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Tim13 Tim13 is offline
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Support Space Shuttle Ultra v5.xx ascent checklist condensed
by Tim13 05-30-2018, 02:28 AM

I've been playing around with the SSU in Orbiter 2016. One thing I noticed as I was looking around for help in operating the SSU, was that there really weren't any "get started" type tutorials, or videos. While it's true that the SCOM can be used to fly the SSU, it's a bit much to expect someone to read 1,100 pages of actual documentation. I think it's a better idea to give people a way to get started with a few wins, then that will make them eager to learn more on their own.

This is for the version 5 of the SSU that is being developed for Orbiter 2016. There is a thread started by me in one of the addon sub forums, that will be very helpful to anyone wanting to create a SSU v5 in Orbiter 16.

The tutorial has 5 parts to it. The scenario file, mission file, ascent condensed checklist PDF, and readme are required. The video on YouTube is optional, but worth watching.....it's only 2 hours long...LOL.

Ascent checklist link: Updated 06-10-2018
https://www.dropbox.com/s/hnc7bwlhv4...SCENT.pdf?dl=0

Scenario link: Updated 05-30-2018
https://www.dropbox.com/s/9hq75ty0bj...%202A.scn?dl=0

Mission CFG file link: Updated 05-30-2018
https://www.dropbox.com/s/vsod9fykem...T%202.cfg?dl=0

Readme link: Updated 06-02-2018
https://www.dropbox.com/s/x9csehjjfx...adme.docx?dl=0

The optional part of the tutorial is a YouTube video:


This is the first tutorial of any kind I've ever done, so don't be too hard on me. It's not easy to blather on about pretend rockets for two hours...hahahahaha.

I hope this is of some value to someone along the way.

Regards,

Tim

Last edited by Tim13; 06-10-2018 at 08:14 PM.
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Old 05-30-2018, 04:57 AM   #2
Gingin
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Nice one good initiative
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Old 05-30-2018, 11:33 AM   #3
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I didn't watch it all, but it looks very nice!
Some small errors (e.g. the dump from the SSMEs, it's really a dump of LOX, not a burn, and the venting on the left side is the LH2), but nothing major that takes away the value of the video.
BTW: relaxing voice, you should do more videos.
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Old 05-30-2018, 12:13 PM   #4
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Some feedback here:

The maneuvering after SRB sep is not because of uneven bolt firing (we are not even modelling it this accurate), but rather its the moment, when the guidance software switches from open-loop guidance (pitch angle as function of time) to closed-loop guidance (pitch angle as function of current state vector vs. MECO target). The transition is a bit rougher than it should be in our case, in reality it should be a smoother transition - but we lack the precise guidance function there.

After real SRB SEP, the astronauts usually check if the TMECO prediction in the ASC TRAJ CRT display converges (The predicted time approaches a constant value). If it shows strong variations or oscillations in that predicted time, the closed loop guidance would have a malfunction (never happened AFAIR).

And yes, the exhaust jet graphics are wrong at that time. They show the exhaust jet under-expanded as it is during launch, in reality, it would be over-expanded in that altitude. Its some limitation of Orbiters API there, we tried some workarounds in the past, but those did not look right during rendering.
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Old 05-30-2018, 12:21 PM   #5
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Quote:
Originally Posted by Urwumpe View Post
 After real SRB SEP, the astronauts usually check if the TMECO prediction in the ASC TRAJ CRT display converges (The predicted time approaches a constant value). If it shows strong variations or oscillations in that predicted time, the closed loop guidance would have a malfunction (never happened AFAIR).
In SSU, TMECO is estimated to be earlier, and will trend up, as our guidance algorithm only works in a "constant-thrust" mode and so it does not take into account the 3g throttling, when it should do a "constant-acceleration" mode. It's another item on the long TODO list... hopefully it will be done before the end of the universe...
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Old 05-30-2018, 12:58 PM   #6
Urwumpe
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Quote:
Originally Posted by GLS View Post
 In SSU, TMECO is estimated to be earlier, and will trend up, as our guidance algorithm only works in a "constant-thrust" mode and so it does not take into account the 3g throttling, when it should do a "constant-acceleration" mode. It's another item on the long TODO list... hopefully it will be done before the end of the universe...
You have just one life. Never forget this.
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Old 05-30-2018, 01:50 PM   #7
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I've read so much about the shuttle recently, that I was sure the dump actually combined the propellants and burned them. But after reviewing the SCOM, you are most certainly correct. It is a purged and vacuum dump only.

I made a few blunders during the video for sure. Not easy trying to think on my feet, and talk at the same time....LOL. I'll go back and add some annotations for sure.

Once there is a fully compiled and downloadable version for v5, I may revisit this, and do a tutorial specific to that frozen in time version.

Tim

---------- Post added at 01:50 PM ---------- Previous post was at 01:02 PM ----------

Quote:
Originally Posted by Urwumpe View Post
 Some feedback here:

The maneuvering after SRB sep is not because of uneven bolt firing (we are not even modelling it this accurate), but rather its the moment, when the guidance software switches from open-loop guidance (pitch angle as function of time) to closed-loop guidance (pitch angle as function of current state vector vs. MECO target). The transition is a bit rougher than it should be in our case, in reality it should be a smoother transition - but we lack the precise guidance function there.
I was going off what was said by the launch announcer in one of the umteen shuttle launch videos online. He commented that the physical act of the SRB's leaving the the stack introduced a small guidance error, that is quickly corrected.

I wondered why the MECO time kept updating. The 3g throttling makes sense.

Thanks for the feedback.

Tim
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Old 05-31-2018, 06:23 AM   #8
Thorsten
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Quote:
In SSU, TMECO is estimated to be earlier, and will trend up, as our guidance algorithm only works in a "constant-thrust" mode and so it does not take into account the 3g throttling, when it should do a "constant-acceleration" mode.
Just in case you haven't considered it yet - Taylor-expanding the acceleration function a(t) in the time gives you the result as an analytically integrable power series - which computes fast enough to even run optimization over it (I've done so for the droop alt prediction - which is a similar problem except for the minimum-finding).
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Old 05-31-2018, 11:32 AM   #9
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Very nice job Tim! It is good to see someone else is helping to get SSU more use friendly and hence potentially more attractive to a wider range of users.
I still have to review my SSU checklists where my intentions where to get something to guide users through SSU ops saving them the pain of going through thousands of FDF pages but still keeping the same format/structure.
Your condensed checklist are a very good idea to make things even more simple
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Old 05-31-2018, 02:40 PM   #10
Gingin
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Wolf and TIm

You should do a sticky post in SSU section with links to your Video/Checks/ Tuto
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Old 06-01-2018, 02:37 PM   #11
Tim13
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Originally Posted by Gingin View Post
 Wolf and TIm

You should do a sticky post in SSU section with links to your Video/Checks/ Tuto
I thought about that, but I didn't want to double post, and violate forum rules. I know double posting is frowned upon.

Tim
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Old 06-01-2018, 03:16 PM   #12
Urwumpe
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Quote:
Originally Posted by Tim13 View Post
 I thought about that, but I didn't want to double post, and violate forum rules. I know double posting is frowned upon.

Tim
I see. So all you really need right now is a friendly agent who is willed to take all the wrath of the moderators and administrators for doing nasty things with their forum rules?

Consider it done.
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Old 06-01-2018, 10:19 PM   #13
Tim13
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Originally Posted by Urwumpe View Post
 I see. So all you really need right now is a friendly agent who is willed to take all the wrath of the moderators and administrators for doing nasty things with their forum rules?

Consider it done.

Hahahahahaha! Exactly. I'll be the good cop, and you be the bad cop.

Tim
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Old 06-12-2018, 12:48 AM   #14
ShoeShockTV
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I watched the video to understand how SSU works Thanks just waiting for decent
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Old 07-05-2018, 01:30 AM   #15
Kubala95
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Great job! If I can present some issuses:
1. OMS-2 burn can be quick calculated more precisely using MECOTool.exe available in Orbitersdk/Space Shuttle Ultra.
The most accurate method (which allows to predict PeA and also ApA after burn) depends more knownledge of astrophysics and programming (to solve numerical equations). Some formulas are here: https://gssc.esa.int/navipedia/index...ating_Elements
2. Align planes burn (called NPC) was historical performed after NC-2 (second phasing burn).
Secondly it also needs better determination - the equation is simply: dV = 2Vi * sin(theta/2), where Vi is tangential velocity of shuttle in node and theta is of course angle between planes. More is here: http://www.braeunig.us/space/orbmech.htm
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