Assembly in orbit question

[Biggen]

If one is doing multiple launches to orbit in order to assemble either a rocket/station, I assume a probe core is needed for each launch to control the remaining parts being launched?  I'm just trying to figure out if I need 3 or 4 launches to complete what it is I'm doing, I have to use 3 or 4 probe cores on each launch, right?  After everything is docked together, those extra cores are useless, correct?

Is this standard practice?  Seems to me if you were building a very large structure you are sending up lots of extra probe cores/batteries with each piece and they become useless once finally docked with the completed structure.

[Gaarst]

I usually stick the functional parts such as probe cores, solar panels and batteries on the orbital upper stage so that the station part I want to add contains the necessary minimum. I dock with the station and then decouple the upper stage and let it burn in the atmosphere.

This also removes the RCS, fuel tanks and engines from the station itself if not needed.

Edited January 21, 2017 by Gaarst

[ForScience6686]

You could fly up the modules placing the core in the booster stage, allowing you to return the booster to kerbin.  Then use a tug to attach the modules together.  I have used this technique myself to reduce the parts on each module, as well as get some return on the booster stage.

[bewing]

Well, there are ways of reusing things, even in stock KSP. When you launch a rocket, it has to be controlled, of course. So it needs a kerbal in a pod, or a probe core. Once you are in orbit, you decouple the stuff that's meant to go into the station. As said above, a spacetug can push the station parts into place, so they don't explicitly need to have a probe core and an engine. So the question is, what do you do with the rest of the stuff -- and which piece should have the probe core in it?

I always like to have more tankers and spacetugs in orbit. The central LF booster stage that gets things to orbit usually makes a very nice tanker. So that's the part that I usually leave the probe core attached to.

 

Edited January 21, 2017 by bewing

[Biggen]

Ok, an orbit tug makes sense.  Push stuff to orbit, decouple and leave parts in orbit, bring back probe/stage, and use tug to dock and assemble.  That is a good idea.

I sent up the 1st half of my refueling depot in LKO. It has the core/batteries/panels/living space etc. Basically all the pretty stuff. I now need to send up my girder docking piece. This is basically a length of about 6 or 7 stacked vertical girders with a four way docking "cross" on one end that will have 4 tanks attched eventually, and a single docking port on the opposite vertical end to attach to my core piece already in orbit.

Without a tug, I have to use a probe core to get this girder segment in orbit. Its so damn hard to get up there though that my rocket bounces and wiggles on the way up becoming uncontrollable. Guess I need to research a better lifter design to get this piece up.

 

Edited January 21, 2017 by Biggen

[ForScience6686]

Proper strutting is the key.  It isn't about how many struts, but how they are placed.

 

[AeroGav]

2 hours ago, Biggen said:

and they become useless once finally docked with the completed structure.

Science labs do require a lot of power, a continuous draw while processing data (which it will be constant in career mode) with heavy bursts when transmitting the processed stuff back to Kerbin.   So all those batteries scattered around will help with that.  The probe cores are pretty light compared with the lab and hab modules they attach to, and provide a bit of reaction wheel torque for the station.

All those docking adapters are an overhead compared with doing fewer, larger launches but of course there are limits to how much you can easily launch in one go.

Most of my spacecraft don't have a full rcs system (since most are spaceplanes/tech not researched in career mode) and can't translate up/down/left right, they just have a main engine and reaction wheels.    So to dock,  i bring the two vessels close together, set the other vessel's docking port as target, point myself at it with RW, then switch to the other vessel and do the same.   Then i just use a tiny nudge from the main engine to go forward, and the two things will meet nose to nose.