Tutorial Space Shuttle Ultra v5.xx ascent checklist condensed

Tim13

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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/hnc7bwlhv4k4m5t/SSU%20CONDENSED%20ASCENT.pdf?dl=0

Scenario link: Updated 05-30-2018
https://www.dropbox.com/s/9hq75ty0bjyibjk/Ascent%20TEST%20%202A.scn?dl=0

Mission CFG file link: Updated 05-30-2018
https://www.dropbox.com/s/vsod9fykem286kz/TEST%202.cfg?dl=0

Readme link: Updated 06-02-2018
https://www.dropbox.com/s/x9csehjjfxl6jcc/Readme.docx?dl=0

The optional part of the tutorial is a YouTube video: [ame="https://youtu.be/u74QzhBL-W8"]SSU Ascent Tutorial Video - YouTube[/ame]

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
 
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GLS

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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. :thumbup:
 

Urwumpe

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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.
 

GLS

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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... :uhh:
 

Urwumpe

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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... :uhh:

You have just one life. Never forget this.
 

Tim13

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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 ----------

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
 

Thorsten

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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).
 

Wolf

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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
 

Gingin

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Wolf and TIm

You should do a sticky post in SSU section with links to your Video/Checks/ Tuto :)
 

Tim13

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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
 

Urwumpe

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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. :tiphat:
 

Tim13

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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. :tiphat:


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

Tim
 

ShoeShockTV

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I watched the video to understand how SSU works Thanks just waiting for decent :)
 

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.php/Osculating_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
 

Marg

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Just wanted to ask - are there somewhere AERODYNAMIC parameters for Space Shuttle available? I mean - to use with spacecraft3. in ini file. I know spacecraft3 allows quite a lot of parameters, like VAIRFOIL=... etc., I have something, seems to be from default Atlantis (?) in some older STS-101.ini , but it is hard to follow the SHUTTLE curves in GLIDESCOPE. In spite of this, I have managed to arrive near HAC regularly. A know that someone (DavidS) wrote that those parameters are not quite right, and it is definitely so - speed is not decreasing as fast as it should, although I tried to keep AoA as much as possible close to 40 degrees.
 

GLS

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Just wanted to ask - are there somewhere AERODYNAMIC parameters for Space Shuttle available? I mean - to use with spacecraft3. in ini file. I know spacecraft3 allows quite a lot of parameters, like VAIRFOIL=... etc., I have something, seems to be from default Atlantis (?) in some older STS-101.ini , but it is hard to follow the SHUTTLE curves in GLIDESCOPE. In spite of this, I have managed to arrive near HAC regularly. A know that someone (DavidS) wrote that those parameters are not quite right, and it is definitely so - speed is not decreasing as fast as it should, although I tried to keep AoA as much as possible close to 40 degrees.

We have some "aero files", that I have no idea how they are used or where they came from. They are the .csv files in the Config folder.
 

Thorsten

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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).

If I may use the opportunity and again mention my LEO targeting code - which is a numerical optimizer/solver for things like Shuttle burns and does things like 'find the most fuel-efficient ignition time to meet the insertion PEG-4 target' or 'find the burn parameters that will give me a 3800 mile range from entry interface to site'.

(Of course you can always program the same thing, it's not exceedingly complicated, just tedious).

Just wanted to ask - are there somewhere AERODYNAMIC parameters for Space Shuttle available?

Tons actually. For a rather comprehensive collection look into

Aerodynamic design of the Space Shuttle Orbiter, Bornemann and Surber, Rockwell International Space Systems Group.

Entry Dynamics of Space Shuttle Orbiter With Longitudinal Stability and Control --- Uncertainties at Supersonic and Hypersonic Speeds, Stone and Powell, NASA.

Space shuttle: Determination of the aerodynamic interference between the space shuttle orbiter, external tank, and solid rocket booster on a 0.004 scale ascent configuration, Ramsey, Buchholz, Allen and Dehart, NASA.

(All of these are in public domain and can be found on the web - NASA document server has them most likely).

I also have them in a nice and streamlined version (aka same unit definitions, gaps interpolated,...) in my FG Shuttle project. Be warned - the Shuttle is exceedingly yaw-unstable if you use real aerodynamics - so you need to invest lots of work into the Aerojet DAP to make it fly properly, the controllers have to be rather carefully tuned to switch over from jets to elevons and finally rudder with Mach-dependent gains.
 
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Marpilot

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Hi,
thanks for the idea of condensed chacklists of SSUltra :)
Will you be doing deorbit, reentry also ?
Cheers
 
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