Orbiter-Forum  

Go Back   Orbiter-Forum > Orbiter Addons > Addon Development
Register Blogs Orbinauts List Social Groups FAQ Projects Mark Forums Read

Addon Development Developers post news, updates, & discussions here about your projects in development.

Reply
 
Thread Tools
Old 12-23-2014, 03:24 PM   #91
Astro SG Wise
Future Orion MPCV Pilot
 
Astro SG Wise's Avatar
Default

I think you could also make a jump for an updated VC, like 4throck's Constellation CEV.
Astro SG Wise is offline   Reply With Quote
Old 12-25-2014, 09:21 AM   #92
francisdrake
Addon Developer
Default

For those who whish to re-create an Apollo 8 - style Christmas mission to the Moon, here is the scenario:

It uses the SLS by gattispilot. The scenario has been set up for an in-plane transfer orbit to the moon. Launch heading will be due east.

Tips:
Launch by pressing 'O'.

Set up the TLI burn over Australia, using the Transfer or TransX MFD.

If you would like to add some realism, F3 to the Orion, extend the solar panels with 'S' and F3 back to the iCPS. Be aware, switching vessels clears any MFD settings.

Keep the second stage (iCPS) attached, it will be handy for midcourse maneuvers and can even insert you into an elliptical lunar orbit.

After the iCPS stage is spent jettison the Orion with 'J' and F3 to it.

Circularize your lunar Orbit and watch the Earth rise

Getting back from the Moon may be tricky. Tutorials are available for this, like the one by Flytandem.

Merry Christmas!


... You got a color film? ...
Attached Files
File Type: zip SLS_Orion_Moon.zip (1.1 KB, 55 views)

Last edited by francisdrake; 12-25-2014 at 11:09 PM. Reason: Earthrise picture added.
francisdrake is offline   Reply With Quote
Old 12-25-2014, 07:57 PM   #93
simcosmos
Addon Developer
 
simcosmos's Avatar
Default

Hello

I haven't tried the SLS addon and related scenario but the description caught my attention:

Quote:
Originally Posted by francisdrake View Post
 If you would like to add some realism, F3 to the Orion, extend the solar panels with 'S' and F3 back to the iCPS. Be aware, switching vessels clears any MFD settings.

Keep the second stage (iCPS) attached, it will be handy for midcourse maneuvers and can even insert you into an elliptical lunar orbit.

As usual, what follows is only being written in a spirit of constructive feedback


-----------------------------------
I. SLS + iCPS + Orion
-----------------------------------


If using:

a) an optimistic ISP of 465s for iCPS (instead of the ~459s that I believe, from feedback of people who know better, may be closer to the actual average performance of RL-10B-2)

b) and if assuming a low mass for that stage / departure stack (I remind readers that ~>1t of extra mass also needs to be accounted somewhere to represent the iCPS-to-SM interface + Orion's SM bottom adapter and that the iCPS is also slightly heavier – dry mass - than the usual stage used on Delta IV Heavy)

c) and also if assuming full tanks load (~27.2t), which is not true because iCPS would need to raise the perigee for stable Earth orbit insertion, before TLI happens (and there is also the problem of boil-off and using the stage beyond more than a few hours, if using it for middle course corrections and any kind of lunar proximity ops, days ahead!...)

d) and last but not least, if assuming a low mass for Orion, for example, 15t (which, under current assumptions, would practically mean an empty - zero main prop. load - Orion or else, a very specific Orion variant with a lighter CM + SM configuration and a much smaller main prop. load)


Like I was saying, if assuming all these very (and I mean VERY) optimistic assumptions plus if burning all iCPS propellants down to zero (which is not realistic and would do nasty things to the engine), I get, from the rocket equation:

465*9.807*ln((3.5+27.2+15)/(3.5+27.2*0.00+15)) = 4124 m/s


This seems a good number for a TLI (and LOI) but...

Yes, if making the simulation based on official info, the departure would be from ~185x1800 km orbit (which helps to cut down a little the dV for TLI) but... even then, the above great dV estimation quickly starts decreasing by hundreds of m/s if assuming:
- 459s ISP,
- ~4.2t for ICPS related masses,
- ~>25t or so if wishing to represent a full Orion (plus do not forget the SM bottom adapter)
- and if assuming less than 27.2t at the start of the TLI burn (because of raising perigee to 185 km from the the suborbital value required for SLS core disposal).
- This TLI is also a loooooong burn (with low T/W), with some gravity losses associated.

As mentioned, note that the prop. load assumed at the start of the ICPS burn depends of SLS perigee parameters (a burn of 35m/s up to 80m/s may be required, depending of simulation specificities) and of boil-off simulation. This could then mean an iCPS prop. amount, at the start of TLI, at anywhere between 26.7 to 26t or so.


Only as example, and using more realistic assumptions to feed new numbers to the rocket equation plus based on a past custom simulation, the impulse provided by the iCPS could be ~2700m/s up to 2800 m/s or so, if also taking in consideration gravity losses and if keeping a prop. margin somewhere between ~1% up to 2% (of the initial iCPS prop. load) at the end of TLI (for stage disposal burns, performance reserves, residuals, etc).


All the above only to say that if realism is a concern, then the assumption of using iCPS after the TLI moment may not be a very realistic one, at least from the way I'm doing the math and also based on past custom simulation work + available official information (but maybe I'm missing something related with the overall launcher configuration being specifically linked in the scenario)


Just to be clear, we are talking about SLS block1 (4 RS-25, 2 x 5 seg. SRB) with something on top which would be similar to the stage used on Delta IV Heavy, correct?

If the answer is yes, I would find a lot more plausible to only assume Orion SM burns and no iCPS burns after TLI.


Another factor that enters in these brainstorms is how much time the virtual astronauts wish to spend on the way to the Moon (and back): if wishing relatively fast transfers (similar to Apollo, ~3d) then the TLI burn may need a little of extra help from Orion's SM (or else, the departure trajectory may need to be wider = take more days for the spacecraft to reach the Moon).





----------------------------------------------------
II. About Orion, Quick Feedback
----------------------------------------------------


Thanks for the '06' files, much appreciated!

The main engine parameters seem to be a little on the high side: during Constellation the SM's engine was expected to have a longer nozzle and an ISP of ~326s. The current MPCV design is apparently assuming something without such extension and an almost 'drop-in' utilization of Shuttle's OME, with an ISP of ~316s or so.

The '06' files are assuming an ISP of ~347s, which already starts to enter the realm of something burning methane-lox: no problems here, I think that it was a mistake to abandon methane for Orion's SM (and Altair's Ascent Module) and, for these 'higher mass Orion simulations', methane-lox could bring some balance to the Force (and provide greater playability)


Just for completeness, quick and simplistic dV estimation, assuming 3% margin (to account for RCS, performance reserves, non-nominal scenarios, non-used prop, etc, etc):

326*9.807*ln((10.3+5.2+9.2)/(10.3+5.2+9.2*0.03)) = 1433 m/s (Constellation's hypergolic, optim. nozzle)
316*9.807*ln((10.3+5.2+9.2)/(10.3+5.2+9.2*0.03)) = 1389 m/s (ESA SM using Shuttle's OME)
347*9.807*ln((10.3+5.2+9.2)/(10.3+5.2+9.2*0.03)) = 1526 m/s (methane-lox / playability tweak?)

and then, if using an high-end methane-lox (this would probably need a slightly longer nozzle or other assumptions):

365*9.807*ln((10.3+5.2+9.2)/(10.3+5.2+9.2*0.03)) = 1605 m/s

Note: the above assuming that the 5.2t mass of the SM would protect for all these different configurations, which may or may not be true. Another suggestion: if not using the hypergolics numbers, maybe the documentation could include a small note about the 'playability tweak', just to let people know that they are getting greater performance from Orion than what is baselined.



About the solar panels swivel, accordingly with documentation, the panels have canting angles of -60º for TLI (ex: with iCPS) and +55º for LOI/TEI (when just using SM). As a suggestion, perhaps it would be interesting to also implement the -60º setup


Thanks for all,
Happy flights and Merry Christmas!
António Maia

Last edited by simcosmos; 12-25-2014 at 09:35 PM. Reason: clarifications, fixed some typos on RL-10B-2 ISPs / iCPS calcs and on Orion's ME but without impact on the main conclusion
simcosmos is offline   Reply With Quote
Thanked by:
Old 12-25-2014, 08:52 PM   #94
pclaurent
Daydreamer
 
pclaurent's Avatar
Default

Many thanks to Francis Drake for Orion-MPCV addon!
I'm currently playing with your last beta test version. I noticed that some autopilots don't work well with it, especially the Universal Autopilot (UAP MFD). When trying the Auto Dock feature, the vessel can't align to the docking port of the ISS, and oscillates from right to left without succeding in aligning the port. And generally speaking, the autopilots make a huge use of the RCS without any obvious reason. FYI, I did not have these problems with your "old" Orion-CEV module.
Philippe
pclaurent is offline   Reply With Quote
Old 12-25-2014, 09:42 PM   #95
francisdrake
Addon Developer
Default

Antonio, you are a sharp observer! To answer the second point first:

#define RCS_ISP 2900 // = 2650 + 10% for playability
#define MAIN_ISP 3400 // = 3100 + 10% for playability
#define LAS_ISP 2700 // m/s

Indeed Orion's main engine is the Shuttle OMS engine without nozzle extension. I added +10% ISP to allow for less-than-perfect maneuvers. Exaggerated ISP's date back to the early years of Orbiter. They still can be found in the default Atlantis.h file for the main engines. You are probably the first one to notice I am doing this also for the Orion engine

Improving the solar panels is on the list for the next version. I intend to animate them later on, but can provide a downward swiveled mesh as an intermediate solution.
____

Regarding the SLS performance: I guess the Velcro configuration does not yet properly consider the payload mass. Indication is: If the scenario is quit and restarted during the parking orbit, the Orion has to be attached manually in the scenario file. Then the iCPS performance is just enough for the TLI burn, as you described it. But hey: It's Christmas ...
francisdrake is offline   Reply With Quote
Old 12-26-2014, 03:20 AM   #96
Astro SG Wise
Future Orion MPCV Pilot
 
Astro SG Wise's Avatar
Default

Great job francisdrake! Apollo 8 recreated! Can't wait till Orion becomes as good as Space Shuttle Addons.

---------- Post added at 03:20 AM ---------- Previous post was at 12:10 AM ----------

The Orion MPCV and MTV over Mars. Merry Christmas!

Astro SG Wise is offline   Reply With Quote
Thanked by:
Old 12-26-2014, 08:41 AM   #97
francisdrake
Addon Developer
Default

Thanks for pointing me to the UAP autopilot. Many programs seem to work, but not docking. Reason: The oblique placement of RCS nozzles causes unwanted rotation if more than one direction is activated simultaniously. This is not a bug, it is a feature ...

Cannot be fixed easily, could be worked worked around:
Would require to render the 'real' RCS nozzles with dummy exhausts only, placing invisible orthogonal thrusters instead. This would be a major hack of the flight dynamics.

Other possible solution would be asking Artlav to modify his UAP to fire RCS in one direction at a time only. Don't know, if he is still active developing.

The situation can be somewhat improved by hittig Killrot from time to time. This dampens the over-swinging of target directions and reduces tumbling, but does not truly solve the problem.
francisdrake is offline   Reply With Quote
Thanked by:
Old 12-26-2014, 06:44 PM   #98
Astro SG Wise
Future Orion MPCV Pilot
 
Astro SG Wise's Avatar
Default

For the RCS, you could try to create a docking autopilot for Orion yourself, taking into account the thruster feature.

On a random note, my brother got me Mission Orion on the iPad for Christmas, and I docked with Skylab II first try!
Astro SG Wise is offline   Reply With Quote
Old 12-27-2014, 05:14 PM   #99
pclaurent
Daydreamer
 
pclaurent's Avatar
Default

Another tricky behaviour, probably linked to the RCS too: during atmospheric reentry, when using the standard Retro autopilot (for presenting the heat shield in front), the Orion crew module swings with nose down, hardly compensated by the RCS constantly trying to raise its nose up. Thus, the shield is not well aligned with the main orbital vector, and the capsule does not follow a straight line (using Aerobrake MFD shows a big delta between the original, theoretical landing point and the real one).
pclaurent is offline   Reply With Quote
Old 12-27-2014, 06:20 PM   #100
francisdrake
Addon Developer
Default

Atmospheric reentry procedure:
(Sorry, I did not document that well. Will include it in the next readme.)

- When returing to Earth align the vessel retrograde, easiest by using the retrograde navmode (= autopilot).
- Once stabilized switch off the retrograde navmode.
- Roll the vessel 90° to the right to a heads down attitude.
- Kill the rotation. Deactivate the killrot navmode afterwards (should go out by itself).
- Separate the service module [Ctrl J]
- When entering the upper layers of the atmosphere the vessel will (butt first, heads down) pitch up 20-30°. This is due to a built-in off-center of gravity. It provides lift, reducing G-load and heat load on the vessel. Do not fight that pitch up.
- You may, however, use the roll control thrusters to adjust your flight to the left or right for better splashdown targeting.

When coming back from the Moon aim for a perigee of ~30 km. The capsule will by itself perform a skipping maneuver, climbing back to ~55 km after the first reentry, before dropping back into the atmosphere.

The Aerobrake MFD needs - if I remember correctly - that the vessel is intialized by performing a 360° pitch-up and fully around, to determine its lift value for all angles-of-attack.
francisdrake is offline   Reply With Quote
Thanked by:
Old 12-27-2014, 09:33 PM   #101
pclaurent
Daydreamer
 
pclaurent's Avatar
Default

Ok, thanks for your detailed answer. So I understand that the "nose down" effect is normal and of mechanical origin, and so does the "real" Orion crew module...
pclaurent is offline   Reply With Quote
Old 12-30-2014, 03:23 PM   #102
Astro SG Wise
Future Orion MPCV Pilot
 
Astro SG Wise's Avatar
Default

Sorry guys, but I just learned how to take screenshots!




Anyway, one other addition I think you should add to the next version is making the interior more metallic and grey than the current tan/brown. Slowly, that would step up to a more realistic cockpit.

---------- Post added 12-30-14 at 03:23 PM ---------- Previous post was 12-29-14 at 05:11 PM ----------

Sorry for all the suggestions, but you could also put in the inflatable red safety balloons when the Orion splashes down.
Astro SG Wise is offline   Reply With Quote
Old 12-30-2014, 09:03 PM   #103
francisdrake
Addon Developer
Default

I'm open to suggestions

Contents for next update (This will take until next year ...)
- Work over the solar panels, incl up & down swiveled meshes
- Basic virtual cockpit
- Red safety balloons

On the virtual cockpit: The aluminium interior is probably only temporary. I cannot imagine a crew to live in that surrounding for months. Remings me of a butchers shop or state prison. The interior of the CST-100 seems more cozy, and this is for an 48 h trip to LEO only. I will make a few propsals on that.

The MFD's in the virtual cockpit give me headaches. Even after small changes in the mesh they stop working. I count the group numbers in the .msh file and change them in the code accordingly, but no joy. Would you know any good examples in the SDK?
francisdrake is offline   Reply With Quote
Old 12-30-2014, 09:19 PM   #104
gattispilot
Addon Developer
 
gattispilot's Avatar
Default

She looks good with Skylab II:
gattispilot is offline   Reply With Quote
Old 12-31-2014, 03:01 PM   #105
francisdrake
Addon Developer
Default


Splashdown!

Balloons inflated. The water is a textured rectangle, just for fun. Don't know if to keep the water. It does not blend with the default water texture, and would look funny if Orion dropped on land.

** New version 07 on the front page **
Balloons, solar panels swivel up & down, very early virtual cockpit.
MFDs still not working.
Auxillary thrusters [ A ] now only fire while key is pressed.

Last edited by francisdrake; 12-31-2014 at 04:56 PM. Reason: New version
francisdrake is offline   Reply With Quote
Reply

  Orbiter-Forum > Orbiter Addons > Addon Development


Thread Tools

Posting Rules
BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
Forum Jump


All times are GMT. The time now is 04:08 AM.

Quick Links Need Help?


About Us | Rules & Guidelines | TOS Policy | Privacy Policy

Orbiter-Forum is hosted at Orbithangar.com
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2019, vBulletin Solutions Inc.
Copyright ©2007 - 2017, Orbiter-Forum.com. All rights reserved.