition of the P1 ITS in December 2002, the last ISS mission prior to the fateful STS-107 mission. STS-114 was LF1. Also, the inboard/outboard radiators on S1/P1 were deployed after STS-120/10A. Up until then, only the center radiators had been deployed. The reason for waiting to deploy the remaining radiators was that the FGB solar arrays had to be retracted to provide enough clearance as the Thermal Radiator Rotary Joints (TRRJ, pronounced "targ") rotates the radiators to keep them mostly shaded for optimal cooling performance.

Correct. I haven’t added the P3/P4 truss yet, so it is up to 11A

[Gingin]

Nice Indy for the new release
Well done Wolf
Camera mfd looks nice ��

[Wolf]

Is it ok to use FDO MFD (0.1.9) with Non Spherical Gravity enabled?
I am asking since I am checking it with STS-114 and I get an extremely high DV in the plan for the NPC burn. I am using the actual launch date/time with the ISS state vectors uploaded via the closest time available from Celestrak. With Gravity disebled I end up at MECO with a 0.1° RInc and with Gravity enabled I have 0.05°. I guess this does not work well in the latter case since my mis-alignment will likely get bigger and bigger as I proceed with the mission (I guess due to the nodal regression effect) and that is probably why I have such a huge DV for the NPC burn.
Could it be my ISS state vectors are off?

Here is the plan before OMS-2 where NPC DV is 171 fps!

[indy91]

Yes, the MFD should give good results with non-spherical gravity enabled in the most recent versions.

The differential nodal regression can cause as much as 0.5° in two days and I've seen NPC DVs of 200 ft/s and more. I've only really had one case where I got a small DV after the ascent. It could be the ISS state vector, but the SSU ascent guidance might also be the problem. I used the "Scenario Editor TLE" for the target vectors, I wonder if it has a problem with propagating a TLE backwards, because in those cases I had bad results. But that is just a theory, it could just be a SSU issue.

The trajectory calculation in the MFD is always reliable, so if the TI and MC4 DVY are small, then you know that the NPC targeting worked right.

[DaveS]

Scenario Editor TLE definitely has issues with historical TLEs. I experienced this first hand when I was setting up the STS-109 launch scenario, that the HST wasn't where it was supposed to at T0. I knew exactly where it was supposed to be at T0 (directly over Tampa, FL) so I checked when it overflew Tampa and adjusted the epoch accordingly. IIRC, it was to make the epoch earlier by about 83 seconds.

[GLS]

Quote:

Originally Posted by indy91

 but the SSU ascent guidance might also be the problem.

It is a problem, as it only targets orbital inclination, so launch time is very critical as that is the only way to control LAN. Plus, the pad being in the wrong place, means that even launching at the correct time will very likely not work perfectly.

---------- Post added at 08:59 PM ---------- Previous post was at 08:50 PM ----------

Quote:

Originally Posted by DaveS

 Scenario Editor TLE definitely has issues with historical TLEs. I experienced this first hand when I was setting up the STS-109 launch scenario, that the HST wasn't where it was supposed to at T0. I knew exactly where it was supposed to be at T0 (directly over Tampa, FL) so I checked when it overflew Tampa and adjusted the epoch accordingly. IIRC, it was to make the epoch earlier by about 83 seconds.

I'm pretty sure I've read in some thread that Orbiter doesn't use "our clock time", so launching, e.g., at noon just because STS-XYZ launched at noon, probably won't result in the same trajectory. This will affect the TLE conversion.
Plus, for 28.45º orbits, launching on time almost certainly will not work perfectly as the pad isn't where it should, so the vehicle does a dog leg to correct the inclination, and doing this with no control over LAN... how knows exactly what happens.
What we can do is get a way to convert "our time" to "Orbiter time", and if the TLEs also need a time conversion, figure that out as well, and that should fix the on-orbit issues. For the launch issues, currently it's all about timing, as we lack LAN target capability. Maybe for SSU 6.0...