How do you achieve rendezvous with space craft after launch?

[Unimatrix1]

Hi Kerbalnaughts I am trying to dock two space craft but it seems to take a couple of orbits to do so, I was wondering is there any way to achieve a rendezvous after launch?

I know it's possible because iv seen HOC do it by accident but was wondering is it possible to be able to achieve the launch to rendezvous every time? I want to be able to do so without much Jeb but if I have to use phase angles that's fine, but the problem that I can see is every rocket will be different and it would be hard to work out the time for assent through the atmosphere, any idea?

I'm guessing it's going to a case of trial and error each time or can you use TWR and delta v to work it out. Cheers for any help in advance.

Edited December 14, 2013 by Unimatrix1
Post answered

[KvickFlygarn87]

Yup, trial and error basically. After a bunch of times you will be able to guesstimate it completely.

[celem]

Yeah, we could sit and spew out some angles and altitudes. For instance my current station is at 125km, I tend to launch off the pad when the station is about 12-15 degrees behind KSC, which leads to direct rendezvous off the pad.

Your exact angles are gonna depend on the TWR of your various ascent stages (how long it takes to reach required altitude) and the altitude of the station itself.

As KvickFlygarn87 (oh look, another swede) says, do a couple of dry runs and before you know it, dock direct off launch will be something you do without even thinking about it.

Edited December 14, 2013 by celem

[Unimatrix1]

Cheer guys i thought so, so here I go with with limited understanding, ignorance and brute force I will succeed (You only fail when you stop trying).

[LethalDose]

I wouldn't recommend trying to orbit in a way that the orbital burn ends in rendezvous... It would be REALLY hard to pull off, and even more difficult to perform reliably. You're better off orbiting, and THEN achieving a rendezvous as a separate maneuver.

[photogineer]

I wouldn't recommend trying to orbit in a way that the orbital burn ends in rendezvous... It would be REALLY hard to pull off, and even more difficult to perform reliably. You're better off orbiting, and THEN achieving a rendezvous as a separate maneuver.

Actually, before I (stupidly) moved my station in to an inclined higher orbit, this was pretty easy with practice. My method makes a few assumptions:

1. You're flying a consistent launch vehicle, I was always using the same lifter or crew transport rocket.

2. Your station/target is in a circular equatorial orbit

Do some practice launches, get it to the point where you're consistently flying the same launch profile and circularizing on your target orbit so you're always ending up in the same orbit, in the same amount of time (this can be done if the rocket is stable and you practice). Take this time, and calculate/guesstimate how far your station travels along it's orbit arc in that time. Launch when it's that far from KSC.

Unfortunately I never thought to take video, but I've done multiple launches where my circularization burn was done using the target retrograde marker with the station selected. I shut down at 0.0m/s relative velocity and I was in a matched orbit ~400m from the station reliably. Then RCS to dock.

It's worth the practice, it is really fun, and saves time and fuel.

Matt