3rd October 2012, 11:27
Setting a Communication network[Pics+Tutorial(kinda)]
Hi there kerbonauts! I wanted to make this mission back in 0.16, but then 0.17 came out and the modpacks weren't properly working. Finally, mods are working fine and I can make this mission.
I'd like this thread to be both a description of my mission and a tutorial, if you don't mind.
Optional: ZOxygene if you want to make it more realistic
*Although I used the ReEntry Heat plugin and the aeroshell heatshield, I didn't notice any reentry difference. It was my first time with this mod, I will give it another try.
Not needed: *craft http://www.mediafire.com/?f9gcb2yilxlb68d I love my design, but it has a huge bug: Even though I put an RCS tank on the stage 2, it didn't use it. It used only the "orbital" RCS tank. If anybody knows how to correct this, please let me know. Also, you are free to try your own design. Also, check stages. The sepatrons weren't working
Basics of satellite networks:
The remotetech plugin allows you to make unmanned probes and control them, with the addition of a delay between communications because of the speed of light.
If you try to launch an unmanned vehicle, as soon as you lose radio contact you won't be able to control it. Radio contact will stop once you don't have visual contact with KSC.
[spoiler=In the diagram you can see that you can control it at periapsis, but not at apoapsis][/spoiler]
(Thanks to MS Paint)
Unless you set up satellites.
[spoiler=In this diagram you can see that you would need at least two satellites to control your craft at apoapsis:][/spoiler]
But then again, you wouldn't be able to control it in every place.
For our network we will use satellites in a 0º (or 270º) inclination circular orbit. Now you have to choose between two parameters: Orbit altitude or number of satellites.
Of course, altitude should be higher than 70km unless you want to lose your satellites due to atmospheric drag
If you choose number of satellites, you want to know the altitude, right? Well, this can be done by (almost) only drawing.
You have to draw an n-gon (n=number of satellites) such as the sides are tangent* to a circle, which will be Kerbin.
*Actually, you absolutely don't want to go with the perfect precision of a tangent line. You want to add some more distance. This will ensure that at least one of your satellites has visual contact with KSC.
[spoiler=Two examples, for a 6-gon and a 4-gon][/spoiler]
Oh, you want your n-gon to be regular
As I said, you don't really want it to be tangent, mainly because you won't be able to set such precision when orbiting and maneuvering.
So I decided to make a network consisting of 6 satellites. That leaves me with an hexagon. Note: I didn't do the actual calculations for orbit altitude. I did it by intuition, my satellite altitude will be 247km as you will see. I think at this altitude I could have done it with 5 satellites, but I'm not sure.
Ok, after this (innecessary?) wall-o-text, here come some pics:
[spoiler=My rocket] 2+1 stages, where the +1 means orbital maneuvering stage.[/spoiler]
[spoiler=The inside, where the satellites are held][/spoiler]
[spoiler=Standing in launchpad] Ascent autopilot is set to 247 km.[/spoiler]
[spoiler=Apoapsis is set at 247km], there's fuel left in the stage I but I don't want to put that many debris, so I decouple[/spoiler]
*As I said, sepatrons didn't work, I didn't put them in the correct stage
[spoiler=Since we left the atmosphere]it's time to decouple those fairings[/spoiler]
[spoiler=Lot of RCS thrusters to turn into prograde][/spoiler]
Ok, so we are at a 247 km circular orbit. Time to return to kerbalSCIENCE.
We will now decouple our first satellite. Since the decoupling applies a force to the satellite, it won't be in a perfect orbit, that's why I recommend using the lowest ejection strength decoupler possible. You can modify the part.cfg of a decoupler and set it to a force of 0.
As I said, time for science. This is really basic science, but it's always worth remembering
That's one of Kepler's laws. Basically, it tells you that the period of the orbit will increase with the radius of said orbit, that's what we want to know right now.
We are at almost the same place as our satellite, but we want to make an n-gon. That means we have to set the next satellite in a different place. Since we are travelling at the same speed as the satellite, we need to go to either:
-A higher orbit, and thus we will travel slower
-A lower orbit, we will travel faster.
Since we will put n satellites, there's a lot of orbit changes, thus, lots of delta-V spent. If I'm right, switching to a higher orbit (and coming back again to a 247km orbit) spends less delta-V, but I'm not sure.
[spoiler= I went for the lower orbit], more precisely, a 175km[/spoiler]
Lowering periapsis to 175km (yes, there's some other satellites in orbit, I didn't take screnshots of every moment )
While it's not absolutely neccessary to circularise this orbit, it's highly recommended, as it will make this mission easier. So, we are now on a 175km orbit.
Now we will time warp until we are almost at the next vertex of our n-gon*. We will now raise our apoapsis to 247 km. Latter we'll circularise that orbit and set another satellite. Rinse and repeat until you have your 6 satellites online.
*If you want to calculate it precisely, you can use Kepler's Law to calculate the time it will take you to reach to your apoapsis in your 175x247km orbit (well, that's in my case of course). Note that you will complete only half orbit.
I'm doing this the kerbal way: map viewing, not calculations.
Some more pics:
[spoiler=4 more to go][/spoiler]
[spoiler=This start to looks like an hexagon][/spoiler]
Now, time for deorbit and reentry. MechJeb didn't calculate accurately the fuel left, so I landed in the KSC sea.
So that's it!
[spoiler=Finally, this is how it looks][/spoiler]
It's not a perfect hexagon, but it will work
Oh, one last thing I wanted to say. I had a mod in 0.16 for a deployable satellite, it would deploy from a square attached to the side. I'd love to put it in my satellites, but I didn't find it
Last edited by profesorfrink42; 3rd October 2012 at 12:16.
Reason: Adding spoiler tags
3rd October 2012, 11:49
Absolutely excellent thread, profesorfrink42, really well done.
However, could I ask that you use 'spoiler tags' for the images as there are quite a lot and each one is large.
To use them just do this [spoiler=Spoiler Name Here]Image URL Here[/spoiler]. That spoiler would look like this:
[spoiler=Spoiler Name Here]Image URL Here[/spoiler]
Again, very good tutorial and a nice mission description.
3rd October 2012, 12:00
nice, i like the all in one craft, i myself think ill try somthing moer kerblacatied.
i want slightly larger satlilites, because i want them to look really kerbal-fictiony, so im going to launch one at a time, the first one will set the orbit, likey about the same height as yours give or take, then ill launch the next sat, to about 100-150, then use the relay network from the first sat to position it into its spot, and continue thus far.
i exspect it to go aswell as my first muner collision.
3rd October 2012, 12:05
I didn't know that tag existed! I'm editing the post right now
Originally Posted by Ted
3rd October 2012, 12:21
Originally Posted by Ted
As I said, I'd love to add some solar panels and batteries, but I don't remember the exact mod for that! I have to check the kerbal.net
Originally Posted by opticalshadow
As for realism, I could've tried ZOxygene, but for some reason it crashes my game after a while (If I can get to orbit).