Building a Space Station

[pattersoncr]

Those headings don't sound right at all. They ought to be much closser to 90*.
Read this for info on how to calculate launch heading:
http://www.orbiterwiki.org/wiki/Launch_Azimuth

 

[Nemoricus]

I used that page to calculate the launch azimuth.

What would the correct headings be?

I'm launching into a 500x500 orbit at an inclination of 23.45 degrees, from a latitude of 7.970 S.

The inertial heading that I initially calculated was 67.87 degrees. Those other headings are for the rotational heading.

 

[Oceanic]

i made a small test flight with the DG-IV from Wideawake

i calculated the azimuth with Azimuth calculator v. 1.5 by enjo. it gave me this numbers

Launch with azimuth = 66.5121 (ascending), or 113.4879 (descending) degrees.

engaged the pro903spec66 launch autopilot and reached a 255km orbit with a inclination of 24.4°

i had some lag spikes which probably threw the autopilot a bit off

 

[pattersoncr]

The correction arising from Earth's rotation should only be a degree or two (maybe more for a polar orbit). In fact if you use align planes MFD to correct during ascent, you can ignore the rotation correction completely.

 

[Nemoricus]

Hmm....it turns out that if I add or subtract the angle I came up with, 23.51 degrees, to or from 90, I get about the same number. Is this just a coincidence?

Anyways, I'm in orbit right now putting together the initial space station. I got into orbit with plenty of margin this time. I have over fifty percent main fuel. I ended the scram phase with about eleven or twelve percent left in the scram tanks, but I dumped that to just under six to reduce mass. I overshot with my apoapsis intially. I ended up going up to 770 kilometers. I then raised periapsis to about five hundred kilometers, corrected my inclination (I was .68 degrees off), and then circularised the orbit to 500x500. I've got two modules together now and should have the rest put together before too long.

I'm taking pictures as I go and I'll put some up after I land.

I'm also debating whether I should leave a crew up in orbit to tend to it. There's only one hab module, but since the next mission is in two weeks, it should be livable.

I also need to decide what to bring up next. I'd like some idea of the power requirements of the various modules and how much heat they're likely to produce. Also, since I plan for this station to be a fuel depot, should I try to use the next mission to make the station partially operational in this capacity? Or should I expand its living space first?

---------- Post added 08-24-2009 at 10:20 AM ---------- Previous post was 08-23-2009 at 07:26 PM ----------

I ultimately did leave a crew up in orbit. The reentry was again smooth, but the landing was terrible. I clipped right through Ascension Island's mountain, but I did touchdown at safe speeds. However, in real life, hitting a mountain at 150 m/s can't be good for the crew.

Anyway, as promised, some pictures.



Liftoff occurred around 0600 local time, just after sunrise. The launch was smooth, except for an initial apoapsis overshoot to 770 kilometers. The orbit was corrected to 500x500 and its plane aligned with the ecliptic.



This is the station after two module were put together. However, it was discovered that the URMS was too small to position modules on the BT201 Truss Anchor. The XR5 was therefore transferred to an end of the truss to facilitate construction.



Attaching the second solar panel was tricky. The XR5 had to undock and move slightly away from the station to position it. However, this was done and assembly of the initial station was completed. The XR5 is transferring back to the main dock to power up the station.



Deployment of the solar panels and radiators went smoothly. The ends of the panels are just barely in the XR5's cargo bay, but that did not prove problematic. Undocking went smoothly after two days in orbit to ensure all initial systems were operational. A crew of three was left to tend to the station until the next construction flight.



The XR5 over South America during reentry.



Reentry went smoothly and the XR5 went subsonic just after passing over Ascension Island.



Alas, my landing was not so smooth. This picture shows the position of the XR5 after it stopped.

Atmospheric flight is not my forte. Are there any good tutorials on the subject?

Anyways, I now need to decide what to bring up for the second construction flight. As I asked before, should I expand the living space or should I try to bring the station partially online first?

 

[n122vu]

Okay, I've figured out what I'm going to bring.

1 BM230 Trussed Habitation Module.
1 BT201 Truss Anchor
2 BP101 Solar Panel Arrays
2 BR101 Radiators.

Exactly how I started my first base. Later used the XR5 to take up 2 more trusses, a couple other modules, and a ShuttlePB for emergency/escape situations.

XR5 - Love that bird.

Congrats on two successful missions thus far!

 

[Nemoricus]

I didn't even think about an escape vehicle. Given that the astronauts that I left up in the station using UMMUFA have disappeared, I'm going to retcon things and say that I didn't leave a crew up there after all.

Hmm...escape vehicle, escape vehicle. What should I bring up?

I don't have much extra room in the cargo bay for a large vessel.

My current loadout for the next construction mission is:

1 BM201 Hab Module
1 BM211 Hab Module
1 BN201 Hab Node Module
4 BT101 Truss Elements
1 BTank101 Fuel Tank
1 BArm1 RMS

I've got just enough space to put in something that's about the size of the BN201. I don't want to bring up a Shuttle PB (I don't much care for it), but I seem to lack other crew escape options.

Hmm....I've got it! After this construction mission, I'll send up an XR2 with a crew. If I can, I'll put in a few components as well.

It's not ideal, but it does provide both a crew and an escape vehicle. I may want to find another option, though.

Thoughts?

 

[Oceanic]

you have quite a few option regarding a escape vehicle.

my favorites are the CTV which is UMMU capablecapable, the Soyuz TMA, the excellent, advanced and complex SoyuzTMA found in the International Space Station v2.0.5 add-on or the Crew Emergency Rescue Vehicle

there are many more out there it depends on your needs and on your taste.

or you could just use a DG-IV in safe mode as a return vehicle

 

[Nemoricus]

Hmm...I'll take a look at those vehicles in more detail after I finish my current mission.

Here's something that has me scratching my head. I launched with a heavier cargo this time, about fifty tons compared to fifteen, and yet at hard dock, I had more fuel than I did the previous mission. Also, at scram cut-off. I had a whopping fifty percent of scram fuel left! I was going about 6 km/s over ground at that point, too. Naturally, I dumped the scram fuel to lighten the XR5, but I was amazed at how much fuel was left. If it matters, I did most of the scram phase around forty to sixty kilometers up.

I've also run into a slight problem with how I have my truss elements stowed. They have a tendency to dock to each other, making it impossible for the URMS to grapple them. I've gotten the first element attached, but it was pretty annoying to do so.

In other news, the larger URMS is working very well indeed. It's so nice to be able to reach points on the station without having to maneuver to do so.

 

[pattersoncr]

For escape vehicles, I would suggest the Sift Lifeboat included with Greg Burch's [ame="http://www.orbithangar.com/searchid.php?ID=3371"]SSS[/ame]. It has 4 small reentry vehicles crammed into the space occupied by one hab module.

 

[Nemoricus]

I'm going to take a look at the SSS. However, I'm finding the XR series of vessels to be quite enjoyable to fly. There's no question that I'm going to take an XR2 up to deliver the first permanent crew. It's also going to serve as the escape vessel, for a while at least. Rule of cool wins here.

Now, I need to figure out when to send them. Should I wait until after this construction mission is over, or shall I send them up sooner?

I'm inclined to send the XR2 up at the next favorable launch window.

I do know which modules I want to send up next, though. Two more habitation modules, another fuel tank, four truss elements, and as many consumables tanks as I can fit in. Perhaps another RMS, too.

Actually, definitely another RMS. My station has, or will have, two major truss sections. One is a fuel boom going perpendicular to the rest of the station. The other will be the solar panel/radiator/comms system trusses. Both are long enough that a Vanguard mounted RMS can't reach both ends. An RMS is needed on both.

That fuel boom has four truss elements. The first tanks that I'll send up will be clustered at the end of it. However, should I place fuel tanks all along the length of the boom?

Also, I'll note that most of my questions in my initial post haven't been answered yet.

 

[Kaito]

Pictures? I wanna see!

about the scram ascent for the XR-5: Mach 4 at 20km is when I usually engage them, and keep adjusting the main engines until the scram engine force goes up on its own. IE: Self-sufficient. Adjust trim to keep the vertical speed about 100m/s. And seeing as how my Scram ascents are always bad, I start with 80% main fuel and end up with 14% left...which I save for re-entry.

as for your initial questions:

1. Orbit: I'd like for this station to serve as a waypoint between Earth, the Moon, or beyond. What inclination and altitude would be good for this purpose?

Station already setup, cant do anything about it now

2. Modules: Now, with the XR5 I can bring almost all of the initial components up into space at one go, but I'm wondering what I should bring up. In particular:

Power: How much energy do you think can be generated by a single solar panel? How much energy would a station need?

Heat Dissipation: How much heat can one radiator discharge and how much heat is a station likely to produce?

Habitable Volume: Given that this station is meant to be a fuel depot and waypoint, how much living space is it likely to need?

Power: answered
Heat Dissipation: Not sure, but put a radiator right next to the power systems just to make sure
Habitable Volume: In my station, each habitat module can sustain 2 "parties" of 2 people each. Each party would be on each half of the module, and the tunnel going through the module would be the "hallway". That way, you can stack them
As far as volume goes, I would suggest being able to hold a max of 20 people. In my experience, the XR-5 can carry 6 habitat modules and 6 cargo modules up in one load without having them exposed outside of the cargo bay doors...this is using UCD.

3. Propulsion: Is there a good propulsion system that I can use to control the attitude and orbit of the station after it has been constructed?

SSBB comes with a prop module, but as far as attitude goes...just keep an XR-5 docked up there and press the kill rot button to keep it stable

As for the RMS...learn to use the Dragonfly. Use the RMS to pull it out of the bay, and the Dragonfly to move it around. The XR-5 is big and hard to position around a station. The dragonfly is good for most operations (except when moving 160k kg of fuel. Dont try that, its impossible to do. Trust me, i've tried )
Hope this helps!

 

[Tommy]

What I've found to be the most efficient ascent profile for the XR series is to get up to about 24k quickly, then keep the hull temps just below the yellow during the scram ascent.

Immediately after "wheels up" reduce throttle to maintain 200 to 250 m/s, depending on load. Turn onto your launch heading. Then throttle up and increase pitch until your ACC on surface MFD is very low, but not negative. This should be around 70 to 80 degrees. This keeps the speed down while you are in the really thick part of the atmosphere, and get's you above it quickly. At 10k, apply about 1/2 down elevator trim. You should go supersonic about 15k, and be leveled out by 24k. When you are at mach 3.5 engage scrams. Then trim up to maintain about 150m/s vertical speed, and watch the temps. Keep them just below the yellow, this ensures a good air supply to the scrams and they will produce more thrust. You should redline the scrams at about 60k, and meco should be before 80k. Coast up to Ap, and circularize. On a very heavy XR-5, lower climb rates will be required. You will usually need 150 to to 20 m/s of VS from 25k to 33k (peak heat is around 28k for this profile) and then settle down to 100 or less over 35k.

Many people will argue for a higher profile to reduce the rate of aerodynamic drag, and that is the reason for the initial steep climb. However, the XR's scram engines produce more thrust if they get a lot of air. Also, it's more efficient to increase your velocity when closer to the gravity source. By reducing the duration of the drag, you more than make up for the increased rate of drag.

As you near redline on the scrams (or are running out of scram fuel) increase VS to about 150 for the final rocket engine phase of the ascent, and end the burn when you're ApA is at it's desire altitude. (NOTE: due to the Oberth effect, it's best to keep parking orbits low, just over 200k in the current version) It's not uncommon for the Ap to be a quarter of an orbit or more away at MECO, just maintain about 3 degrees A0A until you are over 125k, then engage prograde.

BTW, it's not that hard to re-enter a fully loaded and fueled XR-5. Landing it that way without snapping the gear is darn near impossible!

 

[Nemoricus]

Thank you for your answers, Tommy and Kaito. They're very informative. I still don't a good answer for how much power each module is likely to need, though. And where is that propulsion module?

I decided to send the XR2 up at the next launch window and it went very smoothly indeed. I engaged the scrams just over 20km and cut them off around sixty kilometers up. I was going 6300 m/s over ground at this point. I was actually wondering which would happen first, running out of scram fuel or the diffusers overheating. Turned out to be the diffusers with just under six percent scram fuel left in the tanks.

Phasing took most of the rest of the day. I'm currently on approach to the station.

I also remembered that the XR series has navigational lights. I must say, watching those lights as the vessels approach is fascinating. I'll put up some pictures after I land the XR5.

 

[wehaveaproblem]

You could re-boost easily with an XR2, since you seem to be sending them up anyway, perhaps you don't need a propulsion module?

As for power use. Unless you are actually super keen to do the maths right, I would just gestimate. Look at the ISS for a RL example. How much array surface area does it have and what power does it consume. All that info is available online and will give you a good ballpark figure to aim for, based on module mass vs. array area... ?

 

[Nemoricus]

Reboosting's going to be a pain if I want to do it the proper way. At least I don't have to worry about exospheric drag in this version of Orbiter.

Anyways, more pictures!



Ascent was nominal and only a minor plane changing maneuver was needed before station approach could begin.



Before assembly could begin, however, one of the radiators and one of the solar panel arrays had to be stowed in order to keep them out of the way during construction of the station.



The node and hab modules were the first to be added. In order to attach the node, though, the XR5 had to undock and maneuver slightly away from the station. However, this went smoothly and the two new habitation modules were added without incident.



Construction of the fuel boom was a frustrating exercise due to the fact that the docking sensors on the truss elements kept reading 'Docked' when in fact they were not. This did not stop construction and the new Burchismo RMS (not easily visible in the picture) worked out well.



With the second assembly mission completed, the first crew was sent up in an XR2 Ravenstar. Ascent was again nominal and again required only a minor plane change maneuver.



The navigational lights were turned on on both vessels to help facilitate rendezvous and docking. It's hard to see, but there's a light in one of these pictures in the top right quarter of the picture.



This picture was taken not long before rendezvous and docking. The XR2's lights are visible down and to the left of the station.



A picture from the XR2's cockpit shortly before docking and another shortly after capture and hard dock.



About twelve hours later the XR5 undocked from the station and performed yet another smooth reentry.



Landing, however, was rough. I got to this point with a dead stick and a little too much vertical speed. However, the crew sustained only minor injuries and the XR5 will be back in service in a few months.

I'm not sure if that landing means that I'm getting better or not. That was my first completely dead stick landing from orbit. It could have turned out much worse.

Anyways, onto the third construction mission!

 

[Oceanic]

can't see any of the pictures

 

[Nemoricus]

Strange. I can see them just fine.

I wonder what's up with that.

 

[Oceanic]

now i see them

nice station you got there. keep it going!

Edit:

i just took a look at your wideawake international space port and it looks like you have missing textures

open your base.cfg in ..orbiter\config..

and add this:

roof_blue
roof_fan
roof_hangar
wall_corr
wall_door
wall_door_n
wall_hq
wall_hq_n
wall_logo
wall_logo_n
wall_obs
wall_obs_n
wall_office
wall_offwin
wall_offwin_n
wall_plant
wall_window
wall_window_n
concretetex

 

[ar81]

For planetary transfers, ecliptic orbit inclination would be better.
For earth to moon, moon inclination would work.