Orbital Ship Construction

[funkcanna]

Hi all,

So I've managed to get to most planets but the only one I've managed to return from is Duna. Ive come to the conclusion ill have to build my interplanetary ships in orbit to remove the Dv required to get away from Kerbin. However I really don't know where to start! Ive tried putting a lander in orbit then sending up the rockets and docking them but having a lifter actually capable of sending up the rockets for the lander was very hard and a failure on all accounts.

Can anyone offer advice or tips on what to do in this case? What parts do I send up and how do I link them together in orbit? I have KAS.

Thanks!

Edited March 22, 2015 by funkcanna

[impyre]

I use what I like to call the "wagon train" method. As described here: http://forum.kerbalspaceprogram.com/threads/113703-I-d-like-guidance-with-setting-up-a-future-Duna-base

As for orbital construction specifically, I do have a couple tips:

1) Use the biggest docking ports available.

2) Tri-docking by using the three-way adapters and three docking ports is much stronger than even the larger docking port by itself.

3) Using sections that interlock (like building a cube) will greatly increase rigidity and mobility. (There's no need to combine #2 and #3, but you could)

4) Consider supplies if you use life support (regenerative technology really extends supply time and decreases mass).

5) Consider sending a second ship (probe controlled) that has very lightweight return vehicles, and leave everything else behind. (This will reduce the total fuel required for the return trip)

6) RE: KAS, use the KAS struts, they are your friend.

7) As for linking up, standard docking procedures apply. It's helpful to ensure that the ship which takes up the piece to be docked (the tug) can leverage lots of torque for controlling all that dead weight, though adding RCS or SAS to every part you dock can improve the mobility of the finished ship.

Edited March 22, 2015 by impyre

[Randazzo]

Hi all,

So I've managed to get to most planets but the only one I've managed to return from is Duna. Ive come to the conclusion ill have to build my interplanetary ships in orbit to remove the Dv required to get away from Kerbin. However I really don't know where to start! Ive tried putting a lander in orbit then sending up the rockets and docking them but having a lifter actually capable of sending up the rockets for the lander was very hard and a failure on all accounts.

Can anyone offer advice or tips on what to do in this case? What parts do I send up and how do I link them together in orbit? I have KAS.

Thanks!

It really depends on what you want to do at the planets you visit. Pretty much all of my interplanetary ships are two-module vessels. Main Engine Module and Lander Module. Although I typically just send them up as a single stack when possible, they can also be assembled in orbit. Here's an example:

Assembled in orbit, it's simply a lander module docked with a giant engine. Those are KAS struts to help keep it stable. You can get a lot more complicated though:

That was assembled entirely in orbit. Thread link: http://forum.kerbalspaceprogram.com/threads/104160

[impyre]

Also, this may go without saying, but if you want to build something complicated in orbit out of smaller pieces... your payloads will generally have some docking solution on the bottom and the top (so that once detached from the launcher, something can be attached at both ends). Lastly, I prefer structural fuselage to build structure in my vessel. It's lighter than beams and girders, and sturdier.

[Norcalplanner]

You can actually launch a pretty big ship in one go if you do it right - check out my Eve Rocks and Jool-5 entries in my sig. KJR is helpful. If you're assembling really big ships, check out SpaceY - they have a variety of 5m parts, and include both 3.75m and 5m docking ports if you still want to assemble things in orbit. Speaking for myself, my usual method is to launch a craft, then send up a tanker to top things off before departing LKO.

[Wanderfound]

If all you're trying to do is avoid the delta-V expenditure of the climb to LKO, you don't need orbital construction, you just need orbital refuelling.

Send up a big fuel tank with a probe core, some solar and a few docking ports on it. Then launch your interplanetary ship, refill it in orbit, and off you go.

Efficient design helps a great deal as well, of course. Long-ranged doesn't necessarily require huge ships. For example, even without an orbital top-up, this one has about 7,000m/s in the tanks after getting to LKO:

http://kerbalx.com/Wanderfound/Kerbodyne%20Spearhead

[celem]

Its fairly rare that I assemble in orbit these days, tending to single-launch all but the biggest craft.

If you want to split the ship up then dont be scared to break it into more pieces than 2. If the entire craft is too big for your launch systems then chances are the transfer vehicle alone is also too much, generally the lander is only a fraction of total mass in LKO.

Assembling ships from more than 2 parts requires a little thought when it comes to RCS/torque. Each piece needs to be controllable and balanced if it is going to dock itself, other options include making the launcher final stage a tug, or having a dedicated tug for assembly. If you do have each chunk be RCS balanced then you will need to disable a lot of ports and rings once things are docked so that they dont all fight each other and so the completed craft is somewhat balanced.

When making something really big, lets say a jool multi-moon mission;

I launch the main lander, its docked to a small RCS powered tug with a range of port sizes. (seriously...small. 2 or 3 ton tops for your tug, most of which is monoprop)

I launch the midsections. Often lifesupport, science labs, kerbal seating, maybe the primary fuel can. It launches to rendezvous and cancels relative velocity but is not designed to dock. It just needs to get to within a handful of km and stop relative. The tug undocks, gathers components and installs them.

Launch the drive section. Usually small fuel cans with engines on them, this docks to the main fuel can launched earlier to let the engine get at the fuel. Once the build is finished you can deorbit and crash the assembly tug (or park it somewhere if its got the fuel to get to a station)

The advantage i've found to this (especially the module drive sections) is flexibility. You can reuse sections in other ships and with the right design can refit ships on the fly.

My favorite recently was a Moho mission. I assembled the craft in LKO with mainsail engines for the good TWR, but also docked 2 NERVAs onto lateral ports along the sides. Once I'd arrived at Moho and made all the really TWR sensitive burns I undocked the mainsails and docked the NERVAs (to avoid carrying a tug each engine module had a probe head and RCS). I ultimately left the mainsails orbiting Moho and sent the ship on to Eve with the nukes. The NERVAs got left at Eve for a future mission and the craft borrowed a pair of LV-T30s left there by an earlier Gilly mission for the Kerbin return. Most of the planetary bodies in my game have a mixture of engines in orbit, all capable of docking itself to any compatible craft that arrives.

edit: finally some designs will fly SSTO from Kerbin, usually if you are of the type that likes TWR on their interplanetary sections. They tend to arrive empty of fuel but you then send them a tanker. This is how I get my Eve Ascent Vehicles into LKO. They are designed with enough dV/TWR to stage their way off Eve, but can also SSTO themselves at Kerbin by just ignoring the asparagus stages. (its not efficient, usually burns all 12kdV for LKO since its not staging)

Edited March 22, 2015 by celem

[DoToH]

Build your lander with a SSTO rocket launcher. Put at least 1 docking port in the launcher. Once in LKO, don't ditch the launcher, just refuel it and you'll end with a high TWR interplanetary ship with more than 4500dV. You can go wherever you want. High TWR is recommended for Moho trips (because its small SOI, capture burn is easier). Your interplanetary burns will be much shorter and thus more precise. That why I don't use nukes. For the return trip, with a high dV lander, you can return with just the lander, refueling it with fuel not used from the main ship and aerobraking/aerocapturing at Kerbin. With low dV landers, add a pod and a crew can to the launcher. Once landed dicht the lander and return with the launcher (refuel mission might be neccesary)

Edited March 22, 2015 by DoToH
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[funkcanna]

Thanks Guys!

[WuphonsReach]

Kerbal Joint Reinforcement (KJR) - with the Jan 17th version of the DLL - is a big help for larger crafts as it reduces the wobble without having to resort to lots of KAS strutting (which is another useful tool for reducing wobble).

[GoSlash27]

I construct all my interplanetary missions in orbit.

I launch the ship sections without fuel and assemble them in place (large docking ports are sturdy), then fuel and crew them using shuttles.

Best,

-Slashy

[G'th]

What I like to do is to the "fleet" method, particularly when it comes to manned missions, as it allows a much longer and more simpler mission.

I send an unmanned station core ahead of the crew (ususally I do it for the first transfer window then crew on the next) equipped with life support supplies to last the intended mission duration (usually 1-2 days for Duna) plus the return trip into a polar orbit of Duna. This serves as a waypoint for the entire mission, and also allows for mapping of the surface while it waits for the crew.

That way, when I send the crew and lander(s), I only need to supply life support for the trip to Duna, which cuts down on mass very heavily. It also saves FPS.