are docks suppossed to be this poorly rigid?

[endl]

so i made a modular mission ship linked together with docking ports which i took it for a spin after assembling it at my staging area around my space station. this is the result, i should have named it gumby

Edited September 7, 2014 by endl

[Boomerang]

Yup. Think about what you're putting together. Several 2.5m segments which are fairly heavy and you've got narrow 1.25m docking ports connecting them. The ports are rigid enough when used in conjunction with crafts of a reasonable mass. They'll never be as rigid as connections between parts made in the VAB though.

You really need the 2.5m docking ports to join those pieces and even then, it's awfully long. If you really can't condense that design any, then take turning very slowly with the help of RCS. And for things that are so long and with flex to them, you're better off having your drive section *pulling* the craft. If the CoM is behind the CoT, it dampens the oscillations that occur during burns. The reverse situation tends to amply the flexing and you risk being thrown off your node/breaking your ship apart.

Edit: Also, there's something to be said of transferring components of ships like that individually to their destinations and assembling them on site. So if that whole ship is bound for Duna, send each part separately and dock them in Duna orbit, rather than around Kerbin. Not always the best option, but if you've got huge pieces that you actually need to be huge, sometimes it's more practical to assemble them on the other end.

Edited September 7, 2014 by Boomerang

[slavik]

woops used my friends login by mistake

Edited September 7, 2014 by slavik

[endl]

actually that ship is supposed to be all landed on duna as separate craft, the idea was to have one delivery system after achieving orbit for the various modules, i can dock the ship using other ports located perpendicular to the thrust without having to redesign so that its less of a linear configuration but i was hoping for better tolerances between craft in order to deliver bigger designs. seeing as how this is a game and being constrained by a limited design philosophy isnt what i think a agency with an "unlimited budget" would settle for.

if need be i can launch more of the back end of the fuel/booster module and break down the craft further but my goal was to get it there in one shot using one modular system

[Simes]

So, look at what Boomerang said. Redesign your drive section, put the engines on outriggers, put a docking port on the base, and tow the ship instead of pushing it.

Don't cant the outriggers back like that, though. That was a dumb idea. It might make it look a bit more like a Starfury but they're more likely to foul on bits of the thing you're trying to tow.

Edited September 7, 2014 by Simes

[Geschosskopf]

The general rule with docking ports is to use ports the same diameter as the body of the module you're connecting. If you do that then you won't get much if any wobble, PROVIDED you don't then turn around and hang lots of heavy stuff on the sides of the module body. Doing that basically increases the diameter of the body so it's bigger than the port.

Of course, in career mode, you don't get 2.5m docking ports until long after you want/need them. So now it's like in your pics, heavy 2.5m modules connected by 1.25m ports. In this case, your best bet is to reinforce the joints using KAS struts, which you attach with an EVA Kerbal in orbit after you've docked everything together.

[chrisb2e9]

In addition to what everyone else said, look for Quantum struts. i design my ships so that after they dock, the struts are aimed in such a way that they attach several parts away from the docking port. Sorry for a lack of picture to show this, i'm at work. But the struts added after you dock, can give stability in an otherwise unstable design.