Orbital Rendevouz

[Sanic]

I've docked before, and I think I have the RCS controls down. But that was because of rather lucky timing at launch. I want to dock with my second station, Kalyut 2. But I cannot rendevouz the two in LKO. How can I meet them up without having to wait a day? (It's at 105x105, so timewarp takes forever at a snail 50x)

Edited September 27, 2015 by Sanic

[Phil deCube]

Increase your orbit to, say, 150 km. You can then timewarp faster, and the other ship will catch up with you quicker to, because of the orbit difference.

[Superfluous J]

May I suggest the first of my 3-video series on Rendezvous, Approach, and Docking?

[Vegetal]

The way I do:

When just behind your target, launch to a lower orbit, say, 80x80km. From there, create a maneuver node pointing prograde, with apoapsis the same altitude as the station (105km in this case). Now slide the node around until you have the best encounter. Easy peezy

You might want to correct the inclination before this though, in order to get the best encounter.

It's kinda like what the Soyuz does to rendezvous with the ISS. The launch is never super accurate, so they make a lower orbit first.

Edited September 22, 2015 by Vegetal

[RCgothic]

From any random starting orbit, first you need to match orbital inclination. Set your target in the map view and it'll plot ascending and descending nodes. Burn normal/anti-normal at one of these nodes to reduce your relative inclination to zero.

Next you need to get your apoapsis and periapsis in phase with your target (ie get both apoapsis on a line through the centre of Kerbin). This is accomplished by burning radial-out or radial-in. This step can be skipped if your target is in a nearly-circular orbit, but is necessary if your target is highly elliptical.

Third you need to catch up to or wait for your target. If you are ahead of your target you need to be in a higher (slower) orbit. If you are behind it you need to be in a lower (faster) orbit. If you're approx 180 deg away it doesn't matter. If you're not concerned about it taking longer you can wait to go the long way round (for example you are ahead of target in a lower orbit) for a dv saving.

Fourth, you match periapsis to perapsis (you are higher) or apoapsis to apoapsis (you are lower). This is accomplished by burning pro/retrograde at the opposite node until the altitudes match. This will slow your rate of catching/waiting, so feel free to leave this until you're nearly caught up. Or you can do this immediately if you don't mind waiting a little longer.

At this stage you should start getting intercept markers that show your closest approach to the target. If your orbit crosses your target you will get a closest approach for each crossing. For this reason when acomplishing step 4 I make sure I don't cross the orbits because I find dealing with a single intercept marker makes things clearer. You can now adjust the closeness of your intercept by burning pro/retrograde at either apoapsis or apoapsis (whichever you earlier matched with your target) to adjust your orbital period. You can usually do thus in one burn to get a rendezvous on your next orbit, but it may be cheaper in dv to wait a few orbits do that you don't have to adjust as much, or you may be constrained in how much you can adjust by a planetary surface, atmosphere or lunar sphere of influence. Don't de-orbit yourself by accident! If you did all the previous steps accurately you should easily be able to get an intercept >0.5km. Hover the mouse over an intercept marker to see the separation at that point.

To complete the rendezvous match target velocity at closest approach. The nav-ball should automatically switch to target mode when you get close. It may also accidentally switch to target mode if you pass within visual range of your target at any earlier stage. If this happens don't let it screw up your orbital manoeuvres! Target prograde != orbital prograde! Switch between nav-ball modes by clicking on your velocity. Burn retrograde to target velocity to match.

Congratulations! You should now be rendezvoused within 500m! You're close enough now to manoeuvre directly at the target, but keep your velocity low (>10m/s) so as not to mess up your orbit. Docking is now relatively straightforward if you've got the rcs controls down.

[tsotha]

When I'm doing a minimum-fuel rendezvous I usually go to the tracking station and time warp from there. You can warp at whatever speed you want.

[FyunchClick]

It's at 105x105, so timewarp takes forever at a snail 50x

You can always revert to KSC or the tracking station and time warp from there. It's not capped there.

[Superfluous J]

You can always revert to KSC or the tracking station and time warp from there. It's not capped there.

Not revert. Jump to. If you revert to KSC you'll have to launch again.

[Sanic]

Thanks guys!

[Der Anfang]

I've docked before, and I think I have the RCS controls down. But that was because of rather lucky timing at launch. I want to dock with my second station, Kalyut 2. But I cannot rendevouz the two in LKO. How can I meet them up without having to wait a day? (It's at 105x105, so timewarp takes forever at a snail 50x)

Who wants snail speed anyway? Gotta go fast!