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OFMM Discussions for the OFMM project.

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Old 05-10-2010, 09:27 PM   #1
cymrych
The Probe abides
Post OFMM Development: Spacecraft

OK, so given that we're at some 19 pages already on the main forum thread for the OFMM, aka Project Prometheus, with everybody clamouring for attention on countless various subjects pertaining to this Project, it seemed best to start a page devoted exclusively to development of The Stack and the realistic Mission Architecture derived from that final design.

Obviously, as The Stack will be the workhorse getting the people and materials we need to establish a permanent foothold on the Red Planet until we beg/borrow/steal an Arrow-class freighter, it is important to get the vehicle configured correctly and optimally. Let's face it, designing nifty resource extractors and semi-subterranean habitats is neat and definitely interesting in its own way, but all those features amount to a hill of beans until a vehicle design and Mission Architecture is agreed upon by Project members (or Project Manager?).

So, to summarize what I recall seeing thus far, The Stack is presently:

-Modular, composed primarily of units from SSBB v4, with some extraneous units from elsewhere
-Powered by NERVA2
-Capable of carrying 2 DG- or XR- class vessels for Near-Earth and Near-Mars operations
-The exact configuration remains completely undetermined at this point, pending information from the Exploration Team members on what they want on Mars

Our goals (as I see them):

-Determine a basic, "bare-bones" Stack vehicle, to which we add modules as needed per Exploration requirements
-Determine allowable additional cargo/module mass and size limits
-Determine experimentally the capabilities of The Stack both "bare-boned" and fully loaded, to develop a workable Mission Architecture

Not exactly a small task, but I think it is imminently do-able. As in all such group undertakings, it's always a matter of good communication.
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Old 05-10-2010, 10:02 PM   #2
cymrych
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So let me start this ball rolling.

I've been playing with the scenario posted by Izack bck on page 10 of the main Orbiter-forum OFMM thread. I exchanged the Tanker he used for main propulsion with a NERVA2 (without custom dll, just the "stock" one), and two DG-IV's (without cargo).

A few observations:

- Stack too massive. Even with 2 Nerva-droptanks, I ended up repeatedly with only vapors in the droptanks (but near full volume in NERVA's main tank) after a near-Hohmann TMI burn.

- Nerva's RCS apparently burns LH2/LOX, because attitude maneuvers directly drain the main tank.

- RCS ridiculously sluggish. It's a large Stack, granted, but it simply takes too much fuel to get the ship to begin to move, then an equal amount to stop its rotation when it's pointed where you need it. It's not a trivial fuel cost either; rotating all 3 axes 90 degrees took over 5% of total main fuel!

That's it for now. I'll try to actually post some useful data next time, rather than just anecdotal reports. Cheers!
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Old 05-11-2010, 01:47 AM   #3
Wolfer
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There was also an inflatable heat shield to be placed at the front of the stack.

For the control problem, I tried a smaller stack with a Tranzit tug as an RCS. It's slow and sluggish but consumes a lot less fuel than the Nerva 2 alone. As an added bonus it can be used as the MSS attitude and station keeping system once it will have separated from the main propulsion module.
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Old 05-11-2010, 04:27 AM   #4
Arrowstar
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Agreed on the Tranzit tug... it was designed for that kind of work.
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Old 05-11-2010, 04:46 AM   #5
Izack
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Sorry about that stack...not really sure why I posted it. I also didn't intend the tanker as the main engine, but I couldn't get the NERVA2 to load in my scenarios.
So far I have 4 possible designs, none of which are nearly as large as that ugly thing. I have to keep changing them as the mission plan has been, let's say 'fluctuating.'
I'll post them here once I get myself up to speed with the program. I kind of missed the past few days, thanks to real life. Sorry about that.
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Old 05-11-2010, 06:35 PM   #6
Wolfer
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To determine the proper size, we need to know how many people we are going to send and in what conditions they can spend the trip.
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Old 05-11-2010, 07:26 PM   #7
Bloodworth
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People will be between 10 and 20 most likely. As far as condition, i don't believe that orbiter can simulate cryosleep as yet so they will have to be awake and active. This will necessitate 02 reserves for 6 months (at least), storage areas for food and water and habitat areas, as well as shielding from radiation.
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Old 05-14-2010, 09:35 PM   #8
Wolfer
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Okay, I just found a solution to the RCS problem. If we make the stack long enough we can use the translation thrusters instead of the ones for rotation. this makes the whole thing turn MUCH faster and consumes a lot less fuel. Also this is much better than using the tranzit since it saves quite a lot of useless mass. One problem is that it's impossible to use the stock autopilots and the ones from IMFD so everything must be done manually.
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Old 05-18-2010, 09:14 PM   #9
Izack
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It will need to be positioned manually, but once it's there, the grade autopilots should be able to hold it there as long as no one accelerates time.
I've been doing a good deal of deep-space manoeuvring for this lately, which is telling me a lot about stack-commanding. I think I started a thread on it, to.
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Old 06-03-2010, 04:23 AM   #10
Alexw95
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When pictures come available i would love to see a picture of the stalk please
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Old 06-05-2010, 05:54 AM   #11
Alexw95
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i have just recently figured out how to make meshes so if anyone wants to me to make some meshes and then you code them il help with that
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Old 06-11-2010, 01:53 AM   #12
kwan3217
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I love to write code. Someone come up with the meshes, I'll write the DLLs.
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Old 06-17-2010, 09:15 PM   #13
Voyager
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Copy that, could I launch the com satellites in Mars Orbit? I am thinking of SkyLinkSat as perhaps the main communication array for transmitting orders from spacecraft en route or leaving Mars, or transmitting communication from Mars to Earth, and Earth to Mars. I am most likely going to figure out someway to get SkyLinkSat in Mars orbit.

Note: Moved to Spacecraft Thread

Last edited by Bj; 06-17-2010 at 09:32 PM.
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Old 06-17-2010, 09:22 PM   #14
lennartsmit
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Quote:
Originally Posted by Voyager View Post
 Copy that, could I launch the com satellites in Mars Orbit? I am thinking of SkyLinkSat as perhaps the main communication array for transmitting orders from spacecraft en route or leaving Mars, or transmitting communication from Mars to Earth, and Earth to Mars. I am most likely going to figure out someway to get SkyLinkSat in Mars orbit.
I think we're in the planning-stage so I don't think signing up for a mission has any use yet as we don't know how and even if we're gong to do it like this.
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Old 06-17-2010, 09:23 PM   #15
Voyager
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But, setting up the comsat's will be essential for the first expeditions! We will need to set up one comsat for now, for communication.
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