Equally space 4 satellites in KEO

[guitarxe]

Hey guys, can someone explain to me the concept of how to get 4 satellites equally spaced in KEO? So the rotational period of Kerbin is 6hours (and 1 second). And means if I want 4 there to be, they need to have a spacing of 1h30m between each other. But how can I accomplish such feat of precise timing? Currently I am launching all 4 of them from a single launcher which travels at an elliptic orbit that intersects the KEO height, at which point the satellite is deployed and uses its own thrust to correct the PE to the correct height. But the launcher has a minimal orbital period of about 2.5 hours. Any less and the PE will dip into the atmosphere . So that's a spacing of 2.5 hours for each satellite where I need a spacing of 1.5hrs. How should I do this? Should I drop down a satellite into lower orbit and wait for it to speed up and reduce the spacing amount and then correct itself again to KEO? Or is there a more simpler method?

Edited July 26, 2014 by guitarxe

[cantab]

Can you put the launcher in an orbit with a 4 1/2 hour period?

[Mitchz95]

Step 1: Put the launcher into a circular KEO orbit. (6h)

Step 2: Decouple one of the satellites. No engine burn is needed; it's in its final orbit.

Step 3: Change the orbit of the launcher (with its three remaining satellites) to have an orbital period of 4.5h.

Step 4: Once you go around and reach apoapsis again, push your periapsis up so your orbital period is once again 6h.

Step 5: Repeat steps 2-4 until all four satellites are deployed correctly.

That's all there is to it.

[guitarxe]

Oh! I feel silly now Any way to ensure that I will be more or less above the KSC when I reach my AP?

[AlexinTokyo]

Once you're in an LKO parking orbit, make your Keostationary insertion burn directly opposite KSC.

Also note that as of version 0.24, Kerbin's rotational period was changed. It's now 5 h 59 m 9.4 s, so you'll need the KEO period to be this number, not 6 hours.

[guitarxe]

Hm, well that's what I thought and when I tried that I ended up with the KSC overshooting me. I guess the real question is actually how do I more accurately eyeball when I am directly opposite the KSC

[AlexinTokyo]

Actually, thinking about it, you want to do the periapsis burn slightly before directly opposite, so the apoapsis is slightly before the KSC. That way, when you do the apoapsis burn, you should get fairly close. How far will depend on the TWR of your ship.

Another alternative is to get into an orbit with a period slightly more (if KSC is behind) or less (if ahead) and wait a few orbits until you're close enough for your liking. Then adjust the period to equal the sidereal day.

As for eyeballing it, you can plant a flag at KSC to enable you to locate it easily in map mode, which might help.

Alternatively, you can use an informational mod (I like KER; others are available) and go off the longitude readout.

[guitarxe]

Yay, it worked! I got all four of them into nearly perfect KEO. Then my game crashed And so for the next try I think I might try sending up individual satellites one by one. Is the timing on that easier or harder?

[Mitchz95]

Yay, it worked! I got all four of them into nearly perfect KEO. Then my game crashed And so for the next try I think I might try sending up individual satellites one by one. Is the timing on that easier or harder?

I would guess much harder. You'd have to eyeball it, so it's very likely the satellites will not be perfectly spaced out.

[Redjoker]

If you want to be able to follow the same method but launch separately, you would simply launch the first sat. The second sat you would launch to rendezvous, then adjust your orbital period and wait one orbit. For the third and fourt your would do the same but wait two and three orbits respectively.

[guitarxe]

Thanks for all the help